B11

Question 1

Thermoregulatory centre

Answer 1

In brain
Contains receptors sensitive to temperature of blood in brain
Receives information from skin cells about skin temperature

Question 2

When body too hot

Answer 2

Sweat produced from sweat glands and evaporates from skin, transferring energy to environment
Blood vessels supplying skin dilate so blood flows closer to surface - vasodilation

Question 3

When body too cold

Answer 3

Hairs stand up to trap insulating layer of air
No sweat
Blood vessels supplying skin constrict to close of skins blood supply - vasoconstriction
Shiver, which needs respiration which transfers some energy to warm body

Question 4

Pituitary gland

Answer 4

In brain
Produces many hormones
Called master gland as hormones it produces stimulates other glands

Question 5

Ovaries

Answer 5

Produce oestrogen

Question 6

Testes

Answer 6

Produce testosterone which controls puberty and sperm production

Question 7

Thyroid

Answer 7

Produces thyroxine which

Regulates rate of metabolism, heart rate and temperature

Question 8

Adrenal gland

Answer 8

Produces adrenaline

Question 9

Pancreas

Answer 9

Produces insulin used to regulate blood sugar levels

Question 10

When blood glucose level too high

Answer 10

Insulin secreted by pancreas

Glucose moved from blood into liver and muscle cells to be stored as glycogen

Question 11

Blood glucose level too low

Answer 11

Glucagon secreted by pancreas

Liver turns glycogen into glucose and releases into blood

Question 12

Type 1 diabetes

Answer 12

Pancreas produces little or no insulin
Need insulin therapy, injections of insulin throughout day
Limiting intake of food with simple carbohydrates

Question 13

Type 2 diabetes

Answer 13

People become resistant to own insulin
Overweight increase chances of this happening
Regular exercise

Question 14

Menstrual cycle

Answer 14

Stage 1 - Day 0-4 uterus lining breaks down
Stage 2 - Day 4-14 uterus lining builds up again into a thick layer full of blood vessels
Stage 3 - Day 14 ovulation
Stage 4 Day14-28 wall maintained

Question 15

FSH

Follicle stimulating hormone

Answer 15

Produced in pituitary gland
Causes egg to mature in one of ovaries in a structure called a follicle
Stimulates ovaries to produce oestrogen

Question 16

Oestrogen

Answer 16

Produced in ovaries
Causes lining of uterus to grow
Stimulates release of LH
Inhibits release of FSH

Question 17

LH

Luteinising hormone

Answer 17

Produced by pituitary gland

Stimulates ovulation

Question 18

Progesterone

Answer 18

Produced in ovaries by remains of follicle after ovulation
Maintains lining of uterus
Inhibits release of FSH and LH
When progesterone levels fall lining breaks down

Question 19

Hormonal Control for Fertility

Answer 19

If oestrogen is taken every day it inhibits production of FSH and after a while egg development stops
Progesterone reduces fertility - production of thick mucus which prevents sperm getting through
Pill - contains oestrogen and progesterone, over 99% effective, headaches and nausea
Contraceptive patch - oestrogen and progesterone
Contraceptive implant - progesterone stops ovaries releasing eggs
IntaUterineDevice - t-shaped device, kills sperm

Question 20

Barrier methods

Answer 20

Diaphragm - shallow plastic cup fits over cervix to form barrier
Spermicide - only 70-80%

Question 21

Sterilisation

Answer 21

Cutting and tying fallopian tubes in female

Sperm duct in male

Question 22

IVF

In vitro fertilisation

Answer 22

FSH and LH are given to stimulate several eggs to mature so multiple collected
Collecting eggs from ovaries and fertilising in lab
Can involve Intra-Cytoplasm Sperm Injection where sperm is injected directly into egg
Fertilised eggs grown into embryos in a incubator
Once tiny balls of cells 2 transferred to uterus

Question 23

Cons of IVF

Answer 23

Multiple births are common, higher risk of miscarriage, stillbirth
Success rate low, 26%
Unused embryos may be destroyed

Question 24

Thyroxine

Answer 24

Thyroid stimulating hormone released from pituitary gland
Stimulates thyroid gland which release thyroxine
Regulates basic metabolic rate and stimulates protein synthesis for growth and development

Question 25

Auxin

Answer 25

Plant growth hormone
Controls growth near tips of shoots and roots
Shoots grow in response to light (phototropism)
Root response to gravity (gravitropism + geotropism)

Question 26

Shoots grow towards light

Answer 26

Shoot tip exposed to light
More auxin accumulates on side in shade
Makes cells elongate on shaded side so bends towards light

Question 27

Shoot grow away from gravity

Roots towards gravity

Answer 27

When shoot growing sideways more auxin on lower side
Lower side grows faster bending upwards

Root growing sideways also has more auxin on lower side
In roots the auxin inhibits growth so cells on top elongate faster, root bends downwards

Question 28

Auxin commercial uses

Answer 28

Killing weeds - weedkillers have been developed that only affect broad leaves to leave crops untouched
Rooting Powder - add rooting powder to cuttings to grow clones
Growing cells in tissue culture - tissue culture can be used

Question 29

Gibberellin commercial use

Answer 29

Stimulates seed germination, stem growth, flowering
Controlling dormancy - Makes them germinate at certain times of year
Inducing flowering - grow bigger flowers, flower any time they want
Growing larger fruit

Question 30

Ethene

Answer 30

Gas produced by ageing parts of plant
Influences growth by controlling cell division
Stimulates enzymes that cause fruit to ripen
Fruit can be picked unripe and made ripe when transported

Question 31

Adrenaline

Answer 31

Released by adrenal glands just above kidneys

Increases supply of oxygen and glucose to cells in brain and muscles