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134 Cards in this Set

  • Front
  • Back
True or False? Scientists know exactly what an atom looks like.
False. Atoms are simply too small to see. Even using the most powerful microscope in the world, we cannot see them.
Where are the protons and neutrons in an atom?
Packed in the nucleus.
Where are the electrons?
Whirling around the nucleus in circular orbits.
What determines the properties of an atom?
The number of protons, neutrons, and electrons.
True or False? All atoms have equal numbers of protons and electrons.
True. If an atom has 3 protons, you know that it has 3 electrons. If it has 17 electrons, you know that it has 17 protons.
Protons and electrons each have electrical charge. Which one is positive and which is negative?
Electrons have a negative charge, while protons have a positive charge.
It is desirable to have a balance between the protons and electrons, but not entirely necessary. True or False?
FALSE!! There must always be a balance. The number of protons MUST equal the number of electrons.
True or False? Neutrons have no electrical charge at all.
True.
Why is it that the electrons determine the vast majority of an atom's properties?
The protons and neutrons are tucked away in the center of the atom (the nucleus). Since the electrons orbit around the nucleus, they are, in effect, what makes up the “outer layer” of the atom.

Thus, if two atoms were to come close to one another, their electrons would be the first things to interact.
The Bohr model of the atom is sometimes called the “planetary model” of the atom. Why?
Since the electrons orbit the nucleus, they look like planets orbiting a sun.
What determines all of an atom's properties? What determines the vast majority of an atom's properties?
All of an atom's properties are determined by the number of electrons, protons, and neutrons that it contains. The vast majority of an atom's properties, however, are determined by the number of electrons (or protons) that an atom has.
An atom has 13 electrons. How many protons does it have?
Since atoms have the same number of protons and electrons, this atom must have 13 protons.
How do you abbreviate the names of elements?
Usually, an element is abbreviated by the first one or two letters of its name. Helium, for example, is abbreviated “He,” while carbon is abbreviated “C.” Unfortunately, some elements are also abbreviated by the first one or two letters of their Latin names.
What is the abbreviation for Carbon?
C
What is the abbreviation for Hydrogen?
H
What is the abbreviation for oxygen?
O
What is the abbreviation for nitrogen?
N
What is the abbreviation for phosphorus?
P
What is the abbreviation for sulfer?
S
How many protons and electrons does the atoms in carbon have?
6 electrons and 6 protons
Hydrogen is made up of all atoms that have how many protons and electrons?
1 proton and 1 electron.
Oxygen contains all atoms that have how many protons and electrons?
8 protons and 8 electrons
Nitrogen is made up of the atoms that have how many protons and electrons?
7 protons and 7 electrons.
Phosphorus contains those atoms with how many protons and electrons?
15 protons and 15 electrons
Sulfur is made up of the atoms that have how many protons and electrons?
16 protons and 16 electrons.
When different atoms have the same number of protons (and therefore the same number of electrons), they are said to belong to the same element. Why?
because they have the same basic properties
To name an atom, what do you have to do/know?
We call it by the element to which it belongs, followed by the sum of its protons and neutrons.
To name an atom, we call it by the element to which it belongs, followed by the sum of its protons and neutrons.

If you see just the name sulfur (or S), then what does that tell you?
You know that we are talking about an element, which probably contains more than one type of atom. After all, there are several atoms that all have 16 protons and thus belong to the element sulfur but have different numbers of neutrons.
when you see a name like sulfur-32 (or S-32 or sometimes 32S), what does this tell you? What do you know about it?
You know that we are talking about a particular atom, the one that has 16 protons (that's what makes it sulfur) and 16 neutrons (that's how to get a 32 when you add the protons and neutrons together).

Keep in mind that an element (such as sulfur) is composed of many individual atoms (such as sulfur-32, sulfur-33, sulfur-34, and sulfur-36).
What is the most important aspect of identifying and atom?
The element to which an atom belongs is, by far, the most important aspect of identifying an atom.
Two atoms have slightly different properties, but they belong to the same element. What is different about them: their numbers of protons, neutrons, or electrons?
Atoms that belong to the same element have the same number of protons and therefore the same number of electrons as well. Thus, their numbers of neutrons are different.
The element carbon is composed of all atoms that have 6 protons. One of the atoms in the element carbon is carbon-13. How many protons, neutrons, and electrons are in a carbon-13 atom?
Since carbon-13 is a member of the element carbon, it has 6 protons and 6 electrons. The “13” in carbon-13 represents the sum of all protons and neutrons. Thus, there must be 7 neutrons, because you must get 13 when you add the protons and neutrons together. Since the number of protons must be 6, the only possible number of neutrons is 7, as 6 + 7 = 13.
In a chemical formula, what do the numbers in subscript indicate?

(By the way, it is VERY important for you to know that from here on out a subscript will be indicated by the ^ symbol. So carbon dioxide is written CO^2 in these flashcards.)
Numbers that appear as subscripts indicate how many of those atoms are in the molecule.
If no subscript appears after an element, what does that tell you?
We know that there is only 1 atom of that type in the molecule. Since there is no subscript after the “C” in CO^2, we know that there is only 1 carbon in a molecule of carbon dioxide.
What does the number 2 in CO^2 indicate?
The “2” that appears as a subscript after the “O” tells us that there are 2 oxygen atoms in a carbon dioxide molecule.
The properties of a molecule are determined by what two things?
The important thing to realize about molecules is that the properties of a molecule are determined by the type and number of atoms that link together, as well as the way that they link together.

(the difference between carbon dioxide and carbon monoxide...)
True or False? If you have two molecules that are made up of the same exact atoms, but the number of one type of atom is off by a slight amount (say one) then it doesn't make that much of a difference.
False! It makes a HUGE difference! Two molecules can be made up of the same exact atoms, but if the number of even one type of atom is different between the two molecules, the molecules will have completely different properties.
The way in which atoms link up to form a molecule also affects the properties of the molecule. True or False?
True!!
Identify the following as either an atom, element, or molecule:

NH^3
This is a molecule, because it has several atoms (1 nitrogen and 3 hydrogens) linked together.
Identify the following as either an atom, element, or molecule:

P
This is an element, because it is a single abbreviation. With no other atoms linked to it, it is not a molecule. Also, since there is no number following it, we do not know its sum of neutrons and protons, so it is not a specific atom. It represents a group of atoms that all have the same number of protons.
Identify the following as either an atom, element, or molecule:

carbon-14
This is an atom, because it has the element name as well as the total number of neutrons and protons.
Identify the following as either an atom, element, or molecule:

S
this is an element.
Identify the following as either an atom, element, or molecule:

P^4
Even though this has only one element abbreviation, the subscript indicates that there are four phosphorus atoms linked together. Thus, this is a molecule.
A student is told to study the chemicals nitrogen monoxide (NO) and nitrogen dioxide (NO^2) and determine their differences. The student reports back that there are no differences between the molecules because they are made up of the same elements. Is the student right or wrong? Why?
The student is wrong. Even though these molecules are comprised of the same elements, there are different numbers of oxygen atoms. Different numbers of atoms result in molecules with different properties.
Name each element and the number of atoms of that element in one molecule of acetic acid (C^2H^4O^2), which is the active ingredient of vinegar.
The subscript after the “C” tells us that there are two carbons. The subscript after the “H” tells us that there are four hydrogens. The subscript after the “O” tells us that there are two oxygens.
Suppose you were to mix sugar and water. Is this a physical or chemical change? Explain your answer.
That's a physical change.

Before you mixed the sugar in the water, you had sugar in a spoon and water in a glass. What do you have once you mix the two? You still have sugar and water. They are now mixed, but they are still the same substances you started with. Their molecules have not changed; they have just been mixed together.
Why is burning a piece of paper considered a chemical change?
The molecules that made up the paper have been completely changed. They were changed into gases (principally carbon dioxide and water vapor) and ash. One substance (paper) changed into other substances (carbon dioxide, water vapor, and ash). That's a chemical change.
Identify the following changes as chemical or physical:

a. putting milk on cereal
This is a physical change, because it is reversible. You could pick the cereal out of the milk and then dry the cereal.
Identify the following changes as chemical or physical:

b. baking bread
This is a chemical change, because there is no way to “unbake” bread. Thus, it is not reversible.
Identify the following changes as chemical or physical:

c. boiling saltwater
This is a physical change. Remember we gave you the example of boiling a mixture of sugar and water to separate the two. Since saltwater is just salt dissolved in water, the same would apply here.
Thus, phase changes are physical changes, as they do not change the chemical makeup of the substance undergoing the change.

True? Or False?
True.
When you freeze a substance, what are you removing from its molecules?
energy
We also know that to change a substance from its solid phase to its liquid phase, we simply have to melt it. This involves heating it up. What are you adding to its molecules?
energy
If you take energy away from the molecules of a substance, the phase of the substance changes from ______ to _______ to ___________.
gas to liquid to solid.
If you add energy to a substance, the phase of the substance changes from _______ to _________ to ____________.
solid to liquid to gas.
What is the difference between diffusion and osmosis?
In diffusion, both solute and solvent can randomly flow through the membrane. The random movement distributes the solvent and solute evenly.

In osmosis, only solvent can flow through the membrane.
A semipermeable membrane is placed in a beaker. Equal amounts of salt water solution are placed on each side of the membrane, but the solution on one side is twice as concentrated with salt as is the solution on the other side. After one hour, the water level of the solution on the right increases, and the water level of the solution on the left decreases. Which solution (the one on the left or the one on the right) started out with the higher salt concentration?
The water level of the solution on the right increased, while the water level of the solution on the left decreased. Since we are dealing with a semipermeable membrane, this is osmosis. In osmosis, the solvent travels from an area of low solute concentration to one of high solute concentration. Since the water levels indicate that the solvent traveled from left to right, the right side had a higher salt concentration.
What does an arrow indicate in a chemical equation?
Equals.... or interacts to produce
What do the numbers to the left in a chemical formula mean?
These numbers indicate how many of each molecule it took to make the chemical change. If there was only 1 molecule, no number was written.
Write the chemical equation for the following reaction: (make sure it is balanced)

methane and oxygen interact to make water and carbon dioxide
CH^4 + 2O^2 ----> 2H^2O + CO^2
When a chemical reaction occurs, what happens to the molecules on the left side of the arrow? What do the molecules on the right hand side of the arrow mean?
When a chemical reaction occurs, the molecules on the left side of the arrow are destroyed, and the molecules on the right side of the arrow are produced.
The subscripted numbers refer to how many atoms of a certain type are in the molecule. If a subscripted number does not exist after an element's symbol, it means that only 1 such atom is in the molecule. True or False?
True.
The numbers to the left of the chemical formulas tell us how many of each molecule is used or made in the reaction. True? Or False?
True.
One of the main chemical reactions used to run an automobile engine is the combustion of octane (C^8H^18):


2C^8H^18 + 25O^2 ----> 16CO^2 + 18H^2O

a. Write the chemical formulas of the reactants in this equation.
Reactants appear on the left hand side of the arrow. Also, the numbers to the left of the formulas are not part of the formulas. They simply tell us how many of each molecule is in the reaction. Thus, we do not include them in our answer. The reactants, then, are C8H18 and O2.
One of the main chemical reactions used to run an automobile engine is the combustion of octane (C^8H^18):


2C^8H^18 + 25O^2 ----> 16CO^2 + 18H^2O


Write the chemical formulas of the products in this equation
. Products are on the right side of the arrow and, once again, the numbers to the left of the formulas are not a part of the formulas. The products, then, are CO^2 and H^2O.
One of the main chemical reactions used to run an automobile engine is the combustion of octane (C^8H^18):


2C^8H^18 + 25O^2 ----> 16CO^2 + 18H^2O

How many molecules of C^8H^18 are used in the reaction?
The number to the left of the chemical formula for C^8H^18 tells us how many octane molecules are used in the reaction. Thus, the answer is two.
One of the main chemical reactions used to run an automobile engine is the combustion of octane (C^8H^18):


2C^8H^18 + 25O^2 ----> 16CO^2 + 18H^2O

How many molecules of H^2O are made in the reaction?
The number to the left of the chemical formula for H^2O tells us how many water molecules are made in the reaction. Thus, the answer is 18.
Most catalysts speed up chemical reactions, but there are a few which are known to slow down chemical reactions.

True or False?
True.
Most autotrophic organisms use photosynthesis to create their own food. This process is a chemical change that takes 6 carbon dioxide molecules and 6 water molecules to make 1 glucose molecule 6 six oxygen molecules. The glucose is food for the organism, and the oxygen goes back into the atmosphere for organisms to use. In order for this chemical reaction to occur, however, the organism needs more than just carbon dioxide and water.

What else does it need?
It needs energy, which it gets from sunlight, and it needs a catalyst, which is usually (but not always) chlorophyll.
The balanced chemical equation for photosynthesis is:

6CO^2 + 6H^2O ----> C^6H^12O^6 + 6O^2

This is balanced, but it is still missing two things. What are they?
The sunlight factor and the catalyst to speed the process up.
A plant loses all of its chlorophyll. Will it be able to produce any glucose at all?
It can produce some glucose, but without the catalyst, the rate will be far too slow for the plant to sustain itself.
A chemist is trying to speed up a chemical reaction. If the chemist does not have a catalyst, what other means can be used?
The chemist can increase temperature. This speeds up most reactions.
Biosynthesis is an example of anabolism. True or False?
True. It is basically building large molecules out of simple ones.
What is the chemical formula for glucose?
C^6H^12O^6
Sometimes in a structural formula oxygen atom (O) and a hydrogen atom (H) are drawn next to each other but there is no line linking them together. Does that mean they are not linked to one another?
No, not really. It turns out that when an oxygen atom and a hydrogen atom are linked together in a molecule, biologists rarely draw a line to represent the bond that exists between them. This is because the combination of an O and an H linked together is fundamentally important in biology, so to represent this, we purposely do not draw the bond. This makes that part of the molecule stand out. Thus, even though it is not drawn, you need to realize that there is a bond linking the O to the H in an OH group.
Many molecules have more than one structural formula. Is this true or false?
True.
The chemical formula for glucose is the same as that for fructose. If these two molecules have the same chemical formula, how can they be different molecules?
Well, they have the same chemical formula, but they have different structural formulas. These different structural formulas are the reasons behind the taste difference and other chemical differences between glucose and fructose.
True or False? Polysaccharides are sweet and give our food a pleasant taste.
False. Typically, polysaccharides are not sweet, because the sweetness of the monosaccharides is lost when several combine.
Most animals can only use monosaccharides for energy.

Is this true or false?
True. When an organism eats disaccharides or polysaccharides, it must first break them down into their individual monosaccharide components. To break these complex molecules back down into their monosaccharide components, all you have to do is add water to them.
Note to student: Make sure you are familiar with the On Your Own questions in this Module when they are asking about structural formulas. It is impossible to recreate them here.... so go look in your book for a refresher quiz. (Very important to understand them... so take the time to go check it out!)
Note to student: Make sure you are familiar with the On Your Own questions in this Module when they are asking about structural formulas. It is impossible to recreate them here.... so go look in your book for a refresher quiz. (Very important to understand them... so take the time to go check it out!)
A chemist takes a polysaccharide and turns it into many disaccharides. Has the chemist used dehydration or hydrolysis?
To turn a polysaccharide into a disaccharide, you have to break it down. Hydrolysis reactions break polysaccharides down.
Many of the drinks that we enjoy (soda pop and fruit juice) contain:

a. bases
b. acids
c. both
b. acids
The substances we use for cleaning contain:

a. bases
b. acids
c. both
a. bases
When acids and bases react together, they typically form water and another class of molecule called “salts.” Is this true or false?
true.
Why istracking the level of acid or base so very important?
In most of the chemical reactions that make life possible, the amount of acid or base present has a profound effect on the speed and effectiveness of the reaction.
What is the purpose of the “pH” scale?
Used to track the level of acid or base.
The higher the pH, the more like a base the solution becomes. True? Or False?
true
A chemist measures the pH of several solutions. The results are:
Solution A: 8.1,
Solution B: 1.1,
Solution C: 5.5,
Solution D: 13.2.

Which solution is the most alkaline?
The pH scale says below 7 is acidic and above 7 is alkaline. In addition, the higher the pH, the more alkaline the solution. Based on that, then, Solution D is the most alkaline.
A chemist measures the pH of several solutions. The results are:
Solution A: 8.1,
Solution B: 1.1,
Solution C: 5.5,
Solution D: 13.2.

Which solution is the most acidic?
The pH scale says below 7 is acidic and above 7 is alkaline. In addition, the lower the pH, the more acidic the solution. Based on that, then, Solution B is the most acidic.
Give a common example of a lipid found in a kitchen.
cooking oil
Why are lipids the preferred method of storing excess food?
Because more than twice as much energy can be stored in an ounce of fat than in an ounce of carbohydrates. As a result, animals make fats whenever they have excess food. Later, when food is scarce, their bodies can digest the fat for energy.
Why is fat storage a problem when food is not scarce?
Because the fat stores up and if you eat too much of it.... you become overweight.
Is it better to have saturated fat, or unsaturated fat in your diet?
Saturated fats tend to lead to heart troubles while unsaturated fats are less likely to.

As a result, nutritionists suggest that we eat unsaturated fats.
How do you know whether a fat is saturated or unsaturated?
One way is to look at the structural formula of the fat. If there are double bonds between the carbons in the fatty acids, it is an unsaturated fat. Otherwise, it is saturated.

There is another way to distinguish these two types of fats, however. Generally, you can look at their phase. At room temperature, saturated fats tend to be solid while unsaturated fats tend to be liquid. Thus, the solid lard that you use for baking is a saturated fat. (butter)The liquid oils that you use for frying, however, are unsaturated fats.
If plenty of glycerol is available, how many fat molecules can be made from 15 fatty acid molecules?
Each fat molecule takes 3 fatty acids along with a glycerol. As long as we have plenty of glycerol, then, we can make 5 fat molecules with 15 fatty acid molecules.
There are about 20 different amino acids in the proteins that make up life, so what determines the shape and function of a protein?
There are about 20 different amino acids in the proteins that make up life, and the type of amino acid along with the order in which the amino acids are linked up determine the shape and function of a protein.
The simplest protein of life is Ribonuclease. Why can't we easily draw the structural formula for it and other proteins?
the average amino acid has about 20-40 atoms, and even the simplest protein of life contains 124 amino acids linked together. Obviously, then, drawing the structural formula of a protein would be quite a job. The situation would be even worse for the “average” protein in the chemistry of life, which contains several thousand amino acids!
How do you abbreviate an amino acid?
You use three-letter abbreviations that stands for an amino acid. The letters “Lys,” for example, stand for the amino acid called “lysine,” while the letters “Glu” stand for glutamic acid.
Using the concept of proteins and how they are structured, describe why the idea of abiogenesis very hard for a scientist to believe.
Ribonuclease is difficult enough to imagine coming together by accident. Remember, ribonuclease is a “simple” protein. There are proteins in our bodies that contain more than 10,000 amino acids! Clearly the idea that these proteins could form by chance is absurd, which makes the whole idea of abiogenesis very hard for a scientist to believe.
Why are enzymes so important in chemical reactions that support life?
In order to digest disaccharides and polysaccharides, animals must break them down into monosaccharides using hydrolysis. Well, it turns out that hydrolysis reactions like these are incredibly slow, and animals would die long before they could digest polysaccharides if it weren't for enzymes. These proteins are catalysts for the hydrolysis reactions, making them fast enough to allow the proper digestion of food.
Why is the shape that enzyme molecules have important?
Most enzymes do their job based on the shape that the enzyme molecule has.

The shape of a hydrolysis enzyme, for example, complements the disaccharide or polysaccharide that it is trying to break down. As a result, the enzyme can attach itself to the molecule it is breaking down and help force the water between the monosaccharides, speeding up the hydrolysis reaction.
Why do some people have "food allergies" such as lactose intollerance?
Certain cells in their bodies are defective and cannot manufacture the enzyme necessary to catalyze the hydrolysis of lactose. (or the enzymes particular to other foods...)
True or False? Enzymes are fragile and easy to destroy!
True. Because they are so complex and because their function is shape-dependent, they are quite fragile
Why is fresh pineapple different than canned pineapple? (In terms of their enzymes....)
Enzymes are so fragile that most food processing destroys them. So fresh pineapple still contains the original enzymes. Not as many as when they are first formed, as enzymes break down soon after they are formed, but definitely more than canned pineapple!
Why is it important to eat protein in your diet?
The protein that you eat gets broken down into its constituent amino acids, and those amino acids are shipped to the cells in your body so that they can produce the enzymes that your body needs. Since enzymes break down soon after they are formed, your body must continually produce more and more enzymes, just to replace the ones that are breaking down. Hence, the importance of protein!
Since dehydration reactions link amino acids in order to form proteins, you can probably guess that hydrolysis reactions break them down. Why don't proteins quickly break down into their amino acids when they are mixed with water?
As we discussed with regards to enzymes, in order for hydrolysis reactions to work with any worthwhile rate, they need a catalyst. If proteins are mixed with just water, there are no enzymes to catalyze the hydrolysis reaction, so they will not break down into amino acids very quickly.
The nucleotides that make up these two chains int he double helix are composed of three basic constituents. What are they?
1. deoxyribose (a simple sugar that contains 5 carbons)

2. a phosphate group (an arrangement of phosphorous, hydrogen, and oxygen atoms)

3. and a nucleotide base which can be one of four different types.
What are the four different types of nucleotide bases?
1. adenine (ad' uh neen),
2. thymine (thye' meen),
3. guanine (gwah' neen),
4. or cytosine
Luckily for us, nucleotide bases can link together in any way or with any of the other nucleotide bases. True or False?
False. Hydrogen bonding is highly dependent on the molecules involved, and as a result, it turns out that only certain nucleotide bases can link together using hydrogen bonds.

For example: The nucleotide base adenine can only hydrogen bond to thymine. It cannot hydrogen bond to cytosine or guanine.
This represents the fact that only adenines and thymines can link together and that only cytosines and guanines can link together.
True or false?
True. (to remember this, remember that the A's and T's are the only ones that form an actual word... AT .... when they link to gether. Or TA (as in good bye!) C and G can't do that!)
Suppose you have just one strand of a portion of DNA. This strand has the following order of nucleotide bases:

adenine, cytosine, thymine, guanine

If you could find the other strand of DNA that connects to this one to form the double helix, what would the order of nucleotide bases be?
Remember that adenine can only link to thymine and that cytosine can only link to guanine. Thus, if one strand has adenine, the other must have thymine. If one strand has cytosine, the other must have guanine. This tells us that the order on the other strand must be thymine, guanine, adenine, cytosine.


(remember: AT or TA)
Describe where the protons, neutrons, and electrons are in an atom.
In an atom, protons and neutrons cluster together at the center, which is called the nucleus.
Electrons orbit around the nucleus.
What determines the vast majority of characteristics in an atom?
The number of electrons (or protons) in an atom determines the vast majority of its characteristics.
What does the number after an atom’s name signify?
When a number appears after an atom’s name, it tells you the sum of protons and neutrons in the
atom’s nucleus.
What is the difference between an element and an atom?
An element contains all atoms that have the same number of protons (and therefore the same
number of electrons), regardless of the number of neutrons. An atom is a single entity, determined by
its number of protons, electrons, and neutrons.
How many electrons are in an atom that has 32 protons?
Since atoms have the same number of electrons and protons, there must be 32 electrons.
How many atoms (total) are in a molecule of C3H8O? What atoms are present and how many of
each atom?
The subscripts after the elemental abbreviations tell you how many of each atom is in the molecule.
Thus, there are 3 carbons, 8 hydrogens, and 1 oxygen, for a grand total of 12 atoms.
Identify the following as an atom, element, or molecule:

a. H^2CO^3
b. nitrogen-14
c. P
a. Molecule, because it has several atoms linked together

b. Atom, because it specifies number of neutrons and protons

c. Element, because it is by itself but does not specify the number of neutrons and protons
If you add energy to the molecules of a liquid, will it turn into a gas or a solid?
Adding energy causes molecules to go from solid to liquid to gas. Thus, the liquid will turn into a
gas. To turn it into a solid, you must take energy from it.
A chemist wants to study diffusion. Should a semipermeable membrane be used?
A semipermeable membrane should not be used. For diffusion to work, both solute and solvent
must be able to travel across the membrane. Semipermeable membranes typically allow only solvent
molecules to pass.
Two solutions of different solute concentration are separated by a membrane. After a while, the
water levels of the two solutions change. Has osmosis or diffusion taken place? What kind of
membrane is being used?
Since the water levels changed, that means solvent traveled from one side of the membrane to the
other, but solute did not. This is osmosis, which requires a semipermeable membrane
Consider the following chemical reaction:

N^2 + 3H^2 ---->¨ 2NH^3

a. What are the reactants?
b. What are the products?
c. How many molecules of H2 are used in the reaction?
a. Reactants appear to the left of the arrow. The number to the left of the chemical formulas,
however, do not describe the reactants. Instead, they tell you how many of each reactant molecule.

a. Thus, the reactants are N^2 and H^2.

b. Products appear on the right side of the arrow. The product is NH^3.

c. There are three H^2 molecules in the reaction, because of the “3” to the left of H^2.
What is the chemical equation for photosynthesis?

What 4 things are necessary for a plant to carry
out photosynthesis?
. Photosynthesis is represented by:
6CO^2 + 6H^2O ------> C^6H^12O^6 + 6O^2
In order for a plant to carry out photosynthesis, it needs CO^2, H^2O, energy from sunlight, and a catalyst
like chlorophyll.
Other than using a catalyst, how can a reaction be sped up?
Reactions can also be sped up by increasing temperature.
Which of the following is a carbohydrate?
a. NH^3
b. CO^2
c. C^2H^4O
d. C^5H^10O^5
e. C^3H^8O^3
Carbohydrates have carbon, hydrogen, and oxygen and no other elements. In addition, like water,
they must have twice as many H’s as O’s. Only molecule d fits that bill.

Answer: C
What kind of reaction is used for building disaccharides, polysaccharides, fats, and proteins?
What kind of reaction can break these substances down?
Dehydration reactions build up these molecules, and hydrolysis reactions can break them down,
providing the proper enzyme exists.
Describe the pH scale and what it measures.
The pH scale measures the acidity or alkalinity of a solution. On this scale, 7 is neutral. Lower
than 7 pH’s are acidic, and higher than 7 are alkaline. The lower the pH the more acidic, and the
higher the pH the more alkaline
What are the basic building blocks of proteins, lipids, and polysaccharides?
Amino acids link together to make proteins, fatty acids link to glycerol to make lipids, and
monosaccharides link together to make polysaccharides.
If two proteins contain the same type and number of amino acids, but the order in which they link
up is different, are the properties of the two proteins the same?
These two proteins will not have the same properties. Not only the number and type but also the
order of amino acids determine a protein’s structure and function.
What are enzymes, and for what purpose are they usually used?
Enzymes are a special class of proteins that are used as catalysts.
What is the “lock and key” theory of enzyme action?
The “lock and key” theory of enzyme action says that an enzyme has an active site that is shaped
especially for the molecule that it must work on. The action that the enzyme takes cannot happen until
the molecule attaches to that active site. Since the active site is shaped for a specific molecule, such an
enzyme cannot work on other molecules, unless it happens to have the same shape.
What are the basic parts of a nucleotide?
The three basic parts of a nucleotide are the phosphate group, the sugar, and the base.
How does DNA store information?
DNA stores information as a sequence of nucleotide bases, much like all of the English language
can be stored as a sequence of dots and dashes in Morse code.
What holds the two helixes in a DNA molecule together?
Hydrogen bonds between the nucleotide bases hold the two helixes of DNA together.