Practical: Conditions for Germination (Edexcel IGCSE Biology)

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Practical: Conditions for Germination

  • Germination marks the beginning of seed growth

  • Three key factors are needed for successful germination:

    • Water: swells the seed, breaks the seed coat, and activates enzymes for growth

    • Oxygen: necessary for respiration to provide energy

    • Warmth: boosts enzyme activity and improves germination until a certain temperature

  • Carbon dioxide has no effect on germination

Apparatus

  • Test tubes

  • Test tube holder

  • Cress seeds

  • Cotton wool

  • Fridge

Method

  • Prepare 4 test tubes with 10 cress seeds on cotton wool, labeled A, B, C, and D

    • Tube A: Keep the cotton wool dry

    • Tube B: Moisten the cotton wool with water

    • Tube C: Cover the seeds and cotton wool with water and add a layer of oil on top

    • Tube D: Moisten the cotton wool and place the tube in a fridge (~4°C)

  • Keep tubes A, B, and C at room temperature or around 20°C

  • After 3-5 days, ensure the cotton wool in tubes B and D stays moist

  • Compare the number of germinated seeds in each tube

Conditions required for germination, IGCSE & GCSE Biology revision notes

Conditions required for germination: how to set up the experiment

Results and Analysis

  • The test tubes are set up to test the necessity of water, oxygen, and warmth for germination by removing each factor in turn:

    • Tube A: Water is absent

    • Tube B: Control, all factors present

    • Tube C: Oxygen is blocked by oil and water layers

    • Tube D: Warmth is removed by refrigeration

  • As germination requires all three factors, only the seeds in the control tube (B) are expected to germinate

Conditions required for germination: Example results table

Conditions for germination results table, IGCSE & GCSE Biology revision notes

Applying CORMS to practical work

  • When working with practical investigations, remember to consider your CORMS evaluation

CORMS evaluation, downloadable AS & A Level Biology revision notes

CORMS evaluation

  • In this investigation, your evaluation should look something like this:

    • C - We are changing the abiotic conditions in which the seeds are germinating

    • O - The cress seeds will all be taken from the same parent plant (or at least from the same species of cress plant)

    • R - We will repeat the investigation several times to ensure our results are reliable

    • M1 - We will record how many seeds in each test tube germinate

    • M2 - ...after a set time period (e.g. 3 days)

    • S - We will control the temperature for tubes A, B and C. We will also control the type of water used (i.e. sterile water, which is made by first boiling then cooling water)

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Lára Marie McIvor

Author: Lára Marie McIvor

Expertise: Biology Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.