CDS Biology · Free notes
Reproduction: CDS Biology
Reproduction has 5 past-year questions in CDS General Knowledge, from 2016 (II) to 2023 (II): 1 EASY, 3 MODERATE and 1 HARD. Four of them are about flowering plants and one about the first milk of a human mother. The plant questions test order and cells: what comes first, pollination or fertilisation, and which cells of the ovule carry half the chromosomes. The hardest asks for every way a seed can form without fertilisation, so learn all three kinds.
The handout has every subtopic, worked example, formula and trap with answers shown. The formula sheet is the chapter’s formulas and traps alone, on one page.
Subtopic notes
Formula & revision sheet
0 formulas · 3 reference tables · 4 gotchas across all subtopics — the exam-eve cheat-sheet
Formula & revision sheet
0 formulas · 3 reference tables · 4 gotchas across all subtopics — the exam-eve cheat-sheet
Reference tables (3)
Sexual reproduction in a flowering plant6 rows
| Step or cell | What it is |
|---|---|
| Pollination | Pollen reaches the stigma |
| Fertilisation | Male gamete fuses with the egg; a zygote forms |
| Division of the zygote | Builds the embryo inside the seed |
| Seedling | The young plant when the seed germinates |
| Egg, synergids, antipodals | Haploid cells of the embryo sacQ CDS 2023 (II): the nucellus is the cell in the ovule that is not haploid. |
| Nucellus | Diploid tissue of the parent around the embryo sac |
Seeds without fertilisation (apomixis)3 rows
| Kind of apomixis | Embryo grows from |
|---|---|
| Parthenogenesis | An unfertilised eggQ CDS 2016 (II): parthenogenesis, apogamy and sporophytic budding all give an embryo without fertilisation. |
| Apogamy | A cell of the embryo sac other than the egg |
| Adventive embryony (sporophytic budding) | A cell of the nucellus or integument |
Colostrum and the newborn4 rows
| Term | Meaning |
|---|---|
| Colostrum | The first milk; rich in antibodiesQ CDS 2018 (II): the milk essential for the newborn's immune response is colostrum. |
| Placenta | Links the foetus to the mother |
| Oviduct | Where fertilisation takes place |
| Passive immunity | Ready-made antibodies from another body; short-lived |
Watch out for (4)
- Pollination comes before fertilisation→ Sexual reproduction in a flowering plant
- Nucellus is the odd one out→ Sexual reproduction in a flowering plant
- All three count→ Seeds without fertilisation (apomixis)
- Colostrum is the first milk, not later milk→ Colostrum and the newborn
PYQ weightage by concept
3 concepts · 5 PYQs — where the marks actually sit, so you know what to drill first
PYQ weightage by concept
3 concepts · 5 PYQs — where the marks actually sit, so you know what to drill first
| Concept | PYQs | Share |
|---|---|---|
| Sexual reproduction in a flowering plant | 3 | 60% |
| Seeds without fertilisation (apomixis) | 1 | 20% |
| Colostrum and the newborn | 1 | 20% |
Test yourself on a real paper
Sit a past CDS paper, timed and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.