Practice Questions
1.How many pairs of chromosomes are found in a human body cell?
23
2.Explain why the father determines the sex of a baby.
The father determines the sex of a baby because his sperm can carry either an X chromosome or a Y chromosome, whereas the mother’s egg always carries an X chromosome.
If a sperm carrying an X chromosome fertilises the egg → XX (female)
If a sperm carrying a Y chromosome fertilises the egg → XY (male)
Therefore, the sex of the baby depends on whether the father’s sperm provides an X or a Y chromosome.
3.Why is the probability of having a male or female child approximately equal?
Factors affecting the rate of photosynthesis
Measuring & calculating rates of photosynthesis
Inverse square law and photosynthesis
Economics of enhancing the conditions in greenhouses
Investigating the effect of light intensity on the rate of photosynthesis
Data analysis and nervous system
The effect of a factor on human reaction time
Controlling blood glucose concentration
Regulating water and nitrogen levels in the body.
Hormones and human reproduction
Using hormones to treat infertility
Control and coordination in plants using hormones
Investigating the effect of light or gravity on the growth of newly germinated seedlings