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) 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) The ear pinna collects the sounds waves and directs them towards the external auditory canal. The sound waves strike the drum and the ear draw starts vibrating. The vibrations are transmitted through the ear ossicles to the perilymph in the vestibule. The movement of stapes towards the vestibule develops a pressure wave in perilymph. It passes into the scale vestibule towards the tip of the cochlea, where the scale vestibule is continuous with scale tympani. The pressure wave passes through this way along the length of the cochelea back. In this way vibrations are set up in the perilymph and in the basilar membrane which moves up and down, distorting the hair cells. These distortion generate nerve impulse which is carried to the brain by the auditory. Thus sound is perceived.
(b) Proliferative phase begins at the end of menstruation .Growth and rapid division of the walls of uterus, fallopian tube etc. occurs during this phase. The endometrium which had become thin due to shedding starts growing again. The epithelial cells divide and grow rapidly, growth of endometrial stroma occurs and the blood vessels grow. The endometrium gradually becomes 3-5mm thick. The myometrial contractions becomes more strong and secretion of the glands at the cervix of uterus increases.
All these changes in the uterus are due to the rising concentration of estrogen.
These occur simultaneously with the changes in the uterus. In the ovary the immature follicle changes into a mature Graafian follicles.
c)
| Site of Secretion | Function |
| secreted from the Zona fasiculata region of Adrenal cortex | Helps in the metabolism of proteins, lipids, carbohydrates. |
| Calcitonin is secreted by the parafollicular cell of the thyroid gland | The hormone participates in calcium (Ca2+) and phosphorus metabolism. |
| Glucagon is secreted by the alpha cells of the pancreas | They increase the blood sugar level |
(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.
Switch
