Biology 12
Name: key
Practice #2 - metabolism, digestive system, and blood
1.
Secretions from the stomach promote the digestion of
A. fats.
B. proteins.
C. nucleic acids.
D. carbohydrates.
2.
Which of the following statements about insulin is correct?
A. Insulin is produced by the liver.
B. Insulin causes a decrease in blood sugar.
C. Insulin decreases the hydrogen ion concentration in the blood.
D. Insulin is secreted when fats are present in the digestive system.
3.
The structures labelled X are
A. platelets.
B. antibodies.
C. red blood cells.
D. white blood cells.
4.
When Na( sodium ions) are moved across the cell
membrane against the concentration gradient,
A. ATP is used.
B. osmosis occurs.
C. diffusion occurs.
D. vesicles are formed.
5.
Which of the following molecules will pass through a cell membrane by simple diffusion?
A. water
B. an enzyme
C. nucleic acid
D. carbohydrate
6.
Red blood cells are placed in a highly concentrated salt solution. Which of the following
describes their environment and what would happen to the cells?
D
7.
A substance that lowers the energy of activation for a metabolic reaction is called
A. an enzyme.
B. an initiator.
C. a promoter.
D. an inhibitor.
8.
The presence of food at location X indicates a malfunctioning
A. pharynx.
B. epiglottis.
C. esophagus.
D. cardiac sphincter.
9.
Which of the following is not a function of the liver?
A. producing bile
B. secreting insulin
C. detoxifying blood
D. making blood proteins
10.
Which of the following is normally found in
blood plasma but not in lymph?
A. salt
B. urea
C. oxygen
D. platelets
11.
As a cell increases in size, the
A. metabolic rate increases.
B. surface area to volume ratio increases.
C. volume increases and the surface area increases.
D. surface area increases and the volume decreases.
12.
If substance Z inhibits enzyme 2, this will in turn inhibit the production of
A. enzyme 1.
B. enzyme 2.
C. substance W.
D. substance Y.
13.
The structure labelled X is the
A. appendix.
B. epiglottis.
C. duodenum.
D. gall bladder.
14.
Which of the following is a function of thyroxin?
A. to decrease body temperature
B. to increase the amount of ATP used by the cells
C. to increase the reabsorption of water by the kidneys
D. to decrease the breakdown of proteins in the small intestine
15.
Which of the following is not a part of the theory of how an enzyme functions?
A. The shape of the active site facilitates a reaction.
B. The enzyme and substrate fit like a lock and key.
C. The enzyme lowers the activation energy required for the reaction.
D. The shape of the enzyme is permanently changed by the chemical reaction.
16.
The structure that prevents regurgitation of food from the intestine back into the stomach is the
A. pyloric sphincter.
B. cardiac sphincter.
C. duodenal sphincter.
D. atrioventricular valve.
17.
The chemical digestion of polysaccharides begins in the
A. colon.
B. mouth.
C. stomach.
D. small intestine.
18.
The graph shows the effect of pH on three different enzyme-catalyzed reactions. Which of the
following would best describe the effect of pH on enzyme-catalyzed reactions?
A. enzyme action increases as pH increases
B. enzyme action decreases as pH increases
C. enzymes work best in an acid environment
D. each enzyme works best within a specific pH range
19.
How many of the results to the right are from the action of gastric juice?
A. one
B. two
C. three
D. four
20.
Which of the following structures prevents viruses from attaching to host cells?
A. platelets
B. antigens
C. antibodies
D. lymph nodes
Short Answer Questions
1.
What effect would each of the following changes have on the rate of an enzymecatalyzed reaction occurring in the stomach? Give an explanation for the effect.
a) The temperature is increased from 35oC to 37oC (2 marks)
increase rate of reaction – increased molecular movement
b) A competitive inhibitor is added. (2 marks)
decrease rate of reaction – block active site of enzyme
c) The pH is increased from 3 to 8. (2 marks)
decrease rate of reaction – denature enzyme, alters active site, less ES
complexes formed and less product made.
2.
Explain how the liver is involved in each of the following processes.
digestion of fat: (2 marks)
produces bile which emulsifies fats (increase surface area of fat for easier
digestion)
maintenance of blood glucose levels: (2 marks)
converts excess glucose to glycogen after a meal
converts glycogen to blood glucose between meals
maintenance of healthy blood: (2 marks)
detoxify drugs and alcohol
remove old red blood cells