Question 1

Which of the following statements best explains why protists are considered a paraphyletic group?

Accepted Answer

Protists include all eukaryotes except plants, animals, and fungi, but do not share a single common ancestor exclusive to them.

Question 2

Which process is responsible for the origin of plastids in green and red algae?

Accepted Answer

Primary endosymbiosis, where a heterotrophic eukaryote engulfed a cyanobacterium.

Question 3

A scientist observes a protist with thread-like pseudopodia and a hard test. To which group does this organism most likely belong?

Accepted Answer

Rhizaria

Question 4

Which of the following best describes the ecological role of dinoflagellates in marine environments?

Accepted Answer

They are major producers responsible for red tides and can form mutualistic relationships with coral.

Question 5

Which type of life cycle is characterized by mitosis occurring in both the haploid and diploid phases, as seen in many multicellular algae?

Accepted Answer

Sporic life cycle (alternation of generations)

Question 6

A protist is observed to be unicellular, photosynthetic, and possesses flagella with hair-like extensions. Which supergroup does it most likely belong to?

Accepted Answer

Stramenopiles

Question 7

Which of the following is a commercial use of diatoms and brown algae?

Accepted Answer

Tooth polish and food additives

Question 8

What is the main evolutionary significance of endosymbiosis in eukaryotes?

Accepted Answer

It led to the origin of organelles such as mitochondria and plastids, increasing metabolic diversity.

Question 9

Which of the following best describes the difference between primary and secondary endosymbiosis?

Accepted Answer

Primary endosymbiosis involves a eukaryote engulfing a prokaryote, while secondary endosymbiosis involves a eukaryote engulfing another eukaryotic alga.

Question 10

Which protist group is most responsible for mutualistic relationships with coral, providing them with photosynthetic products?

Accepted Answer

Dinoflagellates (zooxanthellae)

Question 11

A protist is found floating in the ocean, is photosynthetic, and forms part of the phytoplankton. Which classification best fits this organism?

Accepted Answer

Algae by ecological role, plankton by habitat

Question 12

Which of the following statements about green algae is correct?

Accepted Answer

They share the same type of plastids and photosynthetic pigments as land plants.

Question 13

Which life cycle is typical of most unicellular protists with sexual reproduction, where the zygote is the only diploid cell?

Accepted Answer

Zygotic life cycle

Question 14

Which of the following is NOT a unifying characteristic of protists?

Accepted Answer

All protists are multicellular organisms.

Question 15

A student observes a protist moving using cilia. Which group does this organism most likely belong to?

Accepted Answer

Alveolates (ciliates)

Question 16

Which of the following best explains why sexual reproduction is adaptive in protists?

Accepted Answer

It increases genetic diversity, allowing populations to adapt to changing environments.

Question 17

Which pigment is responsible for the red coloration in red algae?

Accepted Answer

Phycoerythrin

Question 18

Which equation best represents the alternation of generations in the sporic life cycle?

Accepted Answer

$2n \xrightarrow{meiosis} n \xrightarrow{mitosis} n \xrightarrow{fertilization} 2n \xrightarrow{mitosis} 2n$

Question 19

Which of the following is a correct description of a plastid?

Accepted Answer

A membrane-bound organelle in eukaryotes responsible for photosynthesis and other biosynthetic functions.

Protists: Diversity, Classification, and Life Cycles (BSC 2011 Study Notes)

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