Topic 5c Animal and Plant Hormones

Question 1

What is the main reproductive hormone in women

Answer 1

Oestrogen - produced in the ovaries

Question 2

Give one effect testosterone has on the male body

Answer 2

stimulates the production of sperm

Question 3

Describe the four stages of the Menstural cycle

Answer 3

1. Menstruation - the uterus lining breaks down 1-4 days
2. The lining of the uterus builds up again ready to receive a fertilised egg 4-14 days
3. Ovulation - An egg is released from the ovary at day 14
4. The wall is maintained until day 28. If no egg has landed on the uterus wall the lining starts to break down and the cycle starts again

Question 4

What is FSH

Answer 4

FSH Follicle stimulating hormone causes an egg to mature in one of the ovaries in a structure called a follicle

Question 5

What is LH

Answer 5

Luteinising Hormone stimulates the release of an egg at day 14 (Ovulation)

Question 6

What role do Oestrogen and Progesterone play in the menstural cycle

Answer 6

They are hormones which are involved in the growth and maintenance of the uterus lining

Question 7

Which hormones inhibit the release of Follicle Stimulating Hormones (FSH)

Answer 7

Oestrogen and Progesterone

Question 8

Which two glands secrete the hormones that control the menstrual cycle

Answer 8

The Pituitary Gland and the Ovaries

Question 9

How does Oestrogen in the combined contraceptive pill Reduce fertility

Answer 9

If Oestrogen is taken everyday to keep Oestrogen levels permanently high it inhibits the production of Follicle Stimulating hormone and after a while the egg maturation and therefore release of the egg stop and stay stopped.

Question 10

Apart from Oestrogen what other hormone is found in the Combined Pill

Answer 10

Progesterone

Question 11

List the Negatives to using the combined Pill as a contraceptive method

Answer 11

1. It isnt 100% effective, slight chance of pregnancy
2. It can cause side effects like headaches, nausea, Irregular menstrual bleeding, and fluid retention
3. It dosent protect against STDs

Question 12

List the numerous methods of contraception

Answer 12

1. Combined Pill
2. Contraceptive patch - contains Oestrogen and Progesterone, sticks to skin, lasts one week
3. Implant - inserted under the skin, Releases continual amount of progesterone stopping the release of eggs from the ovaries, making it hard for the sperm to swim to the egg and stops any fertilised eggs implanting in the uterus. Can last 3 years
4. Contraceptive injection - contains progesterone and lasts 2-3 months
5. Condoms - worn over penis to stop sperm entering the vagina
   6 Diaphragm - shallow plastic cup that fits over the cervix to form a barrier to the uterus.
6. IUD Intrauterine device - T shaped device inserted into the uterus to kill sperm and prevent implantation of fertilised eggs
7. Sterilisation - involves cutting the sperm duct or tying the Fallopian tubes

Question 13

Which hormones can be taken to increase fertility in a woman, explain why

Answer 13

Women who have low levels of Follicle stimulating hormone lack the ability to mature their eggs and therefore the ability to release eggs in the ovaries. FSH and LH can be injected in order to stimulate this maturation and release.

Question 14

Describe the steps used in the IVF In Vitro Fertilisation process

Answer 14

1. FSH and LH are injected into the female to stimulate maturation of multiple eggs
2. Eggs are then collected from the females ovaries
3. Eggs are fertilised in the lab using male sperm
4. Fertilised eggs the grow into embryos in a lab incubator
5. Once the embryos are formed 1 or 2 of them are transferred to the uterus.

Question 15

What ethical issues surround IVF

Answer 15

The process of IVF often involves the destroying of unused embryos. Campaigners believe this is unethical as all embryos have the potential to become a human life.
Genetic testing of embryos before implantation also raises ethical issues as some people believe it could lead to the selection of preferred characteristics such as gender or eye colour.

Question 16

Give two roles of thyroxine in the body

Answer 16

Thyroxine:

1. helps regulate the bodies Basal Metabolic Rate (The speed at which all chemical reactions take place inside the body while at rest
2. Helps stimulate Protein synthesis for growth and development

Question 17

which gland are responsible for the release of adrenaline

Answer 17

Adrenal glands are responsible for the release of adrenaline and can be found just above the kidneys

Question 18

Pierre is suprised when a dog jumps up at him. His Heart rate starts to beat faster.

1. Name the hormone responsible for this response
2. Explain the purpose of this response

Answer 18

1. Adrenaline
2. It is released as a response to a stressful or scary situation. Your brain detects fear or stress which sends nervous impulses to the adrenal glands. They then secrete the hormone adrenaline into the blood triggering mechanisms to increase the supply of oxygen and glucose to the cells in the body.

Question 19

What is TSH

Answer 19

TSH refers to Thyroid stimulating Hormone and is a hormone released by the pituitary gland which tells the thyroid to release thyroxine

Question 20

What is Auxin

Answer 20

Auxin - A plant hormone that controls growth of a plant in response to stimuli

Question 21

Where is Auxin produced, what area of the plant

Answer 21

• Auxin is produced in the tips of roots and shoots of a plant.
• Moves backwards in order to stimulate the cell elongation process (Lengthening of Cells)

Question 22

What does Auxin control

Answer 22

• Phototropism = plant growth in response to light

- Gravitropism/Geotropism = Plant growth in response to gravity

Question 23

Explain how plant roots grow in response to gravity

Answer 23

More Auxin accumulates on the lower side of the root. As the extra auxin inhibits cell elongation in the roots, the cells on the top side of the root elongate faster, and the root bends towards gravity

Question 24

Where is the accumulation of auxin in a plant shoot tip exposed to light

Answer 24

The accumulation of auxin will occur on the side with less light exposure maker the cell elongate faster on the shaded side and causing the shoot to bend toward the light

Question 25

How would you investigate the effect of light on the growth of a cress seed

Answer 25

1. Put cress seeds into 3 different petri dishes lined with moist paper
2. shine light onto one of the petri dishes from above and from two other different directions
3. leave them to grow for a week until you can observe their response.
4. You will know the growth response will be a result of the light if you caontrol the variables e.g. number of seeds, temprature, light intensity, amount of water used

Question 26

Nmae the type of plant hormone that is found in rooting powder

Answer 26

Auxins

Question 27

Name the type of plant hormone that controls seed dormancy

Answer 27

Gibberellins

Question 28

What are Gibberellins

Answer 28

They are a type of plant growth hormone which stimulate seed germination, stem growth and flowering.

Question 29

Give three uses for gibberellins

Answer 29

1. Controlling dormancy - Seeds go through a period of hibernation known as dormancy. Seed dormancy must be broken for seeds to germinate (grow into plants) and this can be done by using gibberellins.
2. inducing flowering - some plants require certain conditions to flower e.g. Longer days lower temperature. If these plants are treated with gibberellins they will flower without any change in their environment.
3. Growing larger fruit - seedless varieties of fruit often do not grow as large as seeded fruit. Gibberellins can be used to make them grow larger to match seeded fruit

Question 30

What is ethene

Answer 30

Ethene is a gas produced by aging parts of a plant

Question 31

What does ethene do

Answer 31

• Influences plant growth by controlling cell division

- stimulates enzymes that cause fruit to ripen

Question 32

Describe how the level of thyroxine in the blood is kept to an optimum

Answer 32

The negative feedback loop
When the level of thyroxine in the blood is higher than normal, the secretion of the thyroid stimulating hormone TSH from the pituitary Gland is inhibited. This means the level of thyroxine released from the thyroid Gland is reduced.
So the level of thyroxine in the blood falls back to normal.

Question 33

What does progesterone do

Answer 33

Maintains the lining of the uterus during the second half of the cycle days 14 to 28