Reproduction Routes

Reproduction Routes 🧬

Living things make more of themselves by one of two routes — **sexual** or **asexual** — and the choice shapes whether offspring are all identical or all different. Learn how each works, the cell division behind them, and why nature keeps both around.

Sexual reproduction 💕

**Sexual reproduction** involves **two parents**. Special sex cells — **gametes** (sperm and egg in animals) — are made by **meiosis** and **fuse** at **fertilisation**. Because the offspring gets a **mixture** of genes from both parents, sexual reproduction produces **genetic variation** — no two offspring are quite the same.

Asexual reproduction 🌱

**Asexual reproduction** needs just **one parent**. There are no gametes and no fusion — cells are made by **mitosis**. The offspring are **genetically identical** to the parent — they are **clones** — so there is **no genetic variation**.

Match the term

Spot asexual reproduction

Pick the THREE features of **asexual** reproduction.

• Only one parent is needed
• Offspring are genetically identical clones
• Cells are produced by mitosis
• Gametes fuse at fertilisation
• It produces genetic variation

Where variation comes from

Why does **sexual** reproduction produce variation in the offspring?

• The offspring gets a mixture of genes from two different parents
• Because the cells divide by mitosis
• Because it only uses one parent
• Because it happens faster

Meiosis makes gametes 🔬

Gametes are made by **meiosis** in the reproductive organs. Starting from one normal (**diploid**) cell: • The chromosomes are copied, then the cell divides **twice**. • The result is **four** gametes, each with only a **single set** of chromosomes (**haploid**), and each **genetically different**.

Division outcomes

The output of meiosis

One diploid cell undergoes meiosis. What does it produce?

• Four genetically different haploid gametes
• Two genetically identical diploid cells
• Two haploid gametes
• One large diploid cell

Order the life cycle

An interactive activity.

When each one wins ⚖️

Each route has trade-offs: • **Sexual** — produces **variation**, so if the environment changes, some offspring may survive (a natural-selection advantage). But it needs two parents and is slower. • **Asexual** — **fast**, needs only **one parent** and little energy, producing many identical offspring in stable conditions. But **no variation** means a single disease or change could wipe out the whole population. Some organisms do **both** — the malarial parasite, many fungi, and plants (e.g. seeds *and* runners).

Why sexual reproduction?

Pick the TWO advantages of **sexual** reproduction.

• It produces genetic variation in the offspring
• Variation helps the species survive if the environment changes
• It needs only one parent
• It is faster and uses less energy

The cloned crop

A farmer grows a huge field of genetically identical (cloned) crop plants. A new plant disease arrives. What is the danger?

• With no variation, if one plant is vulnerable they all are — the whole crop could be lost
• The plants will switch to reproducing sexually
• The plants will grow taller to escape
• Nothing — clones are always disease-resistant

In the exam 🎓

Routes mapped. Grade-9 habits for reproduction: • **Sexual** = two parents, gametes fuse, **variation**; **asexual** = one parent, mitosis, **clones**, no variation. • **Meiosis** makes **four genetically different haploid gametes**; **mitosis** makes **two identical diploid cells**. • Link the choice to the **environment**: variation (sexual) helps in **changing** conditions; speed (asexual) suits **stable** ones.