In artificial reproduction
techniques, male gametes can be sorted to separate the sperm bearing the X
chromosome from those bearing the Y chromosome. What makes this possible? (A) X sperm cells are round, and Y
sperm cells have a tail. (B) Males produce Y sperm cells,
and females produce X sperm cells. (C) X and Y sperm cells are not
produced at the same time in the testes. (D) Features such as DNA quantities
are different between X and Y sperm cells.
In humans, we have 46 chromosomes
in most cells. Our gametes, like sperm and egg
cells, contain half this amount, or 23 chromosomes. Chromosomes one to 22 are called
autosomes, while the 23rd chromosome is a sex chromosome.
The sex chromosome determines our
biological sex and can be either X or Y. Inheriting an X and Y chromosome
makes a biological male, while two copies of an X chromosome makes a biological
female. Therefore, since males produce
sperm, the sperm cell will have either an X or Y chromosome, while the egg cell will
only have an X chromosome. So the sperm cell is the gamete
that determines the biological sex of the offspring.
Sperm with an X chromosome have
more DNA than sperm with a Y chromosome because the X chromosome is three times
larger than the Y chromosome. So X sperm cells can be sorted and
separated from Y sperm cells based on different features like DNA quantities. Therefore, the correct answer is
(D). Features such as DNA quantities are
different between X and Y sperm cells.