B10 Animal and Plant Hormones

Question 1

What happens in stage one of the menstrual cycle?

Answer 1

Menstruation- the lining of the uterus breaks down for about 4 days

Question 2

Between which days does the uterus lining build back up?

Answer 2

From day 4-14

Question 3

What occurs in the third stage and when?

Answer 3

An egg is released from the ovary at day 14.

Question 4

For how long is the wall of the uterus maintained?

Answer 4

14 days, until around day 28

Question 5

What happens to the uterus wall if no fertilised egg has been received?

Answer 5

The spongy lining breaks down.

Question 6

What 2 things does follicle-stimulating hormone do?

Answer 6

• Trigger maturation of an egg in an ovarian follicle
• Stimulates the ovaries to produce oestrogen

Question 7

What does luteinising hormone do?

Answer 7

Stimulates the release of an egg

Question 8

What 3 things does oestrogen do?

Answer 8

• Causes uterus lining to grow/maintains it
• Inhibits FSH release
• Stimulates LH release

Question 9

What 2 things does progesterone do?

Answer 9

• Maintains the uterus lining
• Inhibits LH and FSH

Question 10

The falling level of which hormone causes the uterus lining to break down?

Answer 10

Progesterone

Question 11

Why can oestrogen be used as a contraceptive?

Answer 11

Maintaining high oestrogen levels inhibits FSH, so egg maturation and therefore egg release will stop.

Question 12

Why can progesterone be used as a contraceptive?

Answer 12

• Stimulates the production of thick mucus in the cervix which acts as a barrier
• Inhibits egg maturation and release

Question 13

Which contraceptive pill has the least side effects?

Answer 13

progesterone-only

Question 14

List 2 benefits of the oral contraceptive pill:

Answer 14

• 99% efficacy
• Reduces risk of some cancers

Question 15

List 2 disadvantages of the pill:

Answer 15

• Doesn’t protect against STDs
• Side effects- headaches, nausea

Question 16

What is a contraceptive patch?

Answer 16

A small patch containing oestrogen and progesterone that is stuck to the skin

Question 17

What is a contraceptive implant?

Answer 17

An implant inserted under the skin that releases progesterone

Question 18

What is a contraceptive injection?

Answer 18

An injection containing progesterone

Question 19

What is used with a diaphragm to increase its efficacy?

Answer 19

Spermicide

Question 20

Where is a diaphragm fitted?

Answer 20

Over the cervix

Question 21

What are the two types of IUDs?

Answer 21

• Hormonal IUDs- release progesterone
• Copper IUDs- make uterus inhabitable for sperm

Question 22

List 2 problems with fertility drugs

Answer 22

• Not always effective
• Excessive stimulation of eggs could lead to unexpected multiple pregnancies

Question 23

What does IVF stand for?

Answer 23

In vitro fertilisation

Question 24

What steps does IVF entail?

Answer 24

1. Woman given FSH and LH
2. Eggs collected from ovaries
3. Eggs fertilised in lab with sperm
4. Fertilised eggs grow into embryos in an incubator
5. Once formed, 1 or 2 embryos are transferred to the uterus

Question 25

List 3 disadvantages of IVF:

Answer 25

- Low success rate (26% in the UK) - Hormone side effects (abdominal pain, vomiting, dehydration) - Can lead to multiple births, which are riskier

Question 26

Name 2 social and ethical issues regarding IVF:

Answer 26

- Unused embryos are destroyed- killing potential lives - Genetic testing before implantation causes concern for selection based on certain characteristics

Question 27

Which gland releases TSH?

Answer 27

The pituitary gland

Question 28

What does thyroxine regulate?

Answer 28

Basal metabolic rate

Question 29

How is thyroxine level controlled?

Answer 29

By a negative feedback system

Question 30

Where are the adrenal glands found?

Answer 30

Above the kidneys

Question 31

When is adrenaline released?

Answer 31

In response to stress or fear

Question 32

How does adrenaline increase the supply of oxygen and glucose to cells?

Answer 32

By increasing your heart rate

Question 33

What does auxin control in plants?

Answer 33

Phototropism and geotropism

Question 34

Where is auxin produced?

Answer 34

The tips of roots and shoots

Question 35

Where do auxins tend to accumulate?

Answer 35

On the shaded and lower sides

Question 36

Explain what will happen in terms of growth to a shoot with a light source on its right hand side:

Answer 36

The auxins will accumulate on the left hand side as they move away from light. They will stimulate growth on this side, causing the cells on the left side to elongate faster than the right. This imbalance will cause the shoot to curve towards the source.

Question 37

How do shoots grow relative to gravity?

Answer 37

In the opposite direction- they are negatively geotropic

Question 38

Explain what will happen to shoot growing sideways in terms of growth:

Answer 38

The auxin will accumulate on the lower side of the shoot due to gravity, causing the cells on the lower side to elongate faster than on top. The shoot will end up pointing upwards.

Question 39

Auxin [...] root growth.

Answer 39

Inhibits

Question 40

Why do some selective weed-killers contain auxin?

Answer 40

It disrupts the growth patterns of broad-leaved weeds, killing them.

Question 41

How can auxin be used to grow plants from cuttings?

Answer 41

You can add rooting powder (containing auxins), which stimulates the growth of roots from the cutting.

Question 42

What type of plant hormones stimulate seed germination?

Answer 42

Gibberellins

Question 43

List 3 uses of gibberellins:

Answer 43

- Controlling dormancy- plants grow at any time and at same time - Inducing flowering - Growing larger fruit

Question 44

What gas is produced by aging parts of a plant?

Answer 44

Ethene

Question 45

What is the role of ethene?

Answer 45

- Controls cell division - Stimulates enzymes that ripen fruit

Question 46

How is ethene used commercially?

Answer 46

To speed up the ripening of fruit, so that it can be picked whilst still unripe

Question 47

Define ovulation

Answer 47

The release of an egg from the ovary

Question 48

Define phototropism

Answer 48

The growth of a plant in response to light

Question 49

Define geotropism

Answer 49

The growth of a plant in response to gravity

Question 50

Define dormancy

Answer 50

When a seed is temporarily unable to germinate even when conditions are favourable