Long Answer Type(a) Explain in detail the digestion of carbohydrates, as the food passes through the alimentary canal.
(b) Describe step by step what happens in the different phases of the cardiac cycle in human beings.
(c) Write the effects of cytokinins on plants.
(a) Write about the chemical changes which occur during contraction of skeletal muscles.
(b) Draw a neat labelled diagram of the L.S. of a kidney.
(c) What is chloride shift ?
(a) Chemical event during muscles contraction :
(a) (i) A muscle is stimulated by acetyl choline released from the vesicles at the neuromuscular junction or motor end plates.
(ii) Acetyl choline evokes release of Ca++ ion from the sarcoplasmic reticulum into the sacroplasm.
(iii) In the presence of ATP and Ca++ ions, myosin binds to action protein forming actomyosin.
(iv) Calcium ions activate myosin ATPase enzyme, which breaks ATP into ADP and P, Energy, thus released energy is used for muscle contraction. Mg++ions are also essential for ATPase activity and for muscles contraction.
(v) Another high energy compound creatine phosphate helps in immediate conversion of ADP into ATP.
(vi) Glycogen in the muscle changed into lactic acid by glycolysis and energy is liberated.
(vii) A part of this energy is utilized in the reforming creatine phosphate and also in converting lactic acid into glycogen.
(viii) The rest part of lactic acid acid is oxidised into water and carbon dioxide.
b. 
c. Transport of carbon dioxide in the form of bicarbonate requires chloride ions. When the concentration of bicarbonate ions increases in RBC, they escape out from the RBC into the plasma. For each bicarbonate ion that comes out from the RBC, one chloride ion enters into the RBC from the plasma. In the lungs the process is just the reverse where chloride ion moves out of the RBC and bicarbonate ions move in. This is known as the chloride shift.
a) Explain how the human ear helps in hearing.
b) Briefly describe the events that occur during the prolifearative phase of the menstrual cycle.
(c) Mention the site of secretion and function of the following :
(i) Glucocorticoids
(ii) Calcitonin
(iii) Glucagon
(a) Explain the evolution of the long neck of giraffe according to Darwin and Lamarck.
(b) Explain briefly :
(i) Environmental resistance
(ii) Albinism
(iii) Plant introduction
(iv) Palaeontology
(c) Write two uses of each of the following :
(i) Emblica officinalis
(ii) Adhatoda vasica
(a) Give four applications of tissue culture in crop improvement.
(b) What do you understand by the term population growth ? Give three ways of discouraging population growth.
(c) Define :
(i) Coacervates
(ii) Gene bank
(a) Explain the role of Rh factor in blood incompatibility.
(b) State the main morphological changes that occurred in the ancestors of modern man.
(c) Describe briefly the functions of the following :
(i) CT Scan
(ii) External prosthesis
(iii) Pacemaker
a) Explain the role of a genetic counsellor.
(b) Write the causative agent and the main symptoms of the following diseases,
(i) Poliomyelitis (ii) Typhoid
(iii) Tuberculosis (iv) Cholera
(c) State two'similarities between the chromosomes of man and apex.
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