Short Answer Typea) Write the scientific name of the organism Thomas Hunt Morgan and his colleagues worked with for their experiments. Explain the correlation between linkage and recombination with respect to genes as studied by them.
b) How did Sturtevant explain gene mapping while working with Morgan?
State the ‘Central dogma’ as proposed by Francis Crick. Are there any exceptions to it? Support your answer with a reason and an example.
Explain how the biochemical characterisation (nature) of ‘Transoforming Principle’ was determined. which was not defined from Griffith’s experiments.
Following are the responses of different animals to various abiotic factors. Describe each one with the help of an example.
(i) Regulate
(ii) Conform
(iii) Migrate
(iv) Suspend
If 8 individuals in a population of 80 butterflies die in a week, calculate the death rate of population of butteflies during that period.
Describe any two devices in a flowering plant which prevent both autogamy and geitonogamy.
Autogamy: Transfer of pollen grains from the anther to the stigma of the same flower.
Geitonogamy: Transfer of pollen grains from the anther to the stigma of another flower of the same plant.
Two devices that prevent both autogamy and geitonogamy are:
(i) Self – incompatibility: This is a genetic mechanism & prevents self-pollen from fertilising the ovules by inhibiting pollen germination or pollen tube growth in the pistil.
(ii) Dioecious plants: Male and female flowers are present on different plants, that is each plant is either male or female.
Explain the events up to double fertilisation after the pollen tube enters one of the synergids in an ovule of an angiosperm.
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