Module 2

Question 1

Chapter 24

Question 2

Bacterial genome size can vary among individuals from the same species, with some individuals having genomes that are twice as large as other individuals. Which process is the most likely cause of this variation?

Answer 2

Transformation

Question 3

Consider the bacterium Thiomargarita namibiensis. Imagine you are comparing two individuals that are the same size. Individual 1 has a vacuole that is twice as large as Individual 2. Which of the two would you expect to have a higher surface area-to-volume ratio for its membrane relative to its cytoplasm?

Answer 3

Individual 1

Question 4

All bacteria are unicellular.

Answer 4

False

Question 5

Imagine that a scientist is able to reverse the principles of diffusion such that molecules preferentially move from regions of low concentrations to regions of high concentrations. How would this affect the morphology of bacteria?

Answer 5

Bacteria would have to actively transport molecules across the cell membrane, potentially allowing for bacteria to grow larger, and prevent the diffusion of molecules out of the cell, potentially allowing for bacteria to grow wider.

Question 6

Researchers have discovered a new species of prokaryote. Upon closer inspection, they see that it has a single circular chromosome, is capable of methanogenesis, and has histone proteins. To which group does this organism belong?

Answer 6

Archaea

Question 7

Similarity between Bacteria and Archaea includes:

Answer 7

Capability to perform chemoautotrophy

Question 8

Bacteria contain neither organelle-associated membranes nor a cell membrane

Answer 8

False

Question 9

If biologists could quantify all the bacterial and human cells within the human body, they would find that there are far more human cells.

Answer 9

False

Question 10

Bacterial genetic diversity can arise from:

Answer 10

Transduction and conjugation

Question 11

Conjugation is a type of horizontal gene transfer that relies on a structure known as a pilus to bring two cells into close enough contact to transfer genetic material.

Answer 11

True

Question 12

The last common ancestor of fungi, mammals, and archaea likely had which characteristics?

Answer 12

Both a cell membrane and a circular chromosome

Question 13

A student notices two bacteria cells of the same species in close association with one another, with a thin projection running between them. He assumes that these two cells are fusing, forming a new individual. His instructor informs him that this is not the case. Why?

Answer 13

Cell fusion does not occur with bacterial cells, and these cells are likely undergoing conjugation.

Question 14

A researcher is comparing the sequences of genes encoding cell wall proteins in archaea with those coding cell wall proteins in bacteria. How similar do you expect these sequences will be?

Answer 14

These sequences will be dissimilar, as archaea cell walls are not composed of peptidoglycan.

Question 15

Which statement is true regarding Archaea?

Answer 15

Their transcriptional machinery is similar to the machinery used by eukaryotes.

Question 16

Chapter 25

Question 17

Imagine there is a cell that has only long-chain saturated fatty acid tails in the phospholipids making up the plasma membranes. This would _____ the fluidity of the cell’s plasma membrane.

Answer 17

Decrease

Question 18

Imagine there is a mutation in a eukaryotic cell that affects the cell’s ability to produce microtubules. Which of the answer options would you expect to be a characteristic of cells with this mutation compared to cells without the mutation?

Answer 18

Response rates in cell-signaling pathways would be slower.

Question 19

You identify a new organism that has these three characteristics: * Feature 1: a membrane-bound nucleus that houses linear DNA * Feature 2: dynamic membranes and cytoskeleton * Feature 3: reproduction occurs asexually most of the time Is this organism more likely to be prokaryotic or eukaryotic?

Answer 19

All three features are those of a eukaryotic organism.

Question 20

You have learned that having linear DNA has consequences, the major one being that the DNA is shortened every time it replicates. This does not happen with the circular DNA found in prokaryotes. What, then, is the advantage of having linear DNA?

Answer 20

Replication can begin from multiple sites on linear DNA, allowing rapid replication and relieving the evolutionary pressure for a streamlined genome.

Question 21

Eukaryotic genomes often have large amounts of non-coding DNA. A cell must expend energy to replicate all of its DNA. Which statement suggests a selective advantage over the genome organization of prokaryotic cells?

Answer 21

Eukaryotes have a larger portion of the genome available for specific regulation of gene expression.

Question 22

Eukaryotes have more ways to obtain energy than prokaryotes.

Answer 22

False

Question 23

Chapter 26

Question 24

Which statement reflects why we see most simple multicellular organisms in aquatic environments?

Answer 24

Aquatic organisms are surrounded by their environment and are better able to acquire nutrients from their surroundings.

Question 25

Can complex multicellularity be considered a homologous trait among the groups that show this trait?

Answer 25

No, complex multicellularity is not present in the common ancestor of all multicellular organisms.

Question 26

The presence of muscles in animals, and not in plants, could be considered a direct consequence of:

Answer 26

The lack of cell walls in animals

Question 27

Which statement explains why bulk flow is utilized in so many different complex multicellular organisms?

Answer 27

Bulk flow overcomes the time it would take for diffusion to deliver necessary molecules to cells in all parts of the organism.

Question 28

In terms of responding to the environment, growth fulfills the same role in plants as _____ does in animals.

Answer 28

Behavior

Question 29

What is a major difference between plants and animals?

Answer 29

Unlike animal cells, plant cells have walls.

Question 30

Multicellular organisms do not use diffusion to maintain their metabolisms.

Answer 30

False

Question 31

A young boy is staring at the tropical fish tank in his mother's office. He reaches in and pulls out a fern-like plant. When he closely examines this plant, he notices it has very large cells with several dark spots. What is likely true of this plant?

Answer 31

This plant is coenocytic; the dark spots are actually nuclei.

Question 32

If you were to sample the sizes of oxygen-dependent organisms that lack structures for bulk flow in an aquatic environment (the first 10 centimeters of depth), what would you expect to find?

Answer 32

Larger organismal size on the surface, with decreasing overall body size as you move to deeper waters

Question 33

What happens during gastrulation?

Answer 33

Cells migrate to form a layered structure.