Biology, Eighth Edition (Raven)

Chapter 48: The Digestive System

Pre Test

What is the most important limitation of a gastrovascular cavity, as found in cnidaria? (p .964)
A)There is only one opening (i.e. no separate mouth and anus).
B)Specialization of digestive functions is not possible.
C)Only small food particles can be ingested.
D)The size of the animal is limited.
E)all of the above
Birds break up food particles into sizes that can be digested by: (p. 966)
A)chewing with their teeth.
B)the secretion of digestive enzymes in the crop.
C)the grinding action of small stones in the gizzard.
D)the grinding action of small stones in the crop.
E)none of the above
Peristalsis is: (p. 968)
A)the sphincter connecting the esophagus to the stomach.
B)a rhythmic wave of muscular contraction.
C)a digestive enzyme secreted by the stomach.
D)a specialized stomach found in ruminants.
E)none of the above
The main function of the villi and microvilli in the duodenum is to: (p. 970)
A)emulsify fats.
B)provide a very large surface area for absorption.
C)complete the digestive process.
D)complete the break down of proteins.
E)both b and c
True or False: In most vertebrates the reproductive and urinary tracts empty together with the digestive tract into a common cavity, the cloaca. (p. 973)
True or False: Bacteria found in the guts of many animals play no useful role in digestion. (p. 975)
Gastrin: (p. 975)
A)is an enzyme.
B)is a hormone secreted by cells in the stomach.
C)is a hormone secreted by the pancreas.
D)inhibits the secretion of HCl.
E)both b and d
The hormones insulin and glucagon are produced by different cells in the pancreas and have antagonistic effects. Insulin promotes the cellular uptake of glucose into liver, muscle and fat cells. What occurs when blood glucose levels decrease? (p. 977)
A)There is decreased insulin and glucagon production.
B)There is increased glucagon production.
C)Glycogen is hydrolyzed by the liver and glucose is released into the blood.
D)There is increased insulin production.
E)both b and c
Body Mass Index (BMI) is calculated as weight in kilograms divided by the square of the height in meters. A BMI of over _____ is considered obese. (p. 977)
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