Life Cycle of a Silkworm

The question

How to approach this process diagram question

A process diagram shows how something is made or how a cycle works. Describe the stages in order, using sequence language and the passive voice.

1. Say what process the diagram shows and how many stages it has.
2. Overview: the number of stages, where it starts and ends, and whether it is a cycle or a straight line.
3. Describe every stage in order (First, Next, After that, Finally) mostly in the passive: the grain is crushed.
4. Do not add opinions or explain why; describe what happens.

How to plan this answer

Structure

1. Overview: the diagram shows five stages in a circle, starting with eggs and returning to eggs when the moth lays them.
2. Body 1: stage 1 (eggs), stage 2 (larva feeding on a leaf) and stage 3 (cocoon).
3. Body 2: stage 4 (pupa) and stage 5 (moth), and the arrow back to the eggs.

Key features to spot

• The eggs are small, pale and shown in a cluster of about nine.
• The larva is white and segmented, and it is shown feeding on a green leaf.
• The cocoon is a pale, oval, silky casing that surrounds the next stage.
• The pupa is brown and sits inside a shell, after the cocoon stage.
• The moth is white with broad wings, and the arrow from the moth returns to the eggs.

Useful vocabulary

• are laid: The eggs are laid in a cluster.
• hatch into: The eggs hatch into larvae.
• feed on: The larvae feed on leaves.
• spin a cocoon: The larva spins a cocoon around itself.
• is followed by: The cocoon stage is followed by the pupa stage.
• emerges as: The pupa emerges as a moth.
• the cycle is completed: The cycle is completed when the moth lays eggs.
• in a circle: The life cycle is shown in a circle.
• the next stage: The next stage is the cocoon.
• the final stage: The final stage is the moth, which lays the next eggs.

Common mistakes

• Placing the pupa before the cocoon. The cocoon is stage three and the pupa stage four.
• Saying the larva lays eggs. The moth is the stage that lays eggs.
• Describing the moth as the end of the cycle. The arrow leads back to the eggs.
• Confusing the larva with the moth. The larva is a caterpillar-like stage on a leaf.
• Using the wrong sequence words. Start with first for the eggs and then use after that for the larva.

Examiner tip: Name the five stages in the overview and state that the cycle returns to the eggs, since the circular structure is the key feature the examiner will look for.