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.
Females have two copies of the X chromosome, while males have one X and one Y chromosome. The 22 autosomes are numbered by size. The other two chromosomes, X and Y, are the sex chromosomes. This picture of the human chromosomes lined up in pairs is called a karyotype.In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46.Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, differ between males and females.he other two chromosomes, X and Y, are the sex chromosomes. This picture of the human chromosomes lined up in pairs is called a karyotype. In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46.