KCSE 2018 ESSAY Q7 (A) DESCRIBE THE MODE OF REPRODUCTION IN A NAMED FUNGUS. (B) DESCRIBE THE ROLE OF HORMONES IN THE HUMAN MENSTRUAL CYCLE.

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(a) Describe the mode of reproduction in a named fungus.
  • Rhizopus/mucor/ mould; reproduce a sexually; by sporulation; spores develop from a single in the sporangium; which burst on maturity releasing spores; which are dispersed by air currents/ wind; germinating to form new generation / form mycelium (if it lands on a suitable medium);
OR
  • Yeast/saccharomyces/ schizo saccharomyces ; reproduce asexually; by budding; parent cells form an out growth/projection/bud; followed by division of nucleus into two; one of the nuclei moves into the new bud; which grow and develops into a new cell; 
(7 marks Max 5)
(b) Describe the role of hormones in the human menstrual cycle.
  • After/at the onset of menstruation (the anterior lobe) of the pituitary gland; secretes follicle stimulating hormone (FSH); 
  • The FSH causes the Graafian follicle; to develop in the ovary; and stimulate the ovary tissues to secrete oestrogen hormone;
  • Oestrogen hormone brings about repair; healing of the endometrium; It's concentration increases to a level which stimulates the (anterior) pituitary gland; to secrete luteinising hormone (LH); and stops further secretion of FSH;
  • The LH stimulates maturation of the Graafian follicle; LH also stimulates the Graafian follicle to release an ovum (into the funnel of the fallopian tube)/ causes ovulation;
  • LH then stimulates the remains of the Graafian follicle to form a yellow body/ corpus luteum; (in the ovary).
  • The corpus luteum; is stimulated by the LH to produce progesterone;
  • Progesterone then stimulates the thickening of the endometrium/inner uterine wall; in readiness for implantation;
  • As progesterone level increases it Inhibits the pituitary gland from secreting FSH;
  • Further increase in progesterone level inhibits pituitary gland from secreting LH;.
  • It causes the corpus luteum to degenerate; (Rj disintegrate).
  • This reduces the amount of progesterone;
  • The sudden drop in secretion of progesterone causes endometrium to slough off/ menstruation occur; and the cycle is repeated.
(15 marks)
NB :Source of hormones must be mentioned as to score.

TOTAL 20 MARKS

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