Answer:
they need a high ‘surface to volume’ ratio, which is good for exchanging materials between the inside and outside of cells. But this is probably not really the size-limiting reason, since cells vary enormously in size and surface area to volume ratios.
Explanation:
Answer:
If an organism has a beneficial trait, they have a higher chance of survival, and if they can survive they can reproduce too.
Example: Speckled moths camouflage with the bark of trees and are not easily seen by predators. Black moths do not camouflage with the bark of trees and are easily seen by predators, therefore the black moths are eaten. Because the black moths have been eaten they cannot reproduce and pass on the trait for black wings to their offspring, but the speckled moths are able to reproduce because they survived and are able to pass on the speckled wing trait to their offspring.
Answer:
4. B cells become activated by interacting with helper T cells.
1. B cells display antigens in MHC class II receptors on the cell surface.
2. Antibodies released by plasma cells bind to the antigen so they will be destroyed by other cells of the immune system.
3.B cells rearrange their DNA to create a unique B-cell receptor.
5. B cells undergo clonal expansion.
6. B cells digest antigens that bind to the antibodies on their surface.
Explanation:
B-cells get activated by interacting with helper T cells when they bind to the antigen to receptors i.e (MHC class II receptors on the cell surface) on the surface of the cell. Series of activities such as release by plasma cells which cause rearrangement of B cells causes the cell to divide and proliferate. The process through which daughter cells arise from a parent cell called clonal expansion.
They are considered to have originated from cyanobacteria through endosymbiosis—when a eukaryotic cell engulfed a photosynthesizing cyanobacterium that became a permanent resident in the cell
