Question 1

Which of the following best explains why the traditional Kingdom Protista is no longer considered a valid monophyletic group in modern taxonomy?

Accepted Answer

Molecular evidence shows that some protists are more closely related to plants, fungi, or animals than to each other.

Question 2

Which organelle in Paramecium is responsible for regulating water balance, and what is its primary function?

Accepted Answer

Contractile vacuole; it expels excess water from the cell to prevent lysis.

Question 3

According to the endosymbiosis theory, which sequence correctly describes the origin of mitochondria in eukaryotic cells?

Accepted Answer

An archaean cell engulfed an alpha-proteobacterium, which evolved into the mitochondrion.

Question 4

Which cytoskeletal components are primarily involved in phagocytosis and endocytosis in eukaryotic cells?

Accepted Answer

Actin filaments and tubulins

Question 5

A scientist discovers a protist with two nuclei and multiple flagella that lives in the human intestine and survives without oxygen. Which group does this organism most likely belong to?

Accepted Answer

Diplomonads

Question 6

Which of the following best describes secondary endosymbiosis?

Accepted Answer

A eukaryote engulfs another eukaryote that already contains a plastid, leading to complex plastid evolution.

Question 7

Diatoms are among the most important photosynthetic organisms on Earth. What unique feature of their cell wall contributes to their ecological success?

Accepted Answer

Cell walls composed of silica, forming strong, glass-like structures

Question 8

Which protist group is responsible for causing malaria in humans, and what is the name of the organelle that helps it invade host cells?

Accepted Answer

Apicomplexans; apicoplast

Question 9

During the life cycle of brown algae, alternation of generations occurs. Which statement best describes this process?

Accepted Answer

The organism alternates between haploid gametophyte and diploid sporophyte stages.

Question 10

A patient in Africa is diagnosed with African sleeping sickness. Which protist is responsible, and how is it transmitted?

Accepted Answer

Trypanosoma; transmitted by the Tsetse fly

Question 11

Which equation best represents the alternation of generations in brown algae, where $$n is $$the haploid number and $$2n is $$the diploid number?

Accepted Answer

$$n \rightarrow 2n \rightarrow n$$

Question 12

Which of the following protists is a colonial organism composed of many cells, each capable of independent function, and is often used as a model for studying multicellularity?

Accepted Answer

Volvox

Question 13

What is the main ecological role of foraminiferans (forams) in marine environments?

Accepted Answer

They form extensive fossil deposits that are used in geological dating and carbon cycling.

Question 14

Which protist group includes organisms with thread-like pseudopods reinforced by microtubules and often have shells made of silica?

Accepted Answer

Radiolarians

Question 15

Which of the following statements about red algae is correct?

Accepted Answer

Red algae contain the pigment phycoerythrin, allowing them to absorb blue and green light in deep waters.

Question 16

Which of the following best describes the function of the eyespot in Euglena?

Accepted Answer

It detects light, allowing the organism to move toward optimal light conditions for photosynthesis.

Question 17

Which process is illustrated by the equation below, and in which protist group is it commonly observed?

$$	ext{Glucose} + 2	ext{ADP} + 2	ext{P}_i ightarrow 2	ext{ATP} + 2	ext{CO}_2 + 2	ext{H}_2$$

Accepted Answer

Anaerobic metabolism in parabasalids

Question 18

Which protist group is characterized by the presence of alveoli (membranous sacs) under the plasma membrane and includes organisms responsible for red tides?

Accepted Answer

Alveolates (Dinoflagellates)

Question 19

Which of the following is a real-world consequence of the rapid population growth of dinoflagellates in aquatic environments?

Accepted Answer

Formation of red tides that release toxins, causing massive fish kills and human health risks.

Protists: Structure, Diversity, and Evolution (Chapter 28 Study Notes)

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