Answer:
<h2>A</h2>
Explanation:
1. Sickle cell anemia is an inherited condition, disorder (disease).
2. It is a recessive condition, in which red blood cell become mutated and converted to a sickle like shape, and there aren't enough healthy red blood cells to carry oxygen throughout the body.
3. This condition normally occur when, there is inheritance of two abnormal or mutated copies of the β-globin gene, one allele from each parent.
4. β-globin gene makes haemoglobin.
5. Sickle cell anemia results when glutamic acid being substituted by valine at position 6 ( in short E6V substitution).
6. So, it a single base-pair substitution in the gene encoding the beta subunit.
The defense system of the human body is made up of entire organs and vessel systems like the lymph vessels, but also of individual cells and proteins. The inner and outer surfaces of the body are the first barriers against pathogens (germs). These surfaces include the skin and all mucous membranes, which form a kind of mechanical protective wall.
Several things support this protective wall:
<span><span>- The body’s own antibacterial substances can disable different pathogens from the environment at an early stage. A certain enzyme found in saliva, the airways and tear fluid destroys the cell walls of bacteria.
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- Many pathogens that are breathed in get stuck to mucus in the bronchi and are then moved out of the airways by hair-like structures called cilia.
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- Most pathogens that enter the body together with food are usually stopped by stomach acid.
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- Normal flora, harmless bacteria that reside on the skin and many mucous membranes in the body, also help to protect the body.</span></span>
The cough and sneeze reflex can also help to remove pathogens.
Hope this helps (:
<span>This is called, tertiary consumers</span>
Helium, with two protons, will have two electrons. In the chemical classroom, the proton count will always be equivalent to an atom's atomic number. This value will not change unless the nucleus decays or is bombarded (nuclear physics). Figure \(\PageIndex{1}\): The periodic table of the elements.
