<span>All mammals have at least one X chromosome. Female mammals have two X chromosomes, so each of her eggs has a single X chromosome. Male mammals have XY chromosomes, meaning they can generate sperm containing the X chromosome, or sperm containing the Y. If the egg receives sperm containing the X chromosome, then the resulting individual forms ovaries, and is female.</span>
Answer:
Explanation:As previously stated, DNA is a macromolecule that's made up of individual subunits called nucleotides. Each nucleotide has three parts:
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A deoxyribose sugar.
A phosphate group.
A nitrogenous base.
DNA nucleotides can contain one of four nitrogenous bases. These bases are adenine (A), thymine (T), guanine (G) and cytosine (C).
These nucleotides come together to form long chains known as DNA strands. Two complementary DNA strands bond to each other in what looks like a ladder before winding into the double helix form.
The two strands are held together through hydrogen bonds that form between the nitrogenous bases. Adenine (A) forms bonds with thymine (T) while cytosine (C) forms bonds with guanine (G); A only ever pairs with T, and C only ever pairs with G.
Complementary Definition (Biology)
In biology, specifically in terms of genetics and DNA, complementary means that the polynucleotide strand paired with the second polynucleotide strand has a nitrogenous base sequence that is the reverse complement, or the pair, of the other strand.
Fossils are the preserved remains, or traces of remains, of ancient animals and plants
