Question 1

Which structural feature distinguishes Gram-negative bacteria from Gram-positive bacteria and contributes to their increased resistance to penicillin?

Accepted Answer

An outer membrane containing lipopolysaccharides (LPS)

Question 2

A patient is diagnosed with a bacterial infection. The bacteria appear purple after Gram staining and are susceptible to penicillin. Which of the following best describes the cell wall structure of these bacteria?

Accepted Answer

Thick peptidoglycan cell wall without an outer membrane

Question 3

Horizontal gene transfer (HGT) is a major driver of bacterial evolution. Which of the following statements best illustrates the impact of HGT on prokaryotes?

Accepted Answer

HGT allows bacteria to acquire genes from unrelated species, such as antibiotic resistance genes.

Question 4

About what percentage of prokaryotic genes have experienced horizontal gene transfer at some point in their evolutionary history?

Accepted Answer

$$80\%$$

Question 5

Which of the following is NOT a benefit provided by the gut microbiome?

Accepted Answer

Direct synthesis of human DNA

Question 6

Dysbiosis of the gut microbiome has been linked to several health conditions. Which of the following is LEAST likely to be associated with dysbiosis?

Accepted Answer

Increased bone density

Question 7

A researcher is studying the gut-brain axis. Which of the following best describes this concept?

Accepted Answer

The gut-brain axis refers to communication between gut microbiota and the brain, influencing mood and behavior.

Question 8

Which evolutionary adaptation allowed gymnosperms to reduce their dependence on water for reproduction compared to ferns?

Accepted Answer

Production of seeds and pollen

Question 9

Arrange the following plant groups in order of increasing terrestrial adaptation: algae, bryophytes, ferns, gymnosperms, angiosperms. Which group first developed vascular tissue?

Accepted Answer

Ferns

Question 10

Which limitation is shared by both bryophytes and ferns, but overcome by gymnosperms?

Accepted Answer

Dependence on water for fertilization

Question 11

A botanist observes a plant with flowers and fruits. Which evolutionary advantage do these features provide compared to gymnosperms?

Accepted Answer

Improved reproduction and dispersal

Question 12

Which of the following best describes primary endosymbiosis in the evolution of plastids?

Accepted Answer

A heterotrophic eukaryotic cell engulfed a cyanobacterium, resulting in a primary plastid

Question 13

Secondary endosymbiosis results in plastids surrounded by more than two membranes. Which process explains this phenomenon?

Accepted Answer

A eukaryotic host cell engulfed a photosynthetic eukaryote that already contained primary plastids

Question 14

Which plant group is most reliant on pollinators for reproduction, and what is a major limitation associated with this reliance?

Accepted Answer

Angiosperms; high energy cost and dependence on pollinators

Question 15

A scientist is comparing the Gram stain results of two bacterial samples. Sample A retains the crystal violet stain and appears purple, while Sample B loses the stain and appears pink. Which antibiotics would likely be more effective against Sample A?

Accepted Answer

Penicillin

Question 16

Which of the following scenarios best illustrates the role of horizontal gene transfer in the spread of antibiotic resistance?

Accepted Answer

A bacterium acquires a resistance gene from another species via plasmid exchange

Question 17

Which evolutionary adaptation was first seen in bryophytes and helped them survive on land?

Accepted Answer

Cuticle to reduce water loss

Question 18

A plant biologist is studying the transition from water-dependent algae to fully terrestrial angiosperms. Which sequence of adaptations best describes this evolutionary trend?

Accepted Answer

Cuticle → Vascular tissue → Seeds → Flowers

Question 19

Which of the following is a key limitation of gymnosperms compared to angiosperms?

Accepted Answer

No fruit, resulting in less efficient reproduction and dispersal

Exam 2 Review: Bacteria, Horizontal Gene Transfer, Gut Microbiome, Plant Evolution, and Endosymbiosis

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