Explain the difference between self-pollination and cross-pollination.
Pollination is the transfer of pollen grains from the anther to the stigma of the flower which can be achieved by biotic (insects, birds etc.) and abiotic (wind, water etc.) pollinating agents. On the basis of pollinating mechanism, plants can be grouped into two mating systems: self- pollinated and cross- pollinated.
| Self- Pollination | Cross Pollination |
| 1. The pollen grain moves to the female part of the same flower or different flower of the same plant species. | 1. The pollen grains are transferred to the flower present on the different plant. |
| 2. Transfer to the same flower is autogamy; and to another flower on the same plant is geitonogamy. | 2. Cross- pollination is also known as allogamy. |
| 3. No genetic variation occurs. | 3. High genetic variation are found. |
| 4. Identical species are created, i.e. no new species are formed. | 4. New species are formed. |
| 5. Transfer of pollen grains are limited. | 5. Transfer of pollen grains unlimited, i.e. in large amount. |
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Classify the changes involved in the following processes as physical or chemical changes:
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(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
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Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down Across
(D) 1 : Thorough washing (A) 1 : Keeps warm
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Sketch the cross section of soil and label the various layers.
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Here is a crossword puzzle: Good luck!
Across
3. Liquid waste products
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6. A word related to hygiene
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1. Used water
2. A pipe carrying sewage
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Sketch the reproductive parts of a flower.
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Solve the following crossword puzzle with the clues given:
Across
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5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.Down
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Match the items in Column I with those in Column II:
Column I Column II
(i) A home for living organisms (a) Large particles
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