Reproduction and inheritance for N(A)-Level Science (Biology): sexual reproduction in humans, sexual reproduction in flowering plants, and the basics of inheritance and genetic crosses

What this module covers

Reproduction and inheritance is about how living things make offspring and pass on their features. You need to describe sexual reproduction in humans from fertilisation to the development of the baby, describe reproduction in flowering plants from pollination to seed formation, and explain the basics of inheritance using genes and alleles, including how to work out a simple genetic cross.

This overview links every dot point in the module. Work through them in order, then check yourself with the questions at the end. See the full set at /sg-n-level/biology/syllabus.

Sexual reproduction in humans

Start with reproduction in animals. The page on sexual reproduction in humans describes the male and female sex cells, what fertilisation is, and how the fertilised egg develops into a baby in the uterus, supplied through the placenta.

Sexual reproduction in flowering plants

Next, reproduction in plants. The page on sexual reproduction in flowering plants describes the parts of a flower, explains the difference between pollination and fertilisation, and outlines how a fertilised egg becomes a seed.

Inheritance and genetic crosses

Finally, how features pass to offspring. The page on inheritance and genetic crosses explains what genes and alleles are, the difference between dominant and recessive alleles, and how to work out a simple monohybrid cross using a Punnett square.

How this module is examined

At N(A) level there is no standalone pure Biology paper. Biology is taken as part of a combined Science subject, either Science (Physics, Biology) syllabus 5106 or Science (Chemistry, Biology) syllabus 5107, so this module is examined within whichever combination your school offers.

• Separate the two flower processes. State pollination as the transfer of pollen and fertilisation as the joining of nuclei.
• Name the support structures. Human reproduction answers reward naming the placenta, umbilical cord and amniotic fluid and their roles.
• Lay out the cross. Genetics answers reward clear allele symbols, a tidy Punnett square and the correct ratio.

Check your knowledge

A mix of recall, comparison and calculation questions. Attempt them, then check against the solutions.

1. Define fertilisation. (1 mark)
2. State the difference between pollination and fertilisation. (2 marks)
3. Explain the difference between a dominant and a recessive allele. (2 marks)
4. Two parents are each Bb (B is brown eyes, dominant; b is blue eyes, recessive). State the ratio of brown-eyed to blue-eyed offspring expected. (2 marks)