Chapters 2 and 3

Question 1

When water gets heated or cooled, the water’s temperature takes some time to change. What is happening to the bonds in or between the water molecules when the water is heated? What is happening to the bonds in or between the water molecules when the water is cooled?

Answer 1

When the water molecules are heated, hydrogen bonds (between water molecules) are broken so that water molecules can move more and store this energy. Water takes a long time to heat up because it stores energy as a result of its hydrogen bonds. When water is cooled; however, water expands, because heat is being released as the hydrogen bonds stabilize and keep the water molecules from moving around and getting too close to one another. In both instances, water’s chemical makeup doesn’t change and neither do the covalent bonds between the hydrogen and oxygen atoms.

Question 2

Disorders, such as tooth decay, are the result of deficiencies in what?

Answer 2

Trace elements

Question 3

Some people in you class say they don’t understand what a non polar molecule is. You explain that a non polar molecule…..

Answer 3

has electrons that are shared equally by the atoms and therefore no net charge.

Question 4

Stomach acid has a… because….

Answer 4

low pH because it has

Question 5

Stomach acid has a… because….

Answer 5

low pH

Question 6

A substance that cannot be broken down into other substances by ordinary chemical procedures is what?

Answer 6

an element

Question 7

A carbon atom and a hydrogen atom form what type of bond in a molecule?

Answer 7

a nonpolar covalent bond

Question 8

The type of bonding and the numbers of covalent bonds an atom can form with other atoms is determined by what?

Answer 8

the number of unpaired electrons in the valence shell

Question 9

Carbon-12 is the most common isotope of carbon and has a mass number of 12. Why?

Answer 9

Some carbon atoms in nature have more neutrons

Question 10

Water molecules are attracted to one another by>

Answer 10

Hydrogen bonds

Question 11

Which of the following is not a polymer?

Answer 11

an amino acid

Question 12

In the following reaction, galactose is a what?

galactose + glucose&raquo_space; lactose + water

Answer 12

monomer

Question 13

carbohydrates typically include what?

Answer 13

C, H and O atoms

Question 14

Animals store carbohydrates as what?

Answer 14

glycogen

Question 15

The following molecule is best described as a what?

CH3–CH2–CH2–CH2–CH3

Answer 15

a hydrocarbon

Question 16

All of the following is an example of a polysaccharide except…

a. galactose
b. starch
c. glycogen
d. cellulose

Answer 16

Galactose

Question 17

A glycerol with three fatty acids attached is a type of

Answer 17

lipid

Question 18

A fat that is hydrogenated is

Answer 18

more solid at room temperature

Question 19

Changing one amino acid within a protein could change what about a protein?

Answer 19

The 1o structure, the overall shape of the protein, and the function of the protein

Question 20

Proteins are polymers constructed from what?

Answer 20

Carbon, hydrogen, oxygen and nitrogen

Question 21

At which level of protein structure are interactions between the side chains (functional groups) most important?

Answer 21

tertiary

Question 22

What is a good description of the class of molecules known as nucleotides?

Answer 22

a nitrogen containing base , a phosphate group, and a 5-carbon sugar

Question 23

One off the primary functions of RNA molecules is to what?

Answer 23

provide instructions for the synthesis of proteins

Question 24

Base pairing between the nitrogen containing bases on the two strands of DNA occurs through which type of bonds?

Answer 24

hydrogen bonds

Question 25

Adenine and guanine have.....ring/s, and cytosine and thymine have....ring/s.

Answer 25

2;1

Question 26

List three ways in which RNA differs from DNA.

Answer 26

1. RNA has a different sugar. It has ribose, while DNA has deoxyribose, which has fewer oxygen atoms. 2. RNA has the nitrogenous bas uracil instead of thymine, which is found in DNA. 3. RNA is single stranded, whereas DNA has a two strands that form a double helix.

Question 27

The primary (1o) structure is a sequence of what?

Answer 27

The primary structure is the sequence of amino acids.

Question 28

There are two major structural types that exist in the secondary structure. Which are....

Answer 28

The two major types are the double helix and the beta pleated sheet.

Question 29

What is the quaternary structure of proteins?

Answer 29

The quaternary structure of proteins is the interaction between proteins.

Question 30

What clogs arteries as a result of the ability of fatty acid chains to stick.

Answer 30

saturated fat

Question 31

A type of steroid that serves as a precursor to hormones.

Answer 31

Cholesterol

Question 32

Contains carbon, hydrogen, and oxygen in no specific ratio.

Answer 32

Lipid

Question 33

The 3-carbon structure that is covalently bonded to fatty acid chains

Answer 33

Glycerol

Question 34

A synthetically hydrogenated fat

Answer 34

Trans fat

Question 35

contains at least on double bond

Answer 35

unsaturated fat

Question 36

What happens when you try to join two hydrogens or two oxygens?

Answer 36

They repel one another became they have the same charges.

Question 37

What happens when you join hydrogen to oxygen?

Answer 37

They are attracted to one anther because they have opposite charges.

Question 38

A polar molecule has opposite charges one opposite ends. Is water polar?

Answer 38

Water is a polar molecule because oxygen has a negative charge, while the hydrogen atoms have a positive charge; this means that opposite ends of a water molecule have opposite charges.

Question 39

What happens when water molecules come near one another? What type of bonds form between water molecules? How many of these bonds can form around a water molecule.

Answer 39

Water molecules form hydrogen bonds between one another. The oxygen atoms, which are slightly negative, are attracted to the slightly positive hydrogen atoms of another molecule and vice versa. There are 4 hydrogen bonds that form around one water molecule.

Question 40

How do hydrogen bonds relate to the property of cohesion? What is the difference between cohesion and adhesion?

Answer 40

This relates to the property of cohesion because cohesion occurs as a result of the hydrogen bonds between water molecules; when molecules bond in this way, they are able to stick to one another. Cohesion is when molecules of the same substance stick to one another while adhesion is when molecules stick to other substances.

Question 41

What is the biological importance of water's cohesive and adhesive properties?

Answer 41

Water's adhesion and cohesion allows for plants to get water from their roots up to into the rest of the plant. Its properties also allow insects to walk on water because cohesion gives water high surface tension.

Question 42

Why did the food coloring in the hot water move quickly while the food coloring in the cold water move slowly and doesn't mix with the water very well?

Answer 42

There is a difference in the movement because the hydrogen bonds in the hot water are already broken, which makes it easier for the food coloring to move easily in the water. The hydrogen bonds between the water molecules in the cold water are constantly forming and reforming, making it harder to move through the water.

Question 43

What happens to each ice cube in the beaker with water and the one with isopropyl alcohol? Explain the difference.

Answer 43

The ice in the blacker with water floated on top of the water because liquid water is denser than ice. The ice in the isopropyl alcohol sank to the bottom because isopropyl alcohol is less dense than ice, so it's unable to float.

Question 44

Why does water expand when it freezes?

Answer 44

Water expands when it freezes because water in its solid state has stable hydrogen bonds that don't allow water molecules to get close to each other and creates more space between them. Liquid water and ice have the same mass, but ice expands because it has the extra space that isn't present in liquid water.

Question 45

What is the biological importance of the expansion of water when it freezes?

Answer 45

When water freezes, it expands, creating more space between water molecules that acts as an insulator. The layer of ice at the surface of a body of water ensures the survival of organisms that live underneath so that they aren't frozen to death and can continue living in the liquid water beneath the ice.

Question 46

A homogenous mixture of 2 or more substances is...

Answer 46

A solution

Question 47

A dissolving agent is called...

Answer 47

A solvent

Question 48

A material being dissolved is called...

Answer 48

The solute

Question 49

A solution where water is the solvent is called...

Answer 49

an aqueous solution

Question 50

Water loving substances or molecules with an affinity for water are...

Answer 50

hydrophilic

Question 51

Water fearing substances or molecules that do not have an affinity for water are...

Answer 51

hydrophobic

Question 52

When the solvent is water and the solute is salt.....

Answer 52

The solute (salt) dissolves into water quickly and easily because water is polar. The solute dissolved into the water because salt is made of sodium and chlorine ions, which are attracted to water because water molecules are polar.

Question 53

When the solvent is water and the solute is hexane.....

Answer 53

The solute doesn't dissolve into hexane and sits at the bottom of the beaker because hexane is non polar. the solute did not dissolve into the hexane because unlike water it's not a polar solvent that the sodium and chlorine ions are not attracted to it.

Question 54

Why is water a versatile solvent? In general, what kinds of materials will dissolve in water?

Answer 54

Water is a versatile solvent because it is a polar solvent, so it can dissolve compounds formed between multiple ions.

Question 55

What is an acid? Examples?

Answer 55

An acid is a substance that donates hydrogen ions. | Ex. battery acid, lemon juice, soda, milk

Question 56

What is a base? Examples?

Answer 56

A base is a substance that accepts hydrogen ions. | Ex. liquid drain cleaner, soapy water, eggs, bleach

Question 57

Why do scientists us the logarithmic scale to describe acids and bases?

Answer 57

Scientists use the logarithmic scale because the amount of hydrogen ions could be so big that they can't officially count it and could be bigger than a strongly acidic solution or smaller than a strongly basic solution. They can't rely on counting the number of ions alone.

Question 58

What is a disulfide interaction?

Answer 58

The side chains of the amino acid Cysteine are able to form a disulfide interaction, which is a form of covalent bond that is a lot stronger than the other interaction between amino acid side chains (functional groups).

Question 59

What is the interaction between amino acids and proteins?

Answer 59

Amino acids are the monomers that make up proteins.

Question 60

Why does a chain of amino acids "fold" into certain three-dimensional structures?

Answer 60

Amino acids "fold" into certain 3-D structures because amino acids repel or attract one another depending on the amino acids.

Question 61

Why is the "structure" or "shape" of the protein significant?

Answer 61

The "structure" of the protein tells us which protein it is and aligns with its function.

Question 62

In the DNA lab, we used an experimental sample, which was strawberry. Do you think the experimental sample will contain DNA? Why or why not? Will the experimental sample look like the positive (salmon) or negative control (water)?

Answer 62

The experimental sample wil contain DNA because it comes from an organism, and organisms must have DNA in order to function properly. I think that the experimental sample will look like the positive control because it, unlike the negative control, also has DNA.

Question 63

What does the presence or absence of DNA in the experimental sample indicate about it?

Answer 63

The presence of DNA in the experimental sample shows that it has cells and is or comes from a living thing, like the positive control, which is also a living thing.

Question 64

When you make bread, if you just mix flour, sugar and water, the dough does not rise, and the bread will be flat and hard. If you include yeast in the bread dough, then the dough rises and the bread is bigger and fluffier. Can you explain how the yeast helps the bread dough to rise?

Answer 64

The yeast helps the bread dough rise because the yeast uses the sugar as energy and releases carbon dioxide gas, causing the dough to expand and become bigger as well as less dense, so it is fluffier.