<span>The main reasons why cell division is important in organisms are reproduction, repair and growth. Cell division is necessary in order for life to continue.
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The length of the cell cycle is important because it determines how quickly an organism can multiply. For single-celled organisms, this rate determines how quickly the organism can reproduce new, independent organisms. </span><span>Most of the differences in cell cycle duration between species and cells are found in the duration of specific cell cycle phases. DNA replication, for example, generally proceeds faster the simpler the organisms. One reason for this trend is simply that prokaryotic have smaller genomes and not as much DNA to be replicated.</span>
The major histocompatibility complex (MHC<span>) is a set of cell surface proteins essential for the acquired immune system to recognize foreign molecules in vertebrates, which in turn determines histocompatibility. ... The human </span>MHC<span> is also called the </span>HLA<span> (human leukocyte antigen) complex (often just the </span>HLA<span>).</span>
O type blood contains both A and B antibodies.
Answer:
A: Oxygen levels are low and, therefore, more red blood cells are produced, giving the athletes an advantage when competing at lower altitudes.
Explanation:
<em>At high altitudes, the partial pressure of oxygen is lower compared to lower altitudes</em>. The body system try to adjust to lower oxygen level by undergoing several physiological changes. Depending on the duration spent in high altitude, the body can either try to adjust in the short term or acclimatize for a longer term.
One of the processes the body undergoes during acclimatization is an increase in red blood cell production. The kidney secretes erythropotein in response to inadequate oxygen in body tissues, and this makes the liver to increase erythrocyte production.
The increase in red blood cell production correspondingly increases the oxygen-carrying capacity of the blood as a result of increased hemoglobin. This condition persists for a few weeks even after the body returns to lower altitude where oxygen is adequate. Increased oxygen capacity means the rate of energy production (through respiration) within the body will also increase
<em>Hence, those who acclimatize to high altitude usually experience increased capillary density, tissue perfusion and improved athletic performance at lower altitudes. </em>
The correct option is A.
A) Cellular respiration. Source: I'm a Biology teacher. ;)
