Cell-mediated immunity is directed primarily microbes that survive in phagocytes and microbes that infect non-phagocytic cells. It is most effective in destroying virus-infected cells, intracellular bacteria, and cancers. It also plays a major role in delayed transplant rejection.
Answer:
Stratum basale layer of epidermis produces melanin pigment.
Explanation:
The epidermis is composed of mainly four layers. In some areas like palm and foot, they contain five layers - stratum granulosum. All the layers are avascular i.e. lack of blood vessels.
The stratum basale cell is the deep layer of the epidermis. It is a single layer made of basal cells. The basal layer produces the keratinocytes. The keratinocytes divide mitotically and migrate to the upper layers. The keratinocytes provide hardness to the nail and skin, also make the skin waterproof.
Another two types of cells are present in the stratum basale - Merkel cell and melanocyte cell. Merkel cells provide sensory stimulation to the skin. Melanocyte cell produces pigment melanin.
Melanocyte gives color to skin, hair. It spreads from stratum basale to the upper layer of the skin called stratum corneum. Melanin pigment protects the skin from the ultraviolet radiation of the sun.
Answer:
The correct answer is the letter b. The endosymbiotic event that brought chloroplasts into Eukaryotic cells actually happened after Eukaryotic lineages diverged so many lineages never actually possessed chloroplasts
Explanation:
The plastid is an organelle linked to membarna found in the cells of eukaryotic organisms, which contains pigments used in photosynthesis. Some eukaryotic organisms over time have inherited the ability to photosynthesize from cyanobacteria by secondary endosymbiosis or ingestion, and are able to capture and sequester photosynthetic cells and chloroplasts, this process is known as kleptoplasty.
It's because everything has a certain place in DNA. every acid or amino acid carries a specific thing or role in DNA period without all three it wouldn't function well.
Niche diversity refers to the evolutionary process in which species diverge in order to take advantage of open niches in their environment. This can also be seen in species that are somehow threaded from a common ancestor they share.Hope this helps:)