Topic 11: Eukaryotes

Question 1

According to the theory of serial endosymbiosis, which type of prokaryote was engulfed and evolved into the mitochondria found in eukaryotic cells?

Answer 1

An anaerobic alpha proteobacterium

Question 2

The development of a cytoskeleton in eukaryotes was a crucial innovation that enabled new cellular behaviors. Which process, essential for the endosymbiont theory, is directly facilitated by the cytoskeleton?

Answer 2

Phagocytosis

Question 3

The ‘serial’ aspect of the serial endosymbiosis hypothesis proposes a specific order for the acquisition of major organelles. What does this hypothesis suggest?

Answer 3

Mitochondria evolved before plastids as all eukaryotes have mitochondria, but only a subset have plastids

Question 4

What is the key difference between primary and secondary endosymbiosis?

Answer 4

Primary endosymbiosis is the engulfment of a prokaryotic cell, while secondary endosymbiosis is the engulfment of a eukaryotic cell

Question 5

The group ‘Protista’ is considered an informal, polyphyletic taxon. What does this classification imply?

Answer 5

Protists lack key features that define animals, plants, and fungi but do not all share a single common ancestor

Question 6

How did the nuclear envelope and other parts of the endomembrane system likely originate in the ancestral eukaryote?

Answer 6

Through infoldings of the ancestral cell’s plasma membrane

Question 7

Some protists are mixotrophs. What does this nutritional strategy involve?

Answer 7

Switching between photosynthesis and heterotrophy