Question 1

Which of the following statements best explains why 'protists' are considered a 'grade' and not a 'clade' in biological classification?

Accepted Answer

Protists represent a morphological grade, including organisms that are more complex than prokaryotes but do not include all descendants of a common ancestor.

Question 2

Which of the following is NOT a characteristic shared by all eukaryotic cells?

Accepted Answer

Ability to perform photosynthesis

Question 3

Dinoflagellates are important in marine ecosystems because they can cause which phenomenon, and what is its ecological impact?

Accepted Answer

Red Tide; it leads to neurotoxic shellfish poisoning and disrupts food webs

Question 4

Which group of protists is characterized by 'hairy flagella' and includes diatoms, oomycetes, and brown algae?

Accepted Answer

Stramenopiles

Question 5

A scientist discovers a single-celled organism with a shell of calcium carbonate that settles to the bottom of a marine environment. To which group does this organism most likely belong?

Accepted Answer

Foraminiferans (Rhizarians)

Question 6

Which of the following best describes the ecological role of photosynthetic protists in Earth's biosphere?

Accepted Answer

They are primary producers, responsible for about 25% of Earth's photosynthesis.

Question 7

Which protist pathogen is responsible for causing African Sleeping Sickness, and how is it transmitted?

Accepted Answer

Trypanosoma (Euglenozoan); transmitted by tsetse flies

Question 8

Which of the following statements about multicellularity in eukaryotes is correct?

Accepted Answer

Multicellularity has arisen multiple times independently in different eukaryotic lineages.

Question 9

Which lineage includes both green algae and land plants, and is important for studying photosynthesis and primary endosymbiosis?

Accepted Answer

Archaeplastida

Question 10

What is the main reason protist infections are difficult to treat in humans?

Accepted Answer

Protists have cellular machinery similar to ours, making it hard to target them without harming human cells.

Question 11

Which of the following protist groups is mostly parasitic and includes organisms with modified mitochondria and unique flagella?

Accepted Answer

Excavates

Question 12

Which of the following is a correct example of mutualism involving protists?

Accepted Answer

Photosynthetic dinoflagellates living in coral tissues

Question 13

Which of the following best describes the difference between autotrophic and heterotrophic protists?

Accepted Answer

Autotrophic protists use light energy to fix inorganic CO$$_2$$, while heterotrophic protists obtain energy by consuming organic molecules.

Question 14

Which of the following is a shared feature of alveolates?

Accepted Answer

Presence of alveoli (membrane-bound sacs) beneath the cell membrane

Question 15

Which protist group includes organisms that are important decomposers and parasites, and have lost their photosynthetic plastids?

Accepted Answer

Oomycetes (Stramenopiles)

Question 16

A protist is found to be capable of both photosynthesis in the light and heterotrophy in the dark. What is the term for this nutritional strategy?

Accepted Answer

Mixotrophy

Question 17

Which of the following best explains why DNA analysis has been so useful in understanding eukaryote evolution?

Accepted Answer

Morphological traits are often convergent or lost, making it hard to compare groups without genetic data.

Question 18

Which of the following is true about the evolution of chloroplasts in eukaryotes?

Accepted Answer

Chloroplasts arose only once via primary endosymbiosis.

Question 19

Which of the following protist groups is characterized by amoeboid movement using pseudopodia and includes both planktonic and benthic forms?

Accepted Answer

Rhizarians

Question 20

Which of the following is a reason why vertebrates, such as salamanders, cannot perform photosynthesis on their own?

Accepted Answer

They lack the cellular machinery and accessory pigments required for photosynthesis.

Protists: Diversity, Evolution, and Biological Roles

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