Understand endosymbiotic theory

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AP Biology › Understand endosymbiotic theory

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1

Mitochondria and chloroplasts have ribosomes that are ___, similar to __ cells.

80S, prokaryotic

0

70 S, prokaryotic

CORRECT

70S, eukaryotic

0

80S, eukaryotic

0

Explanation

Prokaryotic cells, mitochondria, and chloroplasts have 70S ribosomes, whereas eukaryotic cells have 80S ribosomes. This provides support for the Endosymbiotic Theory, which states that the mitochondria and chloroplast in eukaryotic cells were once aerobic bacteria (prokaryote) that were ingested by a large anaerobic bacteria (prokaryote).

2

Which of the following is NOT evidence for the Endosymbiotic Theory?

Mitochondria and chloroplasts have a double membrane

0

Mitochondria and chloroplasts have circular DNA

0

Mitochondria and chloroplasts have 70S ribosomes

0

Mitochondria and chloroplasts have a single membrane

CORRECT

Explanation

The Endosymbiotic Theory states that the mitochondria and chloroplast in eukaryotic cells were once aerobic bacteria (prokaryote) that were ingested by a large anaerobic bacteria (prokaryote). This theory explains the origin of eukaryotic cells. Numerous lines of evidence exist, including that mitochondria and chloroplasts have their own circular DNA (prokaryotes also have circular DNA), mitochondria and chloroplasts have a double membrane (the inner membrane would have initially been the ingested prokaryote’s single membrane, and the outer membrane initially would have come from the cell that engulfed it), mitochondria and chloroplasts have 70S ribosomes (prokaryotes 70S have ribosomes, whereas eukaryotes have 80S ribosomes).

3

Supporting the Endosymbiotic Theory, mitochondria and chloroplasts have a _________ membrane.

double

CORRECT

single

0

thick

0

thin

0

Explanation

The Endosymbiotic Theory states that the mitochondria and chloroplast in eukaryotic cells were once aerobic bacteria (prokaryote) that were ingested by a large anaerobic bacteria (prokaryote). Mitochondria and chloroplasts have a double membrane (the inner membrane would have initially been the ingested prokaryote’s single membrane).

4

The Endosymbiotic Theory posits that, before being engulfed by a eukaryotic cell, they were

Free-living eukaryotes

0

Viruses

0

Free-living prokaryotes

CORRECT

Organelles

0

Explanation

The Endosymbiotic Theory states that the mitochondria and chloroplast in eukaryotic cells were once aerobic bacteria (prokaryote) that were ingested by a large anaerobic bacteria (prokaryote). The aerobic bacteria were initially free-living prokaryotes, before being ingested by anaerobic bacteria.

5

Reproduction of chloroplasts and mitochondria occurs via

Fission-like process, similar to the reproduction process of bacteria

CORRECT

Fission-like process, similar to the reproduction process of eukaryotes

0

Mitosis

0

Meiosis

0

Explanation

Chloroplasts and mitochondria reproduce through fission, the same process through which bacteria reproduce. Eukaryotes reproduce through mitosis or meiosis, depending upon the type of cell.

6

Mitochondria and chloroplasts have their own DNA, which is similar to the DNA of

bacteria

CORRECT

fungi

0

protozoa

0

humans

0

Explanation

Bacteria, a prokaryote, has circular DNA, as do mitochondria and chloroplasts. This provides support for the Endosymbiotic Theory, which states that the mitochondria and chloroplast in eukaryotic cells were once aerobic bacteria (prokaryote) that were ingested by a large anaerobic bacteria (prokaryote).