Investigate the effect of water, oxygen and temperature on germination. Flashcards
What is seed germination?
Seed germination is the process by which a dormant seed begins to grow into a new plant under suitable conditions (water, oxygen, and temperature).
Why is digestion necessary in a germinating seed?
The seed contains stored food in the form of starch, proteins, and lipids. These macromolecules must be digested into smaller, soluble molecules (glucose, amino acids, fatty acids, and glycerol) to be used for respiration and growth.
What is an agar plate?
An agar plate is a petri dish filled with a gel-like nutrient medium used for growing microorganisms or testing enzyme activity.
Give an example of an extra food material added to the agar plate for demonstration.
Starch is often added to the agar to test for amylase activity in germinating seeds.
What control is used in the experiment?
A control plate with agar containing starch but no germinating seeds is used to show that any starch breakdown is due to the seeds’ enzyme activity and not another factor.
Describe the result obtained in the experimental plate.
Clear zones form around the germinating seeds when iodine is added, indicating starch breakdown by amylase.
Describe the result obtained in the control plate.
The entire plate remains blue-black after adding iodine, showing that no starch was digested.
Why should you cross-reference your results with other groups in the class?
To confirm the accuracy and reliability of results by identifying errors or inconsistencies.
Name another factor apart from temperature that might differ in a fridge compared to other dishes.
Oxygen levels may be lower in a fridge due to less air circulation. Humidity may also differ.
How many seeds are used in each Petri dish for this investigation?
Typically, 5–10 seeds are used per dish to ensure reliable and representative results.
What result would you expect to observe after a few days?
Germinated seeds with visible radicles (roots) emerging from the seed coat. A clearing zone around the seeds on starch agar (if amylase is present).
Explain the need for water during germination.
Water softens the seed coat and activates enzymes for digestion. It helps dissolve stored food for transport to the embryo.
Explain the need for temperature during germination.
Temperature provides optimal enzyme activity for digestion and respiration.
Explain the need for oxygen during germination.
Oxygen is needed for aerobic respiration, which provides energy (ATP) for growth.
Is it the air temperature or soil temperature that controls germination?
Soil temperature has a greater effect because the seed is in direct contact with the soil.
Give one location in a seed where food is stored.
Endosperm (in monocots) or cotyledons (in dicots).
Name a carbohydrate that you would expect to be present in this food store.
Starch (a polysaccharide).
Explain the term embryo.
The embryo is the young developing plant inside the seed, consisting of: Plumule (shoot), Radicle (root), Cotyledons (food storage in some seeds).
What term is used to describe the period of inactivity before germination?
Dormancy – when a seed remains inactive until conditions are suitable for germination.
