D3.1.3—Male vs. female sexes
Male and female sexes are distinguished by the gametes they produce, with males producing sperm and females producing eggs for fertilization.
- Syllabus
- First assessment 2025
- Objective
- D3.1.3
- Level
- HL
Sexes Are Defined by the Gametes Produced
In anisogamous species, the male produces smaller motile gametes and the female produces larger nutrient-rich gametes.
The distinction is based on gamete type, not on every secondary trait or an individual’s identity. Different species organise reproductive roles around these gametes in different ways.
Identify the gametes first, then infer the biological sex category used in the syllabus model.
In humans, sperm are small and motile while ova are large and non-motile, so the model labels their producers male and female.
Gamete definitions do not justify assumptions about behaviour, gender, or all reproductive biology.
Retrieve the Core Reproduction Route
Core D3.1 route: reproduction creates offspring, gametes or pollen move, fertilization or germination follows, and the consequence is variation, embryo formation, seed production, or successful early growth.
- mitosis makes clones; meiosis and fertilization create variation
- hormones, anatomy, fertilization, and IVF support gamete fusion and embryo development
- pollination and pollen-tube growth bring gametes together inside ovules
- dispersal reduces competition and germination starts with water, enzymes, and reserves
Core Reproduction
Core D3.1 exam questions usually combine reproduction strategy with gamete formation, fertilization, human cycles, IVF, plant pollination, or seed germination. Treat each answer as a route: name the process, say what moves or changes, then give the biological consequence.
- Compare asexual and sexual reproduction by mechanism and genetic outcome.
- Link meiosis, fertilization, reproductive anatomy, and hormonal cycles to successful reproduction.
- Explain plant pollination and seed stages by connecting structures to transfer, fertilization, dispersal, and germination.
Concept essentials
- Males are defined by production of sperm gametes.
- Females are defined by production of egg gametes.
- Secondary sexual characteristics support reproduction but are not the primary definition of sex.