Please complete both quizzes below to get ready for AP Bio Unit 3 (Enzymes and Energy)

Quiz 1: Multiple Choice Review

[qwiz qrecord_id=”sciencemusicvideosmeister1961-Units and 1, M.C. Review” random=”true” style=”width: 600px !important;”]

[h] Units 1 and 2 (quarter 1) Multiple choice Review Quiz

[i]Biohaiku

Molecules of Life

Make up cellular structures

The basis of life

[q json=”true” zz=”1″ multiple_choice=”true” unit=”1.Chemistry of Life” dataset_id=”2019 AP Bio Dataset|230e0ef3a0bc5a” question_number=”1″] In the diagram below, letter Y represents a(n)

[c] phosphate group.

[f] No. The phosphate groups connect the deoxyribose sugars, and these sugars are represented as pentagons.

[c*] deoxyribose sugar.


[f] Yes. “Y” represents a deoxyribose sugar.

[c] nitrogenous base.


[f] No. The nitrogenous bases form the internal “rungs” of the DNA ladder. “Y” and “X” make up the sides of the ladder. What makes up the sides?

[c] amino acid.


[f] No. Amino acids are monomers of protein, and this is a molecule of DNA.

[q json=”true” multiple_choice=”true” unit=”DNA|RNA|Protein” dataset_id=”144Qs|9948227d98f34″ question_number=”3″] In the diagram below, letter Z represents a(n)

[c] phosphate group


[f] No. The phosphate groups are on the outside of DNA.

[c] deoxyribose


[f] No. Deoxyribose is the sugar on the outside of DNA.

[c*] nitrogenous base


[f] Excellent! “Z” is one of the four nitrogenous bases.

[c] amino acid


[f] No. Amino acids are monomers of protein. This is DNA.

[q json=”true” multiple_choice=”true” unit=”DNA|RNA|Protein” dataset_id=”144Qs|995277725cb34″ question_number=”2″] In the diagram below, letter X represents a(n)

[c*] phosphate group


[f] Way to go. “X” represents a phosphate group.

[c] deoxyribose


[f] No. Deoxyribose is one of the sugars in DNA. “X” connects the sugars (shown at “Y”) together.

[c] nitrogenous base


[f] No. The nitrogenous bases form the internal rungs of the DNA ladder. “X” (along with “Y”) is on the outside of the ladder. What makes up the ladder?

[c] amino acid


[f] No. Amino acids are monomers of protein, and this is a molecule of DNA.

[q json=”true” multiple_choice=”true” unit=”DNA|RNA|Protein” dataset_id=”144Qs|993da84816f34″ question_number=”4″] In the diagram below, the bonds connecting G and C (guanine and cytosine) are ________ bonds.

[c] covalent


[f] No. Covalent bonds are the strong bonds formed when atoms share electrons. They make up pretty much every bond in DNA, except the much weaker bonds between G and C. What are those weaker bonds (which play a key role in interactions between water molecules) called?

[c] peptide


[f] No. Peptide bonds are the bonds that hold amino acids together in proteins. There are no peptide bonds in DNA (because it’s not a protein, but a nucleic acid).

[c*] hydrogen


[f] Excellent! The bond between the nitrogenous bases C and G (cytosine and guanine) are hydrogen bonds.

[c] ionic


[f] No. Ionic bonds are the bonds formed when atoms trade electrons. Ionic bonds don’t play a role in DNA’s structure. The answer is a much weaker bond: the type that plays a key role in interactions between water molecules

[q json=”true” multiple_choice=”true” unit=”Biochemistry” dataset_id=”144Qs|9281d66491734″ question_number=”131″] As applied to proteins, which of the following best describes “denaturation?”

[c] Breaking peptide bonds


[f] No. Breaking peptide bonds is best described as protein digestion or degradation. Denaturation is much less severe and permanent.

[c] covalently modifying a protein


[f] No. Covalent modification would constitute a chemical change to the protein, and is much more drastic than what happens during denaturation.

[c*] a changing a protein’s tertiary structure


[f] Yes. Denaturation is a change in protein shape brought about by a change in a protein’s environment. Often, these changes involve disruption of tertiary level interactions between amino acids.

[c] a changing a protein’s the primary structure


[f] No. A change in a protein’s primary structure is a fundamental shift in a protein’s identify, chemistry, and structure. Denaturation is often temporary, and involve a much less drastic level of change.

[q json=”true” zz=”1″ multiple_choice=”true” unit=”1.Chemistry of Life” dataset_id=”2019 AP Bio Dataset|216b9be69cf85a” question_number=”135″] In proteins, the beta-pleated sheet and alpha helix result from

[c] hydrogen bonds that form between the side chains of non-polar amino acids.


[f] No. Interactions between side chains are what underlie tertiary (third-level) protein structure. You’re looking for the interactions that underlie secondary structures (like beta-pleated sheets and alpha helices).

[c*] hydrogen bonds that form between the N-H and C=O groups of a protein’s polypeptide backbone.


[f] Fabulous! Hydrogen bonds between amino and carbonyl groups of a protein’s polypeptide backbone are what lead to secondary structures (like beta-pleated sheets and alpha helices).

[c] hydrogen bonds that form between the side chains of polar amino acids.


[f] No. You’re looking for hydrogen bonds, but not between side chains. What other parts of a polypeptide (a chain of amino acids) could form hydrogen bonds with one another?

[c] ionic bonds that form between oppositely charged amino acid side chains


[f] No. Ionic bonds between oppositely charged amino acid side chains are a force involved in tertiary protein structure. You’re looking for the interactions that underlie secondary structures (like beta-pleated sheets and alpha helices)

[q json=”true” multiple_choice=”true” unit=”Biochemistry” dataset_id=”144Qs|921a84d4ebf34″ question_number=”138″] Four different biological molecules are represented in the diagram below. Molecule A is glucose. Molecules B, C and D are composed of glucose subunits that are covalently linked together.

All of the molecules shown above are

[c] lipids


[f] No. In a lipid, you typically see a long hydrocarbon chain. Here’s a hint: this is a class of macromolecules that includes monosaccharides (like the glucose shown above), disaccharides, and polysaccharides.

[c] proteins


[f] No. Proteins (such as oxygen-carrying hemoglobin or the contractile protein myosin) are polymers of amino acids. Here’s a hint: this is a class of macromolecules that includes monosaccharides (like the glucose shown above), disaccharides, and polysaccharides.

[c*] carbohydrates


[f] Excellent. All of the molecules shown above are carbohydrates.

[c] nucleic acids


[f] No. Nucleic acids, such as DNA or RNA, are polymers of nucleotides. Here’s a hint: what’s shown above is a class of macromolecules that includes monosaccharides (like the glucose in the diagram), disaccharides, and polysaccharides.

[q json=”true” multiple_choice=”true” unit=”Biochemistry” dataset_id=”144Qs|920520a7ad334″ question_number=”139″] Four different biological molecules are represented in the diagram below. Molecule A is glucose. Molecules B, C and D are composed of glucose subunits that are covalently linked together.

Molecules “C” and “D” are

[c] monosaccharides


[f] No. Monosaccharides are the monomers of carbohydrates. The are the simplest of sugars, and consist of only one monomer. “C” and “D” consist of many sugar monomers linked together. Here’s a hint: what’s the prefix for “many?”

[c] disaccharides


[f] No. Disaccharides are sugars that consist of two monosaccharids linked together, as is shown in “B.””C” and “D” consist of many sugar monomers linked together. Here’s a hint: what’s the prefix for “many?”

[c*] polysaccharides


[f] Correct! C and D are polysaccharides.

[q json=”true” multiple_choice=”true” unit=”Biochemistry” dataset_id=”144Qs|91f3850dc0f34″ question_number=”140″] Four different biological molecules are represented in the diagram below. Molecule A is glucose. Molecules B, C and D are composed of glucose subunits that are covalently linked together.

If molecule “C”  1) originates in a plant and 2) consists of glucose monomers connected by bonds that allow that that molecule to be broken down by humans for energy, then that molecule must be

[c] cellulose


[f] No. Cellulose is the polysaccharide that makes up plant cell walls. We ingest cellulose everytime we eat fruit or a vegetable, but we lack the enzymes to break apart cellulose into glucose monomers from which we could derive energy. Foods high in cellulose, as a consequence, are very low calorie (think of lettuce or celery). What’s a polysaccharide that we can break down for energy.

[c] glycogen


[f] No. Glycogen is a polysaccharide that can be broken down by humans for energy, but it doesn’t come from plants. Mammals synthesize glycogen when they eat sugar, and store it in liver and muscle tissue for later use. What’s a polysaccharide made by plants that we (and other animals) can break down for energy?

[c] albumin


[f] No. Albumin is a protein (found in egg white, among other places). You’re looking for a molecule that’s a carbohydrate, and more specifically, a polysaccharide made by plants that we (and other animals) can break down for energy?

[c*] starch


[f] Excellent! Starch is a polysaccharide that humans can break down for energy.

[q json=”true” multiple_choice=”true” unit=”Biochemistry” dataset_id=”144Qs|91e51d042e334″ question_number=”141″] Four different biological molecules are represented in the diagram below. Molecule A is glucose. Molecules B, C and D are composed of glucose subunits that are covalently linked together.

If molecule “C” were a component of plant cell walls, then it would most likely be

[c*] cellulose


[f] Correct! Cellulose is the polysaccharide that makes up plant cell walls.

[c] glycogen


[f] No. Glycogen is a polysaccharide, but one that’s used for energy storage in animals.

[c] albumin


[f] No. Albumin is a protein. You’re looking for a polysaccharide.

[c] starch


[f] No. Starch is a polysaccharide, but one that’s used for energy storage in plants.

[q json=”true” multiple_choice=”true” unit=”Biochemistry” dataset_id=”144Qs|91b3334546734″ question_number=”144″] Amino acids differ from one another because

[c*] they have side chains with distinct chemical properties.


[f] Correct! Amino acids all have a central carbon, connected to an amino group and a carboxyl group. They differ in their side chains.

[c] some have greater catalytic activity than others.


[f] No. Enzymes, which are almost always made of amino acids, differ in their catalytic activity. But amino acids don’t really have catalytic activity on their own. Next time you see this question, think about the structure of amino acids.

[c] some have more phosphate groups than others.


[f] No. No phosphate groups on amino acids.

[c] some have more amino groups than others.

[f] No. Every amino acid has one amino groups (and one carboxyl gro

[q json=”true” zz=”1″ multiple_choice=”true” dataset_id=”2019 AP Bio Dataset|2039aa00283c5a” question_number=”232″ unit=”1.Chemistry of Life”] The nucleotide sequence below is part of the template strand for the gene coding protein Q. If, during DNA replication, a complementary nucleotide was transcribed from this sequence, what would be the complementary base for the nucleotide marked as * ?

[c] A  [c] C  [c*] G  [c] T  [c] U


[f] No. This question is checking your understanding of the base pairing rules for DNA: A (adenine) bonds with T (thymine); C (cytosine) bonds with G (guanine).


[f] No. This question is checking your understanding of the base pairing rules for DNA: A (adenine) bonds with T (thymine); C (cytosine) bonds with G (guanine).


[f] Yes. The nucleotide C (cytosine) always bonds with G (guanine)


[f] No. This question is checking your understanding of the base pairing rules for DNA: A (adenine) bonds with T (thymine); C (cytosine) bonds with G (guanine).


[f] No. This question is about DNA replication, not transcription. The RNA base U (Uracil) isn’t involved. Try this again, focusing on DNA replication and the base pairing rules for DNA.

[q json=”true” zz=”1″ multiple_choice=”true” unit=”1.Chemistry of Life” dataset_id=”2019 AP Bio Dataset|2030244386c05a” question_number=”235″] Within a polypeptide, the bond linking the monomers (indicated by the arrow and green circle below) is a(n) _________.

[c] ionic bond


[f] No. An ionic bond is the attraction between positively and negatively charged ions. They’re important in proteins as a kind of tertiary interaction (between side chains). For example, bond number 4 below is an ionic bond. 
Here’s a hint: the name for the bond that connects amino acids, indicated by the arrow and green circle below, begins with the same letter as the word “polypeptide.”

[c] hydrogen bond


[f] No. Hydrogen bonds result from the attraction between partially positive and partially negative parts of a molecule. They’re the kind of bonds that water molecules form with one another, and they’re important in protein structure at the secondary, tertiary and quaternary level. For example, bond number 2 below is a hydrogen bond.
Here’s a hint: the name for the bond that connects amino acids, indicated by the arrow and green circle below, begins with the same letter as “polypeptide.”

[c*] peptide bond


[f] Excellent. The bond that connects amino acids together within a polypeptide is a peptide bond.

[c] Van der Waals interaction.


[f] No. Van der Waals bonds are weak, intermolecular bonds. They’re important in protein structure mostly at the tertiary level. You can see an example below at bond number 1, which shows hydrophobic side chains clustering together.
Here’s a hint: the name for the bond that connects amino acids, indicated by the arrow and green circle below, begins with the same letter as “polypeptide.”

 

[q json=”true” zz=”1″ multiple_choice=”true” unit=”1.Chemistry of Life” dataset_id=”2019 AP Bio Dataset|202c913d45bc5a” question_number=”236″] One of the following molecules will, when mixed with water, organize itself into a bilayer. Which one?

[c] 1  [c] 2  [c*] 3  [c] 4


[f] No. 1 is a fatty acid. When mixed with water, it typically organizes itself into a micelle (shown below). A is the hydrophilic head of the fatty acid, and B is the hydrophobic tail. Here’s a hint: the molecule that forms a bilayer has two fatty acid tails.

[f] No. 2 represents a wax molecule. Here’s a hint: the molecule that forms a bilayer has two fatty acid tails, and a “head” that contains a phosphate group.


[f] Excellent: 3 is a phospholipid, and when mixed with water, one structure it can spontaneously form is a phospholipid bilayer.

[f] No. 4 represents a triglyceride, the type of molecule that makes up oils and fats. Here’s a hint: the molecule that forms a bilayer has two fatty acid tails.

[q json=”true” zz=”1″ multiple_choice=”true” unit=”1.Chemistry of Life” dataset_id=”2019 AP Bio Dataset|2026f00485705a” question_number=”237″] Which of the molecules below is a key component of cell membranes?

[c] 1  [c] 2  [c*] 3  [c] 4


[f] No. 1 is a fatty acid. Here’s a hint. You’re looking for a phospholipid, and the “phospho” part of the name stands for phosphate group.


[f] No. 2 is a wax. Here’s a hint. You’re looking for a phospholipid, and the “phospho” part of the name stands for phosphate group.


[f] Excellent. 3 is a phospholipid, the key structural component of cell membranes (shown at “A” below)
 

[f] No. 4 is a triglyceride (also known as a triacylglyceride): these are the molecules that make up fats and oils. Here’s a hint. You’re looking for a phospholipid, and the “phospho” part of the name stands for phosphate group.

[q json=”true” zz=”1″ xx=”3″ multiple_choice=”true” unit=”1.Chemistry of Life” dataset_id=”2019 AP Bio Dataset|2023ae7be4985a” question_number=”238″] Which of the molecules below is used for energy storage and insulation?

[c] 1  [c] 2  [c] 3  [c*] 4


[f] No. 1 is a fatty acid. It’s a part of the molecule you’re looking for, which is also called a triglyceride. Think of the prefix “tri,” and use the hint I just gave you to figure out the answer the next time you see this question.


[f] No. 2 is a wax, a lipid molecule that’s used for waterproofing. You’re looking for a triglyceride, a molecule that has three fatty acids.


[f] No. 3 is a phospholipid. These molecules are the key structural component of cell membranes. You’re looking for a triglyceride, a molecule that has three fatty acids.


[f] Fabulous. 4 is a triglyceride, commonly known as a fat or an oil (depending on the structure of the fatty acids). This one’s a fat, because the fatty acids are all saturated.

[q json=”true” zz=”1″ multiple_choice=”true” unit=”1.Chemistry of Life” dataset_id=”2019 AP Bio Dataset|2019bda520245a” question_number=”241″] The diagrams below represent various types of biological molecules, or subunits of biological molecules.
Molecules that would be categorized as lipids include

[c] only A.


[f] No. 3 amino acids make up a polypeptide, which, when a bit longer and folded up into a specific shape, becomes a protein.

[c] only B.


[f] No. B is a nucleotide, a building block of nucleic acids like DNA or RNA.

[c] both A and B.


[f] No. W is a polypeptide, and X is a nucleotide.

[c] A, B and C.


[f] No. A is a polypeptide, and B is a nucleotide. but you’re right about C, which is a phospholipid.

[c*] C and D.


[f] Excellent. Both C and D are lipids. C is a phospholipid and D is a triglyceride (the kind of molecule that makes up fats and oils).

[q json=”true” zz=”1″ multiple_choice=”true” unit=”1.Chemistry of Life” dataset_id=”2019 AP Bio Dataset|201672cc4fbc5a” question_number=”242″] The diagrams below represent various types of biological molecules, or subunits of biological molecules.
In a cell, molecule B’s function is

[c*] encoding genetic information.


[f] Excellent. B is a nucleotide. Nucleotides are the monomers of molecules like DNA and RNA, nucleic acids that store and communicate genetic information.

[c] transporting materials into the cell.


[f] No. B is a nucleotide. Nucleotides are the monomers of nucleic acids, which include substances like DNA and RNA. Think of these molecules’ function, and you’ll have the answer the next time you see this question.

[c] long term storage of energy.


[f] No. Long term energy storage is the function of D, a triglyceride (fat or oil). B is a nucleotide.Nucleotides are the monomers of nucleic acids, which include substances like DNA and RNA. Think of these molecules’ function, and you’ll have the answer the next time you see this question.

[c] stabilizing the plasma membrane


[f] No. Stabilizing the plasma membrane is the function of cholesterol, which is not shown in the diagram above. B is a nucleotide. Nucleotides are the monomers of nucleic acids, which include substances like DNA and RNA. Think of these molecules’ function, and you’ll have the answer the next time you see this question.

[q json=”true” zz=”1″ multiple_choice=”true” unit=”1.Chemistry of Life” dataset_id=”2019 AP Bio Dataset|2013234b678c5a” question_number=”243″] The diagrams below represent various types of biological molecules, or subunits of biological molecules.
All of the molecules above are built from smaller subunits. As these subunits are being combined,

[c] peptide bonds are formed.


[f] No. Peptide bonds are the bonds that connect the amino acids in a polypeptide (or protein). In the diagram below, number 4 indicates a peptide bond.
Think of something that happens as all of these molecules are formed.

[c] there is a net energy output.


[f] No. Almost all synthesis reactions require energy to move forward.

[c] a molecule of water is added.


[f] No. Molecules of water are added in hydrolysis reactions, which typically break large molecules apart into their constituent monomers.

[c*] a molecule of water is removed.


[f] Excellent. All of these molecules (and, in fact, almost all biological molecules), are formed through dehydration synthesis reactions.

[q json=”true” zz=”1″ xx=”3″ multiple_choice=”true” unit=”1.Chemistry of Life” dataset_id=”2019 AP Bio Dataset|200ea2c869b05a” question_number=”244″] The diagrams below represent various types of biological molecules, or subunits of biological molecules.

Which molecule is synthesized at a ribosome?

[c*] A  [c] B  [c] C  [c] D


[f] Excellent! Molecule 1 is a chain of amino acids. In living systems, amino acids (1 below) are combined to form proteins at ribosomes (2 below).

[f] No. B is a nucleotide. Here’s a hint. Look at the diagram below. What’s 1?

[f] No. C is a phospholipid. Here’s a hint. Look at the diagram below. What’s 1?

[f] No. D is a triglyceride. Here’s a hint. Look at the diagram below. What’s 1?

[q json=”true” zz=”1″ xx=”3″ multiple_choice=”true” unit=”1.Chemistry of Life” dataset_id=”2019 AP Bio Dataset|200a86636b205a” question_number=”245″] The diagrams below represent various types of biological molecules, or subunits of biological molecules.
Which molecule above forms the key structural component of the cell membrane?

[c] A


[f] No. A represents a polypeptide or protein. Here’s a hint: the molecule you’re looking for is type of lipid, and it forms a structure like the one below.

[c] B


[f] No. B represents a nucleotide, a monomer of nucleic acids. Here’s a hint: the molecule you’re looking for is type of lipid, and it forms a structure like the one below.

[c*] C


[f] Nice job. C is a phospholipid, the basic structural component of the cell’s membrane.

[c] D


[f] No, but you’re on the right track. D is a triglyceride, one of two lipids in this set of molecules. The answer is the other lipid. When it’s in the membrane, it forms a structure like the one below.

 

[q json=”true” multiple_choice=”true” unit=”Cells|Membranes” dataset_id=”144Qs|96ac0e69bb334″ question_number=”55″] Mitochondria have two membranes. Cristae are folds in the inner mitochondrial membrane, and they’re shown at number 2 below. Which of the following is most likely to be true about crustal?

[c] They increase the volume of mitochondrial cells.

[f] No. Volume is the amount of space something takes up. The cristae have no effect on the volume.

[c] cristae decrease the surface area of the inner mitochondrial membrane.

[f] No. Things with lots of folds have lots of surface area, compared with things that are smooth.

[c*] cristae increase the surface area of the inner mitochondrial membrane.

[f] Bingo! Things with lots of folds have lots of surface area, compared with things that are smooth. As we’ll be learning, that provides lots of room for membrane embedded mitochondrial enzymes that carry out cellular respiration.

[q json=”true” zz=”1″ multiple_choice=”true” dataset_id=”2019 AP Bio Dataset|20ec3053e1505a” question_number=”178″ unit=”2.Cell Structure and Function”] Which of the following features can be used to distinguish between a prokaryotic and eukaryotic cell?

[c] DNA is present in the cell.


[f] No. Both prokaryotic cells and eukaryotic cells have DNA.

[c] There is a rigid cell wall.


[f] No. Because there are a few prokaryotic cells (genus mycoplasma) that lack a cell wall, and because all animal cells lack cell walls, you can’t use the presence of a cell wall as a distinguishing feature.

[c] Ribosomes are present in the cell.


[f] No. Both prokaryotic and eukaryotic cells have ribosome.

[c] The cell carries out cellular metabolism.


[f] No. Both prokaryotic and eukaryotic cells carry out cellular metabolism.

[c*] The cell is divided by internal membranes.


[f] Terrific. While eukaryotic cells are divided by internal membranes, prokaryotic cells are not.

[q json=”true” zz=”1″ multiple_choice=”true” dataset_id=”2019 AP Bio Dataset|20f7cd9331a45a” question_number=”175″ unit=”2.Cell Structure and Function”] Which of the following organelles is correctly paired with its function in a cell?

[c] Lysosome, cellular movement


[f] No. Lysosomes are responsible for intracellular digestion. Cellular movement is the function of flagella or cilia.

[c] Ribosome, manufacturing of lipids


[f] No. Ribosomes are responsible for protein synthesis. Manufacturing lipids is the function of the smooth endoplasmic reticulum.

[c*] Central vacuole, storage of materials and waste


[f] Way to go! The central vacuole’s function is storage of materials and waste products. This organelle is found only in plants.

[c] Nucleus, where cellular respiration occurs

[f] No. The function of the nucleus is to hold and protect chromosomes. Cellular respiration occurs in mitochondria.

[c] Mitochondrion, where photosynthesis occurs


[f] No. The function of the mitochondria is production of ATP. Photosynthesis occurs in chloroplasts.

[q json=”true” xx=”3″ multiple_choice=”true” dataset_id=”SMV_AP_Bio_Multiple_Choice_Practice_2018|225a0d1a21b5cf” question_number=”176″ unit=”Cells, Membranes”] Which of the following features applies to both chloroplasts and mitochondria?

Chloroplast Mitochondrion

I. Synthesizes its own protein.
II. Contains a small amount of DNA
III. Not part of the endomembrane system
IV. Can reproduce themselves

[c] I, II, and IV only


[f] No, but you’re very close. Here’s a hint: study this diagram. What’s not there?

[c] II only


[f] No. You’re right in that both chloroplasts and mitochondria have their own small amount of DNA in the form of a single, circular chromosome. But they share other features as well.

[c] II and III only


[f] No. You’re right in that both chloroplasts and mitochondria have their own small amount of DNA (in the form of a single, circular chromosome); and that they’re not part of the endomembrane system. But they share other features as well.

[c] III and IV only


[f] No. You’re right in the both chloroplasts and mitochondria are not part of the endomembrane system, and that they can grow and reproduce themselves. But they share other features as well.

[c*] I, II, III, and IV


[f] Excellent: you’ve identified four features that chloroplasts and mitochondria share.

[q json=”true” zz=”1″ multiple_choice=”true” dataset_id=”2019 AP Bio Dataset|20ef1e0ad6185a” question_number=”177″ unit=”2.Cell Structure and Function”] Which of the following groups of organelles produce molecules necessary for the cell to sustain life?

[c] Lysosome, rough ER, vacuole


[f] No. The lysosome is a digestive organelle, and the function of the vacuole is storage.

[c] Lysosome, ribosome, vacuole


[f] No. The lysosome is a digestive organelle, and the function of the vacuole is storage.

[c*] Ribosome, rough ER, smooth ER


[f] Perfect. The ribosome makes proteins; the rough ER makes proteins that are designated for export, the membrane, or lysosomes; the smooth E.R. makes lipids.

[c] Ribosome, smooth ER. vacuole


[f] No. The vacuole is a storage organelle.

[c] Rough ER, smooth ER, vacuole


[f] No. The vacuole is a storage organelle.

[q json=”true” zz=”1″ multiple_choice=”true” dataset_id=”2019 AP Bio Dataset|20e918b416805a” question_number=”179″ unit=”2.Cell Structure and Function”] Which of the following components are found in all prokaryotic cells?

  1. Ribosomes
  2. Plasma membrane
  3. Genetic information

 

[c] I only


[f] No. You’re right about their having ribosomes, but there are other components that all prokaryotic cells possess.

[c] II only


[f] No. You’re right about their having a membrane, but there are other components that all prokaryotic cells possess.

[c] III only


[f] No. You’re right about their having genetic information, but there are other components that all prokaryotic cells possess.

[c] I and II only


[f] No. You’re right about their having ribosomes and a membrane, but there’s one more component that all prokaryotic cells possess.

[c*] I, II, and III


[f] Excellent: all prokaryotic cells have ribosomes, a membrane, and genetic information.

[q json=”true” zz=”1″ multiple_choice=”true” dataset_id=”2019 AP Bio Dataset|20e34fe68c105a” question_number=”181″ unit=”2.Cell Structure and Function”] Which of the following cellular structures is involved the transport of molecules from the inside of a cell to its outside?

[c] ribosomes


[f] No. Ribosomes synthesize proteins. They’re not directly involved in transport.

[c] Vesicles created by endocytosis


[f] No. Vesicles created by endocytosis bring material from outside of the cell to the inside of the cell. Three types of endocytosis are shown below.

[c*] Vesicles from the Golgi


[f] Exactly. Vesicles from the Golgi (1, below) are used to transport materials out of the cell.

 

 

 


[q json=”true” zz=”1″ multiple_choice=”true” dataset_id=”2019 AP Bio Dataset|20e01eaa3e745a” question_number=”182″ unit=”2.Cell Structure and Function”] In humans lungs, the respiratory cycle involves an inhalation followed by an exhalation. In this type of system, the lungs are never entirely flushed with fresh air. As a result, the oxygen concentration in human lungs is about 56% that of the outside air.
In sparrows and other birds, the lungs maintain a one-way flow of air using a series of air sacs. As a result, a sparrow’s lungs can be entirely flushed with fresh air.
A sparrow can obtain more oxygen from outside air than a human can because the sparrow’s gas exchange system has

[c] a larger diffusion area.


[f] No. The diffusion area is a function of many factors, but a major one is the size of the organism. Humans have a larger diffusion area than sparrows do.

[c] a smaller diffusion distance.


[f] No. In both species, oxygen is diffusing a short distance from the alveoli and other air sacs to nearby capillaries.

[c] less of a diffusion barrier.


[f] No. In both species, oxygen diffuses across a thin epithelial layer and then into thin-walled capillaries that bring oxygenated blood into the circulatory system.

[c*] a steeper diffusion gradient.


[f] Yes. The system that has evolved in birds provides for a steeper diffusion gradient, allowing birds to absorb more oxygen into their blood than mammals can: an essential adaptation for the high energy demands associated with flying.

[q json=”true” xx=”3″ multiple_choice=”true” dataset_id=”SMV_AP_Bio_Multiple_Choice_Practice_2018|22385aba0af1cf” question_number=”191″ unit=”Animal_Systems”] Like humans, elephants maintain a relatively constant body temperature.
Which of the following actions would have the greatest effect on decreasing the body temperature of an elephant in extremely hot conditions?

[c*] Flapping their ears


[f] Excellent! The elephants’ ears provide it with extra surface area. Flapping the ears allows heat to diffuse from the blood in the ears into the external environment.

[c] Huddling with other elephants


[f] No. This question is really about surface area to volume relationships. When elephants huddle together, they decrease their collective surface area (just think about circumstances when humans huddle together: do we do this when we’re hot, or when we’re cold?). Look at the choices and find one that would allow an elephant to use surface area to radiate body heat to the environment.

[c] Decreasing blood flow to the ears


[f] No. Decreasing blood flow away from the extremities is an adaptation for reducing heat loss. That’s why your feet and hands get cold in cold weather. In what’s described above, the elephants need to increase heat exchange with the environment so that they can lower their body temperature. Which of the choices describes something that would enable them to exchange more heat with the environment.

[c] Folding their ears against their body


[f] No. Folding the ears against the body is a way to decrease exposed surface area, which would make it harder for the elephant to radiate heat to the external environment. Think about what we humans do when we’re cold: we fold our arms against our bodies, decreasing our exposed surface area. Which of the choices describes something that would increase the elephant’s available surface area, allowing it to radiate more heat into the environment?

[q json=”true” zz=”1″ multiple_choice=”true” dataset_id=”2019 AP Bio Dataset|20baf78881405a” question_number=”193″ unit=”2.Cell Structure and Function”] Which of the following pairs of statements correctly matches organelles to their function?

[c] The Golgi apparatus is where ATP production occurs. The rough endoplasmic reticulum is where proteins are synthesized for cell secretion.


[f] No. The function of the rough E.R. is correct, but ATP synthesis happens in the mitochondria (not the Golgi apparatus).

[c*] The Golgi apparatus is where proteins are processed. The rough endoplasmic reticulum is where proteins are synthesized for cell secretion (or incorporation into lysosomes or the membrane).


[f] That’s correct! Good job knowing your organelles!

[c] The Golgi apparatus is where proteins are synthesized for cell secretion. The rough endoplasmic reticulum is where ATP production occurs.


[f] No. Study the diagram below. The Rough E.R. is at C, and notice its association with ribosomes (E) and proteins (F). The Golgi is at D. Notice the lack of ribosomes.

[q json=”true” xx=”3″ multiple_choice=”true” dataset_id=”SMV_AP_Bio_Multiple_Choice_Practice_2018|222b469f4039cf” question_number=”197″ unit=”Cells, Membranes”] The figures below depict a plant cell before and after it was placed in a sucrose solution. Which of the following conclusions is most consistent with the changes observed in the plant cell after it was placed in this solution?

[c] Water molecules moved from the hypotonic sucrose solution into the hypertonic cell.


[f] No. Water does flow from hypotonic to hypertonic. But what you’re seeing is the cell interior shrink away from its wall, which indicates that the cell lost water. If the cell lost water, was solution entering or leaving the cell?

[c*] Water molecules moved from the hypotonic cell into the hypertonic sucrose solution.

[f] Excellent. What you’re observing is plasmolysis, the shrinking of the cell membrane away from the wall as water flows out of the hypotonic cell into its hypertonic environment.

[c] Sucrose diffused from higher concentration, outside the cell, to lower concentration, inside the cell.


[f] No. What you’re seeing is the cell interior shrink away from its wall, which indicates that the cell lost water (because water makes up most of the interior of the cell). Think about how water moves during osmosis (the movement of water molecules) when you see this question again.

[c] The membrane of the vacuole is impermeable to water molecules, but allows sucrose molecule to freely pass through.


[f] No. You can observe that the vacuole is shrinking in size, and since water makes up most of the vacuole, this shrinkage has to be due to water loss. Next time you see this question, think about what happens during osmosis (the diffusion of water).

[q json=”true” xx=”3″ multiple_choice=”true” dataset_id=”SMV_AP_Bio_Multiple_Choice_Practice_2018|2226d1c07dd1cf” question_number=”199″ unit=”Cells, Membranes”] The permeability coefficient measures the ease with which a molecule passes through a cell membrane. The graph below displays the permeability coefficients for six different molecules with various solubilities in oil.
Which of the following statements is supported by the data in the graph?

[c] Alcohol is less lipid-soluble than water.


[f] No. First, keep in mind the fact that oil is a lipid, so the X axis on this graph is showing lipid solubility. Knowing that, take another look at the graph. Which is more lipid soluble (further to the right on the X axis): water or alcohol?

[c*] Excess water can diffuse out of a cell faster than urea.


[f] Excellent. Water has a higher permeability coefficient than urea; therefore, water would more easilty move through the cell membrane.

[c] Diethylurea can more easily move through a cell membrane than alcohol.


[f] No. You’re told in the question that the permeability coefficient measures the ease with which a substance moves through the membrane. Look at the Y axis: which molecule, diethylurea or alcohol, has a higher permeability coefficient? Which one would more easily move through the membrane?

[c] Ethylene glycol can more easily move through a cell membrane than codeine.


[f] No. You’re told in the question that the permeability coefficient measures the ease with which a substance moves through the membrane. Look at the Y axis: which molecule, ethylene glycol or codeine, has a higher permeability coefficient? Which one would more easily move through the membrane?

 

 


[q json=”true” xx=”3″ multiple_choice=”true” dataset_id=”SMV_AP_Bio_Multiple_Choice_Practice_2018|220ae5d9e599cf” question_number=”209″ unit=”Cells, Membranes”] The model below depicts a cell membrane. What structures are labelled I, II, and III in the model?

[c] Glycoprotein, peripheral protein, hydrophobic phosphate head

[f] No. You’re right about I. Here’s a hint: the phosphate head at III in touching the cytoplasm. The cytoplasm is mostly water. Would that make the phosphate head hydrophobic or hydrophilic?

[c] Peripheral protein, glycoprotein, hydrophilic phosphate head

[f] No. You’re right about III. Here’s a hint: the protein at I looks like it has a polysaccharide chain attached to it. The name for an important polysaccharide in animals is glycogen. If a glycogen and protein had a baby, what would they call it?

[c*] Glycoprotein, integral protein, hydrophilic phosphate head

[f] Excellent! You know your membranes!

[c] Integral protein, peripheral protein, hydrophobic phosphate head

[f] No. Here’s a hint: the phosphate head at III in touching the cytoplasm. The cytoplasm is mostly water. Would that make the phosphate head hydrophobic or hydrophilic?

[q json=”true” zz=”1″ multiple_choice=”true” dataset_id=”2019 AP Bio Dataset|20872bd3fc245a” question_number=”208″ unit=”2.Cell Structure and Function”] Which of the following is a correct route for flow of materials in the endomembrane system?

[c] Golgi to lysosome to ER to plasma membrane

[f] No. Here’s a hint. Study the endomembrane system diagram below. D is the Golgi, J is a Lysosome, and C is the rough ER. The arrows indicate the direction that material is flowing.

[c*] Rough ER to vesicles to Golgi to plasma membrane


[f] Nice job. You clearly have a good understanding of the cell’s endomembrane system (shown below)

[c] ER to chloroplasts to mitochondrion to cell membrane


[f] No. Study the endomembrane system diagram below. D is the Golgi, J is a Lysosome, and C is the rough ER. The arrows indicate the direction that material is flowing.

[c] Nuclear envelope to lysosome to Golgi to plasma membrane


[f] No. Study the endomembrane system diagram below. D is the Golgi, J is a Lysosome, and C is the rough ER. The arrows indicate the direction that material is flowing.

[q json=”true” xx=”3″ multiple_choice=”true” dataset_id=”SMV_AP_Bio_Multiple_Choice_Practice_2018|2203e2ba15edcf” question_number=”211″ unit=”Cells, Membranes”] Which of the following models best represents the arrangement of phospholipids in a cell membrane?

 

[c*] A  [c] B  [c] C  [c] D


[f] Exactly. Because phospholipids have a hydrophobic tail and a hydrophilic head, the lowest energy state that they can assume is the one shown in A above, with the heads pointing out (interacting with water in the cell exterior and the cytoplasm) and the tails clustering together in a water free zone.
Here’s how I describe this in my Membranes! Rap:
Cause when phospholipids into water get submerged,
A phospholipid bilayer structure will emerge
The tails hang together in a water free zone,Hear their hydrophobic moan, “water leave me alone!”
While the heads are sticking out touching all those H2Os
Tails in, heads out, it’s how every membrane goes
Tails in, heads out, in a cellular sphere,
It’s the bilayered basis of membranes everywhere.


[f] No. Remember that for most cells, above and below the membrane are solutions that are mostly water (the cell exterior, and the cytosol). Read these lyrics from my Membranes! Rap, and see if you can figure out the correct arrangement:
Cause when phospholipids into water get submerged,
A phospholipid bilayer structure will emerge
The tails hang together in a water free zone,Hear their hydrophobic moan, “water leave me alone!”
While the heads are sticking out touching all those H2Os
Tails in, heads out, it’s how every membrane goes
Tails in, heads out, in a cellular sphere,
It’s the bilayered basis of membranes everywhere.


[f] No. Remember that for most cells, above and below the membrane are solutions that are mostly water (the cell exterior, and the cytosol). Read these lyrics from my Membranes! Rap, and see if you can figure out the correct arrangement:
Cause when phospholipids into water get submerged,
A phospholipid bilayer structure will emerge
The tails hang together in a water free zone,Hear their hydrophobic moan, “water leave me alone!”
While the heads are sticking out touching all those H2Os
Tails in, heads out, it’s how every membrane goes
Tails in, heads out, in a cellular sphere,
It’s the bilayered basis of membranes everywhere.


[f] No. Remember that for most cells, above and below the membrane are solutions that are mostly water (the cell exterior, and the cytosol). Read these lyrics from my Membranes! Rap, and see if you can figure out the correct arrangement:
Cause when phospholipids into water get submerged,
A phospholipid bilayer structure will emerge
The tails hang together in a water free zone,Hear their hydrophobic moan, “water leave me alone!”
While the heads are sticking out touching all those H2Os
Tails in, heads out, it’s how every membrane goes
Tails in, heads out, in a cellular sphere,
It’s the bilayered basis of membranes everywhere.

[q json=”true” xx=”3″ multiple_choice=”true” dataset_id=”SMV_AP_Bio_Multiple_Choice_Practice_2018|220072a08745cf” question_number=”212″ unit=”Cells, Membranes”] Five sucrose-impermeable dialysis bags were filled with different concentrations of sucrose solution. Each bag was placed in a separate beaker that contained a 0.6 M sucrose solution. The bags were weighed every 10 minutes for 60 minutes. The results for each bag, DB1 through DB5, are shown in the graph below as percent mass change over time. Which lines in the graph represent dialysis bags that contain a hypertonic solution at 30 minutes?

 

[c*] DB2


[f] Yes. Notice that the mass in DB2 is increasing. That increase is because of osmosis, as water flows from the 0.6 molar solution in the beaker into the bag (which must be hypertonic to the 0.6 M solution)

[c] DB3


[f] No. DB3’s mass has stayed constant, allowing you to conclude that the solution inside it is isotonic to the 0.6 M solution in the beaker. Find the bag that is gaining mass, because that’s the one with a solution that must be hypertonic to the 0.6 M solution in the beaker.

[c] DB4


[f] No. DB4 is losing mass. This loss is a consequence of osmosis, as water moves from the hypotonic solution in the bag into the beaker. Find the bag that is gaining mass, because that’s the one with a solution that must be hypertonic to the 0.6 M solution in the beaker.

 

 


[q json=”true” zz=”1″ multiple_choice=”true” dataset_id=”2019 AP Bio Dataset|206b115c761c5a” question_number=”217″ unit=”2.Cell Structure and Function”] The body temperature of small ectothermic (“cold-blooded”) animals, such as a small fish, is dependent on the temperature of their environment. Large ectothermic animals, like sea turtles, can retain their body heat to remain warmer than their environment. Which of the following reasons best explains why large ectothermic animals can retain heat?

[c] Larger surface/volume ratio


[f] No. Think of the formulas for the surface area and the volume of a cube. Surface area is (side * 6)2. Volume is side3. Because surface area is a square function and volume is a cubic function, then the larger a cube is, the less surface area it has relative to its volume, as you can see in the graph below.
What’s true of cubes is true of animals (only the calculations for finding area and volume are more complicated. Use that as a hint to think about what’s going on with larger organisms, and how that might relate to these organisms’ ability (or inability) to diffuse heat out of their bodies.

[c*] Smaller surface/volume ratio


[f] Yes. Because surface area is a square function and volume is a cubic function, then the larger an organism is the less surface area it has relative to its volume. That means that it’s much harder for larger animals to diffuse heat out of their bodies, which explains why large ectothermic animals can retain heat.

[c] Higher metabolic rate per gram of body mass.

[f] No. We’ll learn more about this later in the course. The relationship between body size and metabolic rate actually runs in the opposite direction, as you can see in the graph below. Bigger animals like elephants have much slower metabolic rates than smaller animals like mice. 

The key to this question has more to do with surface area to volume relationships. Study the graph below, which shows the relationship between surface area and volume for a cube. What happens to an organism’s surface area to volume ratio as it increases in size, and how might that relate to an organism’s ability to diffuse heat out of its body?

 


[q json=”true” zz=”1″ multiple_choice=”true” unit=”2.Cell Structure and Function” dataset_id=”2019 AP Bio Dataset|1ffdaed1d5905a” question_number=”248″] Which letter in the diagram below represents a ribosome?

 

[c] A  [c] B  [c] C  [c] D  [c*] E


[f] No. A is the Rough Endoplasmic Reticulum. Here’s a hint: what’s making it rough?


[f] No. B represents a protein (or another substance) that’s been exported from the cell. Here’s a hint: the answer is referring to the particles that make the rough E.R. rough.


[f] No. C is a vesicle that’s budded off of the Golgi apparatus.Here’s a hint: the answer is referring to the particles that make the rough E.R. rough.


[f] No. D is the Golgi Apparatus. Here’s a hint: the answer is referring to the particles that make the rough E.R. rough.


[f] Fantastic. E refers to the dots on the Rough Endoplasmic reticulum. These dots (which make the rough E.R. rough) are ribosomes.

[q json=”true” xx=”3″ multiple_choice=”true” unit=”Cells, Membranes” dataset_id=”SMV_AP_Bio_Multiple_Choice_Practice_2018|1a30a44792a46d” question_number=”251″] The cell below is from an animal. By looking at its structure, you could predict that 

[c] it produces a lot of glucose through photosynthesis.


[f] No. This is an animal cell, so there’s no photosynthesis Here’s a hint: the organelles filling up this cell are mitochondria.

[c*] require high levels of oxygen.

[f] Excellent. The organelles that are filling up this cell are mitochondria. Their key role is ATP production from cellular respiration, a topic we’ll be learning about during this term. A cell with this many mitochondria would need a lot of oxygen.

[c] convert carbon dioxide into glucose

[f] No. That would be a great answer if the cell were full of chloroplasts, because that’s exactly what happens during photosynthesis. Here’s a hint: the organelles filling up this cell are mitochondria.

[q json=”true” zz=”1″ multiple_choice=”true” unit=”2.Cell Structure and Function” dataset_id=”2019 AP Bio Dataset|1fb2ec2408a05a” question_number=”263″] Which letter in the diagram below represents the rough endoplasmic reticulum?

[c*] A  [c] B  [c] C  [c] D  [c] E


[f] Nice job. A represents the rough E.R.


[f] No. B is a protein (or other substance) that’s being exported from the cell through exocytosis.


[f] No. C is a vesicle, moving substances from the Golgi Apparatus to (in this case) the membrane.


[f] No. D is the Golgi Apparatus.


[f] No. E represents the cell’s ribosomes.

[q json=”true” xx=”3″ multiple_choice=”true” dataset_id=”SMV_AP_Bio_Multiple_Choice_Practice_2018|123c805924cbb3″ question_number=”301″ unit=”Cells, Membranes”] Amoebas are unicellular protists that are found in aquatic environments. One of these environments (X) is the amoeba’s natural environment. Environments Y and Z have been experimentally manipulated.
Based on the information above, environment Y must be ________ to the amoeba’s natural environment.

 

[c] hypotonic


[f] No. Remember that water always flows from hypotonic to hypertonic. You’re told above that X is the natural environment. The amoeba in environment Y is smaller and more shriveled up than the amoeba in environment X. Would that change be caused by water entering the amoeba, or leaving the amoeba? What kind of environment could cause that change?

[c] isotonic


[f] No. Remember that water always flows from hypotonic to hypertonic. You’re told above that X is the natural environment. The amoeba in environment Y is smaller and more shriveled up than the amoeba in environment X. Would that change be caused by water moving at the same rate between the environment and the cell (which is what would happen in an isotonic environment)? Focus on these questions: is water entering the amoeba, or leaving it? What kind of environment could cause that change?

[c*] hypertonic


[f] Excellent. Water obviously left the amoeba, causing it to shrivel up. Because water always flows from hypotonic to hypertonic, that would only happen if the cell were in a hypertonic environment.

[q json=”true” xx=”3″ multiple_choice=”true” dataset_id=”SMV_AP_Bio_Multiple_Choice_Practice_2018|1239a9eaa6ebb3″ question_number=”302″ unit=”Cells, Membranes”] Amoebas are unicellular protists that live in aquatic environments. A photomicrograph of one is shown immediately below.
The images that follow are simplified representations of amoebas, showing only the membrane and the nucleus. The letters X, Y, and Z represent the amoeba’s environment. Environments X is the amoeba’s natural environmen, while environments Y and Z have been experimentally manipulated.

The most likely explanation for what’s happening to the amoeba in environment Z is that

[c*] water is flowing from the hypotonic environment outside of the amoeba into the amoeba’s hypertonic cytoplasm, causing the amoeba to expand.


[f] Exactly. Water always flows from hypotonic to hypertonic, and that flow of water into the amoeba has caused the amoeba to expand.

[c] water is flowing from the hypertonic environment outside of the amoeba into the amoeba’s hypotonic cytoplasm.


[f] No. If the amoeba is expanding, then water must be flowing into it. Remember that water always flows from hypotonic (higher concentration of water, lower concentration of solutes) to hypertonic (lower concentration of water, higher concentration of solutes).

[c] solutes, including salt and glucose, are diffusing through the amoeba’s membrane into the amoeba’s cytoplasm.


[f] No. While solutes (salt, glucose) are going to diffuse down their concentration gradient, the increase in the cell’s size is going to result from osmosis. Next time, choose an answer that focuses on the movement of water, not the solutes.

[c] active transport pumps are moving water from the hypertonic cell exterior into the hypotonic cell interior.


[f] No. The pumps involved in active transport pump solutes, not water. This question is about osmosis, and the key thing to remember is that water always flows from hypotonic to hypertonic. With that in mind, ask yourself, what could have caused the cell at Z to expand?

[q multiple_choice=”true”] A part found in plant cells but not in animal cells that allows plant cells to thrive in hypotonic environments is/are

[c] chloroplasts

[f] No. The function of the chloroplast is photosynthesis.
Here’ how to think about this question. The challenge of a cell in a hypotonic environment is to avoid bursting as water flows from the hypotonic environment into the hypertonic cell, as shown in the red blood cells on the right side of the diagram below.

What plant cell structure could prevent a cell from bursting due to osmotic pressure?

[c] golgi bodies

[f] No. The function of the Golgi body is packaging and distributing the proteins it receives from the endoplasmic reticulum.
Here’ how to think about this question.The challenge of a cell in a hypotonic environment is to avoid bursting as water flows from the hypotonic environment into the hypertonic cell, as shown in the red blood cells on the right side of the diagram below.

What plant cell structure could prevent a cell from bursting due to osmotic pressure?

[c*] the cell wall

[f] Excellent. The cell wall is what plant cells use to keep from bursting from osmotic pressure in a hypotonic environment, as shown in the cell on the right below.

[c] the rough endoplasmic reticulum

[f] No. The function of the rough E.R. is synthesizing proteins that are destined for export, or incorporation within cellular organelles.
Here’ how to think about this question.The challenge of a cell in a hypotonic environment is to avoid bursting as water flows from the hypotonic environment into the hypertonic cell, as shown in the red blood cells on the right side of the diagram below.

What plant cell structure could prevent a cell from bursting due to osmotic pressure?

[/qwiz]

Quiz 2: Guided Recall and Fill-in-the-Blanks

[qwiz qrecord_id=”sciencemusicvideosMeister1961-Units 2 and 2 Guided Recall” style=”width: 600px !important;”]

[h] AP Bio Units 1 and 2 Guided Recall Questions

[i] Each guided recall question starts by posing a question. Here’s how to maximize your learning.

  1. Say the answer out loud to yourself.
  2. Click “Show me the answer.”
  3. Carefully read the sample answer, comparing it to what you said.
  4. If you knew the answer, click “got it.”
  5. Otherwise, click “need more practice.”

In addition, there are fill-in-the-blank questions.

[q] Explain how hydrogen bonds come about from water’s chemical structure, and describe hydrogen bonds.

[c*] Show me the answer

[f] Water is a polar covalent molecule. Because oxygen’s nucleus has eight protons while hydrogen’s nucleus has one, the electrons shared by the two hydrogen atoms and the one oxygen atom in a molecule of water are shared unequally. The negative electrons cluster around the oxygen side of the molecule, giving that side of the molecule a partial negative charge. In contrast, the region with the hydrogen atoms gains a partially positive charge.
Hydrogen bonds are intermolecular bonds that form between the partially positive (hydrogen) side of one water molecule and the partially negative (oxygen) side of another water molecule. Hydrogen bonds can also form between positive and negatively charged regions of other molecules, such as between the complementary bases in DNA (where adenine bonds with thymine, and cytosine with guanine).

[q] Explain why it takes a lot of energy to make water evaporate. How do some organisms use this as an adaptation?

[c*] Show me the answer

[f] Because the breaking of hydrogen bonds requires energy, water has a very high heat of vaporization. That means that when water is converted into water vapor (which happens when sweat evaporates from human skin or from a dog’s tongue), it carries away a lot of heat energy, lowering the temperature of the body that it evaporated from. This is how evaporative cooling works, and it’s a key thermoregulatory adaptation in humans and other animals.

[q] In terms of hydrogen ions, hydroxide ions, and pH, describe the difference between an acidic and a basic solution.

[c*] [show_me_placeholder]

[f] Acidic solutions have more hydrogen ions (protons or H+) than hydroxide ions (represented by OH-) The pH of an acidic solution is below 7. Bases are substances that have more hydroxide ions than hydrogen ions, and their pH is above 7.

[q] Describe the functions of  monosaccharides and disaccharides.

[c*] [show_me_placeholder]

[f] Carbohydrates consist of monosaccharides, disaccharides, and polysaccharides. Monosaccharides such as glucose are often energy sources, powering cellular respiration. Glucose is also the product of photosynthesis, so it’s the way that carbon, the central atom in living things, enters the biosphere. Disaccharides like lactose and sucrose are often used for energy transfer (lactose transfers energy from a mammalian mother to her offspring; sucrose transfers energy from the leaves of a plant to other, non-photosynthetic parts). Polysaccharides like starch and glycogen are used for energy storage (starch in plants, glycogen in animals), while cellulose is used to build the cell walls of plants.

[q] Describe the basic chemistry, overall structure, and biological importance of lipids.

[c*] [show_me_placeholder]

[f] Lipids are molecules that are either non-polar, or have large nonpolar regions. Many lipids are built of one or more fatty acids, which are hydrocarbon chains that terminate in a carboxyl group. Lipids are used for energy storage, for waterproofing, as essential components of cell membranes, and as building blocks for steroid hormones.

[q] List the four key types of lipids. Briefly describe the function of each.

[c*] [show_me_placeholder]

[f] Lipids include triglycerides (fats and oils), which are used for energy storage and insulation; waxes, which are used for waterproofing; phospholipids, which are the key structural components of cell membranes; and steroids, which are signaling molecules (steroid hormones).

[q] Compare and contrast the chemical structure, properties, and functions of fats and oils.

[c*] [show_me_placeholder]

[f] Fats and oils are both triglycerides. Triglycerides consist of three fatty acids bonded to a glycerol molecule (a 3-carbon alcohol). In fats, the fatty acids are saturated. That means that the hydrocarbon chains in a fat have no double bonds. As a result, the chains are straight, allowing the fat molecules to form weak intermolecular bonds with one another (called “London Dispersion forces). While the bonds are weak, they’re sufficient to enable a cluster of fat molecules to maintain their shape at room temperature, which is why fats are solids.
In oils, one or more of the fatty acids is unsaturated, meaning that they have at least one double bond. This bends the hydrocarbon chains, which prevents oil molecules from forming the intermolecular bonds found in fats. As a result, oils are liquid at room temperature.
Both fats and oils are used for energy storage. In animals, fats also serve as insulation.

[q] Describe the structure of phospholipids, and explain the relationship between phospholipid structure and the role that these molecules play in cell membranes.

[c*] [show_me_placeholder]

[f] Phospholipids have a polar, hydrophilic head; and a non-polar, hydrophobic tail. The central molecule in a phospholipid is a 3-carbon alcohol called glycerol (the same molecule found in fats and oils). Bonded to the glycerol on one side are two fatty acids, forming the hydrophobic tail. On the other side of the glycerol is the hydrophilic head, which contains a negatively charged phosphate group.
Because of this structure, phospholipids can spontaneously form a phospholipid bilayer. In a phospholipid bilayer, the there are two rows, or layers. In each row, the hydrophilic heads face out (interacting with water molecules), while the tails face inward, forming a water-free zone. In addition, the tails are attracted to one another by very weak intermolecular forces (called London Dispersion forces, or hydrophobic bonds). Now imagine this bilayer forming a sphere. Outside of the sphere is the watery exterior. Inside is the watery interior. That bilayer is the framework of the cell membrane.
Note that phospholipids form the basis of cell membranes in two of life’s three domains: bacteria and eukarya (eukaryotes). Archaea use a different lipid to form their cell membranes.

[q] Describe the structure and function of steroids and waxes.

[c*] [show_me_placeholder]

[f] Steroids consist of four or five fused carbon rings, often with hydrocarbons attached. They’re the starting point for steroid hormones (important signaling molecules). Cholesterol is a steroid that plays a stabilizing role in cell membranes.
Waxes consist of two or more hydrocarbon chains that are bonded together. They play an important waterproofing role, especially in leaves, where waxes coat the surface of leaves, where they reduce water loss.

[q] Name the monomer of proteins, and describe that monomer’s structure.

[c*] [show_me_placeholder]

[f] Proteins are polymers of amino acids. Amino acids are built around a central carbon, attached to amino groups, carboxyl groups, a hydrogen atom, and a variable R group. The R group, also called a “side chain” can be polar, non-polar, acidic, or basic. Interactions between amino acids (covered in another card) determine the protein’s three dimensional shape.

[q] Describe the biological importance of proteins.

[c*] [show_me_placeholder]

[f] Proteins are the most diverse macromolecule Their functions include
• catalysis (as enzymes);
• structure (as in the flexible protein collagen or the more fibrous keratin, which makes hair, feathers, and nails; energy storage (albumin);
• motion (as in the proteins actin and myosin, which interact to create contractile muscle tissue);
• transport (as in hemoglobin, which carries oxygen); and
• information transfer (as in protein hormones like insulin or protein neurotransmitters like serotonin).

[q] Describe the biological importance of nucleic acids.

[c*] [show_me_placeholder]

[f] Nucleic acids are life’s key informational molecules. They are polymers of nucleotides (the structure of which is covered in another card). DNA is the molecule of heredity. It’s the repository of genetic information, and the informational component of the chromosomes that get passed from one generation to the next during reproduction, and from mother cell to daughter cells during growth and development. RNA is a hereditary molecule in some viruses, but more frequently is involved in information transfer, as in the messenger RNA that carries a genetic message from chromosomes to ribosomes, where these messages are converted into protein. We haven’t covered this yet, but RNA can also be an action molecule with catalytic properties. Such catalytic RNAs include ribosomes (which translate RNA instructions into proteins) and spliceosomes, which edit eukaryotic RNA so that it can be translated into protein.
In addition, ATP is a nucleotide monomer (a monomer of RNA). ATP is life’s key energy transfer molecule, powering most cellular work.

[q]Describe the biological importance of carbon, and explain why carbon plays the role that it does in living things.

[c*] [show_me_placeholder]

[f] Carbon is the central atom in biological molecules. It’s central to the structure of carbohydrates, lipids, proteins and nucleic acids.
Carbon’s central role stems from its atomic structure: it has six protons, along with six neutrons and six electrons. The six electrons are organized so that carbon has four valence electrons, allowing carbon to form a wide variety of covalent bonds, including single, double, and triple bonds with itself and other elements.
Because carbon can bond with itself, and form double and triple bonds, it can form rings, chains, and branched molecules that are indeterminate in length and shape. This is a capability that no other element (not even silicon) has, and it made possible the evolution of complex molecules that, at a molecular level, underlie life’s properties: replication, energy transfer, encapsulation, etc.

[q] What are monomers? How do they connect to form polymers?

[c*] [show_me_placeholder]

[f] Three of the four macromolecule families that make up living things — carbohydrates, proteins, and nucleic acids — are built from smaller building blocks called monomers. These monomers are, respectively, monosaccharides, amino acids, and nucleotides. Living things build macromolecules with specific three dimensional shapes and functions by combining monomers into polymers through a process called dehydration synthesis.

[q]Compare and contrast dehydration synthesis and hydrolysis.

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[f] Living things combine monomers into polymers through enzyme-catalyzed dehydration synthesis reactions. In these reactions, a hydroxyl group (an -OH) is pulled off of one monomer (or a group of already connected monomers), and a hydrogen atom is pulled off the other. The -H and -OH combine to form water (hence, dehydration synthesis, because it involves removing a water molecule).
When living things digest or recycle polymers, they use the opposite process: enzymes insert a water molecule between the monomers making up the polymer. This breaks the bond that held the two monomers together. This process is called hydrolysis (“breaking with water”).

[q]] Name the monomer of nucleic acids, and describe this monomer’s structure. Describe how these monomers are different in DNA and RNA.

[c*] [show_me_placeholder]

[f] The monomers of nucleic acids are nucleotides, which consist of a 5-carbon sugar, a phosphate group, and one of four nitrogenous bases.
In DNA, the sugar is deoxyribose, and the bases are adenine, thymine, cytosine and guanine. In RNA, the sugar is ribose, and the bases are adenine, uracil, cytosine, and guanine.

[q]Explain how the structure and function of a protein emerges from four levels of interactions between the amino acids making up that protein.

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[f] Protein structure and function emerges from at least three and often four types of interactions between the amino acids that make up a protein.
The first level of structure is primary structure: it consists of the sequence of amino acids in a polypeptide chain. This sequence is genetically determined, and emerges as ribosomes translate messenger RNA into polypeptide chains, with each amino acid’s position and identity spelled out by codons (3 base sequences) in mRNA.
Secondary structure involves interactions between carbonyl groups and amino groups in the polypeptide backbone. These interactions can cause a polypeptide to twist into a coiled alpha helix, or form a regularly folded structure called a pleated sheet.
Interactions between amino acid side chains (also called R-groups) result in a tertiary structure. These interactions involve hydrogen bonds, ionic bonds, covalent bonds or hydrophobic clustering. The result is a complex, three dimensional shape.
Multiple polypeptides can interact to form a quaternary structure, which is found in proteins such as hemoglobin, which consists of four, interconnected, polypeptides. The bonds that stabilize a quaternary structure include hydrogen bonds, ionic bonds, and hydrophobic interactions.

[q] Explain the molecular cause of sickle cell disease.

[c*] [show_me_placeholder]

[f] Hemoglobin is the protein that transports oxygen in red blood cells. It’s a globular protein that consists of four polypeptide chains. Two of these are identical alpha chains, and two are identical beta chains. The beta chain consists of 146 amino acids.
People suffering from sickle cell disease are homozygous for a recessive mutation in which the DNA that codes for the beta chain substitutes the amino acid valine (which has a nonpolar side chain) for glutamic acid (which has an acidic side chain). This changes the overall chemistry of the resulting hemoglobin protein in such a way so that when blood becomes deoxygenated (something that happens to blood all of the time as blood delivers up oxygen to the cells), the mutated hemoglobin molecules form hydrophobic bonds with one another, causing them to aggregate into fibers. This reduces the capacity of hemoglobin to carry oxygen, and deforms the shape of red blood cells. Instead of smooth, indented disks, the cells become elongated and spiked. This in turn, causes these cells to become trapped in capillaries (the smallest blood vessels). This impedes blood flow, causing pain and tissue damage.

[q]Starch and cellulose are both polysaccharides, yet their biological functions are different. Describe the function of each, and explain their differences.

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[f] Both starch and cellulose are polymers. Starch is used by plants to store energy; cellulose is used to build cell walls. Starch can be used for energy storage because the bond that connects the glucose monomers in starch is one that’s easily hydrolyzed by enzymes in many species, including humans. Cellulose, by contrast, can’t be digested by humans. That’s because the bonds between the glucose monomers in cellulose have a configuration that few animal enzymes can hydrolyze. As a result, cellulose, when ingested, serves as a source of fiber, but not of energy.
However, some animals have formed symbiotic mutualistic relationships with microorganisms that enable them to break down cellulose in a way that releases its energy. Among the mammals, ruminants have symbiotic relationships with bacteria that can break off the glucose monomers in cellulose. As a result, ruminants can digest grass and other fibrous plants, and use these foods for energy. Termites have a symbiotic relationship with a protist (a single celled eukaryote, which carries its own bacterial endosymbiont). This enables termites to use wood as a food from which they can derive energy.

[q]Describe the structure of DNA.

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[f] DNA consists of two nucleotide strands. Within each strand, the deoxynucleotide monomers are connected to one another by sugar-phosphate bonds. The strands connect to one another by hydrogen bonds between nitrogenous bases with complementary shapes: adenine bonding with thymine and cytosine binding with guanine.

[q json=”true” unit=”2.Cell_Structure_and_Function” dataset_id=”2019 AP Bio Flashcards|1d5340acab9be4″ question_number=”36″] 1) Describe the endoplasmic reticulum. 2) List the two forms of endoplasmic reticulum, and describe their structural and functional differences.

[c*] [show_me_placeholder]

[f] 1. The endoplasmic reticulum is an interconnected series of channels found between the nuclear membrane and Golgi body in eukaryotic cells.
2. There are two forms of E.R., rough and smooth. Rough ER is studded with ribosomes. Proteins that are destined for inclusion in a lysosome, in any other organelle, in the cell membrane, or for export from the cell are synthesized at the rough E.R.
The smooth ER lacks ribosomes. It’s usually on the outer side of the ER network. While it lacks ribosomes, it has many embedded enzymes. These enzymes vary in function depending on the tissue in which the cell is found, but one function to remember is detoxification of poisons into forms that can be safely excreted from the body.

[q]Describe the structure and function of the Golgi complex.

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[f] The Golgi complex consists of a series of membrane-bound flattened sacs. The Golgi receives vesicles from the rough and smooth ER, and chemically modifies the contents of these vesicles (usually proteins). Once these proteins are modified, they’re packaged into vesicles that bud off from the outer side of the Golgi, and sent to organelles, to the cell membrane, or exported from the cell.
Note that the Golgi complex is also called the Golgi body, or the Golgi apparatus.

[q]Describe the function of mitochondria.

[c*] [show_me_placeholder]

[f] The mitochondria’s overall function is creation of ATP, something that we’ll learn a great deal about this term.

[q]Describe the structure and function of lysosomes.

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[f] Lysosomes are membrane-bound organelles that contain hydrolytic enzymes. They’re only found only in animal cells; (while plant vacuoles play similar roles, the two are considered to be distinct organelles).
One function of the lysosome is intracellular digestion. After a cell ingests a particle by endocytosis, the particle will be enclosed in a vesicle, which will fuse with a lysosome. The lysosome will digest the particle. Lysosomes also recycle worn out, damaged, or excess organelles and molecules. They also play a key role in what’s called programmed cell death, an essential process involved in development (a second semester topic).

[q]Describe the structure and function of vacuoles.

[c*] [show_me_placeholder]

[f] Vacuoles are membrane bound organelles, generally used for storage. Plant cells contain a large central vacuole which stores water, and which also has a variety of other functions, including storing and releasing needed macromolecules, storing waste products, and maintaining turgor pressure.

[q]Describe the function of chloroplasts.

[c*] [show_me_placeholder]

[f] The chloroplast’s function is photosynthesis, something we’ll be learning about this term.

[q]Use the relationship between surface area and volume to explain why cells are small.

[c*] [show_me_placeholder]

[f] Needed substances, such as glucose and oxygen, enter cells by diffusing in through the cell’s membrane, and then diffusing throughout the cell’s volume. Metabolic wastes (like carbon dioxide) are generated inside the cell, and can only leave by diffusing from wherever they’re generated through the membrane. Cells need to be small in order to have sufficient membrane surface area to allow for efficient diffusion of substances in and out.
Small size is required because as an object gets larger, the amount of surface area it has relative to its volume decreases. For example, think of a cubical cell that’s 1 unit in length. Its surface area is 1 x 1 x 6 (six square units of surface area); while its volume is 1 x 1 x 1 (1 cubic unit of volume) so its surface area to volume ratio is 6:1. Increase that cell’s length to 10 units, and its surface area is now 10 x 10 x 6 (600 square units of surface area, and its volume is 10 x 10 x 10 (1000 cubic units of volume). The larger cell’s surface area to volume ratio is 0.6:1. In other words, the larger cell’s surface area to volume ratio is 1/10th that of the smaller cell. With such a small amount of surface area relative to its volume, a large cell can’t efficiently use diffusion to get the nutrients it needs, and to release wastes.

[q]Describe some examples where individual cells or entire organisms need to increase their surface area. Describe how they do this.

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[f] Cells or organisms may need additional surface area in order to increase the amount of molecules that can enter or leave by diffusion, or to increase available surface for radiation of heat from the body to the environment. Cells might also need more working surface for membrane-embedded enzymatic reactions.
An example of increasing the surface for diffusion of molecules is seen in structures like root hairs in roots, the gills of fish (which are organized as thin sheets of tissue) or the epithelial cells that make up the lining of the gut (which have a highly folded shape).
Structures organized for increasing working surface for enzymatic reactions include the highly folded endoplasmic reticulum or inner mitochondrial membrane.
Flattened structures also have lots of surface area relative to their volume: these include structures like the flattened sacs of the Golgi complex. On a much larger level, the flat ears of elephants is an adaptation that increases surface area for radiating heat into the environment.

[q] Describe the role of phospholipids in cell membranes.

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[f] Phospholipids form the basic structure of the membrane. This function emerges from their chemical structure. Phospholipids have a hydrophilic, phosphate-bearing head, and a hydrophobic tail consisting of two hydrocarbon chains. When mixed with water, phospholipids will spontaneously self-organize into several configurations, one of which is a bilayer: the basic structure of a biological membrane.
In a membrane bilayer, two layers of phospholipids form a structure in which the hydrophobic fatty acid tails create a water free zone (the inside of the membrane), while the hydrophilic heads face outwards toward the watery environment outside of the cell, and the cell’s watery, cytoplasmic interior. This structure is further stabilized by weak bonds between the hydrophobic tails (called London dispersion forces).

[q]Describe the difference between transmembrane, integral, and peripheral proteins.

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[f] Proteins can embed into the membrane in several ways. Some proteins are transmembrane proteins: these have a hydrophobic core that fits into the nonpolar inner portion of the membrane, with hydrophilic regions extending into the cytoplasm below and the membrane exterior above. Other proteins might have a nonpolar region that embeds into the hydrophobic membrane middle, with a single hydrophilic region that juts into the cytoplasm or cell exterior. These are called integral proteins. Note that by definition, transmembrane proteins are also integral (but the opposite is not true). Other proteins are peripheral, attaching to phospholipid heads that are either on the cytoplasm side of the membrane, or the cell exterior.

[q]Describe the importance of membrane proteins.

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[f] While phospholipids make up the structural framework of the membrane, many membrane functions are only possible because of membrane proteins (which can outweigh the phospholipid portion by weight). Here are two functions you should already know about.
• Channels or ports, allowing the cell to take in and let out molecules that cannot diffuse through the phospholipid bilayer portion of the membrane.
• Carriers, allowing the cell to perform active transport, moving molecules from low concentration to high concentration.
Here are a few more that you’ll learn about later in the year.
• Attachment points for the fibers of the cytoskeleton, allowing the cell to change its shape and move.
• Membrane-embedded enzymes. These are involved in cell processes like photosynthesis, cellular respiration, and intracellular digestion.
• Receptors, receiving chemical messages (including hormones) and relaying these messages into the cytoplasm.

[q]Describe the fluid mosaic model of the cell membrane.

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[f] Cell membranes can be described as fluid mosaics. They’re fluid because their components are in constant motion, moving laterally within the plane of the membrane. They’re mosaics because they’re composed of a variety of pieces: phospholipids, proteins, and additional molecules like cholesterol. On the membrane’s inside and outside, various additional molecules might be attached to proteins or phospholipids, including glycoproteins (proteins with carbohydrates attached) and glycolipids.

[q]Compare and contrast simple diffusion with facilitated diffusion.

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[f] Biological membranes allow small nonpolar molecules such as carbon dioxide, nitrogen, and oxygen to freely diffuse across the membrane’s phospholipid bilayer, following their diffusion gradient. That’s called simple diffusion.
However, polar molecules and ions won’t diffuse through a phospholipid bilayer. To allow their diffusion, cells have protein channels: transmembrane proteins that only let specific molecules or ions pass, depending on the cell’s needs. This is called facilitated diffusion.

[q]Describe the chemical composition and the function of the plant cell wall.

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[f] Plant cell walls are composed primarily of cellulose, a polysaccharide. The wall’s major function is to serve as a kind of pressure vessel: a rigid boundary that prevents the cell from over-expanding in response to osmotic pressure as water flows into a cell, causing it to expand. This maintains turgor pressure, keeping plant cells firm and preventing plants from wilting.
As you’ll learn later in the year, the cell wall also plays a key structural role in plant stems, making up wood and xylem, the conductive tubes that allow water to move up a plant stem.

[q]Compare and contrast active and passive transport. As you do, explain what powers each process.

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[f] Passive transport is transport that allows molecules or ions to follow their diffusion gradient, diffusing from high concentration to low concentration. Passive transport relies on the kinetic energy in the diffusing molecules or ions, and doesn’t require any metabolic energy to be expended by the cell.
Active transport involves pumping a molecule or ion up its concentration gradient, from lower concentration to higher concentration. This requires energy on the part of the cell.

[q]Compare and contrast endocytosis and exocytosis.

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[f] Movement of very large molecules or other particles across the plasma membrane occurs through bulk transport, a type of process that involves large scale movements of the membrane, and which requires expenditure of cellular energy. In exocytosis, cells dump the contents of vesicles outside of the cell. In endocytosis, the membrane buckles in a way that surrounds a molecule, a particle, or some extracellular fluid, creating a cavity that becomes a vesicle.

[q]What is receptor-mediated endocytosis? What is phagocytosis?

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[f] • In receptor-mediated endocytosis, a piece of the membrane pinches in response to some molecule that binds with a receptor embedded in the membrane. This brings that molecule (and the surrounding fluid) into the cell.
• During phagocytosis, the cell uses its membrane to surround a particle (or even another cell). The membrane pinches in to form a vesicle which enters the cytoplasm. Phagocytosis is used by white blood cells in the immune response to swallow invaders. Single celled organisms like amoebas use phagocytosis to eat.

[q]Compare and contrast the terms hypotonic, hypertonic, and isotonic, and use these terms to explain the flow of water into or out of cells.

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[f] Hypotonic, hypertonic, and isotonic are all relative terms. If a cell is in a hypotonic environment, that means that the solution that the cell is in has less solute and more water than does the cell under consideration. Because water always flows from hypotonic (where the water is more concentrated) to hypertonic, water will flow from the hypotonic solution into the cell. The cell, in short, will gain water.
A cell in a hypertonic environment is in the reverse situation. In this case, the cell’s environment has relatively less water and more solute than the cell does. This makes the cell hypotonic to its environment, and water will flow from the cell to its environment. The cell will lose water.
A cell in an isotonic solution has the same concentration of solutes and water as the solution that it’s in. Water will flow into and out of the cell at the same rate, so it neither gains or loses water.

[q]Describe the consequences of being in a hypotonic or hypertonic environment for animal and plant cells.

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[f] An animal cell in a hypotonic environment will take up water as water flows from the hypotonic environment into the cell. The cell will expand, and eventually burst. In a hypertonic environment, an animal cell will shrink and shrivel as it loses water.
A plant cell in a hypotonic environment will take up water as water flows into the cell. The cell will expand, but its expansion will be limited by the cell’s rigid cell wall. The cell will become turgid, which is a healthy condition for a plant cell. In a hypertonic environment, water will flow out of a plant cell. This will pull the membrane away from the cell wall. The lack of pressure will cause the plant itself to wilt.

[q]Cellular compartmentalization marks a major evolutionary advance. Specify how that advance is thought to have occurred.

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[f] Cellular compartmentalization is the innovation that separates eukaryotic from prokaryotic cells. That means that compartmentalization can be dated back to the origin of eukaryotic cells, which arose about 2 billion years ago. It’s widely thought that compartmentalization initially arose through endosymbiosis, specifically by the incorporation of the ancestor of mitochondria (which was a bacterial cell) into an archaeal cell.

[q]Describe the advantages of cellular compartmentalization.

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[f] Cellular compartmentalization allows for the creation of membrane-enclosed compartments that can have an internal chemistry that differed from the cytoplasm as a whole. For example, the interior of a lysosome contains hydrolytic enzymes that can safely work within the lysosome, without exposing the rest of the cell’s volume to these hydrolytic enzymes. Similar regions of unique chemistry can be found in the ER, the Golgi, or vacuoles.

[q]Compare compartmentalization in prokaryotic and eukaryotic cells

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[f] In general, prokaryotic cells are not compartmentalized, though they do have internal regions with specialized structures and functions. Eukaryotic cells are highly compartmentalized, with many internal membranes that divide the cell into regions with distinct structures, chemistry, and functions. Examples of cellular compartments within eukaryotic cells include lysosomes, the E.R., the Golgi complex, and vacuoles.

[q]What’s the evidence for the idea that chloroplasts and mitochondria were once free living bacterial cells that arose through endosymbiosis?

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[f] There are at least 3 lines of evidence supporting this idea.
• First, both organelles (mitochondria and chloroplasts) have their own DNA, and this DNA is organized into a circular chromosome that is similar to a bacterial chromosome.
• Second both organelles use their own ribosomes to produce some of their own proteins. These ribosomes resemble bacterial ribosomes in terms of their rRNA sequence and structure.
• Finally, both chloroplasts and mitochondria have double membranes. The outer membrane is thought to be a vestige of the host cell membrane that engulfed the ancestral mitochondrion and chloroplast when the endosymbiotic relationship first arose nearly two billion years ago.

[q] Water is a [hangman] molecule. The oxygen side has a partially  [hangman] charge. The hydrogen side has a partially [hangman] charge. The bonds that form between water molecules are called [hangman] bonds. These same types of bonds also form between the complementary nitrogenous [hangman] of DNA (such as between adenine and thymine).

[c] polar

[f] Great!

[c] negative

[f] Great!

[c] positive

[f] Correct!

[c] hydrogen

[f] Correct!

[c] bases

[f] Good!

[q] It takes a lot of energy to make water evaporate because that requires the breaking of [hangman] bonds.

[c] hydrogen

[f] Good!

[q] The monomers of carbohydrates are [hangman]. An example is glucose, a six carbon sugar. Put two of these together and you have a [hangman] like sucrose or lactose. More than three of these monomers together make a [hangman], like starch or cellulose.

[c] monosaccharides

[f] Great!

[c] disaccharide

[f] Excellent!

[c] polysaccharide

[f] Correct!

[q] Cellulose is used by plants to make up their cell [hangman]. It’s a polymer of [hangman]. Humans lack the [hangman] to break down cellulose for energy, but it’s still and important source of [hangman] in the diet. By contrast, humans have the enzymes to break down another plant polysaccharide, [hangman]. This molecule, found in staples like rice, corn, wheat, and potatoes, which is a hugely important source of food energy.

[c] walls

[f] Good!

[c] glucose

[f] Correct!

[c] enzymes

[f] Excellent!

[c] fiber

[f] Correct!

[c] starch

[f] Great!

[q] [hangman]are molecules that are nonpolar (or have large nonpolar regions). Fats and oils are both [hangman]. With three [hangman] acids, these molecules have the most energy of any nutrient. Another molecule in this family, [hangman],make up cell membranes.

[c] Lipids

[f] Great!

[c] triglycerides

[f] Great!

[c] fatty

[f] Good!

[c] phospholipids

[f] Good!

[q] The [hangman] of a phospholipid is polar and [hangman]. The [hangman] is hydrophobic.  When mixed with water, phospholipids spontaneously form a [hangman], a structure which is the basis for the cell [hangman] of eukaryotes and bacteria.

[c] head

[f] Correct!

[c] hydrophilic

[f] Excellent!

[c] tail

[f] Correct!

[c] bilayer

[f] Great!

[c] membrane

[f] Good!

[q] Proteins are polymers of [hangman] acids. All of the monomers of proteins have a [hangman] group and an amine group. Each protein monomer, however, has a distinct [hangman] chain, also known as an R group.

[c] amino

[f] Good!

[c] carboxyl

[f] Great!

[c] side

[f] Good!

[q] Both DNA and RNA are [hangman] acids. While [hangman] stays within a eukaryotic cell’s nucleus, RNA moves out into the [hangman]. One form of RNA, [hangman] is translated by [hangman] into protein.

[c] nucleic

[f] Good!

[c] DNA

[f] Good!

[c] cytoplasm

[f] Excellent!

[c] mRNA

[f] Excellent!

[c] ribosomes

[f] Correct!

[q] The molecular building blocks of the molecules of life are called [hangman] When many of these are chained together by enzymes during [hangman] synthesis reactions, they form [hangman].

[c] monomers

[f] Excellent!

[c] dehydration

[f] Excellent!

[c] polymers

[f] Good!

[q] The monomer of nucleic acids are [hangman]. In DNA, these monomers consist of a 5 carbon sugar called [hangman], one of four nitrogenous [hangman], and a [hangman] group.

[c] nucleotides

[f] Correct!

[c] deoxyribose

[f] Excellent!

[c] bases

[f] Good!

[c] phosphate

[f] Great!

[q] Proteins have four levels of structure. Primary structure is the linear sequence of [hangman] acids. Secondary structure involves interactions between carbonyl groups and amine groups within the polypeptide [hangman]. Secondary interactions result in structures like the corkscrew-like alpha  [hangman] and the folded beta [hangman] sheet. Tertiary structure creates twists and turns in the protein that are caused by interactions among the [hangman] chains. In quaternary structure, two or more folded [hangman] chains interact with each other.

[c] amino

[f] Excellent!

[c] backbone

[f] Great!

[c] helix

[f] Good!

[c] pleated

[f] Good!

[c] side

[f] Correct!

[c] polypeptide

[f] Excellent!

[q] DNA is a double [hangman]. If DNA were a ladder, its sides would be made of alternating [hangman] and phosphate groups. The rungs would be made of nitrogenous bases, connected by [hangman] bonds.

[c] helix

[f] Great!

[c] sugar

[f] Excellent!

[c] hydrogen

[f] Great!

[q] Moving from the inside out, the cell’s endomembrane system starts with the [hangman] membrane, which separates the DNA from the cytoplasm. Next comes the [hangman] E.R., which contains many [hangman]. The smooth ER follows: its function includes synthesis of [hangman]. Proteins move from the ER to the [hangman] complex, which packages and processes these proteins. Proteins move from compartment to compartment by means of membrane-bound [hangman].

[c] nuclear

[f] Good!

[c] rough

[f] Great!

[c]ribosomes

[c] lipids

[f] Great!

[c]Golgi

[c] vesicles

[f] Great!

[q] Cell membranes can be described by the fluid [hangman] model. The basic idea is that a [hangman] bilayer forms the overall framework. Into this framework are many membrane embedded [hangman] which act as channels, receptors, and attachment points for the cytoskeleton. A lipid molecule called [hangman] has the function of maintaining membrane fluidity and stability.

[c] mosaic

[f] Correct!

[c] phospholipid

[f] Correct!

[c] proteins

[f] Excellent!

[c] cholesterol

[f] Good!

[q] In [hangman] diffusion, small or nonpolar molecules can diffuse right across the membranes’ phospholipid bilayer. During [hangman] diffusion, molecules diffuse through a protein channel. In [hangman] transport, cells use energy (often in the form of ATP) to pump molecules “uphill,” moving against a [hangman] gradient.

[c] simple

[f] Excellent!

[c] facilitated

[f] Good!

[c] active

[f] Great!

[c] concentration

[f] Good!

[q] If a cell is in a [hangman] environment, then the environment has less solute than the cell has, and water will flow [hangman] the cell. This will cause an animal cell to [hangman] and ultimately burst. However, this same condition is actually healthy for plant cells because of their cell [hangman].

A cell in an [hangman] environment has the same concentration of solutes inside the cell as outside the cell.

[c] hypotonic

[f] Good!

[c] into

[f] Correct!

[c] expand

[f] Correct!

[c]wall

[c] isotonic

[f] Great!

[q] One of the biggest difference between eukaryotic cells and prokaryotic cells is the fact that the former have many internal  [hangman], such as the Golgi, the ER, lysosomes and vesicles. These structures can have an internal chemistry that’s very different from the [hangman] as a whole. In lysosomes, for example, the pH is much [hangman] than in the rest of the cell, allowing that organelle to carry out its unique hydrolytic functions

[c] compartments

[f] Great!

[c] cytoplasm

[f] Excellent!

[c] lower

[f] Good!

[q] Multiple lines of evidence support the idea that chloroplasts and mitochondria were once independent prokaryotic cells that were taken up by another cell to form the first [hangman] cells. This relationship between eukaryotes and their prokaryotic inhabitants has two components. A relationship in which one organism lives inside another one is [hangman]. A relationship where two organisms benefit one another is called [hangman].

Here’s the evidence for this idea:
1) Both mitochondria and chloroplasts have their own [hangman]. organized into a single circular chromosome.
2) Both organelles use their own [hangman] to produce some of their own proteins. These resemble similar structures in bacterial cells.
3) Both chloroplasts and mitochondria have [hangman] membranes. The outer membrane is thought to be a vestige of the membrane  of the host cell that engulfed the ancestral mitochondrion and chloroplast  nearly two billion years ago.

[c] eukaryotic

[f] Great!

[c] endosymbiosis

[f] Excellent!

[c] mutualism

[f] Excellent!

[c] DNA

[f] Good!

[c] ribosomes

[f] Good!

[c] double

[f] Correct!

[q]Cells are small because small objects have a high [hangman] of surface area relative to their [hangman]. Many biological adaptations in large, multicellular organisms are about increasing the amount of internal or external surface area. For example, the intestines have a folded wavy structure to increase the rate of [hangman] of molecules into the bloodstream. The huge ears of elephants are an adaptation for increasing the [hangman] of heat from inside the body.

[c]ratio

[c]volume

[c]diffusion

[c]diffusion

[/qwiz]