IB Biology SL D3.2.11 Sex Determination Questions
Apply XX/XY inheritance and the Y-chromosome SRY/TDF signal to explain embryonic sex determination in IB Biology SL D3.2.11.
- Syllabus
- First assessment 2025
- Course
- Biology SL
- Level
- SL
Exam points
- Calculate the probability of a female offspring from a sex-determination question, including when previous births are stated.
- Explain how a gene on the Y chromosome triggers testis development and how embryonic testes lead to male development.
IB Biology SL D3.2.11 Sex Determination Questions question 1
[Maximum number: 3]
In eukaryotes, the chromosomes are located in the nucleus, and the nucleus can divide by mitosis or meiosis.
Explain how the presence of a Y chromosome in the cells of a human embryo causes it to develop as a male.
a. gene/genetic information on Y chromosome causes embryo to develop testes;
b. (developing) testes in embryo secrete testosterone;
c. testosterone causes male genitalia/penis to develop;
Marking guidance:
Accept SRY gene in mp-a
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