1. Practice Questions
Block 1

2. 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

3. 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.

4. 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.

5. 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

6. Question 5
The overall three-dimensional shape of a single polypeptide is called its __________.
double helix  
quaternary structure  
tertiary structure  
secondary structure  
primary structure

7. 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.

8. 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

9. 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

10. 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.

11. Question 10 Most digestive enzymes function in the __________.
large intestine
oral cavity
stomach
liver
small intestine

12. Question 11 Where does absorption take place in the small intestine?
circular folds
blood capillaries
Lacteals
villi
microvilli

13. 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

14. 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

15. 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.