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प्रश्न
How are the modes for reproduction different in unicellular and multicellular organisms?
उत्तर
In unicellular organisms, reproduction occurs by the division of the entire cell. The modes of reproduction in unicellular organisms can be fission, budding, etc. whereas in multicellular organisms, specialised reproductive organs are present. Therefore, they can reproduce by complex reproductive methods such as vegetative propagation, spore formation, etc. In more complex multicellular organisms, such as human beings, the mode of reproduction is sexual reproduction.
संबंधित प्रश्न
Name two simple organisms having the ability of regeneration.
Draw labelled diagrams to illustrate budding in Hydra.
A student has to focus his compound microscope to observe a prepared slide showing different stages of binary fission in Amoeba. The steps he is likely to follow are listed below in a haphazard manner:
I. Adjust the diaphragm and the mirror of the microscope so that sufficient light may enter to illuminate the slide.
II. Fix the slide on the stage carefully.
III. Adjust the microscope to high power and focus.
IV. Adjust the microscope to low power and focus.
The correct sequence of the above steps to observe the slide under the microscope is
(A) I, II, IV, III
(B) II, I, IV, III
(C) II, IV, I, III
(D) I, IV, II, III
State whether the following statement is true or false :
Spores produced by the bread mould plant are actually its seeds.
What is the name of asexual reproduction method in Spirogyra
Name two organisms which reproduce by the same asexual process as that of Amoeba.
What is the difference between the two asexual methods of reproduction : fission and fragmentation?
Name two fruit trees which are usually propagated by grafting method.
An alga which reproduces by the asexual reproduction method called fragmentation is :
(a) Rhizopus
(b) Salmonella
(c) Plasmodium
(d) Spirogyra
A thickened underground stem X of a plant which is swollen with stored food has a number of points Y on its surface. When the old stem X is planted in the soil of a field in the next growing season, then each point Y present on its surface grows into a new plant.
(a) What is the general name of the underground stems like X?
(b) Give one example of X.
(c) What are points Y present on X known as?
(d) Is it necessary to plant the whole of stem X in the ground to obtain its new plants? Explain your answer.
(e) What is the name of this method of reproduction of plants?
(f) What is the advantage of growing new plants from the underground stems like X?
Fill in the following blank with suitable word :
The process of fusion of gametes is called .............
State whether the following statement is true (T) or false (F):
Bacteria and yeast reproduce by sexual reproduction.
A blue colour flower plant denoted by BB is crossbred with that of white colour flower plant denoted by bb.
(a) State the colour of flower you would expect in their F1 generation plants.
(b) What must be the percentage of white flower plants in F2 generation if flowers of F1 plants are self-pollinated?
(c) State the expected ratio of the genotypes BB and Bb in the F2 progeny.
What is meant by asexual reproduction?
A yeast cell in which budding occurs was seen to have:
(1) one bud cell
(2) two bud cell
(3) three bud cell
(4) a chain of bud cells
Name four plants which can be propagated by stem-cutting.
Asexual reproduction is also known as ______.
During favourable conditions, Amoeba reproduces by ______
Which of the following statements is/are true for sexual reproduction in plants?
(i) Plants are obtained from seeds.
(ii) Two plants are always essential.
(iii) Fertilisation can occur only after pollination.
(iv) Only insects are agents of pollination.
Choose from the options given below.
