4 COORDINATION

Question 1

what are hormones

Answer 1

are special chemicals released from endocrinal glands. they are cell signalling molecules

Question 2

differ between protein and steroid hormones

Answer 2

protein:
cannot pass through csm,
water soluble
bind to receptr molecules on csm
steroid:
- not water soluble
- can pass throggh csm
-bind to receptor molecules in cytoplasm/ nucleus

Question 3

what is a gland

Answer 3

a group of cells that produces or releases one or more substances through secretion

Question 4

which glands control the menstrual cycle

Answer 4

ovaries, the anterior pituitary gland

Question 5

role of oestrogen

Answer 5

maintains uterine lining, thickening of the endometrium, makes it grow and develop numerous blood capillaries. it inhibits FSH AND LH

Question 6

what hormones are secreted by the ovaries

Answer 6

progesterone and estrogen- changes in uterus

Question 7

what hormons escreted by anterior potuatry gland

Answer 7

FSH, LH

Question 8

what causes the dom follicle to burst

Answer 8

the surge of LH causes the dom follicle tp bursts

Question 9

how does oestrgoen and progestoje prevet fertiliziaton

Answer 9

• procedure: women takes 1 pill daily for 21 days annd stops for 7 days
• both oestrogen and progesterone inhibit secretion of FSH AND LH from a.p.g
• this prevents their conc from reaching a level that would stimulate ovulation
• progesterone reduces the ability of the sperm to ferrtilize the egg by making cervical mucous more viscous and so less easily penetrated by sperm
• stopping th epill aftr 21 days allows oes and prog to fall until endometrium is no longer maintaind

Question 10

how does depolarisatioon occur in plants

Answer 10

occurs from outflow of -vely charged chloride ions, acction potentials travel along cell membranes from cell-cell through plasmodesmata

Question 11

name some adaptations of venus fly trap

Answer 11

• stimulation of only 1 hair does not trigger closure for preventing closure during rain, debris, etc
• gaps between bars allow very small insects to leave to avoid wasting energy on a small meal

Question 12

role of auxins, gibberelins

Answer 12

• influence many aspects of growth, which determines oveerall length of roots and shoots
• seed germination, stem elongation controlling

Question 13

how does auxin help growth

Answer 13

1- auxin binds to receptor protein onn csm

• this stimulates ATPase proton pumps to pump H from cytoplasm - cell wall
• this acidifies the clel wall
• it actiates expansins due to decrease in ph, expansins loosen linkages bw cellulose microfibrils.
• cells absorb water by osmos
• pressure potential causes the ccell wall to stretch or elongate

Question 14

how does gibberelins bring about germination

Answer 14

• seed absorsbs water
• this stimulates embryo to prod gibberelins
• gibbberelins diffuse to aleurone layer and stimulate ccells to produce amylase
• amylase hydrolyses starch moleccules and mkaes them soluble by converting them into maltose in endosperm
• maltose cnverted into glucose, trasnported to embryo where it can be used for respiraton for growth