This is because the melanocytes are located in the stratum basale. Lighter-skinned people usually have low basal levels, and exposure to UV radiation causes an increase which makes skin darker.
Dorsal Body Cavity: Cranial cavity, enclosed by the skull and contains the brain. Spinal canal, enclosed by the spine and contains the spinal cord.
Ventral Body Cavity: Thoracic cavity, enclosed by the rib-cage and contains the lungs and heart.
Abdominal cavity/Pelvic cavity, contains the digestive organs, spleen kidneys, bladder, and reproductive organs.
Explanation:
Blood is a specialized body fluid. It has four main components:
- plasma,
- red blood cells,
- white blood cells,
- and platelets.
Blood has many different functions, including: transporting oxygen and nutrients to the lungs and tissues.
It has to be B, because we do not have all the same organs as worms, we have more organs and our brains cannot hold the same amount of information, because flatworms have different nervous systems all together.
So the answer is B.
The correct answers are:
- background extinction;
The background extinction is an extinction that occurs naturally, and small number of species are affected by it in certain periods. It occurs as a natural way of the evolution of the species.
- mass extinction;
The mass extinction occurs after a massive natural catastrophe that influences the whole planet, or big portion of it. In this type of extinction, the ecosystem changes dramatically because the majority of the species die out in a very short space of time.