Question

Plastids that are surrounded by more than two membranes are evidence of

(A) evolution from mitochondria.

(B) fusion of plastids.

(C) origin of the plastids from archaea.

(D) secondary endosymbiosis.

Short answer

1. The option “evolution from mitochondria” isfalse.

2. The option “fusion of plastids” isfalse.

3. The option “origin of the plastids from archaea” is false.

4. The option “secondary endosymbiosis” is true.

Step-by-step solution

Plastids 

Plastids are essential structures found in photosynthetic organisms. These plastids are cell organelles that aid in the photosynthetic process and also facilitate the storage of glucose molecules within them. They carry photosynthetic pigments, due to which they appear green.

Explanation of option ‘(A)’

Plastids are not descendants of mitochondria. They are said to have evolved independently from prokaryotes in a similar way in which mitochondria are said to have evolved. The evolution of mitochondria took place much earlier before the evolution of plastids.

Thus, plastids did not evolve from pre-existing mitochondria.

Therefore, the given statement is false.

Explanation of option ‘(B)’

Plastids are descendants of cyanobacteria that were eukaryotic organisms. These structures did not evolve due to the fusion of plastids. Fusion cannot create plastids because the evidence of plastids before fusion is inevident.

Thus, plastids did not evolve from the fusion of plastids.

Therefore, the given statement is false.

Explanation of option ‘(C)’

Plastids did not evolve from archea because archea and bacteria are both primitive organisms that have a very simple body plan. However, plastids are complex structures that have double-layered membranes, unlike Arachea.

Thus, plastids did not evolve from archaea.

Therefore, the given statement is false.

Explanation of option ‘(D)’

According to several scientific explanations, plastids have evolved from secondary endosymbiosis. The endosymbiotic theory suggests that eukaryotes engulfed cyanobacteria that are thought to be descendants of plastids because of their lineage.

Thus, plastids evolved from secondary endosymbiosis.

Therefore, the given statement is true.