Many parasitic members of the excavates lack plastids and have highly reduced mitochondria. Which of the following statements explains these observations?
A) These parasites typically live in low-oxygen conditions, and therefore it was adaptive to move all plastid and mitochondrial genes to the nucleus.
B) The original, eukaryotic ancestors of these parasites did not engulf prokaryotes.
C) These parasites typically live in low-oxygen conditions and therefore loss of genes for plastids and mitochondria did not result in lower fitness.
D) In the future, natural selection will favor descendants that acquire new plastid genes from today's prokaryotes.

Question

Quizplus · Accepted Answer

These parasites often inhabit environments where oxygen is scarce, making the presence of mitochondria (which are involved in aerobic respiration) and plastids (related to photosynthesis and found in plants and algae) less critical for survival. As a result, the loss of genes associated with these organelles does not significantly impact their fitness in such environments.

Many Parasitic Members of the Excavates Lack Plastids and Have