Question 1

Which of the following best describes the role of autotrophic protists in aquatic ecosystems?

Accepted Answer

They serve as primary producers, converting light energy into chemical energy stored in biomass.

Question 2

During photosynthesis, algae convert light energy into which molecule, and what is its chemical formula?

Accepted Answer

Glucose; $$C_6H_{12}O_6$

Question 3

Which process performed by protists is directly responsible for the production of oxygen in aquatic environments?

Accepted Answer

Photosynthesis

Question 4

How do heterotrophic protists contribute to nutrient cycling in ecosystems?

Accepted Answer

By sequestering nutrients from dead organisms and excreting nutrients, making them available to primary producers

Question 5

A sudden increase in nitrogen and phosphorus in a lake leads to a dinoflagellate bloom. What is a potential consequence for human health?

Accepted Answer

Production of neurotoxins that can cause illness

Question 6

Which of the following best explains why kelp is considered an ecosystem engineer?

Accepted Answer

Kelp provides essential habitat for other species, enabling the existence of harvestable organisms.

Question 7

What is the primary ecological function of decomposer protists?

Accepted Answer

They sequester energy and nutrients from dead organisms, making resources available to other heterotrophs.

Question 8

Which of the following equations represents the photosynthetic process carried out by algae?

Accepted Answer

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

Question 9

Why is the burial of algal cells in sediment important for global carbon cycling?

Accepted Answer

It locks up carbon, reducing atmospheric $$CO_2$$ and aiding in long-term carbon storage.

Question 10

Which of the following is a direct benefit of protists to human well-being?

Accepted Answer

Protists produce oxygen and store carbon, supporting harvestable species and regulating climate.

Question 11

A marine ecosystem experiences a decline in kelp populations. Which of the following is a likely consequence?

Accepted Answer

Loss of essential habitat for many species, leading to biodiversity decline

Question 12

Which group of protists is most likely to cause harmful algal blooms that impact aquatic biodiversity and human health?

Accepted Answer

Dinoflagellates

Question 13

In the context of energy flow through ecosystems, which role do protists most commonly play?

Accepted Answer

Primary producers and consumers, facilitating energy transfer from sunlight to higher trophic levels

Question 14

Which of the following best illustrates the transfer of energy and nutrients from protists to higher trophic levels?

Accepted Answer

Microscopic algae are consumed by small predators, transferring biomass to heterotrophs.

Question 15

Which of the following is NOT a way protists contribute to nutrient flow in ecosystems?

Accepted Answer

Producing oxygen through photosynthesis

Question 16

A scientist measures a decrease in $$O_2$$ levels in a pond following an algal bloom. What is the most likely explanation?

Accepted Answer

Heterotrophic aerobic bacteria consumed the algae, depleting oxygen.

Question 17

Which of the following best describes the relationship between protists and the cycling of phosphorus in aquatic ecosystems?

Accepted Answer

Protists absorb phosphorus during photosynthesis, making it available to higher trophic levels.

Question 18

Which scenario best demonstrates the keystone species concept as it applies to protists?

Accepted Answer

Removal of kelp leads to collapse of the entire marine community due to loss of habitat.

Question 19

Which of the following is a multi-step process involving protists that benefits both ecosystems and human well-being?

Accepted Answer

Algae absorb $$CO_2$$ during photosynthesis, release $$O_2$$, and when buried, lock up carbon, reducing atmospheric greenhouse gases.

Question 20

Which of the following is a plausible consequence of biodiversity decline in aquatic ecosystems due to protist-related events?

Accepted Answer

Loss of essential habitat and reduced ecosystem services

Importance of Protists in Ecosystems and Human Well-being

Study Guide - Practice Questions