Chapter 3 Questions

Double bonds are present in the majority of the fats of which of the following foods? eggs lard margarine peanuts

peanuts

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

phospholipids

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

polypeptides ... genes

Which of the following sugars CAN be accurately represented by the formula C6H12O6?

possibly glucose or fructose

What is the general function of enzymes within a cell?

to speed up chemical reactions

Which of the following is a carboxyl group? -OH -C-O -NH2 -COOH

-COOH

Which of the following is an amino group? -OH -CO -COOH -NH2

-NH2

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

carbon

The production of high fructose corn syrup involves the hydrolysis of __________ from corn into __________, followed by its enzymatic conversion.

starch ... glucose

Which of the following statements about hydrocarbons is false? A) Hydrocarbons are inorganic compounds. B) Hydrocarbons contain only carbon and hydrogen atoms. C) Hydrocarbons can form straight, branched, or ringed structures. D) Hydrocarbons consist of atoms linked by single or double bonds.

A

What is the complementary sequence to the DNA strand TCGATGG?

AGCTACC

Which of the following statements about the functional groups of organic compounds is false?

All functional groups include a carbon atom.

Which of the following statements regarding carbon is false? A) Carbon has a tendency to form covalent bonds. B) Carbon has the ability to bond with up to six other atoms. C) Carbon has the ability to bond together to form extensive branched or unbranched "carbon skeletons." D) Carbon has the capacity to form single and double bonds.

B

Which of the following molecules is a carbohydrate?

C60H100O50

The molecular formula of most monosaccharides represents a multiple of

CH2O.

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

DNA

What feature of fats makes them hydrophobic?

Fats have nonpolar hydrocarbon chains.

Generally, animals cannot digest the linkages between the glucose molecules in cellulose. How then do cows get enough nutrients from eating grass?

Microorganisms in their digestive tracts hydrolyze the cellulose to glucose.

Which of the following statements about the monomers and polymers found in living organisms is false?

Monomers are joined together by the process of hydrolysis.

Which statement correctly describes bonds of the secondary structure of proteins?

Secondary structure involves hydrogen bonding between atoms of the polypeptide backbone.

How are genes used by cells to build proteins?

The genes in DNA direct the synthesis of an RNA molecule, which is used to build a protein.

Two proteins have the same number and type of amino acids. How is it that they can have different shapes and therefore different functions?

The order in which the amino acids are arranged differs between the two proteins.

Your first big biology exam is coming up in a few days, and in order to prepare for late-night study sessions, you buy a box of Yummies, a delicious type of snack cake. After checking out the nutrition facts label on the side of the box, you discover that a single Yummie cake contains 4.5 grams of total fat, 27 grams of carbohydrate, 0 grams of fiber, and 1 gram of protein. The pH of the stomach is extremely acidic (~ pH 2). If you ate a Yummie cake, what do you think would happen to the protein that you ingested as it passes through the stomach?

The protein would become denatured due to the acidic environment.

Lactose is a disaccharide (two monosaccharides joined together). To metabolize lactose, individuals require an enzyme known as lactase. What is true about this reaction?

The reaction hydrolyzes the sugar.

An oil may be converted into a substance that is solid at room temperature by

adding hydrogens, decreasing the number of double bonds in the molecules.

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 _____.

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

Organic compounds

always contain carbon

Lipids differ from other large biological molecules in that they _____.

are not truly polymers

Carbohydrates are mainly used in our bodies _____.

as fuel

Which of the following features are not present in a molecule of caffeine?

carboxyl group

Which of the following foods would contain the most starch? liver carrots celery steak

carrots

A hydroxyl group is

characteristic of alcohols.

DNA differs from RNA because DNA

contains thymine in place of uracil.

A DNA nucleotide is composed of a __________.

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

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

glycogen; starch

The results of dehydration synthesis can be reversed by

hydrolysis

The oil and vinegar in your salad dressing remain separate from one another due to the _____ properties of the oil.

hydrophobic

Fatty acids are

hydrophobic.

Dehydration reactions __________. They do so by __________.

link monomers to form a polymer; removing a water molecule

Cholesterol belongs to which class of molecules?

lipids

Cellulose differs from starch in that

most animals cannot break down cellulose, whereas starch is easily digested.

Below are the structures of three fatty acids, palmitic acid, stearic acid, and oleic acid. What combination of these fatty acids could you use to make a fat that is liquid at room temperature?

one palmitic acid, one stearic acid, and one oleic acid

A protein containing more than one polypeptide chain exhibits the ________ level of protein structure.

quaternary

High-fructose corn syrup is made from corn. The main carbohydrate in corn is a polysaccharide called

starch

When you eat a plant, you derive energy from the stored __________, but not from the __________ component.

starch ... cellulose

Which of the following would be affected when a protein is denatured?

tertiary structure

The primary structure of a protein is

the amino acid sequence of the polypeptide chain.

The tertiary structure of a polypeptide refers to

the overall three-dimensional structure.

A disaccharide forms when

two monosaccharides join by dehydration synthesis.

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

unsaturated

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

uracil pairs with adenine and cytosine pairs with guanine