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
Regulate: Some organisms are able to maintain homeostasis by regulating their body temperatures. The mechanisms used by most mammals to regulate their body temperature are similar to what we humans use.
Eg: Body temperature remains constant at 370C. In summer, when outside temperature is more than our body temperature, we sweat profusely and when the temperature is much lower than 370C, we shiver thus body temperature remains constant.
(ii) Conform :Many animals, cannot maintain a constant internal environment. Their body temperature changes with the ambient temperature. These are conformers. Heat loss or heat gain is a function of
surface area. Since small animals have a larger surface area relative to their volume, they tend to lose body heat very fast when it is cold outside. Eg. Shrews and hummingbirds.
(iii) Migrate: The organism can move away temporarily from the stressful habitat to a more hospitable area & return when stressful period is over.
Eg: Every winter, the famous Keoladeo National Park in Bharatpur host thousands of migratory birds coming from Siberia & other northern regions.
(iv) Suspend: In animals, if migration is not possible, they might avoid the stress by escaping in time.
Eg: (1) Bears go into hibernation during winter.
(2) Fishes go into aestivation to avoid summer related problems heat & desiccation.
If 8 individuals in a population of 80 butterflies die in a week, calculate the death rate of population of butteflies during that period.
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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