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Basic 4 · Science · Cycle of Organism

Seeds and How They Germinate

In this topic you will examine common seeds, their parts and how they germinate.

By the end of these notes you should be able to:

  • Identify the parts of a seed
  • Compare bean and maize seeds
  • Describe the conditions and stages of germination

What you already know

  • Watching seeds germinate (Basic 3)

Copy everything that has a blue line on its left into your notebook. The other parts are for reading.

Strand
Cycles
Sub-strand
Cycle of Organism
Indicator
B4.2.2.1.2 – Examine some common seeds and how they germinate

Introduction

Soak a bean seed overnight. Gently remove the coat and split it open. Inside you will find a tiny baby plant waiting to grow.

1. Parts of a Seed

Seed parts
PartFunction
seed coat (testa)protects the inside of the seed
cotyledon(s)store food for the young plant
embryothe baby plant: radicle (first root) and plumule (first shoot)
An opened bean seed showing the seed coat, cotyledons, radicle and plumule
Figure 1: Inside a bean seed Draw an opened bean seed and label four parts.Illustration: Sirbus

2. Bean and Maize Seeds

Comparing seeds
FeatureBeanMaize
cotyledonstwo (dicot)one (monocot)
food storein the cotyledonsin the endosperm
germinationseed leaves come above the soilseed stays below the soil

3. Conditions and Stages

Seeds need water, air and warmth to germinate.

Stages

  1. The seed absorbs water and swells.
  2. The seed coat bursts.
  3. The radicle grows down into the soil.
  4. The plumule grows up towards light.
  5. The first leaves open and start photosynthesis.

New words

seed coat
The outer covering of a seed.
cotyledon
A seed leaf that stores food.
embryo
The baby plant inside a seed.
radicle
The first root.
plumule
The first shoot.
monocot
A plant whose seed has one cotyledon.

Summary

  • A seed has a seed coat, cotyledons and an embryo.
  • Beans have two cotyledons; maize has one.
  • Seeds need water, air and warmth to germinate.
  • The radicle grows first, then the plumule.

Class activity: Seed Investigation

  1. Soak bean and maize seeds overnight.
  2. Open a bean seed and find its parts.
  3. Set up seeds on cotton wool in jars and record germination daily.

You need: Bean, Maize seeds, Cotton wool in clear jars, Cup of water

Exercises

Answer in your exercise book first, then check your answers.

  1. 1. Which part of the embryo becomes the root?

    • A. Radicle
    • B. Plumule
    • C. Seed coat
    • D. Cotyledon
    Show answer
    Answer: RadicleIt grows down.

  2. 2. How many cotyledons does a bean seed have?

    • A. Two
    • B. One
    • C. Three
    • D. None
    Show answer
    Answer: TwoBeans are dicots.

  3. 3. Which part stores food in a bean seed?

    • A. Cotyledons
    • B. Seed coat
    • C. Radicle
    • D. Leaves
    Show answer
    Answer: CotyledonsThey feed the young plant.

  4. 4. Seeds need water to germinate.

    • A. True
    • B. False
    Show answer
    Answer: TrueWater wakes the seed.

  5. 5. Maize seed leaves come above the soil like beans.

    • A. True
    • B. False
    Show answer
    Answer: FalseMaize stays below the soil.

  6. 6. The first shoot of a seed is the ______.

    Show answer
    Answer: plumuleIt grows up.

  7. 7. State the three conditions needed for germination.

    Show answer
    Answer: Water, air and warmth.These start growth.

  8. 8. Why does a germinating bean not need soil nutrients at first?

    Show answer
    Answer: It uses food stored in its cotyledons.Cotyledons feed the seedling.

Homework

  1. Plant a bean and a maize seed at home. Record what you see each day for a week.