Question 1

Which of the following best describes secondary endosymbiosis and its significance in eukaryotic evolution?

Accepted Answer

It is the process by which a eukaryotic cell engulfs another eukaryotic cell that has already undergone primary endosymbiosis, leading to the origin of complex plastids.

Question 2

Which group of protists is characterized by the presence of a spiral or crystalline rod inside their flagella?

Accepted Answer

Euglenozoans

Question 3

A patient presents with symptoms of Chagas’ disease after being bitten by a kissing bug. Which protist is responsible for this disease, and what is a key feature of its mitochondrion?

Accepted Answer

Trypanosoma; a single mitochondrion with a kinetoplast

Question 4

Which of the following is a defining feature of the SAR supergroup?

Accepted Answer

It includes Stramenopiles, Alveolates, and Rhizarians, which are grouped based on DNA similarities.

Question 5

Diatoms play a significant role in the global carbon cycle. What happens to the carbon they fix after a diatom bloom?

Accepted Answer

It is sequestered on the ocean floor for decades to centuries as dead diatoms sink and decompose slowly.

Question 6

Which structure in brown algae is analogous to the stem of a plant, and what is its function?

Accepted Answer

Stipe; supports the leaflike blades

Question 7

Dinoflagellate blooms can cause 'red tides.' What is a major ecological consequence of these events?

Accepted Answer

They can produce toxins that accumulate in shellfish and cause illness in humans and marine animals.

Question 8

Which of the following statements about the life cycle of Plasmodium, the causative agent of malaria, is correct?

Accepted Answer

It requires both a mosquito and a human host to complete its sexual and asexual stages.

Question 9

Which of the following best describes the difference between radiolarians and foraminiferans?

Accepted Answer

Radiolarians have silica-based skeletons, while foraminiferans have calcium carbonate shells.

Question 10

Which of the following is true about the evolutionary relationship between green algae and plants?

Accepted Answer

Charophytes, a group of green algae, are the closest relatives to land plants.

Question 11

Which of the following is a unique feature of ciliates among protists?

Accepted Answer

They possess two types of nuclei: macronuclei and micronuclei.

Question 12

A scientist is studying a protist that lacks plastids, has reduced mitochondria called mitosomes, and lives in anaerobic environments. Which group does this organism most likely belong to?

Accepted Answer

Diplomonads

Question 13

Which of the following best explains why brown algae are not considered true plants?

Accepted Answer

They lack true tissues and organs.

Question 14

Which of the following protists is responsible for amebic dysentery, and what is its ecological role?

Accepted Answer

Entamoeba histolytica; parasite of vertebrates

Question 15

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

Accepted Answer

Dinoflagellates living within coral polyps, providing them with nutrients via photosynthesis.

Question 16

Which of the following equations best represents the process of photosynthesis carried out by protist producers?

Accepted Answer

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2$$

Question 17

Which of the following adaptations allows Euglenids to survive in environments with varying light availability?

Accepted Answer

They are mixotrophs, capable of both photosynthesis and heterotrophy.

Question 18

Which of the following best describes the ecological role of photosynthetic protists in aquatic environments?

Accepted Answer

They are primary producers, converting solar energy into organic compounds.

Question 19

Which of the following is a key difference between plasmodial and cellular slime molds?

Accepted Answer

Plasmodial slime molds form a unicellular feeding mass, while cellular slime molds form multicellular aggregates.

Protists: Diversity, Evolution, and Ecological Roles

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