unit 3

Question 1

How many different kinds of amino acids are there in most proteins?

Answer 1

20

Question 2

Which of the following substances is made of lipids?

Answer 2

steroids

Question 3

Which element is closely associated with the field of organic chemistry?

Answer 3

carbon

Question 4

Which of the following molecules is a carbohydrate?

Answer 4

C60 H100 O50

Question 5

Amino acids can be distinguished from one another by

Answer 5

the chemical properties of their R groups.

Question 6

A disaccharide forms when

Answer 6

two monosaccharides join by dehydration synthesis.

Question 7

Which of the following lists contains only polysaccharides?

Answer 7

cellulose, starch, and glycogen

Question 8

Which of the following contains a carboxyl and an amino group?

Answer 8

amino acid

Question 9

Carbohydrates are mainly used in our bodies _____.

Answer 9

as fuel

Question 10

A DNA nucleotide is composed of a __________.

Answer 10

deoxyribose sugar, which is bonded to a phosphate group and a nitrogenous base

Question 11

Fatty acids are

Answer 11

hydrophobic

Question 12

A molecule with the formula C7H14O7 is probably a(n)

Answer 12

monosaccharide

Question 13

Fatty acids with double bonds between some of their carbons are said to be

Answer 13

unsaturated

Question 14

What is the general function of enzymes within a cell?

Answer 14

to speed up chemical reactions

Question 15

How are these two amino acids attached together?

Answer 15

amino group to carboxylic acid group

Question 16

DNA carries the instructions for building _____, and these instructions are found in informational units called _____.

Answer 16

polypeptides … genes

Question 17

The lipids that form the main structural component of cell membranes are _____.

Answer 17

phospholipids

Question 18

Which of the following is a carboxyl group?

Answer 18

-COOH

Question 19

A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture _____.

Answer 19

DNA

Question 20

The results of dehydration synthesis can be reversed by

Answer 20

hydrolysis

Question 21

What feature of fats makes them hydrophobic?

Answer 21

Fats have nonpolar hydrocarbon chains.

Question 22

Select the hydrocarbon

Answer 22

C3H8

Question 23

The storage form of carbohydrates is ________ in animals and ________ in plants.

Answer 23

glycogen; starch

Question 24

When two monosaccharides link to form a disaccharide, the by-product is __________.

Answer 24

water

Question 25

A glucose molecule is to starch as _____.

Answer 25

a nucleotide is to a nucleic acid

Question 26

When an RNA strand forms using DNA as a template, _____.

Answer 26

uracil pairs with adenine and cytosine pairs with guanine

Question 27

Although the structures of the functional groups important to life (hydroxyl, carbonyl, carboxyl, amino, and phosphate) vary in chemical structure, they share one thing in common: They _____.

Answer 27

all are hydrophilic and increase the organic compound's water solubility

Question 28

Dehydration reactions __________. They do so by __________.

Answer 28

link monomers to form a polymer; removing a water molecule

Question 29

Many names for sugars end in the suffix

Answer 29

-ose.

Question 30

These two molecules are structural isomers. What is the difference between them?

Answer 30

the location of a double-bonded oxygen atom

Question 31

A fatty acid containing at least one double bond is called _____.

Answer 31

unsaturated

Question 32

Which of the following would be correctly classified as a protein?

Answer 32

an enzyme

Question 33

The reaction that joins two monomers to form a polymer is known as a _____ reaction. The molecule of water formed is due to the interaction between _____ and a hydrogen ion.

Answer 33

dehydration ... a hydroxyl group

Question 34

Which of the following foods would contain the most starch?

Answer 34

Carrots

Question 35

Based on the way the nitrogen-containing bases in DNA and RNA pair, you would expect the percentage of _____ to be equal to the percentage of _____. Look at the figure carefully.

Answer 35

A ... T

Question 36

Glucose molecules are to starch as ________ are to proteins.

Answer 36

amino acids

Question 37

How does DNA differ from RNA?

Answer 37

RNA contains ribose, DNA does not.

Question 38

A phospholipid is composed of

Answer 38

one glycerol molecule linked to one phosphate group and two fatty acids.

Question 39

In a hydrolysis reaction, __________. In this process, water is __________.

Answer 39

a polymer breaks up to form monomers ... consumed

Question 40

Organic compounds

Answer 40

always contain carbon.

Question 41

You work for a company that manufactures food products. A new "wonder food" is being distributed by a rival company. The researchers in your company determined that the "wonder food" contains only carbon, oxygen, and hydrogen. At this point, your researchers can say with certainty that the food

Answer 41

does not include proteins or nucleic acids.

Question 42

A major type of lipid found in cell membranes is

Answer 42

phospholipids.

Question 43

Which of the following is an amino group?

Answer 43

-NH2