Answer:
The Skeleton
Explanation:
because the softer tissues and skin usually do not last long enough to become fossilized
The regulatory centers for the respiratory and circulatory systems are found in the cerebrum
Answer:
Because natural selection selects for it. Thus it persists.
Explanation:
You have to understand heterozygote advantage. Basically, it's where heterozygotes have an advantage over homozygotes. In the case of sickle cell disease, heterozygotes have an advantage, and natural selection favors whatever is advantageous. Thus, because heterozygotes each have one recessive sickle-cell allele, as natural selection favors the heterozygotes, the recessive sickle-cell allele persists and remains in the gene pool.
Answer:
i can only define the terms for you.
Explanation:
chromosome - a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
chromatid - each of the two threadlike strands into which a chromosome divides longitudinally during cell division, each containing a double helix of DNA.
gene - a distinct sequence of nucleotides that forms a part of a chromosome, the order of which determines the order of monomers in a polypeptide or nucleic acid molecule which a cell or virus that may synthesize
