Polygenic inheritance. The characteristics of a person aren't controlled completely by a single gene, but rather several genes that generally only make a small contribution to how the child turns out in the outcome. At one point there was a study that showed over 400 genes were linked to height, so imagine any other characteristics of a person. Environmental effects also serve a large purpose in how a child is to turn out. These children may all be growing up in the same environment, however that's not to say they all grow up the same. They could all be treated the same way and react differently to it, this counts both for physical and mental traits. All human's features such as eye colors, hair color and height are determined by several different genes. As an example, there are around 2 major eye color genes, however there are also around 14 different genes that actually contribute in determining a person's exact eye color. Some are bound to look the same, as they have the same parents, however, just because they have the same parents doesn't mean they all will look exactly alike.
<span>The immune system is the body's natural defense mechanism against organisms that can cause infection.There are three types of mechanisms:
1. Cellular :</span><span> refers to the recognition and/or killing of virus and virus-infected cells by leukocytes and the production of different soluble factors (cytokines) by these cells when stimulated by virus or virus-infected cells
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2. Structural: </span>barriers and the immune system defend the body<span> against organisms that can cause infection. </span>Natural<span> barriers include the skin, mucous membranes, tears, earwax, mucus, and stomach acid.
3. Chemical: </span><span>Some of these include the low pH of the stomach, which inhibits the growth of pathogens; blood proteins that bind and disrupt bacterial cell membranes; and the process of urination, which flushes pathogens from the urinary tract.
</span><span>antibodies - chemical
tissues lining hollow organs - cellular
phagocytes - cellular
skin - structural
antigen - chemical
leukocytes - cellular</span>
Answer:
There are three main types of blood vessels:
1)Artery ---
i) It is a blood vessel having a thick wall.
ii) It carries blood from the heart to different parts of the body.
iii) On regulatory demand of the body it can dilate or constrict.
iv) It doesn't contain any valve.
v) All arteries carry oxygenated blood except the pulmonary artery.
2)Vein ---
i) It is a blood vessel having a thin wall.
ii) It brings blood from different parts to the heart.
iii) It can't dilate or constrict under normal conditions.
iv) It contains valves that allow the blood to flow in one direction towards the heart.
v) All veins carry deoxygenated blood except the pulmonary vein.
3)Capillary ---
i) It is a very narrow blood vessel that has very thin walls.
ii) It forms a network throughout the body in all living cells connecting arteries to veins.
iii) It can dilate or constrict according to the requirement of tissue.
iv) It doesn't have any valve.
v) It contains mixed blood as it connects arteries and veins
Answer:
Nutrients makes the most sense.
