(a)(i) Name two types of germination of seeds giving one example of each type. (ii) Describe a simple experiment to demonstrate that oxygen, water and warmt...
Question 1 Report
(a)(i) Name two types of germination of seeds giving one example of each type.
(ii) Describe a simple experiment to demonstrate that oxygen, water and warmth are necessary for germination of seeds.
(b) State two distinguishing features each of
(i) epiphytes
(ii) parasites
(c) Give two examples o parasitic plants.
Answer Details
(a)(i) Two types of germination of seeds, with examples
- Epigeal germination - the cotyledons are carried above the soil surface. Example: cowpea (or groundnut).
- Hypogeal germination - the cotyledons remain below the soil surface. Example: maize (or oil palm).
(a)(ii) Experiment to show that oxygen, water and warmth are necessary for germination
Aim: To demonstrate that seeds need oxygen, water and warmth to germinate.
Set up four boiling tubes (labelled A, B, C, D), each containing a few viable bean seeds resting on cotton wool:
| Tube | Conditions provided | Factor being tested |
|---|---|---|
| A (control) | Moist cotton wool, air present, kept warm (room temperature) | All three conditions present |
| B | Dry cotton wool (no water), air, warm | Tests need for water |
| C | Seeds covered with boiled, cooled water topped with oil (no air), warm | Tests need for oxygen |
| D | Moist cotton wool, air, but kept in a refrigerator (cold) | Tests need for warmth |
The boiled, cooled water in C removes dissolved oxygen and the oil layer prevents air from re-entering. Leave the tubes for several days (about a week).
Observation: Only the seeds in tube A (the control), which has water, air/oxygen and warmth, germinate. The seeds in B (no water), C (no oxygen) and D (no warmth) fail to germinate.
Conclusion: Since germination occurs only when water, oxygen and warmth are all present, these three factors are necessary for the germination of seeds.
(b) Distinguishing features
(i) Two features of epiphytes
- They grow on (are attached to) other plants for support but are not parasitic.
- They possess special aerial (clinging) roots and manufacture their own food, absorbing moisture from the air/rain.
(ii) Two features of parasites
- They live on or in a host from which they obtain their food (they possess haustoria that penetrate the host tissues).
- They usually lack chlorophyll or have it reduced, and they harm the host.
(c) Two examples of parasitic plants
Cassytha (dodder / love-vine) and mistletoe (Loranthus / Tapinanthus); Striga is another.
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