Hello!
Barack Obama has had many professions and he's quite educated!
Education:
Harvard Law School, Columbia University, Harvard University, Occidental College, Columbia College.
Professions/Jobs:
Lawyer, Politician, Law Professor, Author.
Answer:
Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a biological membrane that forms the boundary between an organism and its extracellular environment.
Gases are constantly consumed and produced by cellular and metabolic reactions in most living things, so an efficient system for gas exchange between, ultimately, the interior of the cell(s) and the external environment is required. Small, particularly unicellular organisms, such as bacteria and protozoa, have a high surface-area to volume ratio. In these creatures the gas exchange membrane is typically the cell membrane. Some small multicellular organisms, such as flatworms, are also able to perform sufficient gas exchange across the skin or cuticle that surrounds their bodies. However, in most larger organisms, which have a small surface-area to volume ratios, specialised structures with convoluted surfaces such as gills, pulmonary alveoli and spongy mesophyll provide the large area needed for effective gas exchange. These convoluted surfaces may sometimes be internalised into the body of the organism. This is the case with the alveoli, which form the inner surface of the mammalian lung, the spongy mesophyll, which is found inside the leaves of some kinds of plant, or the gills of those molluscs that have them, which are found in the mantle cavity.
Explanation:
I hope this helps u ^_^
Answer:
The correct answer from the provided option is D.
Explanation:
The evidence that supports the vitamin D hypothesis for the evolution of lighter skin tones is indigenous peoples living at high latitudes have darker skin, but they eat foods rich in vitamin D.
This shows that consuming food rich in Vitamin D is not the only factor that determine the skin color as indigenous people live in high latitude areas and consume food rich in vitamin D and still have darker skin.
Answer:
B. a nonspecific defense against infection
Explanation:
Answer:
B. Kidney
Explanation:
The kidneys play a central role in the regulation of arterial blood pressure. A large body of experimental and physiological evidence indicates that renal control of extracellular volume and renal perfusion pressure are closely involved in maintaining the arterial circulation and blood pressure
