Apentix/AP Biology/Unit 2: Cell Structure and Function/Question
AP Biologyhardmcq1 pt

Which set of traits supports the hypothesis that mitochondria descended from an ancestral alpha-proteobacterium?

A.A single membrane, linear histone-bound chromosomes, mitotic segregation
B.Cristae continuous with the nuclear envelope, ribosome exchange with the ER
C.A genome encoding every mitochondrial protein independently of the nucleus
D.A double membrane, a small circular chromosome, bacterial-type ribosomes, and division by fission

Explanation

Core Concept

These traits are consistent with descent from an engulfed bacterial ancestor. Mitochondria retain a small circular genome, divide by fission, have bacterial-type translation machinery, and are surrounded by two membranes. Ribosome sedimentation values vary among modern mitochondria, so the broader phrase 'bacterial-type ribosomes' is more accurate than claiming all mitochondria have 70S ribosomes.

Correct Answer

DA double membrane, a small circular chromosome, bacterial-type ribosomes, and division by fission

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