Q.1. Why is variation beneficial to the species but not necessary for the individual?
Ans- Variation is beneficial to the species as it enables a species for its survival. A favourable variation makes an organism to live better in a changed environment and an unfavourable variation will not. So it is not necessarily true that a variation is beneficial to the individual always.
Q.2. What is the advantage of reproduction through spores in the case of Rhizopus?
Ans: The spores are covered by thick walls that protect them until they come into contact with another moist surface and can begin to grow.
Q.3. The simple animals such as planaria can be cut into number of pieces and each piece grows into a complex organism. What is this process known as?
Q.4) Name the unicellular organism which caused the disease known as kala-azar.
Ans : Leishmania
Q.5) Which process taking place in the nucleus of a cell leads to variation in the offspring during reproduction?
Ans : DNA copying
Q.6. What causes joining up of stock and scion in grafting technique of vegetative propagation in plants? Define the terms stock and scion. Name one positive trait each of the plant contributing scion and stock should have.
Ans : The stock and scion unite due to cambial cavity. Stock is the portion on which
grafting is done and it provides the roots. Scion is the portion of the plant which is grafted on the other plant and it contributes the stem. The plant contributing scion should have large sized fruits and the plant contributing stock should have deep root system.
Q.7 . Which type of layering is done in Jasmine?
Ans : Air Layering (Gootee)
Q.8 . Where does fertilization takes place in human female?
Ans : Oviduct (fallopian tube)
Q.9 . Why is it said that “sexual reproduction promotes diversity of characters in the offsprings”?
Ans : It is because sexual reproduction results from the fusion of two gametes coming from two different and sexually distinct individuals. This leads to variation, is necessary for evolution.
Q.10. What happens if the fallopian tubes are partially blocked and the ovulated eggs are prevented from reaching the uterus?
Ans : Fertilization may take place but the zygote may develop in the tube instead of uterus.
Q.11 . Name the causative organism of syphilis and gonorrhoea.
Ans : Treponema pallidum and Nisseria gonorrhoeae.
Q.12 . Why are variation possible in progeny of sexually reproductive individuals?
Ans-Variations are possible in progeny of sexually reproductive individuals because copy of DNA in newly formed cell is not identical to copy DNA of original cell.
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