Deck 8: Microbial Evolution: the Origin and Diversity of Life

Question 1

Why is it that natural selection can never result in organisms that are perfectly adapted to their environment?

Answer 1

All organisms must be able to do many different things, and a characteristic that is valuable for one task is often much less valuable or even a hindrance for a different task. An organism's various characteristics represent a compromise between the competing demands with which all living things must contend.

Question 2

It is believed that mitochondria were acquired by primitive eukaryotic cells before chloroplasts were. What is the evidence for this?

Answer 2

Virtually all eukaryotic cells contain mitochondria, whereas only certain groups of eukaryotic cells have chloroplasts. It is therefore assumed that mitochondria were acquired before the eukaryotes diverged into the separate lineages that gave rise to animals, plants, fungi, and the single-celled protists. Later, after this diversification had begun, photosynthetic bacteria were acquired only by the branch that gave rise to photosynthetic eukaryotes.

Question 3

Molecules composed of RNA that have enzymatic activity are known as:

A) ribosomes.
B) RNases.
C) catalases.
D) ribozymes.
E) nucleases.

Answer 3

D

Question 4

Which of the sequences below is believed to be correct for the order in which the following evolved?

A) liposomes » first heterotrophic prokaryotes » first oxygen-yielding photosynthetic prokaryotes » first eukaryotes
B) first heterotrophic prokaryotes » first oxygen-yielding photosynthetic prokaryotes » liposomes » first eukaryotes
C) first oxygen-yielding photosynthetic prokaryotes » first heterotrophic prokaryotes » first eukaryotes » liposomes
D) eukaryotes » first heterotrophic prokaryotes » first oxygen-yielding photosynthetic prokaryotes » liposomes
E) liposomes » first oxygen-yielding photosynthetic prokaryotes » first heterotrophic prokaryotes » eukaryotes

Question 5

We might expect virulence of a particular human pathogen to decrease:

A) when opportunities for transmission are limited.
B) when opportunities for transmission are abundant.
C) when animal reservoirs for the pathogen are scarce.
D) in very large human populations, such as a large city.
E) when it uses insect vectors for transmission.

Question 6

Which of the following points is not part of the theory of natural selection?

A) Under ideal conditions, all populations can grow exponentially if all individuals survive and reproduce.
B) As environmental resources become limited, some individuals within a population are more likely to reproduce than others.
C) Individuals within a population are not genetically identical.
D) Those with a genetic makeup that results in the best adaptation to a particular set of environmental conditions are those most likely to reproduce. They will then pass on genes for these adaptations to their offspring.
E) Specific environmental conditions can cause specific favorable mutations to occur, resulting in better adaptation to those environmental conditions.

Question 7

Under which of the following conditions would resistance to a specific antibiotic most likely evolve?

A) when the antibiotic is not commonly used
B) when the antibiotic is routinely used, even in inappropriate situations
C) when the antibiotic is used, but only in carefully controlled and appropriate situations
D) when the use of the antibiotic is suddenly curtailed
E) when several antibiotics, including the specific antibiotic under consideration, are used together

Question 8

An experiment by Stanley Miller in the 1950s demonstrated that abiotic synthesis of organic molecules could occur:

A) in a reducing environment.
B) in an oxidizing environment.
C) on the ocean floor.
D) at extremely high temperatures.
E) at extremely low temperatures.

Question 9

The idea that sexual reproduction evolved as a way to increase genetic diversity in a population, rendering that population less vulnerable to pathogens, is called:

A) the sexual selection hypothesis.
B) the artificial selection hypothesis.
C) the red queen hypothesis.
D) the white rabbit hypothesis.
E) the pathogen vs. host hypothesis.

Question 10

Which of the following is believed to be the correct sequence for the order in which the following metabolic processes evolved?

A) glycolysis » aerobic respiration » photosynthesis
B) photosynthesis » aerobic respiration » glycolysis
C) aerobic respiration » glycolysis » photosynthesis
D) photosynthesis » glycolysis » aerobic respiration
E) glycolysis » photosynthesis » aerobic respiration

Question 11

Explain the rationale for the "RNA world" hypothesis.

Question 12

Which of the following facts provides evidence for endosymbiosis?

A) Mitochondria and chloroplasts have their own DNA, which replicates independently of the nuclear DNA.
B) Ribosomes in mitochondria and chloroplasts have a structure similar to bacterial ribosomes.
C) Chloroplasts have certain gene sequences in their DNA, which indicate a relationship with cyanobacteria.
D) Both "a" and "b" above provide such evidence.
E) All of the above provide such evidence.

Question 13

One hypothesis of viral origin suggests that viruses began as parasitic prokaryotes that gradually lost most of their genetic information and ultimately became completely dependent on host cells. This hypothesis is called:

A) the regressive hypothesis.
B) the escaped gene hypothesis.
C) the coevolved hypothesis.
D) the transposon hypothesis.
E) the parasitic hypothesis.