Question 1

Which of the following best explains why viruses are not considered living organisms?

Accepted Answer

They lack a plasma membrane and cannot replicate independently outside a host cell.

Question 2

Which of the following is a key difference between the lytic and lysogenic cycles in bacteriophages?

Accepted Answer

In the lytic cycle, the host cell is immediately destroyed, while in the lysogenic cycle, the viral DNA integrates into the host genome and can remain dormant.

Question 3

Which hypothesis about the origin of viruses suggests that viruses predate cellular life?

Accepted Answer

The virus-first hypothesis

Question 4

What is the primary evidence supporting the endosymbiotic origin of mitochondria?

Accepted Answer

Mitochondria have circular DNA and ribosomes similar to those of alpha-proteobacteria.

Question 5

Which of the following steps was crucial for the evolution of phagocytosis in early eukaryotes?

Accepted Answer

Loss of the rigid prokaryotic cell wall and development of a cytoskeleton

Question 6

During secondary endosymbiosis, which of the following is true about the membranes surrounding the plastid?

Accepted Answer

The plastid is typically surrounded by three or four membranes, originating from both the engulfed eukaryote and the original cyanobacterium.

Question 7

Which of the following best describes a mixotrophic protist?

Accepted Answer

An organism that can switch between photoautotrophy and chemoheterotrophy depending on environmental conditions.

Question 8

Which life cycle is characterized by both haploid and diploid multicellular stages?

Accepted Answer

Alternation of generations

Question 9

Diatoms are responsible for approximately what percentage of global photosynthesis?

Accepted Answer

20%

Question 10

A harmful algal bloom (HAB) can lead to the creation of 'dead zones' in aquatic environments. What is the primary cause of these dead zones?

Accepted Answer

Decomposition of massive protist blooms by prokaryotes consumes oxygen, leading to anoxic conditions.

Question 11

Which of the following is NOT a characteristic shared by mitochondria and plastids that supports their endosymbiotic origin?

Accepted Answer

They are surrounded by a single membrane.

Question 12

Which of the following best describes the role of dinoflagellates in coral reefs?

Accepted Answer

They are endosymbionts that provide fixed carbon to corals through photosynthesis.

Question 13

Which of the following is a real-world consequence of protist diversity in marine environments?

Accepted Answer

Diatom oil deposits contributed to the formation of petroleum and natural gas.

Question 14

Which of the following best explains why the ability to endocytose was a key innovation in eukaryotic evolution?

Accepted Answer

It allowed ancestral eukaryotes to engulf and retain other cells, leading to the origin of organelles like mitochondria and plastids.

Question 15

Which of the following is true about the mitochondria of all living eukaryotes?

Accepted Answer

They are homologous, indicating a single origin from an alpha-proteobacterium.

Question 16

Which of the following is a correct statement about the diplontic life cycle?

Accepted Answer

The only multicellular stage is diploid, and gametes are the only haploid cells.

Question 17

Which of the following protists is responsible for causing malaria in humans?

Accepted Answer

Plasmodium

Question 18

Which of the following is a plausible reason why viral origins are difficult to study?

Accepted Answer

Viruses do not leave fossils and have rapidly evolving, small genomes.

Question 19

Which of the following best describes the process of primary endosymbiosis?

Accepted Answer

A eukaryote engulfs a cyanobacterium, which becomes a plastid with two membranes.

Question 20

Which of the following is a correct definition of phagocytosis?

Accepted Answer

The process by which a cell engulfs solid particles using extensions of its plasma membrane.

Viruses, Eukaryote Origins, and Protist Diversity: Study Notes for General Biology

Guida di studio - Domande di pratica

Study guide - Flashcard