1. Unit 4 Learning Objectives

Topics 4.1.-4.4: Cell Signaling, Cell Communication, and Signal Transduction

Describe three ways that cells communicate with one another, and provide examples of each one.
- Cell-to-cell contact (examples: immune signaling, plasmodesmata)
- Short distance signaling using local regulators (examples: neurotransmitters, quorum sensing, morphogens during embryonic development)
- Long-distance signaling (examples: endocrine signaling)
Describe the function of signal transduction
- linking signal reception with a cellular response
List the three components of signal transduction systems
- reception, transduction, response
Describe the key features of reception
- specific receptors — usually membrane proteins — bind with ligands.
Describe the key features of signal transduction
- ligand binding leading to changes in the intracellular domain of a membrane protein;
- propagation of the signal to and through second messengers such as cyclic AMP;
- amplification of the signal through phosphorylation cascades.
List examples of cellular responses that result from signal transduction
- Examples: cell division, secretion of molecules, gene expression, apoptosis.
Explain how changes in the components of a signaling system (ligand, receptor, transduction components) can alter cellular responses.
- Mutations in receptors (changes in shape or number) can affect downstream signal transduction.
- Chemicals interfering with any part of a signaling system component can change transduction.

Topic 4.5: Feedback and Homeostasis

Describe the function of feedback mechanisms
- Maintaining internal environments and responding to internal and external environmental changes.
Define the physiological concept of a set point.
- The value around which a physiological process fluctuates. For example, the temperature set point in humans is 37 degrees C.
Explain how negative feedback helps to maintain homeostasis
- Returning a perturbed system to its target set point.
Explain how positive feedback works
- Amplifying responses and processes in a way that increases the initial stimulus, which further activates the response.

Topic 4.6: Cell Division and the Cell Cycle

Compare and contrast cell division in prokaryotes and eukaryotes
- binary fission v. mitosis
Describe the functions of cell division in eukaryotes
- Asexual reproduction, growth, and repair.
List the phases of the cell cycle, and explain what happens during each phase
- List: interphase, G₁, S, G₂, M
Explain the importance of the G₀ phase.
Describe, on a big-picture level, what happens in mitosis
- Cloning of a parent cell’s entire genome into two genetically identical daughter cells
List and describe the phases of mitosis.

Topic 4.7: Cell Cycle Regulation

Describe how the cell cycle is regulated
- answers should include a general description of internal checkpoints, and how these checkpoints work to control progression through the cycle
Explain how interactions between cyclins and cyclin-dependent kinases control the cell cycle.
Describe how disruptions to the cell cycle can lead to cancer.
- Cancer can result from any process that increases cell division, removes inhibition of cell division, or both.
- Processes that increase cell division are connected to mutations in oncogenes. Processes that remove cell division inhibitors are connected to mutations in tumor suppressor genes.
Define apoptosis
- A regulated process resulting in cell death.

2. Unit 4 Flashcards

[qdeck style=”width: 550px !important; min-height: 400px !important;” bold_text=”false” scroll=”true” qrecord_id=”sciencemusicvideosMeister1961-Unit 4 Flashcards (v2.0)” dataset=”Unit 4 Cumulative Flashcards Dataset, v2.0″ dataset_intro=”true”]

[h] Unit 4 Flashcards

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|142764643a3ff9″ question_number=”1″ topic=”4.1.Cell_Communication”] On the most fundamental level, what are the two ways that cells communicate with one another?

[a] Cells can communicate with one another by 1) direct contact, or by 2) sending chemical signals to one another. These chemical signals might travel very short distances between cells that might be close to one another. Or they might travel between distant parts of the body (endocrine signaling), or even between different organisms (pheromone signaling).

*Note: Terms like “paracrine” (or “juxtacrine”) are not important to know. On the other hand, every biology student should know what the endocrine system is. It’s the system of glands that release hormones into the blood.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|14274ac7b773f9″ question_number=”2″ topic=”4.1.Cell_Communication”] Describe how cell communication via cell-to-cell contact occurs in plants.

[a] Plant cells can directly communicate via plasmodesmata. These are gaps in the cell walls of adjacent cells. These gaps allow the cell membranes of adjacent cells to form an open channel through which cytoplasm can flow, allowing for the passage of molecules and ions from cell to cell, including ions and molecules that serve as cell signals.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1427153aa5f7f9″ question_number=”3″ topic=”4.1.Cell_Communication”] In terms of cell communication, what’s a “local regulator?” How is this type of signaling different from endocrine signaling?

[a] Local regulators are signaling molecules that work over short distances (but without the cells touching). Endocrine glands, by contrast, release their signals (hormones) into the blood and can have an effect on the most distant parts of the body.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.1.Cell_Communication” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1426f94a1747f9″ question_number=”4″] How do neurons (nerve cells) communicate with one another (or with their targets)?

[a] Neurons signal one another (or their targets) by releasing molecules called neurotransmitters (a) across tiny gaps called a synapse (2). The neurotransmitters bind with receptors (d and e) in the second cell.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.1.Cell_Communication” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1426e201a05ff9″ question_number=”5″] Local signaling is a key part of embryonic development. Describe how this works.

[a] During embryonic development ligands called morphogens (1) are synthesized and released in one group of cells (A), and then diffuse to nearby cells (B), activating genes or inducing apoptosis (programmed cell death).

[q json=”true” unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1426c61111aff9″ question_number=”6″ topic=”4.1.Cell_Communication”] What’s a biofilm? Explain how bacteria use quorum sensing during biofilm formation.

Illustrative Example, Cell Communication

[a] A biofilm is a slimy matrix of extracellular polymers that improve the ability of bacteria to stick to a substrate (such as your teeth, where they contribute to the formation of dental plaque). As the bacteria form a biofilm, they use quorum sensing to determine when to secrete molecules that provide them with increased virulence and antibiotic resistance, and when to form spores that would enable them to create additional bacterial colonies.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1426aec89ac7f9″ question_number=”7″ topic=”4.1.Cell_Communication”] What is quorum sensing?

Illustrative Example, Cell Communication

[a] Quorum sensing is a process by which organisms restrict the expression of certain genes (represented by “4” on the right) until cell density reaches a certain level. That’s because only at that level will the phenotype that results from the expression of these genes be beneficial. The use of quorum sensing has been documented in bacteria, plants, and social insects (but might be more widely used).

[!]4.2 – 4.4. Signal Transduction[/!]

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1426952c17fbf9″ question_number=”8″ topic=”4.2-4.Signal_Transduction”] Cell signaling involves 3 key phases. List them.

[a] The three phases of cell signaling are I) reception; II) signal transduction (often with signal amplification), and III) cellular response.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.2-4.Signal_Transduction” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1426793b894bf9″ question_number=”9″] On a big-picture level, describe what happens during the reception phase of cell to cell signaling.

[a] During reception a receptor molecule embedded in the cell membrane (2) binds with a signal molecule (1: also called a ligand). This binding is based on complementary shape.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.2-4.Signal_Transduction” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|14265d4afa9bf9″ question_number=”10″] Briefly describe what happens during the transduction phase of cell to cell signaling.

[a] During transduction, binding of the ligand with the receptor induces a conformational change in the receptor on its cytoplasmic side, which activates a second messenger, often cyclic AMP (6). This second messenger then interacts with molecules in the cytoplasm (8) in a way that results in cellular response (9)

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.2-4.Signal_Transduction” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1426415a6bebf9″ question_number=”11″] Briefly describe what happens during the response phase of cell signaling.

[a] During the response phase, the amplified signal that arose during transduction (represented by 4 and 5 on the right) finally reaches the target (6). Changes in the target molecule, which often involve the activation of an inactive enzyme, bring about the cellular response.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|14260e216653f9″ question_number=”12″ topic=”4.2-4.Signal_Transduction”] Describe how binding of epinephrine with receptors on the surface of liver cells leads to the release of cyclic AMP.

Illustrative Example: Cell communication

[a] Epinephrine (8) binds with a G-protein coupled receptor. Binding causes a change in shape on the cytoplasmic side of the receptor, enabling the receptor to bind with a G protein (2). Binding causes the G protein to release GDP (3) and bind with GTP (9). This activates the G protein, allowing it to move until it hits the membrane-embedded enzyme adenylyl cyclase (4), which converts a molecule of ATP into cyclic AMP (cAMP).

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1425f484e387f9″ question_number=”13″ topic=”4.2-4.Signal_Transduction”] When epinephrine binds with a G-protein coupled receptor in cells in the liver, changes in the membrane result in the release of a second messenger, cyclic AMP. Describe how, as part of the fight or flight response, the release of this second messenger can result in the conversion of glycogen to glucose.

Illustrative Example: Cell communication

[a] Cyclic AMP (5) binds with proteins called kinases (b-k) which activate other kinases in what’s called a phosphorylation cascade. Through signal amplification, millions of target molecules (in this case, glycogen phosphorylase) are activated. As a result, glycogen is hydrolyzed to glucose, which diffuses from the liver into the bloodstream, where it can assist the skeletal muscles as they carry out the fight-or-flight response.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1425d89454d7f9″ question_number=”14″ topic=”4.2-4.Signal_Transduction”] Describe how steroid hormones (such as testosterone or estrogen) work.

Illustrative Example: Cell communication

[a] Steroid hormones (F) are nonpolar, and therefore able to diffuse through the membrane’s phospholipid bilayer and into the cytoplasm. Once there, they bind with mobile cytoplasmic receptors (G). This creates a hormone-receptor complex (H), which can diffuse through nuclear pores and enter the nucleus. There, the hormone-receptor complex can interact with DNA and activate genes. This often causes long-term cellular changes, such as changes associated with puberty, which are caused by steroid hormones such as testosterone and estrogen.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1425bca3c627f9″ question_number=”15″ topic=”4.2-4.Signal_Transduction”] List some of the cellular responses that can be elicited by signal transduction pathways, and provide specific examples.

Illustrative Example: Cell communication

Note: on the AP exam you won’t need to list these by memory, but there could be questions about any of the examples in the answer on the reverse side of this card.

[a] Signal transduction pathways can result in

enzyme activation (epinephrine acting upon liver cells),
cell division (cytokines inducing cell division, which is an important part of mobilizing an immune response).
changes in gene expression (various morphogens activating genes in other cells during development), and
apoptosis (programmed cell suicide, which occurs in a variety of circumstances, including during development).

[q json=”true” unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.2-4.Signal_Transduction” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|14258716b4abf9″ question_number=”16″]Explain how changes in any of the components of a signaling system (ligand, receptor, transduction components) can alter cellular responses.

[a]

Mutations in receptors (changes in shape or number) can affect downstream signal transduction. One such mutation in HER2 receptors is strongly associated with abnormal signaling during cell division, resulting in breast cancer.
Chemicals interfering with any part of a signaling system component can change transduction. This can change cell behavior and growth patterns in tissues and organs.

[!]4.5.Feedback[/!]

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.5.Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|142553ddaf13f9″ question_number=”17″] What are the functions of feedback mechanisms?

[a] Feedback mechanisms allow organisms to maintain homeostasis as they respond to changes within their bodies or in their external environment.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.5.Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|14253a412c47f9″ question_number=”18″] Define the physiological concept of a setpoint.

[a] A setpoint is the value around which a physiological process fluctuates. For example, the setpoint for human body temperature is 37 degrees C. The setpoint for blood glucose is about 90 mg/dL (milligrams/deciliter)

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|142520a4a97bf9″ question_number=”19″ topic=”4.5.Feedback”] Explain the difference between positive and negative feedback.

[a] In positive feedback, the output of a system feeds back into the system, increasing the system’s activity and output. Positive feedback drives a biological process (such as childbirth) to a conclusion, after which the system shuts down.

In negative feedback, the output of a system feeds back to the system in a way that decreases the system’s output. Negative feedback is essential in homeostasis, returning a system to its set point.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|142504b41acbf9″ question_number=”20″ topic=”4.5.Feedback”] Describe how feedback functions during childbirth.

Illustrative Example: Cell communication

[a] Childbirth is an example of positive feedback. During childbirth, the baby’s head pushes against its mother’s cervix (the tip of the uterus at the end of a female mammal’s vagina), stretching the tissue. Nerve impulses from the cervix to the brain cause secretion of the hormone oxytocin from the pituitary gland into the blood. In the uterus, oxytocin causes the uterine muscles to contract. This pushes the baby’s head against the cervix even more, which feeds back to the pituitary, which secretes more oxytocin, increasing uterine contractions. The process ends when the baby is born.

[q json=”true” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1424ed6ba3e3f9″ question_number=”21″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.5.Feedback”] Describe how feedback functions during fruit ripening.

Illustrative Example: Cell communication

[a] Fruit ripening is an example of positive feedback. As a fruit ripens, a variety of cellular changes occur, one of which is the production of the hormone ethylene, a gas that is released into the surrounding air. Ethylene receptors in nearby fruit bind with the ethylene, inducing them to ripen and produce their own ethylene. Increased concentration of ethylene accelerates the ripening process in all the affected fruit, causing the release of more ethylene, which in turn enhances the ripening process.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1424d17b1533f9″ question_number=”22″ topic=”4.5.Feedback”] Explain how insulin works to maintain blood glucose homeostasis.

Illustrative Example: Homeostasis

[a] When blood glucose levels increase above their optimal set point (about 90mg/dL), Beta cells in the pancreas secrete insulin into the blood. When insulin binds with insulin receptors in tissues in the liver and skeletal muscles, these cells open up glucose channels. Glucose diffuses from the blood into these cells, where it’s converted into glycogen, a polysaccharide. In fat cells, the absorbed glucose is converted into fat. This absorption of blood glucose lowers blood glucose levels back to the set point, and this feeds back to the pancreas, shutting down insulin secretion.

[q json=”true” unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1424b0e26ebbf9″ question_number=”23″ topic=”4.5.Feedback”] Explain how glucagon works to maintain blood glucose homeostasis.

Illustrative Example: Homeostasis

[a] When blood glucose levels fall, alpha cells in the pancreas secrete glucagon. Glucagon diffuses into the bloodstream. When glucagon binds with receptors in its target cells in the liver and skeletal muscles, it causes these cells to break down glycogen into glucose. The glucose diffuses into the bloodstream, raising blood glucose levels back to the set point. This is detected by cells in the pancreas, which shut down glucagon secretion.

[q json=”true” unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.5.Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|142476ad4577f9″ question_number=”24″] Sketch a diagram showing how glucagon and insulin maintain blood glucose homeostasis.

Illustrative Example: Homeostasis

Importance for the AP exam: High

[a] Key to unlabeled parts:

A. Glucose set point; D. Insulin; G. Blood glucose falls; J. Glucagon; L. Blood glucose rises.

[!]4.6.Cell Cycle[/!]

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|14245abcb6c7f9″ question_number=”25″ topic=”4.6.Cell_Cycle”] List the two major phases of the cell cycle. Then list the sub-phases of each phase. (note: this is not asking you to describe the stages of mitosis, but the entire cycle).

[a] The cell cycle consists of two major phases: Interphase (I) and M Phase. Interphase has 3 sub-phases: G₁, S, and G₂. M Phase has 2 sub-phases: mitosis and cytokinesis.

[q json=”true” unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|14243ecc2817f9″ question_number=”26″ topic=”4.6.Cell_Cycle”] Describe what occurs in each of the three sub-phases of interphase.

[a] Interphase involves three sub-phases.

G₁ is a growth phase in which the cell increases in size. At the end of G₁ is a checkpoint in which the cell checks that everything is ready for DNA replication.
If a cell passes the G₁ checkpoint, it enters the S (synthesis) phase. During this phase, DNA is replicated.
Following S the cell enters into G₂. G₂ involves the continued growth and production of molecules and structures required for the M phase. G₂ ends with another checkpoint.

If the G₂ checkpoint is passed, the cell enters into the M phase (mitosis and cytokinesis)

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1424252fa54bf9″ question_number=”27″ topic=”4.6.Cell_Cycle”] On the big picture level, what does mitosis do? List three of its key functions in living things. Note that in this context, “mitosis” is synonymous with “eukaryotic cell division.”

Importance for the AP exam: High

[a] Mitosis duplicates the chromosomes of a eukaryotic cell, transmitting that cell’s entire genome to its daughter cells. In multicellular organisms, mitosis is how the organism grows and repairs itself. In unicellular eukaryotes, mitosis is how reproduction occurs.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1423e1aa4c77f9″ question_number=”28″ topic=”4.6.Cell_Cycle”] Describe the three phases of mitosis that follow metaphase.

Importance for the AP exam: Medium

[a] During anaphase, the sister chromatids are pulled apart (3), and dragged to opposite ends of the cell. Non-kinetochore microtubules cause the cell to elongate. During telophase, a new nuclear membrane (2) forms around each set of chromosomes. The chromosomes spread out, and a nucleolus appears in each nucleus. During cytokinesis, the cell splits apart into two daughter cells.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.6.Cell_Cycle” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1423a2cd0b6bf9″ question_number=”29″] Briefly describe the first three stages of mitosis.

[a] During interphase, the cell grows and replicates its DNA. (2). During prophase, the chromosomes (3) condense, the nuclear membrane (2) disintegrates, and a spindle apparatus (1) begins to form. During metaphase, the spindle fibers, pull each chromosome to the cell equator. Each chromosome is doubled, consisting of two sister chromatids.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.6.Cell_Cycle” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|142386dc7cbbf9″ question_number=”30″] Explain the importance of the G₀ phase of the cell cycle.

Importance for the AP exam: Medium

[a] Not all cells go through the entire cycle. Any specialized cell — muscle cells and nerve cells, for example — leaves the cell cycle and enters into what’s called G₀. Cells in G₀ no longer divide. Certain stimuli, however, can induce a cell in G₀ to reenter the cell cycle.

[!]4.7.Regulation of the Cell Cycle[/!]

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|14236d3ff9eff9″ question_number=”31″ topic=”4.7.Regulation_of_the_Cell_Cycle”] What are cyclins and cyclin-dependent kinases?

[a] Cyclins are molecules whose concentration rises and falls throughout the cell cycle. Kinases are a class of molecules that activate other molecules, often by phosphorylating them. Cyclin-dependent kinases, or CDKs, are kinases that respond to rising and falling cyclin levels.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1423514f6b3ff9″ question_number=”32″ topic=”4.7.Regulation_of_the_Cell_Cycle”] What can happen when the cell cycle is disrupted?

[a] Disruptions to the cell cycle can cause cells to divide when they’re not supposed to. Abnormally accelerated cell division can lead to cancer. Alternatively, if cells don’t divide correctly during embryonic development, then the pattern of development might be disrupted, leading to developmental abnormalities.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|14230225d6f7f9″ question_number=”33″ topic=”4.7.Regulation_of_the_Cell_Cycle”] What is apoptosis?

[a] Apoptosis is programmed cell death. Unlike cell death which results from traumatic injury, apoptosis is highly regulated. Cells are broken down into cytoplasmic fragments called blebs (at “b” and “c”) that can be consumed by cells of the immune system, preventing cellular debris and enzymes from damaging nearby cells.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.7.Regulation_of_the_Cell_Cycle” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1422e889542bf9″ question_number=”34″] Describe the role that checkpoints play in regulating the cell cycle.

Importance for the AP exam: High

[a] Cell cycle checkpoints are moments when the cell “checks” its internal conditions and “decides” whether to progress to the next phase of the cell cycle. If certain molecules are in the right concentration, the cell continues through the cell cycle. If not, the cell moves into G₀ or, in certain cases, initiates apoptosis (programmed cell death). The primary checkpoints occur during G₁, G₂, and M. (“1,” “2,” and “3”).

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.7.Regulation_of_the_Cell_Cycle” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1422cc98c57bf9″ question_number=”35″] Explain how interactions between cyclins and cyclin-dependent kinases (CDKs) control the cell cycle.

Importance for the AP exam: High

[a] CDKs are present at a constant level throughout the cell cycle. By contrast, the level of cyclins (of which there are several) rises and falls. When cyclin levels are high, cyclin binds with CDK to form a complex called MPF (maturation promoting factor). MPF allows the cell to pass through the G₂ checkpoint and divide. During M phase, cyclin is broken down, allowing the process to repeat in each daughter cell.

[q json=”true” yy=”4″ unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.7.Regulation_of_the_Cell_Cycle” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1422b2fc42aff9″ question_number=”36″] What are the two types of genetic mutations that are connected to cancer?

Importance for the AP exam: High

[a] Disruptions to the cell cycle that increase cell division are often connected to mutations in proto-oncogenes, which mutate to become cancer-causing oncogenes. Disruptions to the cell cycle that remove cell division inhibitors are connected to mutations in tumor suppressor genes.

[q json=”true” unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.7.Regulation_of_the_Cell_Cycle” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|1422970bb3fff9″ question_number=”37″] Using the diagram below, describe how a mutation in the RAS proto-oncogene can induce a noncancerous cell to become cancerous.

[a]

RAS (C) is a G protein. As a proto-oncogene (Image I), RAS only becomes active when an outside growth-factor ligand (A) binds with RAS’s coupled receptor (B). This causes RAS to bind with GTP (D), enabling it to initiate a signaling cascade (E) that results in a transcription factor that results in a protein (I) that promotes cell division (J)

When RAS mutates into an oncogene (Image II), it becomes constitutively active. In this condition (K), RAS can bind with GTP even in the absence of a growth signal (notice the unbound receptor at “J”). Because RAS is always active, the molecule that results in cell division (L) is overproduced, resulting in too much cell division.

[q json=”true” unit=”4.Cell_Communication,_Cell_Cycle,_Feedback” topic=”4.7.Regulation_of_the_Cell_Cycle” dataset_id=”Unit 4 Cumulative Flashcards Dataset, v2.0|142271caf5bff9″ question_number=”38″] Using the image below, explain how mutations in a tumor suppressor gene such as the p53 gene can contribute to the development of cancer.

[a]

p53 is a tumor suppressor gene. When it’s working, it functions as shown in Image 1. When cells experience DNA damage (A), a signaling cascade (B) activates p53. If the DNA can be repaired, p53 will halt the cell cycle (1) while DNA repair enzymes fix the damage (2). If the damage is too great, p53 will signal the cell to initiate apoptosis.

If mutations lead p53 to become non-functional (C in Image 2) then the cell will continue to divide, even with damaged DNA (A). That will increase the chance of the cell acquiring further mutations that can lead it to become cancerous.

[/qdeck]

3. Unit 4 Cumulative Multiple Choice Quiz

[qwiz style=”width: 550px !important; min-height: 400px !important;” qrecord_id=”sciencemusicvideosMeister1961-Unit 4 Summative Multiple Choice (v2.0)” dataset=”Unit 4 Cumulative Multiple Choice Dataset, v2.0″ dataset_intro=”false”]

[h] Unit 4 Cumulative Multiple Choice Quiz

[i]

[q json=”true” xx=”1″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|14217afe0957f9″ question_number=”1″ topic=”4.1.Cell_Communication”] The image below represents a signal transduction pathway. Which letter could represent a hormone?

[c]IE Eg[Qq][c]IEIg[Qq][c]IEMg[Qq][c]IEQ=

Cg==[Qq]

[f]IEV4YWN0bHkuICYjODIyMDtBJiM4MjIxOyB3b3VsZCByZXByZXNlbnQgYSBob3Jtb25lLg==[Qq]

[f]IE5vLiAmIzgyMjA7QiYjODIyMTsgaXMgdGhlIHJlY2VwdG9yLiBUaGUgaG9ybW9uZSBpcyB0aGUgbW9sZWN1bGUgdGhhdCBiaW5kcyB3aXRoIHRoZSByZWNlcHRvci4=[Qq]

[f]IE5vLiBJZiB0aGlzIGRpYWdyYW0gd2VyZSBhIHJlcHJlc2VudGF0aW9uIG9mIGEgRy1jb3VwbGVkIHJlY2VwdG9yLCB0aGUgbGV0dGVyICYjODIyMDtDJiM4MjIxOyB3b3VsZCByZXByZXNlbnQgYSBHIHByb3RlaW4uIFRoZSBHIHByb3RlaW4mIzgyMTc7cyBmdW5jdGlvbiBpcyB0byBhY3RpdmF0ZSBhIHNlY29uZCBtZXNzZW5nZXIgdGhhdCB3b3VsZCBzZW5kIGEgbWVzc2FnZSB0aHJvdWdoIHZhcmlvdXMgcmVsYXkgbW9sZWN1bGVzIGluIHRoZSBjeXRvcGxhc20gdG8gYWN0aXZhdGUgYSBjZWxsdWxhciByZXNwb25zZS4gVGhlIGhvcm1vbmUgaXMgdGhlIG1vbGVjdWxlIHRoYXQgYmluZHMgd2l0aCB0aGUgcmVjZXB0b3Iu[Qq]

[f]IE5vLiBJZiB0aGlzIGRpYWdyYW0gd2VyZSBhIHJlcHJlc2VudGF0aW9uIG9mIGEgRy1jb3VwbGVkIHJlY2VwdG9yLCB0aGUgbGV0dGVyICYjODIyMDtEJiM4MjIxOyB3b3VsZCByZXByZXNlbnQgYSBzZWNvbmQgbWVzc2VuZ2VyIG9yIGFuIGVudGlyZSBwaG9zcGhvcnlsYXRpb24gY2FzY2FkZS4gVGhlIGhvcm1vbmUgaXMgdGhlIG1vbGVjdWxlIHRoYXQgYmluZHMgd2l0aCB0aGUgcmVjZXB0b3Iu[Qq]

[q json=”true” xx=”1″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|14215f0d7aa7f9″ question_number=”2″ topic=”4.1.Cell_Communication”] The image below represents a signal transduction pathway. Which roman numeral represents reception?

[c]IE kg[Qq][c]IElJIA==[Qq][c]IElJSQ==

Cg==[Qq]

[f]IFllcy4gJiM4MjIwO0kmIzgyMjE7IHJlcHJlc2VudHMgcmVjZXB0aW9uLg==[Qq]

[f]IE5vLiAmIzgyMjA7SUkmIzgyMjE7IHJlcHJlc2VudHMgc2lnbmFsIHRyYW5zZHVjdGlvbiAoY29udmVyc2lvbiBvZiB0aGUgaW5pdGlhbCBzaWduYWwsIHRoZSBob3Jtb25lLCBpbnRvIG9uZSB0aGF0IGNhbiBiZSBjYXJyaWVkIGludG8gdGhlIGN5dG9wbGFzbSB0byBicmluZyBhYm91dCBhIGNlbGx1bGFyIHJlc3BvbnNlKS4=[Qq]

[f]IE5vLiAmIzgyMjA7SUlJJiM4MjIxOyByZXByZXNlbnRzIHRoZSBjZWxsdWxhciByZXNwb25zZS4=[Qq]

[q json=”true” xx=”1″ xx=”3″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|14213e74d42ff9″ question_number=”3″ topic=”4.2.Intro_to_Signal_Transduction”] The images below illustrate and describe the key steps in a diagnostic test for HIV infection.

Antibodies are proteins produced by the immune system that fight off invading pathogens (disease-causing agents). Infection can be detected by the presence of specific antibodies.
Antigens are foreign substances that elicit antibody production.

Which of the following statements best explains why this diagnostic test is valid?

[c]IFRoZSBkeWUgYnJlYWtzIGRvd24gdGhlIGFudGlib2RpZXMgaW4gdGhlIHBhdGllbnQmIzgyMTc7cyBibG9vZCBzZXJ1bS4=[Qq]

[f]IE5vLiBOb3RlIHRoYXQgaW4gc3RlcCAyLCB5b3Ugc2VlIHRoZSBwYXRpZW50JiM4MjE3O3MgSElWIGFudGlib2RpZXMgYmluZGluZyB3aXRoIHRoZSBhbnRpZ2VuIHRoYXQmIzgyMTc7cyBvbiB0aGUgc3VyZmFjZSBvZiB0aGUgY29udGFpbmVyLiBJbiB0aGUgc3Vic2VxdWVudCBzdGVwcywgdGhhdCBhbnRpYm9keSBpcyBuZXZlciBicm9rZW4gZG93bi4gTG9vayBvdmVyIHRoZSBkaWFncmFtIGFnYWluIGFuZCBhc2sgeW91cnNlbGYgJiM4MjIwO0hvdyBpcyB0aGlzIHRlc3Qgc2hvd2luZyB0aGF0IHRoZSBwYXRpZW50IGlzIHByb2R1Y2luZyBhbnRpYm9kaWVzIHRvIEhJViAoYW5kIG11c3QgdGhlcmVmb3JlIGJlIGluZmVjdGVkKT8mIzgyMjE7[Qq]

[c]IFRoZSBlbnp5bWUgaGFzIGFuIGFjdGl2ZSBzaXRlIGZvciB0aGUgSElWIGFudGlnZW4u[Qq]

[f]IE5vLiBUaGUgZW56eW1lIChFKSBpcyBvbiB0aGUgZW5naW5lZXJlZCBhbnRpYm9keS4gVGhlIGVuZ2luZWVyZWQgYW50aWJvZHkgaXMgYmluZGluZyB3aXRoIHRoZSBwYXRpZW50JiM4MjE3O3MgSElWIGFudGlib2RpZXMuIExvb2sgb3ZlciB0aGUgZGlhZ3JhbSBhZ2FpbiBhbmQgYXNrIHlvdXJzZWxmICYjODIyMDtIb3cgaXMgdGhpcyB0ZXN0IHNob3dpbmcgdGhhdCB0aGUgcGF0aWVudCBpcyBwcm9kdWNpbmcgYW50aWJvZGllcyB0byBISVYgKGFuZCBtdXN0IHRoZXJlZm9yZSBiZSBpbmZlY3RlZCk/JiM4MjIxOw==[Qq]

[c]IFRoZSBISVYgYW50aWdlbiBoYXMgYSBjb21wbGVtZW 50YXJ5IHNoYXBlIHRvIHRoZSBISVYgYW50aWJvZHku[Qq]

[f]IEV4Y2VsbGVudC4gVGhlIHZhbGlkaXR5IG9mIHRoaXMgdGVzdCBpcyBiYXNlZCB1cG9uIHRoZSBmYWN0IHRoYXQgYXMgc2hvd24gaW4gc3RlcCAyLCB0aGUgYW50aWdlbiBpbiB0aGUgY29udGFpbmVyIHdpbGwgYmluZCB3aXRoIEhJViBhbnRpYm9kaWVzIGluIHRoZSBwYXRpZW50JiM4MjE3O3MgYmxvb2QuIFRoZSBiaW5kaW5nIGhhcHBlbnMgYmVjYXVzZSB0aGUgc2hhcGUgb2YgdGhlIGFudGlnZW4gaXMgY29tcGxlbWVudGFyeSB0byB0aGUgc2hhcGUgb2YgdGhlIGFudGlib2R5Lg==[Qq]

[c]IFRoZSBlbmdpbmVlcmVkIGFudGlib2R5IGhhcyB0aGUgc2FtZSBzaGFwZSBhcyB0aGUgSElWIGFudGlnZW4u[Qq]

[f]IE5vLiBUYWtlIGEgZ29vZCBsb29rIGF0IHN0ZXAgMy4gV2hhdCBpcyB0aGUgZW5naW5lZXJlZCBhbnRpYm9keSBiaW5kaW5nIHdpdGg/IExvb2sgb3ZlciB0aGUgZGlhZ3JhbSBhZ2FpbiBhbmQgYXNrIHlvdXJzZWxmICYjODIyMDtIb3cgaXMgdGhpcyB0ZXN0IHNob3dpbmcgdGhhdCB0aGUgcGF0aWVudCBpcyBwcm9kdWNpbmcgYW50aWJvZGllcyB0byBISVYgKGFuZCBtdXN0IHRoZXJlZm9yZSBiZSBpbmZlY3RlZCk/JiM4MjIxOw==[Qq]

[q json=”true” xx=”1″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|14212284457ff9″ question_number=”4″ topic=”4.2.Intro_to_Signal_Transduction”] In the image below, which letter represents a receptor?

[c]IEEg[Qq][c]IE Ig[Qq][c]IEMg[Qq][c]IEQ=

Cg==[Qq]

[f]IE5vLiBBIGlzIHRoZSBsaWdhbmQuIFlvdSYjODIxNztyZSBsb29raW5nIGZvciB0aGUgcmVjZXB0b3IsIHdoaWNoIGlzIHRoZSBtZW1icmFuZSBwcm90ZWluIHRoYXQgYmluZHMgd2l0aCB0aGUgbGlnYW5kLg==[Qq]

[f]IENvcnJlY3QhICYjODIyMDtCJiM4MjIxOyBpcyB0aGUgcmVjZXB0b3Iu[Qq]

[f]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[Qq]

[f]IE5vLiBJZiB0aGlzIGRpYWdyYW0gd2VyZSBhIHJlcHJlc2VudGF0aW9uIG9mIGEgRy1jb3VwbGVkIHJlY2VwdG9yLCB0aGUgbGV0dGVyICYjODIyMDtEJiM4MjIxOyB3b3VsZCByZXByZXNlbnQgdGhlIGFjdGl2aXR5IG9mIGEgc2Vjb25kIG1lc3Nlbmdlciwgb3IgYW4gZW50aXJlIHBob3NwaG9yeWxhdGlvbiBjYXNjYWRlLiBZb3UmIzgyMTc7cmUgbG9va2luZyBmb3IgdGhlIHJlY2VwdG9yLCB3aGljaCBpcyB0aGUgbWVtYnJhbmUgcHJvdGVpbiB0aGF0IGJpbmRzIHdpdGggdGhlIGxpZ2FuZC4=[Qq]

[q json=”true” xx=”1″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|1420e3a70473f9″ question_number=”5″ topic=”4.2.Intro_to_Signal_Transduction”] The image below represents a signal transduction pathway. Which letter represents a ligand?

[c]IE Eg[Qq][c]IEIg[Qq][c]IEMg[Qq][c]IEQ=

Cg==[Qq]

[f]IEV4YWN0bHkuIEEgaXMgdGhlIGxpZ2FuZC4=[Qq]

[f]IE5vLiAmIzgyMjA7QiYjODIyMTsgaXMgdGhlIHJlY2VwdG9yLiBUaGUgbGlnYW5kIGlzIHRoZSBtb2xlY3VsZSB0aGF0IGJpbmRzIHdpdGggdGhlIHJlY2VwdG9yLg==[Qq]

[f]IE5vLiBJZiB0aGlzIGRpYWdyYW0gd2VyZSBhIHJlcHJlc2VudGF0aW9uIG9mIGEgRy1jb3VwbGVkIHJlY2VwdG9yLCB0aGUgbGV0dGVyICYjODIyMDtDJiM4MjIxOyB3b3VsZCByZXByZXNlbnQgYSBHIHByb3RlaW4uIFRoZSBHIHByb3RlaW4mIzgyMTc7cyBmdW5jdGlvbiBpcyB0byBhY3RpdmF0ZSBhIHNlY29uZCBtZXNzZW5nZXIgdGhhdCB3b3VsZCBzZW5kIGEgbWVzc2FnZSB0aHJvdWdoIHZhcmlvdXMgcmVsYXkgbW9sZWN1bGVzIGluIHRoZSBjeXRvcGxhc20gdG8gYWN0aXZhdGUgYSBjZWxsdWxhciByZXNwb25zZS4gVGhlIGxpZ2FuZCBpcyB0aGUgbW9sZWN1bGUgdGhhdCBiaW5kcyB3aXRoIHRoZSByZWNlcHRvci4=[Qq]

[q json=”true” xx=”1″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|1420a4c9c367f9″ question_number=”6″ topic=”4.2.Intro_to_Signal_Transduction”] The image below represents a signal transduction pathway. Which letter represents second messengers?

[c]IEEg[Qq][c]IEIg[Qq][c]IEMg[Qq][c]IE Q=

Cg==[Qq]

[f]IE5vLiBBIGlzIHRoZSBsaWdhbmQuIFRoZSBzZWNvbmQgbWVzc2VuZ2VycyBhcmUgbW9sZWN1bGVzIHRoYXQgcmVsYXkgdGhlIG1lc3NhZ2UgaW50byB0aGUgY3l0b3BsYXNtIHRvIGJyaW5nIGFib3V0IGEgcmVzcG9uc2Uu[Qq]

[f]IE5vLiAmIzgyMjA7QiYjODIyMTsgaXMgdGhlIHJlY2VwdG9yLiBUaGUgc2Vjb25kIG1lc3NlbmdlcnMgYXJlIG1vbGVjdWxlcyB0aGF0IHJlbGF5IHRoZSBtZXNzYWdlIGludG8gdGhlIGN5dG9wbGFzbSB0byBicmluZyBhYm91dCBhIHJlc3BvbnNlLg==[Qq]

[f]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[Qq]

[f]IEZhYnVsb3VzISBJZiB0aGlzIGRpYWdyYW0gd2VyZSBhIHJlcHJlc2VudGF0aW9uIG9mIGEgRy1jb3VwbGVkIHJlY2VwdG9yLCB0aGUgbGV0dGVyICYjODIyMDtEJiM4MjIxOyB3b3VsZCByZXByZXNlbnQgYSBzZWNvbmQgbWVzc2VuZ2VyIChvciBhbiBlbnRpcmUgcGhvc3Bob3J5bGF0aW9uIGNhc2NhZGUpLg==[Qq]

[q json=”true” xx=”1″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|142088d934b7f9″ question_number=”7″ topic=”4.2.Intro_to_Signal_Transduction”] The image below represents a signal transduction pathway. Which roman numeral represents transduction?

[c]IEk=[Qq]

[f]IE5vLiAmIzgyMjA7SSYjODIyMTsgcmVwcmVzZW50cyByZWNlcHRpb24u[Qq]

[c]IE lJ[Qq]

[f]IFllcy4gJiM4MjIwO0lJJiM4MjIxOyByZXByZXNlbnRzIHNpZ25hbCB0cmFuc2R1Y3Rpb24gKGNvbnZlcnNpb24gb2YgdGhlIGluaXRpYWwgc2lnbmFsLCB0aGUgaG9ybW9uZSwgaW50byBvbmUgdGhhdCBjYW4gYmUgY2FycmllZCBpbnRvIHRoZSBjeXRvcGxhc20gdG8gYnJpbmcgYWJvdXQgYSBjZWxsdWxhciByZXNwb25zZSku[Qq]

[c]IElJSQ==[Qq]

[f]IE5vLiAmIzgyMjA7SUlJJiM4MjIxOyByZXByZXNlbnRzIHRoZSBjZWxsdWxhciByZXNwb25zZS4=[Qq]

[q json=”true” xx=”1″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|14206ce8a607f9″ question_number=”8″ topic=”4.2.Intro_to_Signal_Transduction”] In the diagram below, which stage represents reception?

[c]IE kg[Qq][c]IElJIA==[Qq][c]IElJSSA=[Qq][c]IElWIA==[Qq][c]IFY=

Cg==[Qq]

[f]IE5pY2UhIFN0YWdlIEkgaXMgcmVjZXB0aW9uLg==[Qq]

[f]IE5vLiBTdGFnZSBJSSBpcyB0cmFuc2R1Y3Rpb24uIFJlY2VwdGlvbiBpcyB3aGVuIHRoZSBsaWdhbmQgKHVzdWFsbHkgYSBob3Jtb25lKSBiaW5kcyB3aXRoIGEgcmVjZXB0b3IgKHVzdWFsbHkgb24gdGhlIG1lbWJyYW5lKS4=[Qq]

[f]IE5vLiBTdGFnZSBJSUkgaXMgcmVzcG9uc2UuIFJlY2VwdGlvbiBpcyB3aGVuIHRoZSBsaWdhbmQgKHVzdWFsbHkgYSBob3Jtb25lKSBiaW5kcyB3aXRoIGEgcmVjZXB0b3IgKHVzdWFsbHkgb24gdGhlIG1lbWJyYW5lKS4=[Qq]

[f]IE5vLiBJbiBzdGFnZSBJViwgc29tZXRoaW5nIHRoYXQgbGVmdCB0aGUgbnVjbGV1cyAoNSkgaXMgaGVhZGVkIHRvd2FyZCB0aGUgR29sZ2kgYXBwYXJhdHVzLiBSZWNlcHRpb24gaXMgd2hlbiB0aGUgbGlnYW5kICh1c3VhbGx5IGEgaG9ybW9uZSkgYmluZHMgd2l0aCBhIHJlY2VwdG9yICh1c3VhbGx5IG9uIHRoZSBtZW1icmFuZSku[Qq]

[f]IE5vLiBJbiBzdGFnZSBWLCBzb21ldGhpbmcgaXMgYmVpbmcgZXhwb3J0ZWQgZnJvbSB0aGUgY2VsbCAod2hpY2ggaXMgcGFydCBvZiB0aGUgY2VsbHVsYXIgcmVzcG9uc2UpLiBSZWNlcHRpb24gaXMgd2hlbiB0aGUgbGlnYW5kICh1c3VhbGx5IGEgaG9ybW9uZSkgYmluZHMgd2l0aCBhIHJlY2VwdG9yICh1c3VhbGx5IG9uIHRoZSBtZW1icmFuZSku[Qq]

[q json=”true” xx=”1″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|142050f81757f9″ question_number=”9″ topic=”4.2.Intro_to_Signal_Transduction”] In the diagram below, which part represents a ligand?

[c]ID Eg[Qq][c]IDIg[Qq][c]IDMg[Qq][c]IDQg[Qq][c]IDU=

Cg==[Qq]

[f]IE5pY2UhIDEgaXMgdGhlIGxpZ2FuZC4=[Qq]

[f]IE5vLiAyIGlzIGEgcmVjZXB0b3IuIFRoZSBsaWdhbmQgaXMgd2hhdCBiaW5kcyB3aXRoIGEgcmVjZXB0b3Iu[Qq]

[f]IE5vLiAzIGlzIHRha2luZyBhIG1lc3NhZ2UgZnJvbSB0aGUgbWVtYnJhbmUsIGFuZCBicmluZ2luZyBpdCB0byB0aGUgbnVjbGV1cywgbWFraW5nIGl0IGEgc2Vjb25kIG1lc3Nlbmdlci4gVGhlIGxpZ2FuZCBpcyB3aGF0IGJpbmRzIHdpdGggYSByZWNlcHRvci4=[Qq]

[f]IE5vLiA0IGlzIHRoZSBudWNsZXVzLiBUaGUgbGlnYW5kIGlzIHdoYXQgYmluZHMgd2l0aCBhIHJlY2VwdG9yIGF0IHRoZSBtZW1icmFuZS4=[Qq]

[f]IE5vLiA1IGlzIHNvbWV0aGluZyB0aGF0JiM4MjE3O3MgaGVhZGluZyB0b3dhcmQgdGhlIEdvbGdpIGFwcGFyYXR1cywgbWFraW5nIDUgYSBuZXdseSBzeW50aGVzaXplZCBwcm90ZWluLiBUaGUgbGlnYW5kIGlzIHdoYXQgYmluZHMgd2l0aCBhIHJlY2VwdG9yLg==[Qq]

[q json=”true” xx=”1″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|1420305f70dff9″ question_number=”10″ topic=”4.2.Intro_to_Signal_Transduction”] In the diagram below, which part represents a second messenger?

[c]IDEg[Qq][c]IDIg[Qq][c]ID Mg[Qq][c]IDQg[Qq][c]IDU=

Cg==[Qq]

[f]IE5vLiAxIHJlcHJlc2VudHMgYSBsaWdhbmQuIFRoZSBzZWNvbmQgbWVzc2VuZ2VyIHRha2VzIHRoZSBpbml0aWFsIHNpZ25hbCAod2hpY2ggb2NjdXJzIHdoZW4gdGhlIGxpZ2FuZCBiaW5kcyB3aXRoIHRoZSByZWNlcHRvcikgYW5kIHRoZW4gcGFzc2VzIHRoYXQgc2lnbmFsIG9uLCBidXQgaW4gYW5vdGhlciBmb3JtLiBBbiBhbmFsb2d5IHdvdWxkIGJlIHRoaXM6IEpvZSByaW5ncyB5b3VyIGRvb3JiZWxsLiBZb3UgYW5zd2VyIHRoZSBkb29yLCBhbmQgdGhlbiBzaG91dCB0byB5b3VyIHNpc3RlciwgJiM4MjIwO0pvZSYjODIxNztzIGhlcmUuJiM4MjIxOyBKb2UgaXMgdGhlIGZpcnN0IG1lc3NlbmdlciwgYW5kIHlvdSYjODIxNztyZSB0aGUgc2Vjb25kIG1lc3Nlbmdlci4gV2hhdCBjb3VsZCBiZSB0aGUgc2Vjb25kIG1lc3NlbmdlciBpbiB0aGUgZGlhZ3JhbSBhYm92ZT8=[Qq]

[f]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[Qq]

[f]IFdheSB0byBnbyEgMyBpcyB0aGUgc2Vjb25kIG1lc3Nlbmdlci4=[Qq]

[f]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[Qq]

[f]IE5vLiA1IGlzIHBhcnQgb2YgdGhlIGNlbGx1bGFyIHJlc3BvbnNlIChhIHByb3RlaW4gbWFkZSBpbiByZXNwb25zZSB0byBiaW5kaW5nIG9mIHRoZSBsaWdhbmQgYXQgdGhlIHJlY2VwdG9yKS4gVGhlIHNlY29uZCBtZXNzZW5nZXIgdGFrZXMgdGhlIGluaXRpYWwgc2lnbmFsICh3aGljaCBvY2N1cnMgd2hlbiB0aGUgbGlnYW5kIGJpbmRzIHdpdGggdGhlIHJlY2VwdG9yKSBhbmQgdGhlbiBwYXNzZXMgdGhhdCBzaWduYWwgb24sIGJ1dCBpbiBhbm90aGVyIGZvcm0uIEFuIGFuYWxvZ3kgd291bGQgYmUgdGhpczogSm9lIHJpbmdzIHlvdXIgZG9vcmJlbGwuIFlvdSBhbnN3ZXIgdGhlIGRvb3IsIGFuZCB0aGVuIHNob3V0IHRvIHlvdXIgc2lzdGVyLCAmIzgyMjA7Sm9lJiM4MjE3O3MgaGVyZS4mIzgyMjE7IEpvZSBpcyB0aGUgZmlyc3QgbWVzc2VuZ2VyLCBhbmQgeW91JiM4MjE3O3JlIHRoZSBzZWNvbmQgbWVzc2VuZ2VyLiBXaGF0IGNvdWxkIGJlIHRoZSBzZWNvbmQgbWVzc2VuZ2VyIGluIHRoZSBkaWFncmFtIGFib3ZlPw==[Qq]

[q json=”true” xx=”1″ xx=”3″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|14200fc6ca67f9″ question_number=”11″ topic=”4.3.Signal_Transduction”] The image below represents a signal transduction pathway. Which letter could represent one or more protein kinases?

[c]IEEg[Qq][c]IEIg[Qq][c]IEMg[Qq][c]IE Q=

Cg==[Qq]

[f]IE5vLiAmIzgyMjA7QSYjODIyMTsgcmVwcmVzZW50cyBhIGxpZ2FuZC4gVGhlIHByb3RlaW4ga2luYXNlIGlzIGZvdW5kIHdpdGhpbiB0aGUgY3l0b3BsYXNtLCByZWxheWluZyB0aGUgbWVzc2FnZSBmcm9tIHRoZSBtZW1icmFuZSB0byBzb21lIGVmZmVjdG9yIHdpdGhpbiB0aGUgY2VsbC4=[Qq]

[f]IE5vLiAmIzgyMjA7QiYjODIyMTsgcmVwcmVzZW50cyBhIHJlY2VwdG9yLiBUaGUgcHJvdGVpbiBraW5hc2UgaXMgZm91bmQgd2l0aGluIHRoZSBjeXRvcGxhc20sIHJlbGF5aW5nIHRoZSBtZXNzYWdlIGZyb20gdGhlIG1lbWJyYW5lIHRvIHNvbWUgZWZmZWN0b3Igd2l0aGluIHRoZSBjZWxsLg==[Qq]

[f]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[Qq]

[f]IFllcyEgJiM4MjIwO0QmIzgyMjE7IHJlcHJlc2VudHMgcHJvdGVpbiBraW5hc2VzLCBwYXJ0aWNpcGF0aW5nIGluIGEgcGhvc3Bob3J5bGF0aW9uIGNhc2NhZGUgdGhhdCBpcyBhbXBsaWZ5aW5nIHRoZSBjZWxsdWxhciByZXNwb25zZS4=[Qq]

[q json=”true” xx=”1″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|141fecda180bf9″ question_number=”12″ topic=”4.3.Signal_Transduction”] In the diagram below, which stage represents signal transduction?

[c]IEkg[Qq][c]IElJ IA==[Qq][c]IElJSSA=[Qq][c]IElWIA==[Qq][c]IFY=

Cg==[Qq]

[f]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[Qq]

[f]IENvcnJlY3QuIFN0YWdlIElJIGlzIHRyYW5zZHVjdGlvbi4=[Qq]

[f]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[Qq]

[f]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[Qq]

[f]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[Qq]

[q json=”true” xx=”1″ multiple_choice=”true” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|141f9b5c77dff9″ question_number=”13″ unit=”4.Cell Communication, Cell Cycle, Feedback” topic=”4.4.Changes_in_Signal_Transduction_Pathways”] In damaged and aging cells, regulated cell death involves caspases, a type of activated enzyme. Caspase activation causes decomposition of the cytoskeleton, the nuclear membrane, and the mitochondrial membrane. During activation, caspases are cut at a specific amino acid sequence. The model below illustrates one pathway for caspase activation that is triggered by the presence of cytotoxic T cells (a key cell in the immune response), represented as “T_C.”

Which of the following statements is supported by the model?

[c]IEROQSBkYW1hZ2UgdHJpZ2dlcnMgcmVndWxhdGVkIGNlbGwgZGVhdGggdG8gYmVnaW4u[Qq]

[f]IE5vLiBUaGF0IG1pZ2h0IGJlIHRydWUsIGJ1dCBpdCYjODIxNztzIG5vdCBzdXBwb3J0ZWQgYnkgdGhlIG1vZGVsIGFib3ZlLiBTdHVkeSB0aGUgZGlhZ3JhbSwgYW5kIHNlZSBpZiB5b3UgY2FuIGNvbm5lY3QgaXQgdG8gb25lIG9mIHRoZXNlIGNob2ljZXMu[Qq]

[c]IE1pdG9jaG9uZHJpYWwgbWVtYnJhbmUgZGVjb21wb3NpdGlvbiBsZWFkcyB0byBjYXNwYXNlIGFjdGl2YXRpb24u[Qq]

[f]IE5vLiBUaGUgaW5mb3JtYXRpb24gaW4gdGhlIHF1ZXN0aW9uIHN0YXRlcyB0aGUgcmV2ZXJzZTogY2FzcGFzZSBhY3RpdmF0aW9uIGxlYWRzIHRvIG1pdG9jaG9uZHJpYWwgbWVtYnJhbmUgZGVjb21wb3NpdGlvbi4gU3R1ZHkgdGhlIGRpYWdyYW0sIGFuZCBzZWUgaWYgeW91IGNhbiBjb25uZWN0IGl0IHRvIG9uZSBvZiB0aGVzZSBjaG9pY2VzLg==[Qq]

[c]IENhc3Bhc2VzIGFuZCBhZGFwdG9yIHByb3RlaW5zIGNvbXBldGUgZm9yIGJpbmRpbmcgc2l0ZXMgb24gdGhlIEZhcyByZWNlcHRvci4=[Qq]

[f]IE5vLiBUaGF0JiM4MjE3O3MgdW5saWtlbHksIGJlY2F1c2UgdGhlIGFkYXB0b3IgcHJvdGVpbnMgYXJlIGluc2lkZSB0aGUgY2VsbCwgd2hpbGUgdGhlIEZhcyByZWNlcHRvciBpcyBvdXRzaWRlIHRoZSBjZWxsLiBTdHVkeSB0aGUgZGlhZ3JhbSwgYW5kIHNlZSBpZiB5b3UgY2FuIGNvbm5lY3QgaXQgdG8gb25lIG9mIHRoZXNlIGNob2ljZXMu[Qq]

[c]IEZvciBjYXNwYXNlIGFjdGl2YXRpb24gdG8gb2NjdXIsIHRoZSBGYXMg cHJvdGVpbiBtdXN0IGF0dGFjaCB0byB0aGUgRmFzIHJlY2VwdG9yLg==[Qq]

[f]IFllcy4gQ2FzcGFzZXMgYXJlIGFjdGl2YXRlZCBhZnRlciB0aGUgRmFzIHByb3RlaW4gb24gYSBU_Qw==IGNlbGwgYmluZHMgd2l0aCB0aGUgRmFzIHJlY2VwdG9yLg==[Qq]

[q json=”true” xx=”1″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|141f786fc583f9″ question_number=”14″ topic=”4.4.Changes_in_Signal_Transduction_Pathways”] Researchers are investigating two steroid hormone receptors that they designate X and Y. Both receptors contain a ligand binding domain and a DNA binding domain. The researchers genetically engineer a third, hybrid receptor. This receptor, designated “H,” contains the ligand binding domain of X and DNA binding domain of Y.

The researchers next isolate three groups of cells, each of which over-expresses one of the three receptors: X, Y or H. Each group of cells was then treated separately either with hormone X or with hormone Y.

Assuming that there is no cross-reactivity, which one of the following graphs best represents the receptor-ligand binding in each case?

KEY

[c]IEEg[Qq][c]IEIg[Qq][c]IE Mg[Qq][c]IEQ=

Cg==[Qq]

[f]IE5vLiBUaGlzIHF1ZXN0aW9uIGFzc3VtZXMgdGhhdCB5b3Uga25vdyB0aGF0IGEgbGlnYW5kIGlzIHNvbWV0aGluZyB0aGF0IGJpbmRzIHdpdGggYSByZWNlcHRvci4gSG9ybW9uZSBYLCBmb3IgZXhhbXBsZSwgaXMgdGhlIGxpZ2FuZCB0aGF0IGJpbmRzIHdpdGggcmVjZXB0b3IgWC4=

Cg==

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

Cg==

SWYgeW91JiM4MjE3O3ZlIGdvdCB0aGUgaWRlYSwgdGFrZSBhIGxvb2sgYXQgdGhlIGdyYXBocyBhbmQgZmlndXJlIG91dCB3aGljaCBvbmUgbWFrZXMgc2Vuc2UuIElmIG5vdCwgcmVhZCBiZWxvdyBmb3IgYW5vdGhlciBoaW50JiM4MjMwOw==

[Qq]

Here’s the hint: you’re looking for a graph where cells X and H will have about the same vigorous response to hormone X, and where cell Y will be the only cell vigorously responding to hormone Y.

Cg==

Tm93LCBsZXQmIzgyMTc7cyBsb29rIGF0IGdyYXBoIEIsIGFuZCBmb2N1cyBvbiB0aGUgbGVmdCBzaWRlIChyZXNwb25zZSBob3Jtb25lIFgpLiBUaGlzIGdyYXBoIGlzIHNheWluZyB0aGF0IGNlbGxzIG92ZXItZXhwcmVzc2luZyB0aGUgcmVjZXB0b3IgdG8gSCB3aWxsIHJlc3BvbmQgdGhlIG1vc3QgdG8gWCwgZm9sbG93ZWQgYnkgY2VsbHMgb3Zlci1leHByZXNzaW5nIHRoZSByZWNlcHRvciB0byBZLCBmb2xsb3dlZCBieSBjZWxscyBvdmVyLWV4cHJlc3NpbmcgdGhlIHJlY2VwdG9yIHRvIFguIFRoYXQgZG9lc24mIzgyMTc7dCBtYWtlIHNlbnNlLiBUaGUgY2VsbHMgd2l0aCB0aGUgcmVjZXB0b3IgdG8gWCBzaG91bGQgcmVzcG9uZCB0aGUgbW9zdCB0byBYLCBmb2xsb3dlZCBieSB0aGUgY2VsbHMgdGhhdCBvdmVyLWV4cHJlc3MgdGhlIHJlY2VwdG9yIGZvciBIIChiZWNhdXNlIGl0IGFsc28gYmluZHMgd2l0aCBYKS4gVGhlIGNlbGxzIHdpdGggdGhlIHJlY2VwdG9yIGZvciBZIHNob3VsZCBiYXJlbHkgcmVzcG9uZCB0byBYLg==

Cg==

SWYgeW91JiM4MjE3O3ZlIGdvdCB0aGUgaWRlYSwgdGFrZSBhIGxvb2sgYXQgdGhlIGdyYXBocyBhbmQgZmlndXJlIG91dCB3aGljaCBvbmUgbWFrZXMgc2Vuc2UuIElmIG5vdCwgcmVhZCBiZWxvdyBmb3IgYW5vdGhlciBoaW50JiM4MjMwOw==

[Qq]

Here’s the hint: you’re looking for a graph where cells X and H will have about the same vigorous response to hormone X, and where cell Y will be the only cell vigorously responding to hormone Y.

[f]IE5pY2Ugam9iISBZb3UgZ2V0IGhpZ2ggYmFycyBmb3IgcmVhZGluZyBiYXIgZ3JhcGhzISBHcmFwaCBDIGlzIHNob3dpbmcgY2VsbHMgd2l0aCB0aGUgcmVjZXB0b3IgZm9yIFggYW5kIEggcmVzcG9uZGluZyB0byBob3Jtb25lIFgsIGFuZCBjZWxscyB3aXRoIHRoZSByZWNlcHRvciBmb3IgWSByZXNwb25kaW5nIHRvIGhvcm1vbmUgWS4=[Qq]

Cg==

Tm93LCBsZXQmIzgyMTc7cyBsb29rIGF0IGdyYXBoIEQsIGFuZCBmb2N1cyBvbiB0aGUgbGVmdCBzaWRlIChyZXNwb25zZSBob3Jtb25lIFgpLiBUaGlzIGdyYXBoIGlzIHNheWluZyB0aGF0IGNlbGxzIG92ZXJleHByZXNzaW5nIHRoZSByZWNlcHRvciB0byBZIHdpbGwgcmVzcG9uZCBtb3JlIHRvIGhvcm1vbmUgWCB0aGFuIGNlbGxzIG92ZXJleHByZXNzaW5nIHRoZSByZWNlcHRvciB0byBYIG9yIEgmIzgyMzA7YW5kIHRoYXQgZG9lc24mIzgyMTc7dCBtYWtlIGFueSBzZW5zZS4gQ2VsbHMgb3Zlci1leHByZXNzaW5nIHRoZSByZWNlcHRvciB0byBYIHNob3VsZCByZXNwb25kIHRoZSBtb3N0IHRvIGhvcm1vbmUgWCwgYW5kIGJlY2F1c2UgcmVjZXB0b3IgSCBiaW5kcyB3aXRoIGhvcm1vbmUgWCwgaXRzIHJlc3BvbnNlIHNob3VsZCBiZSBhYm91dCB0aGUgc2FtZSBhcyBYcy4=

Cg==

SWYgeW91JiM4MjE3O3ZlIGdvdCB0aGUgaWRlYSwgdGFrZSBhIGxvb2sgYXQgdGhlIGdyYXBocyBhbmQgZmlndXJlIG91dCB3aGljaCBvbmUgbWFrZXMgc2Vuc2UuIElmIG5vdCwgcmVhZCBiZWxvdyBmb3IgYW5vdGhlciBoaW50JiM4MjMwOw==

[Qq]

Here’s the hint: you’re looking for a graph where cells X and H will have about the same vigorous response to hormone X, and where cell Y will be the only cell vigorously responding to hormone Y.

[q json=”true” xx=”1″ multiple_choice=”true” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|141f55831327f9″ question_number=”15″ unit=”4.Cell Communication, Cell Cycle, Feedback” topic=”4.5.Feedback”] 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]IEZsYXBwaW5nIH RoZWlyIGVhcnM=[Qq]

[f]IEV4Y2VsbGVudCEgVGhlIGVsZXBoYW50cyYjODIxNzsgZWFycyBwcm92aWRlIGl0IHdpdGggZXh0cmEgc3VyZmFjZSBhcmVhLiBGbGFwcGluZyB0aGUgZWFycyBhbGxvd3MgaGVhdCB0byBkaWZmdXNlIGZyb20gdGhlIGJsb29kIGluIHRoZSBlYXJzIGludG8gdGhlIGV4dGVybmFsIGVudmlyb25tZW50Lg==[Qq]

[c]IEh1ZGRsaW5nIHdpdGggb3RoZXIgZWxlcGhhbnRz[Qq]

[f]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[Qq]

[c]IERlY3JlYXNpbmcgYmxvb2QgZmxvdyB0byB0aGUgZWFycw==[Qq]

[f]IE5vLiBEZWNyZWFzaW5nIGJsb29kIGZsb3cgYXdheSBmcm9tIHRoZSBleHRyZW1pdGllcyBpcyBhbiBhZGFwdGF0aW9uIGZvciA=cmVkdWNpbmc=IGhlYXQgbG9zcy4gVGhhdCYjODIxNztzIHdoeSB5b3VyIGZlZXQgYW5kIGhhbmRzIGdldCBjb2xkIGluIGNvbGQgd2VhdGhlci4gSW4gd2hhdCYjODIxNztzIGRlc2NyaWJlZCBhYm92ZSwgdGhlIGVsZXBoYW50cyBuZWVkIHRvIGluY3JlYXNlIGhlYXQgZXhjaGFuZ2Ugd2l0aCB0aGUgZW52aXJvbm1lbnQgc28gdGhhdCB0aGV5IGNhbiBsb3dlciB0aGVpciBib2R5IHRlbXBlcmF0dXJlLiBXaGljaCBvZiB0aGUgY2hvaWNlcyBkZXNjcmliZXMgc29tZXRoaW5nIHRoYXQgd291bGQgZW5hYmxlIHRoZW0gdG8gZXhjaGFuZ2UgbW9yZSBoZWF0IHdpdGggdGhlIGVudmlyb25tZW50Pw==[Qq]

[c]IEZvbGRpbmcgdGhlaXIgZWFycyBhZ2FpbnN0IHRoZWlyIGJvZHk=[Qq]

[f]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[Qq]

[q json=”true” xx=”1″ multiple_choice=”true” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|141f1da1f5c7f9″ question_number=”16″ unit=”4.Cell Communication, Cell Cycle, Feedback” topic=”4.5.Feedback”] The figure below represents how carbon dioxide concentration is regulated in the arterial blood of a human.

As the carbon dioxide concentration returns to normal levels, which of the following events is most likely to occur?

[c]IENvbnRyYWN0aW9uIG9mIHRoZSByZXNwaXJhdG9yeSBtdXNjbGVzIHN0b3BzLg==[Qq]

[f]IE5vLiBIYXZpbmcgdGhlIHJlc3BpcmF0b3J5IG11c2NsZXMgc3RvcCB3b3VsZCBiZSBkaXNhc3Ryb3VzIChiZWNhdXNlIGl0IHdvdWxkIGNhdXNlIGJyZWF0aGluZyB0byBjZWFzZSkuIFdoYXQgbWlnaHQgYmUgYSBsZXNzIGRyYXN0aWMgcmVzcG9uc2U/[Qq]

[c]IEEgcGVyc29uJiM4MjE3O3MgYnJlYXRoaW5n IHJhdGUgYW5kIGRlcHRoIGRlY3JlYXNlLg==[Qq]

[f]IFllcy4gSW5jcmVhc2VkIGJyZWF0aGluZyByYXRlcyB3aWxsIGRlY3JlYXNlIGJsb29kIGNhcmJvbiBkaW94aWRlIGNvbmNlbnRyYXRpb24uIEluIHJlc3BvbnNlLCBicmVhdGhpbmcgcmF0ZSBhbmQgZGVwdGggd2lsbCBkZWNyZWFzZSBhcyBob21lb3N0YXNpcyBpcyByZXN0b3JlZC4=[Qq]

[c]IFRoZSBudW1iZXIgb2YgbmVydmUgaW1wdWxzZXMgdG8gdGhlIHJlc3BpcmF0b3J5IG11c2NsZXMgaW5jcmVhc2VzLg==[Qq]

[f]IE5vLiBBcyBjYXJib24gZGlveGlkZSBsZXZlbHMgZGVjcmVhc2UsIHRoZSBudW1iZXIgb2YgbmVydmUgaW1wdWxzZXMgdG8gdGhlIG11c2NsZXMgc2hvdWxkIGFsc28gZGVjcmVhc2Uu[Qq]

[c]IEluIHRoZSBicmFpbiwgdGhlIHJlc3BpcmF0b3J5IGNlbnRlciBmYWlscyB0byB0cmFuc21pdCBtb3RvciBuZXJ2ZSBpbXB1bHNlcy4=[Qq]

[f]IE5vLiBUaGF0IHdvdWxkIGJlIGRpc2FzdHJvdXMgYmVjYXVzZSBpdCB3b3VsZCBsZWFkIGJyZWF0aGluZyB0byBjZWFzZS4gU2VlIGlmIHlvdSBjYW4gdGhpbmsgb2YgYSBsZXNzIGRyYXN0aWMgcmVzcG9uc2Uu[Qq]

[q json=”true” xx=”1″ multiple_choice=”true” unit=”4.Cell Communication, Cell Cycle, Feedback” dataset_id=”Unit 4 Cumulative Multiple Choice Dataset, v2.0|141dd5576933f9″ question_number=”17″ topic=”4.6.Cell_Cycle”] The image below shows stages of cell division, but not necessarily in the correct order. Which of the following lists the correct sequence?

[c]IDEtMi0zLTQ=[Qq]

[f]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[Qq]

[c]IDItMS00LTM=[Qq]

[f]IE5vLiBZb3UmIzgyMTc7dmUgY2hvc2VuICYjODIyMDsyJiM4MjIxOyBhcyB0aGUgZmlyc3Qgc3RhZ2UuIEJ1dCAmIzgyMjA7MiYjODIyMTsgc2hvd3MgY2hyb21vc29tZXMgY29uZGVuc2luZy4gQmVmb3JlIHRoYXQsIHRoZSBudWNsZWFyIG1lbWJyYW5lIGRpc2ludGVncmF0ZXMuIEZpbmQgYSBjZWxsIHdoZXJlIHRoYXQmIzgyMTc7cyBoYXBwZW5pbmcsIGFuZCByZW1lbWJlciB0aGF0IGZpcnN0IHN0ZXAgdGhlIG5leHQgdGltZSB5b3Ugc2VlIHRoaXMgcXVlc3Rpb24u[Qq]

[c]IDQtMi0zLTE=[Qq]

[f]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[Qq]

[c]IDMtMi 00LTE=[Qq]

[f]IEV4Y2VsbGVudCEgTmljZSBqb2IgaWRlbnRpZnlpbmcgdGhlIGNvcnJlY3Qgc2VxdWVuY2Ugb2YgZXZlbnRzOiBudWNsZWFyIG1lbWJyYW5lIGRpc2ludGVncmF0aW9uLCBjaHJvbW9zb21lIGNvbmRlbnNhdGlvbiwgYWxpZ25tZW50IGluIHRoZSBtaWRkbGUsIHRoZW4gc2VwYXJhdGlvbiAob3IsIGlmIHlvdSYjODIxNzt2ZSBsZWFybmVkIHRoZSBuYW1lIG9mIHRoZSBwaGFzZXM6IGVhcmx5IHByb3BoYXNlLCBsYXRlIHByb3BoYXNlLCBtZXRhcGhhc2UsIGFuYXBoYXNlKS4=

Cg==

Cg==[Qq]

[/qwiz]

4. Unit 4 Click-On Challenge 1: Cell Division

[qwiz use_dataset=”mitosis-and-cell-cycle-click-on-challenge” random = “true” style=”width: 600px !important;” quiz_timer=”true” dataset_intro=”false” spaced_repetition=”false” qrecord_id=”sciencemusicvideosMeister1961-Unit 4 Cell Division Click-on Challenge (v2.0)”]

[h]Unit 4 Cell Division Click-On Challenge

[i] Note the timer in the top right. Your goal is accuracy and speed. A good strategy: once through slowly, then additional trials for improvement.

[/qwiz]

5. Unit 4 Click-On Challenge 2: Cell Communication

[qwiz use_dataset=”cell-signaling-click-on-challenge” random = “true” style=”width: 600px !important;” quiz_timer=”true” dataset_intro=”false” spaced_repetition=”false” qrecord_id=”sciencemusicvideosMeister1961-Unit 4 Cell Communication Click-on Challenge (v2.0)”]

[h]Unit 4 Cell Signaling Click-On Challenge

[i] Note the timer in the top right. Your goal is accuracy and speed. A good strategy: once through slowly, then additional trials for improvement.

[/qwiz]