The best and most correct answer among the choices provided by your question is the third choice or letter C.
Plant cells are usually box-shaped, while animal cells tend to be irregularly shaped because u<span>nlike plant cells, animal cells lack a cell wall. </span>
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The Cretaceous Period was the last and longest period of the Mesozoic Era. It lasted 79 million years.
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.