SAMPLE APA PAPER FOR STUDENTS 2. Abstract. You may not have to include an abstract with your paper; if in doubt, ask your instructor. The. abstract is a single paragraph in block format (without paragraph indentation) and should be. between 150 and 250 words. Be sure to understand the difference between the abstract (a.
In the XY sex-determination system, the female-provided ovum contributes an X chromosome and the male-provided sperm contributes either an X chromosome or a Y chromosome, resulting in female (XX) or male (XY) offspring, respectively. Hormone levels in the male parent affect the sex ratio of sperm in humans.
A femaleâs two X chromosomes also have the same genes arranged in the same order. So females have two copies of every gene, including the genes on sex chromosomes. The X and Y chromosomes, however, have different genes. So for the genes on the sex chromosomes, males have just one copy. The Y chromosome has few genes, but the X chromosome has more than 1,000. Well-known examples in people include genes that control color blindness and male pattern baldness.