Biology Topic Practice
How Biological Sex is Determined
In humans, one pair of chromosomes (out of 23 pairs) determines biological sex.
What combination of sex chromosomes do biological females have?
What is How Biological Sex is Determined?
"Sex determination is a biological system that determines the development of sexual characteristics in an organism."
Question 1
What is an allele?
Question 2
What is meant by a dominant allele?
Question 3
Which genotype is heterozygous?
X and Y Chromosomes
Females have two X chromosomes (XX).
Males have one X and one Y chromosome (XY).
Sperm can carry either an X or a Y, while all eggs carry an X.
Exam Tip
This means that the biological father effectively "decides" the sex of the offspring.
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