Chapter 3 MasteringBiology

A glucose molecule is to starch as _____.

a nucleotide is to a nucleic acid

Glycogen is _____.

a polysaccharide found in animals

Dehydration reactions __________. They do so by __________.

link monomers to form a polymer; removing a water molecule

glucose + glucose —> _____ by _____.

maltose + water ... dehydration synthesis

Which of these is a source of lactose?

milk

DNA is composed of building blocks called _____.

nucleotides

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

unsaturated.

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

water

Select the hydrocarbon from the following choices.

C3H8

The molecular formula of most monosaccharides represents a multiple of

CH2O

Which of the following statements about carbon skeletons is true?

Carbon skeletons may be arranged in rings.

_____ is the most abundant organic compound on Earth.

Cellulose

How does DNA differ from RNA?

RNA contains ribose, DNA does not.

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.

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.

When calorie intake is low, proteins are the last resource the body uses for fuel. Which statement below gives the best reason for this?

When the body uses proteins as fuel, it is breaking down substances vital to its structure and essential functions.

A peptide bond is formed through a __________.

a dehydration reaction between the amino group of one amino acid and the carboxyl group of a second amino acid

Proteins are an important class of molecules because of the functions they perform. Proteins can _____.

act as signal receptors to receive signals in cell communication

Choose the pair of terms that completes this sentence: Hydroxyl is to _____ as _____ is to amine.

alcohol ... amino

Although the structures of the functional groups important to life vary in chemical structure, they share one thing in common: They _____.

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

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

are not truly polymers

Carbohydrates are mainly used in our bodies _____.

as fuel

An amino acid is so named because its central carbon is linked to both an amino group and a __________.

carboxyl group

Which of these is a polysaccharide?

cellulose

A DNA nucleotide is composed of a __________.

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

DNA has the appearance of a _____.

double helix

Which is the correct term for compounds that do not mix with water?

hydrophobic

Cellulose is a _____ made of many _____.

polymer ... glucose molecules