Question 1

Which of the following is a telltale sign that a cell is infected by RNA viruses?

Accepted Answer

RNA viruses often produce double-stranded RNA during replication, which can trigger an antiviral response in the infected cell. Therefore, the presence of long segments of double-stranded RNA is a telltale sign that a cell is infected by RNA viruses.

Question 2

Under which of the following evolutionary explanations for disease does the antagonistic pleiotropy hypothesis for aging fall?

Accepted Answer

The antagonistic pleiotropy hypothesis for aging suggests that natural selection favors genes that increase reproductive success in youth, even if they have negative effects on health later in life. This is because natural selection is primarily concerned with maximizing an organism's ability to reproduce and pass on genetic material, rather than ensuring long-term health and survival.

Question 3

Which of the following hypothetical viruses would likely show a "cactus-shaped" population phylogeny?

Accepted Answer

A "cactus-shaped" population phylogeny is indicative of a rapid burst of diversification followed by a period of stasis, which is consistent with a virus that can reinfect previously infected hosts via escape mutants. Such a virus would rapidly evolve in response to immune pressures, leading to a burst of diversification, followed by stasis due to the lack of further host diversity. The other options are unlikely to show this pattern. A mutualistic virus transmitted vertically would be expected to show a tree-like pattern reflecting the host's evolutionary history. A highly virulent virus like Ebola would likely show a star-like pattern, with a single ancestral strain giving rise to multiple branches representing different outbreaks. Lastly, a highly virulent virus that confers long-lasting immunity to naive individuals would be expected to show a tree-like, star-like, or ladder-like pattern, depending on how long immunity lasts and how rapidly the virus evolves.

Question 4

Plants do not have a germ line and gametes are derived from cell lines that are also responsible for the growth of the organism.Can the disposable soma hypothesis be applied to plants?

Accepted Answer

Trade-offs between reproduction and repair are still possible in plants, even though they do not have a germ line.

Question 5

.Ackermann and colleagues (2003)investigated senescence in bacteria.What do the following results demonstrate and why are they surprising given evolutionary theory on aging?

Accepted Answer

The answer of .Ackermann and colleagues (2003)investigated senescence in bacteria.What...

Question 6

The figure below shows the effect of an antagonistic pleiotropic mutation (A).What would be the effect of a mutation (B)that delayed the onset of reproduction without changing the survival curve?

Accepted Answer

The answer of The figure below shows the effect of...

Question 7

Many wild mushrooms make delicious food,but some are highly toxic and can result in a fatal meal.Apply the principle of asymmetric harm to mushroom identification,and recommend a strategy for mushroom identifiers.

Accepted Answer

The answer of Many wild mushrooms make delicious food,but some...

Question 8

Which of the following are strategies with which vertebrate hosts counteract the asymmetries between most pathogens and their hosts?

Accepted Answer

Somatic mutation and recombination are strategies by which vertebrate hosts can counteract the asymmetries between most pathogens and their hosts. Somatic mutation allows for adaptation to new pathogens, while somatic recombination creates genetic diversity within the immune system, increasing the likelihood of finding a match for any given pathogen. Option A and B are not correct strategies used by vertebrate hosts, and option D is unrelated to the question.

Question 9

Under which hypothesis may pathogens ultimately be responsible for the evolution of sexual reproduction in multicellular organisms?

Accepted Answer

The Red Queen hypothesis proposes that sexual reproduction evolved as a way to keep up with the ever-changing and co-evolving pathogen populations. Through sexual reproduction, offspring are generated with new combinations of genes that may be more resistant to the pathogens.

Question 10

Sickle cell anemia (a serious heritable disease)appears to be maintained via balancing selection in some African populations because heterozygous carriers for the fully recessive disease allele are less affected by malaria parasites.Is this a case of antagonistic pleiotropy?

Accepted Answer

Balancing selection maintains the sickle cell trait in some African populations because it provides some resistance to malaria. However, individuals who carry two copies of the sickle cell allele (homozygous) are affected by sickle cell anemia, a serious and potentially life-threatening condition. Therefore, the same allele has both positive effects (resistance to malaria) and negative effects (sickle cell anemia) on different traits. This is an example of antagonistic pleiotropy.

Question 11

Which of the following is an example of a trade-off imposed on an organism that results in a medical problem?

Accepted Answer

This is an example of a trade-off between two traits, sturdier bones and mobility, which can result in medical problems such as decreased mobility or osteoporosis.

Question 12

What is the likely phylogenetic explanation for the crossing of food and air pathways in humans?

Accepted Answer

The crossing of food and air pathways in humans is due to the evolutionary development of the respiratory system, which evolved from pouches in the digestive system. As animals began to breathe air, these pouches evolved into lungs, and the connection between the food and air pathways remained.

Question 13

What two main factors are responsible for the asymmetry in the coevolutionary arms race between microbial pathogens and their multicellular hosts?

Accepted Answer

The answer of What two main factors are responsible for...

Question 14

Explain how ectothermic animals can produce a fever response.Limit your answer to one sentence.

Accepted Answer

The answer of Explain how ectothermic animals can produce a...

Question 15

Define pathogen-associated molecular patterns (PAMPs),and explain why they are crucial to our body's immune response against pathogens.Limit your answer to two sentences.

Accepted Answer

The answer of Define pathogen-associated molecular patterns (PAMPs),and explain why...

Question 16

Why is there no lifelong vaccine protection against flu as there is by a measles vaccine?

Accepted Answer

Flu viruses have a high mutation rate, allowing them to rapidly evolve new variants that can evade host immunity. This means that the vaccine needs to be updated annually to keep up with the new circulating strains. In contrast, the measles vaccine provides lifelong protection because the measles virus does not undergo significant antigenic variation over time.

Question 17

Which of the following represents a similarity between the evolution of tumors and the vertebrate immune response?

Accepted Answer

Both the evolution of tumors and the vertebrate immune response involve somatic mutations. In tumors, these mutations can lead to uncontrolled cell growth and ultimately the formation of a tumor. In the immune response, somatic mutations are responsible for generating diverse immune receptors that can recognize a wide range of pathogens.

Question 18

Patients with severe bacterial sepsis who develop a fever have higher survival rates than those who do not develop a fever.Does this observation provide causative evidence for the beneficial role of fever in fighting infections?

Accepted Answer

The observation does not necessarily provide causative evidence for the beneficial role of fever in fighting infections because it is possible that the disease in nonfever patients was too severe for the body to develop a fever. Therefore, it is not clear that the fever directly contributed to the higher survival rates.

Question 19

Which part of the immune system's "learning system" is responsible for maintaining life-long immunity against measles after a measles infection?

Accepted Answer

The retention of responding cells is responsible for maintaining life-long immunity against measles after a measles infection. Memory B cells and memory T cells are created during the primary immune response to the measles virus and remain in the body, ready to respond quickly and effectively if the virus is encountered again in the future. This is known as the adaptive immune system's memory response.

Question 20

Ask a question about fever at each of Tinbergen's four levels (1,2,3,and 4)of explanation.Limit your answer to one sentence for each level.

Accepted Answer

The answer of Ask a question about fever at each...

Quiz 20: Evolution and Medicine