Some Eukaryotic cells have internal structures that are able to use photosynthesis to convert light energy into chemical energy (as bonds in sugars). Why is this capability not found in all Eukaryotes?

The endosymbiotic event that brought chloroplast in eukaryotic cells happened after the lineage delivered.

Explanation:

The endosymbiotic theory says that the ancestral cell gains the ability of photosynthesis when it engulfed a photosynthetic bacteria and this bacteria remained in a symbiotic relationship with the ancestral cell and evolved as chloroplast in plants that can perform photosynthesis.

All the eukaryotes do not have this internal structure like chloroplast because this endosymbiotic event must be happened after the divergence of the lineage into different groups. Therefore plant cells have chloroplast and animals cell do not have.

The question is incomplete as it does not have the options which are provided in the attached picture.

Option-B

Explanation:

The theory of the endosymbiotic origin of eukaryotes proposed that the organelles like the chloroplast and mitochondria are originated when the proto-eukaryotes engulfed the prokaryotic cells.

The chloroplast was formed in some eukaryotes instead of others as the proto eukaryotes diverged into many lineages before the origin of the chloroplast in them. One of the lineages engulfed the chloroplast and become photosynthetic organism but rest of the proto eukaryotic lineage did no engulfed the bacteria and did not possess the chloroplast.

Thus, Option-B is the correct answer.

the relative standard reduction potential of the half-cell in which reduction occurs; more positive than the other half-cell. reduction is a chemical process in which electrons are added to an atom or an ion; it always occurs accompanied by oxidation of the reducing agent.