Hormone Harvest

Hormone Harvest 🚜 [Higher tier]

The same hormones that bend a shoot to the light are big business. Farmers and growers use them to kill weeds, clone plants, and put ripe fruit on the shelf all year round. This module is the commercial toolkit: **auxins**, **gibberellins** and **ethene** at work. (All of it is **Higher tier**.)

Auxins at work 🌿

**Auxins** have two classic commercial uses: • As **weedkillers** — synthetic auxins act as **selective** weedkillers: they disrupt the growth of **broad-leaved weeds** (making them grow uncontrollably and die) while leaving narrow-leaved crops like grasses and cereals unharmed. • In **rooting powder** — dipping a stem cutting in auxin makes it grow **roots** quickly, so growers can produce many new plants cheaply.

What auxins are used for

Pick the TWO commercial uses of **auxins**.

• As a selective weedkiller
• In rooting powder for cuttings
• To ripen fruit in storage
• To end seed dormancy

Gibberellins 🌸

**Gibberellins** are hormones used to control plant development in three main ways: • **Ending seed dormancy** — making seeds germinate when the grower wants, not just in their natural season. • **Inducing flowering** — bringing plants into flower, or making them flower earlier. • **Increasing fruit size**.

Out of season

A grower wants a batch of seeds to germinate months before they naturally would. Which hormone ends the seeds' dormancy?

• Gibberellins
• Ethene
• Auxins
• Insulin

Ethene: ripening on demand 🍅

**Ethene** is a **gas** released by ripening fruit. It controls **cell division** and the **ripening of fruit**. Growers use this to their advantage: fruit is picked while **unripe and hard** (so it survives transport without bruising), then exposed to **ethene** to **ripen** it just before it reaches the shops.

Match the job to the hormone

In the exam 🎓

Harvest gathered. The Higher-tier hormone-use question almost always wants the **specific hormone matched to the specific use** — learn them as three clean pairs: • **Auxins** → **weedkillers** and **rooting powders**. • **Gibberellins** → **ending seed dormancy** (plus flowering and fruit size). • **Ethene** → controlling **fruit ripening** in storage and transport.