Chloroplasts
In plants and algae, which developed much later, photosynthesis occurs in a specialized intracellular organelle—the chloroplast. Chloroplasts perform photosynthesis during the daylight hours. The immediate products of photosynthesis, NADPH and ATP, are used by the photosynthetic cells to produce many organic molecules. I have taken the test before
I would guess that the answer would be :'<span>These organisms dig more shallow burrows than they used to.</span>' If the crabs actively dig burrows, as many crab species do, and a layer of oil has persisted in the lower soil strata, it makes sense that the crabs would be reducing the depths of their burrows to avoid contact with the oil. The other possibility is that the crabs might might migrate to deeper waters, but this is less likely because the crabs would be evolved to utilise the intertidal zone.
Mesoderm
Mesoderm is the primary germ layer that is responsible for producing both blood and phagocytic brain glial cells.
The mesoderm is the middle of the three germ layers that appears in the third week of embryonic development. The mesoderm is responsible for the formation of various body structures such as epithelia of blood vessels, blood, muscle, bone, phagocytic brain glial cells, lymphatic vessels, adrenal cortex, notochord, and bone marrow.
Alternative RNA splicing determines which proteins are produced from each gene.