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 what you understand by sexual reproduction.
Explain the difference between self-pollination and cross-pollination.
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?
What will happen if there are no platelets in the blood?
Fill in the blanks in the following statements:
(a) When carbon dioxide is passed through lime water, it turns milky due to the formation of _________.
(b) The chemical name of baking soda is _________.
(c) Two methods by which rusting of iron can be prevented are _________ and _________.
(d) Changes in which only _________ properties of a substance change re called physical changes.
(e) Changes in which new substances are formed are called _________ changes.
Explain, with examples, why we find animals of certain kind living in particular climatic conditions.
Consider the following statements:
(a) Both acids and bases change colour of all indicators.
(b) If an indicator gives a colour change with an acid, it does not give a change with a base.
(c) If an indicator changes colour with a base, it does not change colour with an acid.
(d) Change of colour in an acid and a base depends on the type of the indicator.
Which of these statements are correct?
(i) All four (ii) a and d (iii) b and c (iv) only d
State two experiences that made you think that air exerts pressure (other than those given in the text).
How will you help your neighbours in case cyclone approaches your village/town?
Explain the role of forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere.
Which of the two changes frequently, weather or climate?
Describe the process of neutralisation with the help of an example.
Match the items of Column I with those given in Column II:
Column I Column II
Food components Product(s) of digestion
Carbohydrates Fatty acids and glycerol
Proteins Sugar
Fats Amino acids