Question 1

Which of the following features permits a gene to act as a molecular clock?

Accepted Answer

A gene can act as a molecular clock if it has a reliable average rate of mutation. This allows for the estimation of the time since two species diverged by comparing differences in their DNA sequences.

Question 2

Which of the following statements describes a potential drawback for using molecular clocks to measure evolutionary time?

Accepted Answer

The answer of Which of the following statements describes a...

Question 3

Which of the following statements about horizontal gene transfer is accurate?

Accepted Answer

Horizontal gene transfer is a significant evolutionary process that allows genes to move between different organisms, not just among closely related ones, and it affects various genes, not just those involved in metabolism. It is a process that occurs in present times as well, making option A the correct choice.

Question 4

Which of the following statements explains why paralogous genes can diverge from each other within the same gene pool, whereas orthologous genes diverge only after gene pools are isolated from each other?

Accepted Answer

Paralogous genes result from gene duplication within the same organism, allowing one copy to mutate and potentially take on a new function while the other copy continues to perform its original function. Orthologous genes, on the other hand, are homologous genes in different species that originated from a common ancestor, diverging only when the species themselves diverge.

Question 5

The following question refers to this phylogenetic tree, depicting the origins of life and the three domains. Connecting lines indicate instances of gene or genome transfer and time is indicated from left to right.  A possible phylogenetic tree for the three domains of life.
If the early history of life on Earth is accurately depicted by the figure, then which statement is most in agreement with the hypothesis proposed by this tree?

Accepted Answer

The answer of The following question refers to this phylogenetic...

Question 6

Which of the following items is most likely to form a simple linear relationship with the number of gene-duplication events, when placed as the label on the vertical axis of the following graph?

Accepted Answer

The answer of Which of the following items is most...

Question 7

If additional DNA sequence evidence shows that yeast genes for synthesizing proteins are more similar to protein-synthesizing genes in bacteria than those in archaea, what would a systematist do with the current phylogeny?

Accepted Answer

Given the new DNA sequence evidence indicating that yeast (a eukaryote) genes for synthesizing proteins are more similar to those in bacteria than those in archaea, a systematist would likely redraw the phylogeny to reflect a closer evolutionary relationship between eukaryotes and bacteria, as suggested in option A. This would mean adjusting the phylogenetic tree to show eukaryotes sharing a more recent common ancestor with bacteria than with archaea, based on the newly discovered similarity in protein-synthesizing genes.

Question 8

The following question refers to this phylogenetic tree, depicting the origins of life and the three domains. Connecting lines indicate instances of gene or genome transfer and time is indicated from left to right.  A possible phylogenetic tree for the three domains of life.
Which domains have exhibited endosymbiosis?

Accepted Answer

The answer of The following question refers to this phylogenetic...

Question 9

Cyanobacteria were once called blue-green algae because they are photosynthetic. According to the phylogeny shown, to which of the following organisms are the cyanobacteria more closely related?

Accepted Answer

The answer of  Cyanobacteria were once called blue-green algae...

Question 10

A phylogenetic tree is shown for the three domains of life (Eukarya, Archaea, and Bacteria). The tree branches in two directions from the first point, labeled Common ancestor of all life. One branch leads in the direction of Eukarya and Archaea, and the other branch leads to Bacteria. The branch leading to Eukarya and Archaea divide, one branch leading to each domain. The branch leading to Eukarya divides into four branches. One leads to Euglenozoans, and the other three lead to branching points. The first leads to Forams in one direction, and another branching point in the other that leads to Diatoms and Ciliates. The second branching point leads to Red algae in one direction, and a branching point that leads to green algae and land plants in the other direction. The third branching point leads to amoebas in one direction, and a branching point that leads to fungi and animals in the other direction. Land plants, Fungi and Animals are all highlighted.
Which of the following pairs of organisms form a sister group?

Accepted Answer

The answer of  A phylogenetic tree is shown for...

Question 11

Which of the following statements most accurately describes the evolution of chloroplasts?

Accepted Answer

The answer of  Which of the following statements most...

Question 12

Which of the following statements is accurate, at least according to our present knowledge?

Accepted Answer

Horizontal gene transfer from prokaryotes to eukaryotes has been documented, allowing some eukaryotes to survive in extreme environments. This process is a way for organisms to acquire genes that confer advantageous traits, such as tolerance to high temperatures, salinity, or toxic substances.

Question 13

What kind of evidence has recently made it necessary to assign the prokaryotes to either of two different domains, rather than assigning all prokaryotes to the same kingdom?

Accepted Answer

rRNA genes have provided crucial evidence for the division of prokaryotes into two distinct domains, Archaea and Bacteria, due to significant differences in their sequences. This molecular evidence has been pivotal in understanding the evolutionary relationships and diversity among prokaryotic organisms.

Question 14

The kingdom Monera was dismantled because of which of the following reasons?

Accepted Answer

The kingdom Monera was dismantled because it contained organisms from different domains, specifically Bacteria and Archaea, which are fundamentally different at a molecular level.

Question 15

From which taxon did mitochondria evolve?

Accepted Answer

The answer of  From which taxon did mitochondria evolve?
...

Question 16

Which of the following processes would, if it had acted upon a gene, prevent this gene from acting as a reliable molecular clock?

Accepted Answer

Natural selection acts on mutations that affect an organism's fitness, causing certain alleles to become more or less common based on their effect on survival and reproduction. This selective pressure can accelerate or decelerate the rate of change in a gene, making it an unreliable molecular clock. Molecular clocks rely on the assumption that mutations accumulate at a relatively constant rate, which is disrupted by natural selection.

Question 17

In a comparison of birds and mammals, the condition of having four limbs is ________.

Accepted Answer

Both birds and mammals inherited the trait of having four limbs from a common ancestor, making it a shared ancestral character.

Question 18

The question refers to the table, which compares the percent sequence homology of four different parts of a gene (two introns and two exons) that is found in five different eukaryotic species. The data show the percentage of sequence homology of each intron and exon in comparison to the sequences in species A.
Percentage of Sequence Homology

Which of these four gene parts should allow the construction of the most accurate phylogenetic tree, assuming that this is the only part of the gene that has acted as a reliable molecular clock?

Accepted Answer

The answer of The question refers to the table, which...

Question 19

Which eukaryotic kingdom includes members that are the result of endosymbioses that included an ancient aerobic bacterium and an ancient cyanobacterium?

Accepted Answer

The kingdom Plantae includes members that are the result of endosymbioses involving an ancient aerobic bacterium, which led to the formation of mitochondria, and an ancient cyanobacterium, which led to the formation of chloroplasts. This is a key feature distinguishing plants from other eukaryotic kingdoms.

Question 20

Imagine that you discovered the following information about the three domains of life:
Feature Bacteria Archaea Eukaryotes
RNA polymerase small, simple complex complex
Introns absent present present
Antibiotic sensitivity sensitive insensitive insensitive
Membrane Lipids C chains unbranched C chains branched C chains branched
These data would support which of the following conclusions?

Accepted Answer

The similarities between archaea and eukaryotes, such as complex RNA polymerase, presence of introns, insensitivity to antibiotics, and branched membrane lipids, suggest that eukaryotes are more similar to archaea than to bacteria.

Quiz 22: Phylogenetic Reconstruction