Describe the different methods of asexual reproduction. Give examples.
Asexual reproduction is the simplest form of reproduction in which only one parent is involved. It do not involves the meiosis, gamete formation and fusion of gametes. This asexual reproduction is also known as clonal propagation because of their genetically identical products.
The asexual reproduction in plants can take place by the following methods:
1. Vegetative propagation: It is the natural process that is found in many plant species. It is a process by which plant reproduces without the production of seeds and spores. In this growth of new plants from the plant parts (like bulbs, runners, stems cuttings, roots and leaves etc.) occurs. Tissue culture is also the method of vegetative propagation under the sterile conditions.
Examples: Tuber of potato, the rhizome of ginger etc.
2. Budding: In budding process a small part of the body of the parent plant grows as a bulb- like structure called ‘bud’ which then detaches and becomes a new plant or we can say formation of daughter individual from the small projection called the bud that arises on the parent body is known as budding.
Example: Yeast (unicellular fungi), Hydra etc.
3. Fragmentation: The breaking up of the body of a plant into two (or more) pieces on maturing, each of which automatically grows to form a new plant, is called fragmentation. An alga reproduces by the asexual method of fragmentation. An example of common alga is Spirogyra. Spirogyra is a green, filamentous alga plant which is found in ponds, lakes and slow moving streams. Spirogyra reproduces by the asexual method of reproduction called fragmentation.
4. Spore Formation: Propagules which germinate to produce new individuals are known as spores. There are several types of spores: zoospores, sporangiospores, chlamydospores, oidia and conidia.
Sketch the reproductive parts of a flower.
Match items in Column I with those in Column II:
Column I Column II
(a) Bud (i) Maple
(b) Eyes (ii) Spirogyra
(c) Fragmentation (iii) Yeast
(d) Wings (iv) Bread mould
(e) Spores (v) Potato
(vi) Rose
Describe the various ways by which seeds are dispersed.
How does the process of fertilisation take place in flowers?
Explain the difference between self-pollination and cross-pollination.
Explain what you understand by sexual reproduction.
State the main difference between asexual and sexual reproduction.
Tick the correct answer:
(a) The reproductive part of a plant is the
(i) leaf (ii) stem (iii) root (iv) flower
(b) The process of fusion of the male and the female gametes is called
(i) fertilisation (ii) pollination
(iii) reproduction (iv) seed formation
(c) Mature ovary forms the
(i) seed (ii) stamen
(iii) pistil (iv) fruit
(d) A spore producing plant is
(i) rose (ii) bread mould
(iii) potato (iv) ginger
(e) Bryophyllum can reproduce by its
(i) stem (ii) leaves
(iii) roots (iv) flower
Fill in the blanks:
(a) Production of new individuals from the vegetative part of parent is called_____________.
(b) A flower may have either male or female reproductive parts. Such a flower is called_____________.
(c) The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as _____________.
(d) The fusion of male and female gametes is termed as _____________.
(e) Seed dispersal takes place by means of _____________, _____________ and _____________.
State similarities and differences between the laboratory thermometer and the clinical thermometer.
State differences between acids and bases.
Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food
Name the elements that determine the weather of a place.
Fill the missing word in the blank spaces in the following statements:
(a) Wind is——————air.
(b) Winds are generated due to —————— heating on the earth.
(c) Near the earth’s surface __________air rises up whereas ___________ air comes down.
(d) Air moves from a region of ——— pressure to a region of ———.
In addition to the rock particles, the soil contains
(i) air and water
(ii) water and plants
(iii) minerals, organic matter, air and water
(iv) water, air and plants
Why does an athlete breathe faster and deeper than usual after finishing the race?
Match structures given in Column I with functions given in Column II.
Column I Column II
(i) Stomata (a) Absorption of water
(ii) Xylem (b) Transpiration
(iii) Root hairs (c) Transport of food
(iv) Phloem (d) Transport of water
(e) Synthesis of carbohydrates
Classify the following as motion along a straight line, circular or oscillatory motion:
(i) Motion of your hands while running.
(ii) Motion of a horse pulling a cart on a straight road.
(iii) Motion of a child in a merry-go-round.
(iv) Motion of a child on a see-saw.
(v) Motion of the hammer of an electric bell.
(vi) Motion of a train on a straight bridge.
Why do organisms need to take food?
A simple pendulum takes 32 s to complete 20 oscillations. What is the time period of the pendulum?
Solve the following crossword puzzle with the clues given:
Across
2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.
Down
1. In desert soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil.
Fig.14.22 shows four cells fixed on a board. Draw lines to indicate how you will connect their terminals with wires to make a battery of four cells.
Find out the letters of English alphabet or any other language known to you in which the image formed in a plane mirror appears exactly like the letter itself. Discuss your findings.
List the differences between clayey soil and sandy soil.
Out of the following, which are the two terms related to silk production? Sericulture, floriculture, moriculture, apiculture and silviculture.
Hints:
(i) Silk production involves cultivation of mulberry leaves and rearing silkworms.
(ii) Scientific name of mulberry is Morus alba.
Razia conducted an experiment in the field related to the rate of percolation. She observed that it took 40 min for 200 mL of water to percolate through the soil sample. Calculate the rate of percolation.
Fill in the blank:
(a) The insects, butterflies, honeybees and birds help flowering plants in .
(b) A forest is a purifier of and .
(c) Herbs form the layer in the forest .
(d) The decaying leaves and animal droppings in a forest enrich the .
Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell. (T/F)
(b) When the electric current through the fuse exceeds a certain limit, the fuse wire melts and breaks. (T/F)
(c) An electromagnet does not attract a piece of iron. (T/F)
(d) An electric bell has an electromagnet. (T/F)
How is clayey soil useful for crops?