Seeds and germination

Identify the key internal and external parts of a seed (embryo, food store, seed coat) and describe their functions.
Name and describe the four main methods of seed dispersal, providing examples for each method.
Define germination and state the essential conditions required for a seed to germinate.
Describe the key steps as the root and shoot emerge during germination.

Seeds contain everything needed to start a new plant. Key parts include:
- Embryo: This is the tiny, undeveloped baby plant, complete with a miniature root (radicle) and shoot (plumule).
- Food Store: Contains stored energy (like starch) that the embryo uses to grow before it can make its own food.
- Seed Coat: A tough outer layer that protects the embryo and food store.

There are four main ways seeds get dispersed:

1. Wind Dispersal

How it works: Seeds are light and often have special structures like wings or parachutes (think dandelions or sycamore seeds) to help them float away on the wind.
Example: Dandelion 'clocks'.

2. Animal Dispersal

How it works (Inside): Animals eat tasty fruits (like berries). The seeds inside have tough coats, pass through the animal unharmed, and are deposited in droppings far away.
How it works (Outside): Some seeds or fruits have hooks or barbs (like burdock) that catch onto an animal's fur and get carried away before dropping off.
Example: Berries (eaten), burrs (stuck on fur).

3. Water Dispersal

How it works: Plants near water (like willows or coconuts) produce seeds that can float. Rivers, seas, or floods carry them to new places.
Example: Coconuts floating in the sea.

4. Explosive Dispersal

How it works: Some plants (like peas or gorse) have seed pods that dry out and burst open suddenly, flicking the seeds away from the parent plant.
Example: Pea pods popping open.

A seed can stay dormant (asleep) for a long time. To start growing, a process called germination, it needs three key things:
1. Water: Allows the seed to swell up and activates the embryo.
2. Oxygen: Needed for the embryo to respire (release energy) to fuel its growth.
3. Warmth: Speeds up the chemical reactions needed for growth (different plants need different temperatures).
Notice that light is NOT needed for germination itself – the seed uses its food store underground. Light is only needed once the shoot emerges and starts making its own food through photosynthesis.
Germination follows these steps:
1. The seed takes in water and swells.
2. The root (radicle) starts to grow downwards, anchoring the seed and absorbing more water.
3. The shoot (plumule) starts to grow upwards, towards the light.
4. The first leaves appear. Now the young plant can start making its own food using photosynthesis. The food store inside the seed has done its job.

Seed: A structure containing a plant embryo and a food store, protected by a seed coat, from which a new plant can grow.
Embryo: The tiny, undeveloped plant inside a seed.
Food Store: Stored energy (often starch) within a seed that provides nutrients for the embryo during germination.
Seed dispersal: The process by which seeds are spread away from the parent plant.
Germination: The process by which a seed starts to grow into a new plant.
Dormant: A state where a seed is alive but inactive, waiting for the right conditions to germinate.

Design and carry out a simple experiment to investigate the specific conditions (e.g., varying amounts of water, temperature, presence or absence of light) needed for seeds to germinate.
Research the importance of seeds for human food supply and global agriculture, or investigate the role of seed banks in conserving plant biodiversity.