1. Start by watching the video below.

 

2. Water Makes Life Possible

01_499px-2006-01-28_Drop-impact
Source: 2006-01-28 “Drop-impact” by Roger McLassus

Liquid water is the environment in which life occurs. You can think of this on two levels.

2.1. Living things are mostly water

Step on a scale. If you took all of the water out of your body, your weight would only be about 40% of what it is now (source: US Geological Survey). And, of course, you wouldn’t be alive. Most humans can survive for a few weeks without food. But stop drinking, and, in a few days, life ends. And this isn’t only true of humans: it’s true of almost all living things.

2.2. Life Depends on Water.

Astronomically speaking, life only exists where there is water in a liquid form. It’s no accident that of the planets in our solar system, Earth is the one with life. That’s because Earth is in a narrow zone where average surface temperatures let water exist in its liquid form, as opposed to gaseous steam or solid ice. Life needs liquid water. So let’s see how water works.

02_lifezone for planets
The green zone around the sun is where water is a liquid, and where our type of life can exist. Notice that the Earth’s orbit is within the third ring out, solidly in the middle of the green zone. Mercury and Venus (in the red zone) are too hot for liquid water. Mars is just outside the green zone. Not including Earth, that makes Mars the best candidate for life in our solar system.  (Source: Ames Research Center)

3. Interactive Reading: The Structure of Water

[qwiz style=”width: 550px !important; min-height: 400px !important;” qrecord_id=”sciencemusicvideosMeister1961-Structure of Water (I.R., 2.0)”]

[h] The Structure of Water: Interactive Reading 1

[q] To understand water’s chemistry and properties, we need to understand its internal structure. To review how to draw a molecule’s structure, let’s start with the simplest molecule in the universe, hydrogen gas (H2). Remember that a hydrogen atom has one proton and one electron. Your first diagram should be an electron distribution model (showing the atomic nuclei and the electron energy levels). The second should be a structural formula. Note: if you need to review how to draw molecules, go to Basic Chemistry for Biology Students.

[c]IFNob3cgdGhl IGFuc3dlcg==[Qq]

[f]IEFOU1dFUg==

Cg==Cg==Cg==Cg==
[Qq]
Hydrogen, showing energy levels and electron sharing Hydrogen, structural formula

[q] Now let’s look at a molecule of water. Water’s chemical formula is H2O. Hydrogen has one proton and one electron. Oxygen has 8 protons, 8 neutrons, and 8 electrons. Use that information to draw a diagram of a water molecule that shows electron sharing between the single oxygen and the two hydrogens. Then, draw the structural formula. When you’re done, click below to see the solution.

[c]IMKgc2hvdyB0 aGUgYW5zd2Vy[Qq]

[f]IEFOU1dFUg==

Cg==Cg==Cg==Cg==
[Qq]
Water, showing energy levels and electron sharing Water, structural formula

[q multiple_choice=”true”] If you orient water so that the hydrogens are on top, you should be reminded of a very famous Disney cartoon character. Which one?

[c]IA==VHdlZXR5IGJpcmQ=[Qq]

[f]IFNvcnJ5LCBuby4gV2F0ZXIgaXMgdGhlIE1pY2tleSBNb3VzZSBtb2xlY3VsZSE=

Cg==

[Qq]

[c]IA==SG9tZXIgU2ltcHNvbg==[Qq]

[f]IE5vLCB0aGF0JiM4MjE3O3Mgbm90IGNvcnJlY3QuIFdhdGVyIGlzIHRoZSBNaWNrZXkgTW91c2UgbW9sZWN1bGUh

Cg==

[Qq]

[c]IA ==TWlja2V5IE1vdXNl[Qq]

[f]IFllcyEgV2F0ZXIgaXMgdGhlIE1pY2tleSBNb3VzZSBtb2xlY3VsZSE=

Cg==

[Qq]

[q labels = “top”]There’s one more important representation of water that you’ll need to understand. This one is called a space-filling model, and it shows water in a 3-D (three-dimensional) form. Knowing what you know about water, identify the hydrogen and oxygen atoms in the image below.

 

[l]hydrogen

[f*] Great!

[fx] No, that’s not correct. Please try again.

[l]oxygen

[f*] Excellent!

[fx] No, that’s not correct. Please try again.

[x][restart][/qwiz]

4. Interactive Reading: Water and Polarity

[qwiz style=”width: 550px !important; min-height: 400px !important;” qrecord_id=”sciencemusicvideosMeister1961-Water and Polarity (I.R. 2.0)”]

[h] Interactive Reading 2: Water, Polarity, and Hydrogen Bonding

[i] Now that we know what water looks like on a molecular level, let’s see how water’s structure determines its chemical properties.

 

[q labels = “top”]We’ll begin with the concept of polarity.

The Earth is polar. What that means is that it has two _______. A north and a south pole. 

Magnets are also polar.

Like the Earth, a bar magnet has a north and a south pole. The north pole of one __________ is attracted to the _______ pole of another magnet. Two magnetic south poles, by contrast, push each other ________ (as do two magnetic north poles).

[l]apart

[f*] Good!

[fx] No. Please try again.

[l]magnet

[f*] Excellent!

[fx] No, that’s not correct. Please try again.

[l]poles

[f*] Great!

[fx] No, that’s not correct. Please try again.

[l]south

[f*] Great!

[fx] No. Please try again.

[q labels = “top”]The rules for magnets are

  1. Like poles _________________________
  2. Opposite poles ____________________________

[l]attract (pull together)

[f*] Good!

[fx] No. Please try again.

[l]repel (push away)

[f*] Correct!

[fx] No. Please try again.

[q labels = “top”]Like a magnet, water is also polar. We’ll get into the details in a moment, but for now, just take a good look at this electron distribution model of water, and identify where you think there’ll be a more negatively charged side, and where there’ll be a more positively charged side.

 

[l]more negatively charged

[f*] Correct!

[fx] No, that’s not correct. Please try again.

[l]more positively charged

[f*] Great!

[fx] No, that’s not correct. Please try again.

[q labels = “top”]

Let’s dig a little bit deeper so we can understand why water is a polar molecule.

  1. The nucleus of the oxygen atom has eight protons: eight __________ charges.
  2. The two hydrogen nuclei each have only one __________: one positive charge.
  3. Those eight protons in the oxygen nucleus are going to pull on the 10 ____________ in the molecule with a lot more force than the single proton in each hydrogen nucleus.
  4. As a result, the oxygen side of the molecule will tend to have more electrons and have a slight ___________ charge. By contrast, the region around the two hydrogen nuclei will tend to have ______ electrons and have a slight positive charge.
  5. In sum, water isn’t just a covalently bonded molecule. Because electron sharing is unequal, and results in polarity, the bonds have special name: they’re called ______ __________ bonds.

[l]electrons

[f*] Correct!

[fx] No. Please try again.

[l]less

[f*] Good!

[fx] No, that’s not correct. Please try again.

[l]negative

[f*] Correct!

[fx] No. Please try again.

[l]polar covalent

[f*] Great!

[fx] No. Please try again.

[l]positive

[f*] Great!

[fx] No, that’s not correct. Please try again.

[l]proton

[f*] Great!

[fx] No. Please try again.

[q labels = “top”] The charges on a water molecule are not full charges, like the ones you’d find on a positive or negative ion. They’re much weaker (though, as we’ll see, they have important consequences). These partial charges are represented with the symbol”δ” (Greek for “delta”). So, a partial positive charge is represented by δ+ and a partial negative charge is represented by δ. Use these symbols to label all three of the representations of water below.

 

[l]δ+

[f*] Excellent!

[fx] No, that’s not correct. Please try again.

[l]δ

[f*] Excellent!

[fx] No, that’s not correct. Please try again.

[/qwiz]

5. Interactive Reading: Water’s Polarity Leads to Hydrogen Bonding

[qwiz style=”width: 550px !important; min-height: 400px !important;” qrecord_id=”sciencemusicvideosMeister1961-Water and Hydrogen Bonding (I.R., 2.0)”]

[h] Hydrogen Bonding; Interactive Reading 3

[i] The polarity of water has significant consequences. Read on.

[q multiple_choice=”true”] Here are two water molecules. Because water molecules are polar, weak bonds will form between any two water molecules that get close to one another. The dotted line below represents one of these weak bonds. Which of the images below makes sense?

[c]IA==[Qq]

[f]IMKgTm8uIFJlbWVtYmVyIHRoYXQgb3Bwb3NpdGVzIGF0dHJhY3QuIFRoZSBjb3JyZWN0IHJlcHJlc2VudGF0aW9uIG9mIHRoaXMgYXR0cmFjdGlvbiBpcyB3aGF0JiM4MjE3O3Mgc2hvd24gaGVyZS4gTm90ZSBob3cgdGhlIHBvc2l0aXZlIHNpZGUgb2Ygb25lIHdhdGVyIG1vbGVjdWxlICh3aGljaCBpcyB3aGVyZSB0aGUgaHlkcm9nZW5zIGFyZSkgaXMgYXR0cmFjdGVkIHRvIHRoZSBuZWdhdGl2ZSBzaWRlIG9mIGFub3RoZXIgd2F0ZXIgbW9sZWN1bGUgKHdoZXJlIHRoZSBveHlnZW4gaXMpLg==[Qq]

[c]IA ==[Qq]

[f]IEV4Y2VsbGVudC4gWW91IGNvcnJlY3RseSBjaG9zZSBhIHJlcHJlc2VudGF0aW9uIHdoZXJlIHRoZSBwb3NpdGl2ZSBzaWRlIG9mIG9uZSB3YXRlciBtb2xlY3VsZSAod2hpY2ggaXMgd2hlcmUgdGhlIGh5ZHJvZ2VucyBhcmUpIGlzIGF0dHJhY3RlZCB0byB0aGUgbmVnYXRpdmUgc2lkZSBvZiBhbm90aGVyIHdhdGVyIG1vbGVjdWxlICh3aGVyZSB0aGUgb3h5Z2VuIGlzKS4=

Cg==

[Qq]

[q labels = “top”]Water molecules, as you can see here, are “sticky.” Remember that this stickiness is on a molecular level. Here are two key points to keep in mind.

  • The oxygen end of one water molecule, with its partially ___________ charge, will temporarily bond with the ____________ end of another water molecule, with its partially positive charge.
  • The bond that forms between one water molecule and the next is called a hydrogen bond.

[l]hydrogen

[f*] Great!

[fx] No, that’s not correct. Please try again.

[l]negative

[f*] Excellent!

[fx] No, that’s not correct. Please try again.

[q multiple_choice=”true”] Hydrogen bonds are weak and temporary. But, in any body of water — anything from the tiniest droplet to an ocean — they have enormous consequences. We’ll look at these consequences in the next tutorial. Before that, though, let’s compare water to another molecule that you might be familiar with: methane: CH4.

Take a good look at the electron sharing between carbon and the four hydrogens in methane. Based on the way it looks, do you think that methane is polar or non-polar?

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Cg==[Qq]

[f]IE5vLiBXYXRlciBpcyBwb2xhciBiZWNhdXNlIGFsbCBvZiB0aGUgZWxlY3Ryb25zIGFyZSBidW5jaGVkIHVwIG9uIHRoZSBveHlnZW4gc2lkZSBvZiBhIHdhdGVyIG1vbGVjdWxlLCB3aGlsZSBmZXdlciBlbGVjdHJvbnMgYXJlIG9uIHRoZSBoeWRyb2dlbiBzaWRlIG9mIHRoZSBtb2xlY3VsZS4gSW4gbWV0aGFuZSwgYWxsIG9mIHRoZSBlbGVjdHJvbnMgYXJlIGVxdWFsbHkgZGlzdHJpYnV0ZWQuIFRoZXJlIGFyZSBubyBjaGFyZ2VkIHBvbGVzLCBtYWtpbmcgbWV0aGFuZSBub24tcG9sYXIu[Qq]

[f]IFRoYXQmIzgyMTc7cyByaWdodC4gSW4gbWV0aGFuZSwgYWxsIG9mIHRoZSBlbGVjdHJvbnMgYXJlIGVxdWFsbHkgZGlzdHJpYnV0ZWQuIFRoZXJlIGFyZSBubyBjaGFyZ2VkIHBvbGVzLCBtYWtpbmcgbWV0aGFuZSBub24tcG9sYXIu[Qq]

[q multiple_choice=”true”] Will two methane molecules form hydrogen bonds with one another?

[c]IFllcw==[Qq]

[f]IFRoYXQmIzgyMTc7cyBub3QgcmlnaHQuIFRoZSBvbmx5IG1vbGVjdWxlcyB0aGF0IGNhbiBmb3JtIGh5ZHJvZ2VuIGJvbmRzIGFyZSBwb2xhciBtb2xlY3VsZXMsIGxpa2Ugd2F0ZXIuIE1ldGhhbmUsIGFzIGEgbm9uLXBvbGFyIG1vbGVjdWxlLCBjYW4mIzgyMTc7dCBmb3JtIGh5ZHJvZ2VuIGJvbmRzLg==[Qq]

[c]IE 5v[Qq]

[f]IEV4Y2VsbGVudC4gVGhlIG9ubHkgbW9sZWN1bGVzIHRoYXQgY2FuIGZvcm0gaHlkcm9nZW4gYm9uZHMgYXJlIHBvbGFyIG1vbGVjdWxlcywgbGlrZSB3YXRlci4gTWV0aGFuZSwgYXMgYSBub24tcG9sYXIgbW9sZWN1bGUsIGNhbiYjODIxNzt0IGZvcm0gaHlkcm9nZW4gYm9uZHMu[Qq]

[q multiple_choice=”true”] Methane, with its non-polar electron sharing, is the opposite of a magnet. There’s no positive or negative pole. Methane molecules aren’t attracted to one another (or to anything else).

Keeping that in mind, make a prediction (and feel free to use prior knowledge in your answer). Methane and water have just about the same molecular weight (they both have about the same number of neutrons and protons). At room temperature, methane will be a

[c]IGxpcXVpZA==[Qq]

[f]IE5vLiBCZWNhdXNlIG1ldGhhbmUgbW9sZWN1bGVzIGRvbiYjODIxNzt0IGZvcm0gaHlkcm9nZW4gYm9uZHMsIHRoZXkgd29uJiM4MjE3O3Qgc3RpY2sgdG9nZXRoZXIgaW4gYW4gb3BlbiBjb250YWluZXIgYXQgcm9vbSB0ZW1wZXJhdHVyZSwgYXMgd2F0ZXIgZG9lcy4gQXMgYSByZXN1bHQsIG1ldGhhbmUgaXMgYSBnYXMgYXQgcm9vbSB0ZW1wZXJhdHVyZS4gVG8gbWFrZSBtZXRoYW5lIGludG8gYSBsaXF1aWQsIHlvdSBoYXZlIHRvIGdldCBpdCB0byBiZSByZWFsbHkgY29sZCYjODIzMDthcyBpbiAtMTYxIGRlZ3JlZXMsIENlbHNpdXMu[Qq]

[c]IGdh cw==[Qq]

[f]IENvcnJlY3QuwqBCZWNhdXNlIG1ldGhhbmUgbW9sZWN1bGVzIGRvbiYjODIxNzt0IGZvcm0gaHlkcm9nZW4gYm9uZHMsIHRoZXkgd29uJiM4MjE3O3Qgc3RpY2sgdG9nZXRoZXIgaW4gYW4gb3BlbiBjb250YWluZXIgYXQgcm9vbSB0ZW1wZXJhdHVyZSwgYXMgd2F0ZXIgZG9lcy4gQXMgYSByZXN1bHQsIG1ldGhhbmUgaXMgYSBnYXMgYXQgcm9vbSB0ZW1wZXJhdHVyZS4gVG8gbWFrZSBtZXRoYW5lIGludG8gYSBsaXF1aWQsIHlvdSBoYXZlIHRvIGdldCBpdCB0byBiZSByZWFsbHkgY29sZCYjODIzMDthcyBpbiAtMTYxIGRlZ3JlZXMsIENlbHNpdXMu[Qq]

[q]And just to make sure you’ve got this, label the diagram below (and the ones that follow).

[l]sticky

[f*] Good!

[fx] No, that’s not correct.  Please try again.

[l]not sticky

[f*] Excellent!

[fx] No.  Please try again.

[q]

[l]non-polar

[f*] Good!

[fx] No.  Please try again.

[l]polar

[f*] Excellent!

[fx] No, that’s not correct.  Please try again.

[q]

[l]hydrogen bonding

[f*] Great!

[fx] No.  Please try again.

[l]no hydrogen bonding

[f*] Excellent!

[fx] No.  Please try again.

[q]Here’s a different version of the molecules

 

 

[l]non-polar

[f*] Excellent!

[fx] No.  Please try again.

[l]polar

[f*] Great!

[fx] No, that’s not correct.  Please try again.

[q]And here’s yet another version of these two molecules

 

 

 

[l]sticky

[f*] Good!

[fx] No.  Please try again.

[l]non-sticky

[f*] Correct!

[fx] No.  Please try again.

[x][restart]

[/qwiz]

6. Flashcards: Chemistry and Properties of Water

Before we go on to learning about the properties of water caused by its polarity, let’s review what we’ve learned so far. Read over these key ideas, then work on the flashcards below.

  1. Water is the most important molecule, by weight, in living things.
  2. When atoms in a molecule share electrons unequally, the molecule becomes polar.
  3. Water molecules are polar.
  4. Because water molecules are polar, they form hydrogen bonds with one another.

[qwiz random=”true” qrecord_id=”sciencemusicvideosMeister1961-Chemistry and Properties of Water Quiz (2.0)”]

[h]Quiz: The Chemistry and Properties of Water
[i]This quiz includes both multiple-choice and fill-in-the-blank questions.

[q]Water is the most important compound by [hangman] in any living thing.

[c]d2VpZ2h0[Qq]

[q] In a water molecule, the region with a partially negative charge is near the [hangman] atom(s)

[c]b3h5Z2Vu[Qq]

[q] In a polar molecule (like water), electrons are shared [hangman] among the atoms in that molecule.

[c]dW5lcXVhbGx5[Qq]

[q] In a water molecule, the region with a partial positive charge is near the [hangman] atom(s)

[c]aHlkcm9nZW4=[Qq]

[q] Because water molecules are polar, they form [hangman] bonds with one another.

[c]aHlkcm9nZW4=[Qq]

[q] If you compared hydrogen, covalent, and ionic bonds, the weakest one would be the _________ bond.
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Cg==[Qq]

[c]Y292YWxlbnQ=[Qq]

[c]aW9uaWM=[Qq]

[f]RXhjZWxsZW50ISBJZiB5b3UgY29tcGFyZWQgaHlkcm9nZW4sIGNvdmFsZW50LCBhbmQgaW9uaWMgYm9uZHMsIHRoZSB3ZWFrZXN0IG9uZSB3b3VsZCBiZSB0aGUgaHlkcm9nZW4gYm9uZC4=[Qq]

[f]Tm8uIFRoZSB3ZWFrZXN0IG9mIHRoZSB0aHJlZSBib25kcyBpcyB0aGUgb25lIHRoYXQgb2NjdXJzIGJldHdlZW4gcG9sYXIgbW9sZWN1bGVzLiBXaGljaCBib25kIGlzIA==YmV0d2Vlbg==IG1vbGVjdWxlcyAoYXMgb3Bwb3NlZCB0byB3aXRoaW4gYSBtb2xlY3VsZSk=[Qq]

[f]Tm8uIFRoZSB3ZWFrZXN0IG9mIHRoZSB0aHJlZSBib25kcyBpcyB0aGUgb25lIHRoYXQgb2NjdXJzIGJldHdlZW4gcG9sYXIgbW9sZWN1bGVzLiBXaGljaCBib25kIGlzIA==YmV0d2Vlbg==IG1vbGVjdWxlcyAoYXMgb3Bwb3NlZCB0byB3aXRoaW4gYSBtb2xlY3VsZSk=[Qq]

[q]Two bonds that are relevant to water are the covalent and the hydrogen bond. Which of these bonds is INSIDE a water molecule?
[c]aHlkcm9nZW4=

Cg==[Qq]

[c]Y292YW xlbnQ=[Qq]
[f]Tm8uIEh5ZHJvZ2VuIGJvbmRzIG9jY3VyIGJldHdlZW4gd2F0ZXIgbW9sZWN1bGVz

Cg==[Qq]

[f]RXhjZWxsZW50LiBDb3ZhbGVudCBib25kcyBvY2N1ciBiZXR3ZWVuIHRoZSBoeWRyb2dlbiBhbmQgb3h5Z2VuIGF0b21zIA==aW5zaWRlIGEgd2F0ZXIgbW9sZWN1bGUu[Qq]

[q]In this diagram, the dotted line between the two water molecules indicates a ___________ bond.[hangman]

 

[c]aHlkcm9nZW4=[Qq]

[q] In a molecule like methane, all of the electrons are shared equally among the atoms in the molecule. As a result, methane is a ___________.

[c]cG9sYXIgbW9sZWN1bGU=[Qq]

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[f]WWVzLsKgSW4gYSBtb2xlY3VsZSBsaWtlIG1ldGhhbmUsIGFsbCBvZiB0aGUgZWxlY3Ryb25zIGFyZSBzaGFyZWQgZXF1YWxseSBhbW9uZyB0aGUgYXRvbXMgaW4gdGhlIG1vbGVjdWxlLiBBcyBhIHJlc3VsdCwgbWV0aGFuZSBpcyBhIA==bm9uLXBvbGFywqBtb2xlY3VsZS4=[Qq]

[f]Tm8uIElvbmljIGNvbXBvdW5kcyBhcmUgY29tcG91bmRzIHdoZXJlIGlvbmljIGJvbmRzIGhvbGQgdG9nZXRoZXIgY2hhcmdlZCBpb25zLg==[Qq]

[q] True or false: Non-polar molecules won’t form hydrogen bonds with one another

[c]VHJ1 ZQ==[Qq]

[c]RmFsc2U=[Qq]

[f]TmljZSBqb2IuIFRoZSBzdGF0ZW1lbnQgYWJvdmUgaXMgdHJ1ZTrCoE5vbi1wb2xhciBtb2xlY3VsZXMgd29uJiM4MjE3O3QgZm9ybSBoeWRyb2dlbiBib25kcyB3aXRoIG9uZSBhbm90aGVy[Qq]

[f]VGhhdCYjODIxNztzIG5vdCByaWdodC7CoE5vbi1wb2xhciBtb2xlY3VsZXMgd29uJiM4MjE3O3Q=IGZvcm0gaHlkcm9nZW4gYm9uZHMgd2l0aCBvbmUgYW5vdGhlcg==[Qq]

[q]The best description for the bonds that hold the oxygen and hydrogen atoms together inside a water molecule would be

[c]aW9uaWMgYm9uZHM=[Qq]

[c]Y292YWxlbnQgYm9uZHM=[Qq]

[c]cG9sYXIgY292YW xlbnQgYm9uZHM=[Qq]

[c]aHlkcm9nZW4gYm9uZHM=[Qq]

[f]Tm8uIElvbmljIGJvbmRzIGhvbGQgdG9nZXRoZXIgY2hhcmdlZCBpb25zLiBBIGRpZmZlcmVudCBraW5kIG9mIGJvbmQgaXMgYXQgd29yayB3aXRoaW4gYSB3YXRlciBtb2xlY3VsZS4=[Qq]

[f]Tm8sIGJ1dCB5b3UmIzgyMTc7cmUgY2xvc2UuIFRoZSBib25kcyB0aGF0IGFyZSBhdCB3b3JrIHdpdGhpbiBhIHdhdGVyIG1vbGVjdWxlIGFyZSBpbmRlZWQgY292YWxlbnQsIGJ1dCB0aGVyZSYjODIxNztzIGEgbW9yZSBzcGVjaWZpYyB3YXkgdG8gZGVzY3JpYmUgdGhlbS4=[Qq]

[f]RXhjZWxsZW50LiBUaGUgYm9uZHMgdGhhdCBob2xkIHRoZSBveHlnZW4gYW5kIGh5ZHJvZ2VuIGF0b21zIHRvZ2V0aGVyIA==aW5zaWRlIGEgd2F0ZXIgbW9sZWN1bGUgYXJlIGNhbGxlZCBwb2xhciBjb3ZhbGVudCBib25kczogJiM4MjIwO2NvdmFsZW50JiM4MjIxOyBiZWNhdXNlIG9mIHRoZSBzaGFyZWQgZWxlY3Ryb25zLCAmIzgyMjA7cG9sYXImIzgyMjE7IGJlY2F1c2Ugb2YgdGhlIHVuZXF1YWwgc2hhcmluZyB0aGF0IHJlc3VsdHMgaW4gd2F0ZXImIzgyMTc7cyBvdmVyYWxsIHBvbGFyaXR5Lg==[Qq]

[f]Tm8uIEh5ZHJvZ2VuIGJvbmRzIG9jY3VyIA==YmV0d2Vlbg==IHdhdGVyIG1vbGVjdWxlcyAob3IgYmV0d2VlbiB3YXRlciBhbmQgb3RoZXIgcG9sYXIgbW9sZWN1bGVzLCBvciBiZXR3ZWVuIG90aGVyIHBvbGFyIG1vbGVjdWxlcyku[Qq]

[x]

If you want more practice, please press the restart button below. Otherwise, continue below.
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Next steps

  • Water Virtual Lab (The next tutorial in this AP Bio Unit 1. This tutorial is a virtual lab, with additional key AP Bio concepts)