The endosymbiont theory suggests that mitochondria and chloroplasts evolved from ancient bacteria that were ingested by primitive nucleated cells. Biologists have proposed that endosymbiosis led to the evolution of other cellular structures, such as flagella and peroxisomes, as well. Over hundreds of millions of years, the ingested bacteria lost features not essential for survival inside the host cell. (please answer both part d and f) Thank you.

Part D

How would loss of this feature prevent the bacteria from living outside the host?

A. Without cell walls, the bacteria might burst due to osmotic pressure or might be more vulnerable to invasion by fungi.

B. Without cell walls, the bacteria might burst due to osmotic pressure or might be more vulnerable to invasion by viruses.

C. Without cell walls, the bacteria might burst due to partial pressure or might be more vulnerable to invasion by viruses.

D. Without cell walls, the bacteria might burst due to partial pressure or might be more vulnerable to invasion by alien bacteria.

Part F

Describe one advantage peroxisomes might have conferred on ancient nucleated cells.

A. Peroxisomes might have enabled ancient cells to expand the use of oxidases−which generate the potentially useful compound H2O for a variety of metabolic processes.

B. Peroxisomes might have enabled ancient cells to expand the use of oxidases−which generate the potentially toxic compound H2O2 −for a variety of metabolic processes.

C. Peroxisomes might have enabled ancient cells to reduce the toxicity of a variety of compounds by using the molecules as electron donors for recovery of H2O2.

D. Peroxisomes might have enabled ancient cells to generate acetyl coenzyme A reductase from short-chain fatty acids, providing additional carbon sources for the cell.