Question 1

Which of the following best describes the contribution of cyanobacteria to Earth's early atmosphere during the 'Oxygen Revolution'?

Accepted Answer

They produced oxygen as a byproduct of photosynthesis, increasing atmospheric oxygen levels.

Question 2

Which of the following equations correctly represents the process of photosynthesis?

Accepted Answer

$$6\ \mathrm{CO}_2 + 6\ \mathrm{H}_2\mathrm{O} \rightarrow C_6H_{12}O_6$ + 6\ \mathrm{O}_2$$

Question 3

Which of the following is a key piece of evidence supporting the endosymbiotic theory for the origin of mitochondria and chloroplasts?

Accepted Answer

Both organelles contain their own circular DNA similar to prokaryotes.

Question 4

Which adaptation allowed early plants to overcome the challenge of desiccation (drying out) when colonizing land?

Accepted Answer

Formation of a waxy cuticle to reduce water loss

Question 5

Which of the following best describes the relationship between an endosymbiont and its host cell?

Accepted Answer

Both the endosymbiont and the host cell benefit from the relationship.

Question 6

Which of the following is NOT a domain in the three-domain system of classification?

Accepted Answer

Protista

Question 7

Horizontal gene transfer can occur in prokaryotes through which of the following mechanisms?

Accepted Answer

Conjugation via a pilus

Question 8

Which nutritional mode do most fungi exhibit?

Accepted Answer

Chemoheterotrophy

Question 9

Why is nitrogen fixation by prokaryotes such as cyanobacteria important for plants and humans?

Accepted Answer

It converts atmospheric nitrogen ($$N_2) $$into ammonia ($$NH_3$$), which plants can use to make proteins.

Question 10

Anabaena, a cyanobacterium, overcomes the inactivation of nitrogen fixation by oxygen by:

Accepted Answer

Using specialized cells called heterocysts that create an anaerobic environment.

Question 11

Which of the following best describes the difference between aerobic and anaerobic organisms?

Accepted Answer

Aerobic organisms require oxygen for metabolism, while anaerobic organisms do not.

Question 12

Which of the following best describes the shell of a diatom?

Accepted Answer

It is made of silica and fits together like a petri dish.

Question 13

Which pigment is primarily responsible for the green color of green algae?

Accepted Answer

Chlorophyll (a and b)

Question 14

Which of the following best explains why red algae living in deeper waters appear much redder than those in shallow water?

Accepted Answer

They have higher concentrations of phycoerythrin, which absorbs blue and green light and reflects red.

Question 15

Which of the following best describes the feeding stage of a cellular slime mold?

Accepted Answer

A haploid amoeba that feeds on bacteria.

Question 16

Which of the following is a real-world example of mutualism involving protists?

Accepted Answer

Dinoflagellates living inside coral tissues, providing them with photosynthetic products.

Question 17

Which of the following best describes the process of secondary endosymbiosis in protist evolution?

Accepted Answer

A eukaryotic cell engulfs another eukaryotic cell that already contains a plastid.

Question 18

Which of the following is a major ecological role of diatoms in the global carbon cycle?

Accepted Answer

They sequester carbon by incorporating it into their silica shells, which sink to the ocean floor after death.

Question 19

Which of the following best describes the difference between the thallus of a brown alga and the body of a plant?

Accepted Answer

The thallus lacks true roots, stems, and leaves, while plants have these structures.

Question 20

Which of the following best explains why diatomaceous earth is useful as a filtering medium?

Accepted Answer

It is highly porous due to the intricate silica shells of diatoms.

Guided Study for BIOL&213: History of Life, Phylogeny, Prokaryotes, and Protists

Study Guide - Practice Questions