Question 1

Which of the following statements best explains why protists are considered more structurally and functionally diverse than other eukaryotic groups?

Accepted Answer

Protists carry out all biological functions within a single cell, leading to a wide range of adaptations.

Question 2

A patient presents with severe diarrhea after drinking untreated stream water while camping. Microscopic examination reveals a protist with two nuclei and multiple flagella. Which of the following is the most likely causative agent?

Accepted Answer

Giardia intestinalis

Question 3

Which of the following best describes the nutritional strategy of mixotrophic protists?

Accepted Answer

They combine photosynthesis and heterotrophic nutrition.

Question 4

Which structure in brown algae is analogous to the roots of land plants, and what is its primary function?

Accepted Answer

Holdfast; anchoring the alga to a substrate

Question 5

A scientist discovers a unicellular organism with a two-part, glass-like wall composed of silicon dioxide. Which group does this organism most likely belong to?

Accepted Answer

Diatoms

Question 6

Trypanosoma, a kinetoplastid, is responsible for which human disease, and what is its primary mode of transmission?

Accepted Answer

Sleeping sickness; tsetse fly bite

Question 7

Which of the following best explains why similarities between brown algae and land plants are considered examples of analogous structures?

Accepted Answer

They evolved similar features independently due to similar environmental pressures.

Question 8

Which protist is responsible for causing malaria, and what is a key feature of its life cycle?

Accepted Answer

Plasmodium; requires both mosquito and human hosts to complete its life cycle

Question 9

Which of the following is a major ecological role of photosynthetic protists in aquatic environments?

Accepted Answer

They are the main producers of organic matter, forming the base of aquatic food webs.

Question 10

A sudden increase in phosphorus in a lake leads to a rapid growth of diatoms. What is the most likely consequence of this event?

Accepted Answer

A bloom of diatoms, followed by accumulation of their silica walls on the lake floor.

Question 11

Which of the following protists is a symbiont that benefits its host by digesting cellulose in the gut of termites?

Accepted Answer

Wood-digesting protists

Question 12

Red algae are most abundant in which type of environment, and what pigment gives them their characteristic color?

Accepted Answer

Coastal tropical waters; a pigment that masks the green of chlorophyll

Question 13

Which of the following best describes the impact of rising sea surface temperatures on photosynthetic protists and global ecosystems?

Accepted Answer

Declining protist biomass may disrupt marine ecosystems and the global carbon cycle.

Question 14

Which of the following is a correct match between a protist and the disease or ecological effect it causes?

Accepted Answer

Phytophthora ramorum – sudden oak death

Question 15

Which of the following equations correctly represents the process of photosynthesis carried out by photoautotrophic protists?

Accepted Answer

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

Question 16

Which of the following best explains why diatomaceous earth accumulates on the ocean floor?

Accepted Answer

Diatoms have silica walls that resist decomposition and settle after blooms.

Question 17

Which of the following is a real-world example of a protist acting as a vector-borne parasite?

Accepted Answer

Plasmodium, transmitted by mosquitoes, causing malaria in humans

Question 18

Land plants are most closely related to which group of green algae?

Accepted Answer

Charophytes

Question 19

Which of the following best describes the role of dinoflagellates in coral reef ecosystems?

Accepted Answer

They nourish coral polyps through symbiotic photosynthesis.

Question 20

A researcher observes a protist that can switch between photosynthesis and ingestion of organic particles depending on environmental conditions. Which term best describes this organism?

Accepted Answer

Mixotroph

Protists: Diversity, Structure, and Ecological Roles

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