Chapter 5 Practice Test Biology

What is the process by which monomers are linked together to form polymers

Dehydration or condensation reactions When monomers are linked together to form a more complex polymer, a water molecule is removed by dehydration reactions

In a hydrolysis reaction; ___, and in this process water is ___.

A polymer is broken up into its constituent monomers…consumed

The type of bond that forms to join monomers (such as sugars and amino acids) into polymers (such as starch and proteins) is a ___bond.

Covalent Monomers are joined together by a deydration reaction in which two molecules are covalently bonded to each other through the loss of a water molecule.

Which of the following is a polymer

Cellulose, a plant cell wall component The polysaccharide cellulose is a major componenet of plant cell walls. It is a polymer composed of many glucose monomers joined together by glycosidic linkages

Cellulose is a __ made of many__.

Polymer…glucose molecules Cellulose is a polysaccharide and therefore a polymer, constructed from many monosaccharide glucose monomers.

Generally animals cannot digest the glycosidic 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 individual glucose units. Cows have digestive chambers populated by microorganisms that can produce certain hydrolytic enzymes that cows cannot. The enzymes hydrolyze the cellulose polymer into glucose monomers

In what polysaccharide form do plants store glucose to be available later as an energy source?

Starch

Which of the following carbohydrate molecules has the lowest molecular weight?

Glucose

….They were crunchy because their exoskeletons contain the polysaccharide___.

Chitin Chitin is the structural polysaccharide found in arthropod exoskeletons

Carbohydrates are used in our bodies mainly for ___.

Energy storage and release Simple sugar molecules, stored in polysaccharides such as glycogen in animals and starch in plants, are a major energy source for cellular work

The polysaccharide that you are most likely to have eaten recently is ___.

Starch

A polysaccharide that is used for storing energy in human muscle and liver cells is ___.

Glycogen Humans and other vertebrates store glucose as a polysaccharide called glycogen in their liver and muscle cells

Carbohydrates can function in which of the following ways?

Structural support and energy storage

Amylase is an enzyme that breaks down starch. Why can’t the same enzyme break down cellulose?

The monosaccharide monomers in cellulose are bonded together differently than in starch The glucose monomers in cellulose are bonded in a beta glycosidic linkage, whereas those in starch have an alpha glycosidic linkage. The enzyme amylase is specific for the alpha glycosidic linkage.

The subunits in cellulose are linked together by ___.

glycosidic linkages The glucose monomers of cellulose are linked together by a specific type of covalent bond known as a glycosidic linkage

Which of the following components of a tossed salad will pass through the human digestive tract and be digested the least?

Cellulose (in the lettuce) Cellulose contains glycosidic linkages that cannot be broken down by human digestive enzymes

What is a distinguishing feature of most naturally occuring fats?

Nearly all naturally occuing unsaturated fats have cis double bonds Naturally occuring unsaturated fats found in plants and fish are distinguished by the presence of one or more cis double bonds in their hydrocarbon chains

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

are not true polymers Lipids are not all made up of the same type of monomer. Their association as a group (fats, phospholipids, and steroids) is related to their solubility behavior.

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

Hydrophobic

Nutritionally, saturated triacylglycerols are considered to be less healthful than unsatruated tracylglycerols. What is the difference between them?

Saturated tracylglycerols have more hydrogen atoms than unsaturated tracylglycerols

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

Phospholipids Phospholipids have a hydrophilic head and two hydrophobic tails. This permits the phospholipids to be arranged in a bilayer, or double layer, which forms a boundary between the cell and its external environment.

Which of the following is a true statement comparing phospholipids and triacylglycerols(fats and oils)?

Phospholipid molecules have a distinctly polar head and distinctly nonpolar tail, wheras tracylglycerols are predominantly nonpolar. Triacylglycerols consist of three (nonpolar) fatty acid tails attached to a glycerol molecule. Phospholipids have two fatty acid tails and a hydrophilic head containing a negatively charged phosphate group.

The sex hormones estrogen, progesterone, and testosterone belong to which class of molecules?

Lipids

High cholesterol levels are considered a major risk factor for heart disease. If it is so bad for humans, why does the body make cholesterol in the first place?

Cholesterol is the basis for many important molecules such as sex hormones

Manufacturers make vegetable oils solid or semisolid at room temperature by ___.

adding hydrogen atoms to the double bonds in the fatty acid hydrocarbon chains

Which of the following is the major energy storage compound of plant seeds?

oils

Some lipids are formed when fatty acids are linked to glycerol. These subunits are linked together by ___.

ester linkages In making a fat, each of the three fatty acid molecules is bonded to a glycerol by an ester linkage type of covalent bond.

The fatty acid tails of a phospholipid are ___ because they ___.

Hydrophobic…have no charges to which water molecules can adhere

The overall three-dimensional shape of a single polypeptide is called the ___.

Tertiary structure The tertiary structure is determined by hydrogen bonds, hydrophobic R groups, ionic bonds between R groups, can der Waals interactions, and disulfide bridges.

When a protein is denatured why does it lose its functionality?

Denaturation breaks the weak bonds, such as hydrogen bonds and van der Waals interactions, that hold the protein in its three-dimensional shape. Without the proper shape, the protein cannot function. Denaturation disrupts secondary, tertiary, and quaternary protein structure, causing the protein to lose its form and thus its function.

Which of the following lists ranks these molecules in the correct order by size?

Protein, sucrose, glucose, water (largest to smallest)

Enzyme molecules require a specific shape to perform their catalytic function. Which of the following might alter the shape of an enzymatic protein?

All of the listed responses are correct

The alpha helix and beta pleated sheet represent which level of protein structure?

secondary structure

The peptide bond is ___.

a covalent bond joining amino acids together to form a polypeptide.

Protein molecules are polymers (chains) of ___.

amino acid molecules Polymers of amino acids are called polypeptides. A protein consists of one or more polypeptides folded into specific conformations

The "primary structure" of a protein refers to ___.

the sequence of amino acids

Which type of protein shields a newly forming protein from cytoplasmic influences while it is folding into its functional form?

Chaperonins Chaperonins shield proteins from "bad influences" while they are folding into their functional forms.

A glucose molecule is to starch as ___.

a nucleotide is to a nucleic acid Nucleotides are the monomers that make nucleic acid polymers, just as glucose is the monosaccharide from which starch is constructed

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

DNA

On the basis of the principle of complementary base pairing, you would expect the percentage of ___ to be equal to the percentage of __.

adenine…thymine

Which of the following are pyrimidines found in the nucleic acid DNA?

thymine and cytosine

A nucleotide is made of which of the following chemical components?

a nitrogenous base, a phosphate group, and a pentose sugar

Which of the following is true regarding complementary base pairing in DNA and RNA molecules?

Although the base pairing between two strands of DNA in a DNA molecule can be thousands to millions of base pairs long, base pairing in an RNA molecule is limited to short stretches of nucleotides in the same molecule or between two RNA molecules.