Homeostasis & Response - Animal & Plant Hormones

Question 1

what is the main reproductive hormone in men

Answer 1

testosterone. produced in testes and stimulates sperm production

Question 2

what is the main reproductive hormone in females

Answer 2

oestrogen. produced in ovaries

Question 3

what are the 4 stages of the menstrual cycle

Answer 3

1. lining of uterus breaks down ( bleeding starts about 4 days)
2. lining of uterus builds up ( from day 4 to 14)
3. egg is released ( called ovulation (day 14))
4. uterus lining maintained ( until day 28)

Question 4

what does the follicle stimulating hormone do and where is it made

Answer 4

causes egg to mature in one of the ovaries in a structure called a follicle. also stimulates ovaries to produce oestrogen

produced in pituitary gland

Question 5

what does luteinising hormone do and where is it made

Answer 5

stimulates ovulation at day 14

Question 6

what does oestrogen and progesterone do

Answer 6

growth and maintenance of uterus lining. oestrogen stimulates the release of LH and inhibits FSH.

progesterone is produced in ovaries by the remains of the follicle after ovulation. it maintains the lining of the uterus so when progesterone levels fall, the lining breaks down. also inhabits release of LH and FSH

Question 7

how can oestrogen be used to reduce fertility

Answer 7

if taken daily it keeps oestrogen levels permanently high so FSH production will be inhabited which will stop egg maturation and therefore release.

Question 8

how can progesterone be used to reduce fertility

Answer 8

stimulating production of thick cervical mucus which prevents sperm getting through and reaching an egg

it can inhabit egg maturation and therefore the release of an egg too.

Question 9

benefits of the combined oral pill

Answer 9

over 99% effective

reduced risk of getting some types of cancer

Question 10

problems with combined oral pill

Answer 10

extremely slight chance of getting pregnant
side effects like headaches, nausea, irregular bleeding and fluid retention
doesn’t protect against STDs

Question 11

what is a contraceptive patch

Answer 11

contains oestrogen and progesterone. 5x5cm that stuck to the skin that lasts one week

Question 12

what is a contraceptive implant

Answer 12

inseted under skin of arm. releases a continuous amount of progesterone which stops ovaries releasing eggs. Can last for 3 years

Question 13

what is a contraceptive injection

Answer 13

contains progesterone and last 2 to 3 months

Question 14

what is a diaphragm

Answer 14

a plastic cup that fits over cervix to form a barrier. has to be used w a spermicide

Question 15

what is a intrauterine device

Answer 15

t shaped device inserted into uterus to fill sperm and prevent implantation of a fertilized egg. some release progesterone and there are copper ones that prevent sperm surviving

Question 16

surgical methods of contraception

Answer 16

sterilization- cutting or tying fallopian tubes or the sperm duct in a male. parament but small chance tubes can re-join

Question 17

what is a natural method of contraception

Answer 17

avoiding seggs on days when woman is most fertile

abstinence- not having seggs

Question 18

how can fertility drugs increase fertility

Answer 18

woman who’s fsh level is too low for egg to mature, the hormones FSH and LH can be injected to stimulate egg maturation and release into the ovaries

Question 19

problems with fertility drugs

Answer 19

dont always work it can become expensive

too many eggs can be stimulated so too many babies

Question 20

In Vitro Fertilization

Answer 20

FSH & LH given to woman to stimulate maturation of multiple eggs

eggs collected from ovaries and fertilised in lab with mans sperm

grow into embryos in lab incubator

one or two transferred into uterus

Question 21

cons of IVF

Answer 21

multiply births can happen which makes risks
low success rate 26% so stresful and upsetting
physically stressful e.g. vomiting dehydration and abdominal pain

Question 22

how has micro tools improved ivf success rate

Answer 22

use on egg and sperm under microscope and remove single cells from embryo for genetic testing

Question 23

how has time lapse imaging improved ivf

Answer 23

(using a microscope and camera built into incubator) so embryos can be monitored to identify those more likely to succeed

Question 24

social and ethical issues with ivf

Answer 24

unused embryos get destroyed

genetic testing makes ppl think it could lead to selection of preferred characteristics

Question 25

where is thyroxine made and what does it do

Answer 25

thyroid gland
regulates basal metabolic rate
also stimulating protein synthesis
released in response to TSH which is released from pituitary gland   
released on negative feedback loop

Question 26

where is adrenaline released from and what does it do

Answer 26

adrenal glands, just above kidney
in response to stressful or scary situations
brain sends nervous impulses to adrenal glands
increased oxygen supply and glucose to muscle and increased heartrate

Question 27

auxin

Answer 27

controls growth, phototropism, gravitropism.
produced in tips of shoots and roots and moves backwards to stimulate the cell elongation process. so if shoot is removed, no auxin is available so shoot may stop growing

Question 28

what is phototropism

Answer 28

plant growth in response to light

Question 29

what is gravitropism

Answer 29

plant growth due to gravity

Question 30

why do shoots grow towards light

Answer 30

more auxin accumulates on the side that’s in shade so it elongates faster on the shaded side so shoot bends towards the light

Question 31

why do shoots grow away from gravity

Answer 31

gravity causes auxin to go to lower side of shoot when horizontal so it will grow faster on the lower side, causing it to bend upwards

Question 32

why do roots grow towards gravity

Answer 32

when a root is horizontal, more auxin will accumulate on its lower side. in a root, extra auxin inhabits growth so the cells on top will elongate faster so the root bends downwards

Question 33

how can auxins be used for killing weeds

Answer 33

weeds in grass and narrow crop usually have broader leaves. weed killer with auxins which only affect the broad leave plants disrupt their normal growth patterns which soon kills them

Question 34

how are auxins used in rooting powder to grow cuttings

Answer 34

rooting power contains auxins that when added to cuttings will produce rapid roots so the cutting can grow in the soil as a new plant. growers can produce clones like this quickly

Question 35

how are auxins used to grow cells in tissue cultures

Answer 35

auxins added to growth medium along w nutrients to stimulate cells to divide to produce shoots and roots

Question 36

what are gibberellins

Answer 36

growth hormone in plants that stimulates germination, stem growth and flowering

Question 37

how can dormancy be altered

Answer 37

seeds can be treated with gibberellins to change wen they germinate. also make sure all seeds in a batch germinate at the same time

Question 38

how can flowering be induced

Answer 38

plants treated with gibberellins will flower without any change in the environment. gibberellins can also be used to make bigger flowers

Question 39

why may gibberellins be used to grow larger fruits

Answer 39

seedless variants do not often grow as big

Question 40

what does ethene naturally do to a plant

Answer 40

influences growth by controlling cell division and stimulates enzymes that cause fruit to ripen

Question 41

what can ethene be used for commercially with plant s

Answer 41

speed up ripping so can be picked when unripe and ripened on way

ripening can be delayed by adding chemical that blocks ethene or react with it to remove it from the air so the fruit can be stored for longer