On cutting the body of an organism into many pieces it was observed that many of these pieces developed as new individuals. Name the process and list two organisms in which this process may be observed. Draw a schematic diagram to illustrate the changes that are likely to be observed during the development of new individuals in any one of the organisms named.
CBSE DELHI - SET 3 2014
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If the individual is somehow cur or broken up into many pieces,many of these pieses grow into separate individuals. For examplw, simplw animals like Hydra and Planaria can be cur into and number of pieces and each piece pgows into a copmlete organism. This is known as regeneration (see the below figures). Regenaration is carried out by specialised cells. These cells proliferate and make large numbers of cells.
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Name the two types of mammalian gametes. How are these different from each other? Name the type of reproduction they are involved in. Write the advantage of this type of reproduction.
Write two examples each of sexually transmitted diseases caused by (i) virus, (ii) bacteria. Explain how the transmission of such diseases be prevented?
Draw diagrams to explain the regeneration that takes place in each of the body parts of planaria when its body is cut into three pieces. Name any other organism in which a similar process can be observed.
List three techniques that have been developed to prevent pregnancy. Which one of these techniques is not meant for males? How does the use of these techniques have a direct impact on the health and prosperity of a family?
List four methods of contraception used by humans.
Justify the following statement:
‘‘The use of contraceptive methods has a direct effect on the health and prosperity of a family.’
From the internet, gather information about the chromosome numbers of five animals and five plants. Correlate the number with the size of organism and answer the following questions.
Do larger organisms have more number of chromosomes/ cells?
Can organism with fewer chromosomes reproduce more easily than organisms with more number of chromosomes?
More the number of chromosomes/ cells greater is the DNA content. Justify.