Practice Questions

Block 1

Question 1

• Carbohydrates are used in our bodies mainly for __________.

• lipid storage • membrane construction • structural molecules, such as hair and fingernails

• building genetic material • energy storage and release

Question 2

• Amylase is an enzyme that breaks down starch. Why cannot the same enzyme break down cellulose?

• The enzyme cannot attack cellulose because of its helical shape.

• The bonds between the monosaccharide monomers in cellulose are much stronger.

• Starch is made of glucose; cellulose is made of fructose. • The monosaccharide monomers in cellulose are bonded

together differently than those in starch. • Cellulose molecules are much too large.

Question 3

• What is a distinguishing feature of most naturally occurring unsaturated fats?

• Nearly all naturally occurring unsaturated fats have cis double bonds.

• Most unsaturated fats have trans double bonds, causing a kink in the hydrocarbon chain wherever they occur.

• All organisms share an equal ratio of saturated and unsaturated fatty acids.

• They are distinguished from other lipid forms by their chief role as components of cell membranes.

• They all share four fused rings as a carbon skeleton.

Question 4

• Lipids differ from other large biological molecules in that they __________.

• are much larger • do not contain nitrogen and phosphorus atoms • are not truly polymers • do not have specific shapes • do not contain carbon

Question 5

• The overall three-dimensional shape of a single polypeptide is called its __________.

• double helix • quaternary structure • tertiary structure • secondary structure • primary structure

Question 6• Which of the following describes a difference between DNA and RNA?

• RNA molecules generally consist of a single polynucleotide chain, whereas DNA molecules generally consist of two polynucleotide chains organized into a double helix.

• Both molecules contain adenine, guanine and cytosine, but DNA also contains thymine and RNA also contains uracil.

• They contain different sugars. • The first and second listed responses correctly describe differences

between DNA and RNA. • The first three listed responses correctly describe differences between

DNA and RNA.

Question 7• A breakfast cereal advertises that it contains essential vitamins and

minerals. In this context, the word essential means __________.

• that it contains the essence of vegetables used to extract the nutrients

• that they can be made in the body but it is important to eat food containing these nutrients so that we do not waste essential energy in making them

• that the nutrients must be supplied in the diet and cannot be made in the body

• that they are necessary for life • nothing: this is just a gimmick

Question 8

• In general, B vitamins function in your body as __________.

• a source of energy • structural components of cell membranes • a source of minerals • coenzymes • antioxidants

Question 9

• How is the stomach lining protected from the strongly acidic pH of its contents?

• It releases a hormone called gastrin, which stops gastric juice secretion.

• Mucous cells secrete a protective lubricant into the stomach. • Bile neutralizes the acid soon after it enters the stomach. • Parietal cells secrete a protective buffer to neutralize

hydrochloric acid. • The acid is neutralized quickly when it combines with

pepsinogen to make pepsin.

Question 10

• Most digestive enzymes function in the __________.

• large intestine • oral cavity • stomach • liver • small intestine

Question 11

• Where does absorption take place in the small intestine?

• circular folds • blood capillaries• Lacteals • villi • microvilli

Question 12• During some types of antibiotic treatments, patients often

experience diarrhea because __________.

• antibiotics are toxic to the colon's epithelium and to bacteria • the bacterial flora of the large intestine that normally break

down undigested organic material are killed by the antibiotics• antibiotics interfere with the vitamin absorption normally

occurring within the large intestine • after intestinal bacteria have been killed, an unusually large

amount of water is reabsorbed • antibiotics affect the hormones that control intestinal peristalsis

Question 13

• Type 1 diabetes mellitus __________.

• is an autoimmune disease in which the immune system attacks beta cells in the pancreas

• is a common disorder in overweight individuals older than 40

• is treated by improving insulin receptor efficiency rather than by giving insulin

• is the most common form of the disease; more than 90% of all diabetics have type 1 diabetes can be controlled for many years with exercise and a proper diet

Question 14

• Which sequence below correctly describes the maintenance of blood glucose levels?

• low blood sugar, pancreatic beta cells stimulated, insulin released, breakdown of glycogen in target cells

• low blood sugar, pancreatic alpha cells stimulated, glucagon released, breakdown of glycogen in target cells

• high blood sugar, pancreatic alpha cells stimulated, insulin released, uptake of glucose by target cells

• high blood sugar, pancreatic alpha cells stimulated, glucagon released, glycogen synthesis in liver None of the listed responses is correct.