7. Insulin is another example of a protein. Which of the following statements best describes the role of insulin in the body?

a. Insulin regulates how the body stores and uses glucose and fat.
b. Insulin turns glucose into glycogen
c. Insulin triggers the formation of fatty acids
d. Insulin allows glucose transporter-4 to move glucose through the plasma membrane

8. Name the cellular process that all cells require glucose as a reactant for:

a. Photosynthesis
b. Cell division
c. Respiration
d. Reproduction

9. Which of the following conclusions are correct, relating to insulin’s effect on glucose uptake:

a. When blood glucose levels are low, insulin causes the liver as well as muscle and fat cells to remove glucose from the blood.
b. Insulin prevents glucose from moving through the glucose transporter molecule when glucose levels are high
c. The more glucose is in the blood; the more insulin is released to control it
d. Insulin triggers the muscle cells to take up excess glucose and store it as glycogen.

Population Dynamics
Beneficial Mutations

In many cases mutations that cause changes in protein sequences can be harmful to an organism. However, on occasion, in a given environment, some mutations can have a positive effect, for example, it may allow a mutant organism to withstand particular environmental stresses better than wild-type organisms, or reproduce more quickly. In these cases, a mutation will tend to become more common in a population through natural selection.

In an experiment, random mutations were introduced into a vesicular stomatitis virus by site-directed mutagenesis, and the fitness of each mutant was compared with the ancestral type, the processed results can be seen below. A fitness of zero, less than one, one, more than one, respectively, indicates that mutations are lethal, deleterious, neutral, and advantageous.

10. Which level of fitness is most frequent in the virus after introduction?

a. Lethal
b. Deleterious
c. Neutral
d. Advantageous

11. What is the total frequency of individuals with deleterious fitness?

a. 2.8
b. 0.33
c. 0.4
d. 5

12. Comment on the frequency of the mutation in the population, if it was left for several generations.

a. The mutation will become more common in the population
b. The mutation will become less common in the population
c. The mutation will remain static in the population
d. This mutation will cause the population to become extinct

13. Which of the following statements is true regarding this example of natural selection:

a. Natural selection determines which trait (mutant or ancestral) will survive.
b. Natural selection acts on the genotype of the virus
c. Natural selection will determine the environment the virus is in.
d. None of these

1. C
Choices A and B are incorrect as the text tells us they are structural proteins. 1 C Choices A and B are incorrect as the text tells us they are structural proteins. Choice C is correct as amino acids are the sub-units which join together to make a protein.Choice D is also incorrect as the text tells us that they are globular proteins.

2. B
Choices A and D are incorrect – enzymes reduce the amount of energy needed, they do not create the reaction or provide the energy.  Choice B is correct – the definition of a catalyst “speeding up a chemical reaction by lowering the amount of energy needed.”Choice C is incorrect – enzymes are not involved in reactions, they are not a reactant nor become a product, which is why they can be reused again once a reaction has finished.

3. D
Enzymes lower the energy needed to begin the reaction, they are specific, meaning that each enzyme only catalyzes one reaction. The text also tells us that they are proteins; therefore choices A, B and C are incorrect. Enzymes are not antibodies. Therefore choice D is the correct choice.

4. B
Choice A – hemoglobin is a globular protein, carrying oxygen in red blood cells and is incorrect. Choice B is correct as keratin is a protein found in skin and nails, a building material for the body. Choice C is incorrect – insulin controls blood glucose levels. Choice D is incorrect – estrogen is the female reproductive hormone.

5. C
An inability to make or produce sufficient levels of insulin results in diabetes.

6. D
Choice A is incorrect; this is where food is digested before it enters the bloodstream. Choice B is incorrect, this where bile is stored C is incorrect; the liver does store excess glucose taken out of the blood as glycogen.D is correct; the pancreas is responsible for producing insulin

7. A
A is correct; insulin helps control bloo>d glucose levels by signaling the liver and muscle and fat cells to absorb glucose from the blood.  If the body has enough energy, insulin signals the liver to take up glucose and store it as glycogen. Choice B is incorrect; insulin does not turn glucose into glycogen; this is the product that the liver turns glucose into for storage. Choice C is incorrect as it only gives a partial answer. Choice D is incorrect as this is a partial answer.

8. C
Choice A is incorrect as glucose is a product of photosynthesis and only occurs in plants.  Choice B is incorrect as glucose is not used directly in cell division C is correct as glucose is one of the essential reactants needed to for respiration. D is incorrect as- glucose is not a primary reactant needed for reproduction.

9. C
Choice A is incorrect as this occurs when blood> glucose levels are high.  Choice B is incorrect as insulin will allow glucose to cross the plasma membrane removing excess glucose from the bloodstream. Choice C is the correct answer; the concentration of glucose directly correlates to the amount of insulin needed. Choice D is incorrect as this process occurs in the liver.

10. A
Choice A is correct – the greatest frequency in the population is a fitness of 0, which is considered lethal.

11. B
(0.3 x0.02) + (0.4 x 0.02) + (0.6 x 0.05) + (0.7 x 0.05) + (0.8 x 0.05) + (0.9 x 0.15)= 0.325 (0.33 rounded)

12. B
For a mutation to become widespread in a population it needs to be inherited by the offspring, alleles that are lethal or deleterious are not passed on in most cases, as the carrier often does not reach reproductive maturity.  Therefore we can expect the mutation to become less common, making choice B is correct.

13. A
Choice A is correct, as the interactions between individuals and their environment (i.e., the trait) are what determines whether their genetic information will be passed on or not. In this case, the individuals who are wild type would have a higher level of fitness and therefore be more likely to reproduce (or in the case of viruses, replicate) and pass on their non-mutant genotype.