B3.2

Question 1

What are hormones?

Answer 1

Chemical messengers made in the endocrine glands and secreted in the blood
Cause a response in specific cells within target organs

Question 2

What is homeostasis?

Answer 2

Keeping the body conditions constant

Question 3

What are the major endocrine glands?

Answer 3

Hypothalamus & Pituitary - regulate production of other hormones
Thyroid - produced thyroxine
Adrenal glands - produce adrenaline
Pancreas - produces insulin
Ovaries - produced oestrogen + progesterone
Testes - produce testosterone

Question 4

What are target cells?

Answer 4

Even though hormones travel all through the body in the bloodstream they only diffuse out and bind to the organs that have the specific receptors for that hormone
Once bound to the receptors the hormone stimulates a response from the target cells

Question 5

What is the endocrine system?

Answer 5

Collective name for all the endocrine glands and hormones they produce

Question 6

Differences between the nervous system & the endocrine system?

Answer 6

Nervous system used the nerves to send messages, endocrine used hormones
Nervous system is much fast
Messages travel as electrical impulses along an axon of a neurone, but through the blood in endocrine
Longer response with hormones
More precise area targeted with nervous system

Question 7

What is thyroxine?

Answer 7

• Produced in the thyroid gland
• regulates metabolic rate (speed at which body transfers energy from chemical stores)

Question 8

What is adrenaline?

Answer 8

• prepares body for intensive action

Question 9

What is negative feedback?

Answer 9

A mechanism that detects a change in the body condition, then corrects it so conditions are back to normal

Question 10

How is thyroxine controlled?

Answer 10

1) when more energy is required the hypothalamus causes the pituitary gland to release more TSH
2) this stimulates the thyroid gland to release thyroxine which increases the metabolic rate so cells transfer more energy
3) when the cells have enough energy, the hypothalamus inhibits the release of TSH
4) which causes the thyroid gland to stop releasing thyroxine

Question 11

How are adrenaline controlled?

Answer 11

1) when feeling threatened or scared, the brain signals the adrenal glands to secrete adrenaline
2) the body respites more quickly so produces more ATP
- increases the rate of breathing for higher oxygen demand
- increases heart rate
- diverts blood away from areas like the digestive system towards the muscles
3) when the stress is removed the brain signals the adrenal glands to stop secreting adrenaline

Question 12

What is the menstrual cycle?

Answer 12

Cycle in which the woman’s body gets ready for pregnancy
Lasts around 28 days
1)Each month the uterus lining thickens ready to receive a fertilised egg
2) At the same time an egg in the ovaries begins to mature
3) 14 days later the egg is release from the ovary (ovulation)
4) The uterus lining remains thick
If the egg is fertilised the egg will implant in the thick lining where it is protected and can receive the necessary minerals
If the egg is not fertilised, the uterus lining and egg are removed from the uterus as a period

Question 13

What are the different structures of the female reproductive system?

Answer 13

Ovary - where the egg matures
Uterus - where the fetid develops
Cervix - entrance to the uterus
Vagina - receives sperm from the penis during sexual intercourse
Fallopian tube (oviduct) - where the egg is fertilised before travelling along the the tube to the uterus

Question 14

What are the 4 key hormones of the menstrual cycle?

Answer 14

FSH (pituitary gland) - stimulates follicle (egg) to mature
Oestrogen (ovaries) - repair and break down of the uterus lining
LH (pituitary gland) - the peak of LH stimulates ovulation
Progesterone (ovaries) - maintains the uterus lining, high levels throughout pregnancy

Question 15

What is contraception?

Answer 15

Any method used to prevent pregnancy

Question 16

What are the two groups of contraception?

Answer 16

Non - hormonal - barrier methods that prevent sperm from contacting the egg or physical devices that release chemicals that kill the sperm cells
Hormonal - use of hormones to disrupt the normal female cycle

Question 17

What are the 3 non-hormonal methods of contraception?

Answer 17

Condom - placed over the penis or inside the vagina, prevents sperm entering the vagina
Diaphragm/cervical cap - inserted into vagina to cover up the cervix, prevents speed cells from entering the uterus
IUD - inserted into the uterus, releases copper which prevents sperm surviving in the uterus and oviducts

Question 18

What are the 3 hormonal methods of contraception?

Answer 18

Oestrogen and progesterone pill (combined pill) - prevents ovulation, thickens mucus from the cervix so speed cannot reach the ovum, prevents implantation of a fertilised egg into the uterus
Progesterone pill - thickens mucus from cervix to stop spleen reaching the ovum, thins the lining to prevent implantation
IUS - inserted into the uterus, same effect as progesterone as pill

Question 19

What are some causes of infertility?

Answer 19

• blocked fallopian tubes
• blocked sperm ducts
• not enough sorry produced by testes
• lack of mature eggs in the ovaries
• failure of egg to be released from ovaries

Question 20

What is IVF?

Answer 20

Where a doctor collects the eggs if the mother from the ovary and fertilises them outside the body with the fathers sperm
FSH and LH are given to the mother to ensure as many eggs are mature as possible

Question 21

What are the unethical arguments of IVF?

Answer 21

• not a natural process
• allows parents to conceive a child they wouldn’t have had
• enables older parents to have children
• may result in multiple births, dangerous for mother and babies
• treatment is very expensive
• limited availability through NHS

Question 22

What is a tropism?

Answer 22

The growth of a plant from a response to a stimuli
If the plant grows towards the tropism it is a positive tropism

Question 23

What is phototropism?

Answer 23

Growing towards the light
Stem grows towards the light for more photosynthesis so it can grow faster and increase chance of survival

Question 24

What is gravitropism?

Answer 24

Growing in the same direction as gravity
Roots grow downwards for anchorage and also to be closer to a water source

Question 25

What are auxins?

Answer 25

Coordinate and control directional growth
A plant hormone that stimulates shoot cells to grow more, but inhibits the growth of root cells

Question 26

How do gravitropism affect auxins?

Answer 26

If a shoot is placed on its side the auxins accumulate on the lower side
The cell will elongate on the lower side
In the roots the lower side will be inhibited so the upper part will elongate

Question 27

How does phototropism affect auxins?

Answer 27

If light shines from all directions on the shoot it will grow evenly
When light shines predominantly on one side the auxins accumulate to the other side so the dim side elongates
The shoot bends and grows in the direction of the light

Question 28

What are the other plant hormones?

Answer 28

Gibberellins - promote growth, stem elongation, can end seed dormancy
Ethene - causes fruit ripening, gas

Question 29

What are the commercial uses of auxins?

Answer 29

Killing weeds - makes the weeds grow too fast which kills the plant
Promote root growth - cut off shoot top and dip in rooting powder (contains auxins) and roots will develop
Delay ripening - to allow harvest to be collected at the same time
Producing seedless fruit (parthenocarpic) - auxins are applied to unpollinated flowers

Question 30

What is the commercial use of ethene?

Answer 30

Ripening fruit - sprayed on fruit trees to ripen quicker to be ready for growing season

Question 31

What is the commercial use of gibberellins?

Answer 31

Controlling dormancy - trigger seeds to germinate even in the winter by spraying gibberellins to grow in a greenhouse