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, as shown in the provided micrograph?

Accepted Answer

Euglenozoans

Question 3

A patient is diagnosed with Chagas’ disease after being bitten by the insect shown in the image. Which protist is responsible for this disease, and what is a key feature of its cellular structure?

Accepted Answer

Trypanosoma; it has a single large mitochondrion containing a kinetoplast

Question 4

Which of the following best explains why diatoms are important 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 5

Which structure in brown algae is functionally analogous to the roots of land plants?

Accepted Answer

Holdfast

Question 6

Which of the following statements about the mitochondria-related organelles (MROs) in Excavata is correct?

Accepted Answer

Hydrogenosomes generate ATP anaerobically and produce hydrogen as a byproduct.

Question 7

Which of the following protists is a major cause of harmful algal blooms known as 'red tides'?

Accepted Answer

Dinoflagellates

Question 8

A scientist is studying a protist with threadlike pseudopodia and a shell made of calcium carbonate. Which group does this organism most likely belong to?

Accepted Answer

Foraminiferans

Question 9

Which of the following is a distinguishing feature of ciliates, such as Paramecium?

Accepted Answer

They possess two types of nuclei: macronuclei and micronuclei.

Question 10

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

Accepted Answer

They are primary producers that convert $\mathrm{CO_2}$ to organic compounds using sunlight.

Question 11

Which supergroup includes the closest relatives of fungi and animals?

Accepted Answer

Unikonta

Question 12

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

Accepted Answer

Green algae and plants are both part of the Archaeplastida supergroup and share a common ancestor.

Question 13

Which of the following protists is responsible for malaria, and what is a unique feature of its life cycle?

Accepted Answer

Plasmodium; it requires both a mosquito and a human host to complete its life cycle.

Question 14

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

Accepted Answer

They lack true tissues such as roots, stems, and leaves.

Question 15

Which of the following is a real-world application of brown algae, as shown in the images of commercial products?

Accepted Answer

They are used as food additives and nutritional supplements.

Question 16

Which of the following statements about mixotrophs is correct?

Accepted Answer

Mixotrophs can switch between autotrophic and heterotrophic modes of nutrition depending on environmental conditions.

Question 17

Which of the following is a key difference between radiolarians and foraminiferans?

Accepted Answer

Radiolarians have internal skeletons made of silica, while foraminiferans have shells made of calcium carbonate.

Question 18

Which of the following best describes the process of conjugation in ciliates?

Accepted Answer

It is a sexual process in which two individuals exchange haploid micronuclei.

Question 19

Which of the following is a symbiotic relationship involving protists that benefits their host?

Accepted Answer

Dinoflagellates nourish coral polyps that build coral reefs.

Protists: Diversity, Evolution, and Ecological Roles

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