1.Inbreeding depression is caused by a. a reduction in fitness caused by deleter
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Question
1.Inbreeding depression is caused by
a. a reduction in fitness caused by deleterious recessives.
b. random mating.
c. mutation–selection balance.
d. chromosome inversions
e. frameshift mutations
f. synonymous mutations
g. both (a) and (b)
h. both (c) and (e)
i. (a), (b), (c), (d), and (e) are all correct
2. The biology of sickle-cell trait in humans is important for evolutionary theory because it provides a specific example of:
a. synonymous mutation
b. heterozygote superiority
c. loss of gene function due to insertion of extra nucleotides
d. selection for an elevated mutation rate
e. inbreeding depression caused by harmful recessive alleles
3. In the Hardy-Weinberg equilibrium, allele frequencies remain unchanged because:
a. the force of mutation balances the force of selection
b. random mating tends to restore allele frequencies to their original values even when various agents of evolution are occurring in a population
c. the force of genetic drift balances the effect of mutation
d. the force of natural selection balances the influence of gene flow
e. there are no agents of evolution acting to alter allele frequency
4. Two gene copies are identical by descent if
a. two individuals have the same parents.
b. one allele mutates to a second allele.
c. selfing occurs.
d. they are both inherited from the same gene copy in a recent common ancestor.
e. balancing selection maintains two or more alleles.
5. A homework exercise focused on an experiment by Ajie, Estes, Lynch and Phillips (2005), who measured behavioral responses (velocity, turning rate, directness) of Caenorhabditis roundworms to a repellant chemical (linoleic acid). Why was a difference observed between the behavior of control vs. MA worms in this experiment?
a. MA worms were artificially selected to become resistant to the repellant chemical
b. control worms were protected from natural selection, while MA worms experienced natural selection to increase their turning rate
c. random mutation resulted in MA worms partially losing traits such as the ability to move and orient normally
d. control worms were artificially selected to increase their avoidance behavior toward a repellant chemical (linoleic acid)
e. MA worms were exposed to linoleic acid in an artificial diet, which resulted in conditioned tolerance toward this substance
Explanation / Answer
1.
Inbreeding depression is resulted due to reduction in fitness caused by deleterious recessives. Option a is correct. Inbreeding results in homozygous condition and lethal genes inherited result in genetic disorders thus, inbreeding results in depressed population rate due to which viable offspring produced in reduced numbers.
2.
The biology of sickle-cell trait in humans is important for evolutionary theory because it provides a specific example of heterozygote superiority. Option b is crrect. This is because, sickle cell trait in humans exhibit incomplete recessiveness means heterozygous condition that have advantage during random mating to get select only the dominant allele.
3.
In the Hardy-Weinberg equilibrium, allele frequencies remain unchanged because random mating tends to restore allele frequencies to their original values even when various agents of evolution are occurring in a population. Random mating matain the allele frequencies and the population in quilibrium. Hence, option b is correct.
4.
Two gene copies are identical by descent if they are both inherited from the same gene copy in a recent common ancestor. Same gene copies can be passed on to several generation from ancestors. Hence, option d is correct.
5.
The difference observed between the behavior of control vs. MA worms in this experiment was random mutation resulted in MA worms partially losing traits such as the ability to move and orient normally. This is because, significant increase in the variation among the different mutant lines than in ancestors. Hence, option c is correct.
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