Topic 10 Hormones

Question 1

Describe the endocrine system

Answer 1

a system composed of glands which secrete chemicals called hormones directly into the bloodstream.

Question 2

What does the blood help the hormones with?

Answer 2

The blood carries the hormone to a target organ where it produces an effect.

Question 3

Compare the endocrine system with the nervous system.

Answer 3

Nervous system:
Very fast actions act for a very short time and act on a very precise area

Endocrine systems:
Slower action
Act for a LONG TIME
Act in a more GENERAL way

Question 4

The pituitary gland is the gland in the ——— and can be described as the———-
It:

Answer 4

brain
master gland

secretes several hormones into the blood in response to body conditions. These hormones in turn act on other glands to stimulate other hormones to be released.

Question 5

Identift the different glands:)

Ignore arrow five and three

Answer 5

1. Pituitary gland
2. Thyroid
3. Adrenal
4. Pancreatic
5. Ovary
6. Testes

Question 6

Describe how reproductive hormones cause secondary sex characteristics to develop at puberty.

Answer 6

In men, the main reproductive hormone is testosterone. It’s produced by the testes and stimulates sperm production. As well as the development of facial hair.

In women, the main reproductive hormone is oestrogen. It’s produced by ovaries. As well as bringing about physical changes like development of breasts and periods.

Question 7

Describe how the menstrual cycle is regulated by four hormones. State where the hormones are produced and how they affect a woman’s body:

Answer 7

• FSH (Follicle Stimulating Hormone) is produced in the pituitary gland. Causes an egg to mature in one of the ovaries, in a structure called a follicle. Stimulates the ovaries to produce oestrogen
• Oestrogen
  produced in the ovaries. Causes the lining of the uterus to grow. Stimulates the release of LH (which causes the release of an egg) and inhibits release of FSH.
• LH (Luteinising Hormone)
  Produced by the pituitary gland
  Stimulates the release of an egg at day 14 (ovulation)
• Progesterone
  Produced in the ovaries by the remains of the follicle after ovulation. Maintains the lining of the uterus during the second half of the cycle. When the level of progesterone falls, the lining breaks down.
  Inhibits the release of LH and FSH

Question 8

List barrier methods of contraception and what they do:

Answer 8

condoms and diaphragms which prevent the sperm reaching an egg

Question 9

intrauterine devices do what:

Answer 9

prevent the implantation of an embryo or release a hormone

Question 10

Describe female and male sterilisation and its effects

Answer 10

in female this involved the cutting or tieing of tubes (which connect the ovaries to the uterus) or the sperm duct (the tube between the testes and penis) in a male. This is a permanent procedure however, there is a very small chance that the tubes can rejoin.

Question 11

spermicidal agents which

Answer 11

kill or disable sperm

Question 12

Natural methods of avoiding pregnancy

Answer 12

abstaining from intercourse when an egg may be in the oviduct

general abstinence

Question 13

How do oral contraceptives work:

Answer 13

contain hormones to inhibit FSH production so that no eggs mature

Question 14

injection, implant or skin patch contraceptives use

Answer 14

slow release progesterone to inhibit the maturation and release of eggs for a number of months or years.

Question 15

what is a diaghragm and how does it work?

Answer 15

a shallow plastic cup that fits over the cervix to form a barrier and had to be used with spermicides

Question 16

Explain the use of hormones in modern reproductive technologies to treat infertility:

Answer 16

Some women have levels of FSH that are too low to cause eggs to mature. This means that no eggs are released and the women can’t get pregnant.
FSH and LH can be given as a fertlity drug to stimulate ovulation.

Question 17

Describe In Vitro Fertilisation (IVF) treatment.

Answer 17

IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs.
The eggs are collected from the mother and fertilised by sperm from the father in the laboratory.
The fertilised eggs develop into embryos.
At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother’s uterus (womb).

Question 18

Evaluate IVF and understand and talks about tech adanvancements

Answer 18

Although fertility treatment gives a woman the chance to have a baby of her own:
it is very emotionally and physically stressful some women have strong reactions to the hormones e.g abominal pain dehydration and vomiting
the success rates are not high
it can lead to multiple births when too many eggs are stimulated which are a risk to both the babies and the mother. This is because there is a higher risk of miscarriage and still birth
Advances in the have improved IVF:
-microscope techniques more succesful
-micro tools have been developed to remove single cells from the embryo for genetic testing
- time-lapsing imaging so development of embryos an be monitored continuously

Question 19

Explain the roles of thyroxine and adrenaline in the body.

Answer 19

Adrenaline is produced by the adrenal glands in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’.
Thyroxine from the thyroid gland stimulates the basal metabolic rate. It plays an important role in growth and development

Question 20

Thyroxine levels are controlled by ———————–

Answer 20

the pituitary gland in the brain

Question 21

Plants produce hormones to coordinate and control growth and responses to light ——–
and to gravity ————

Answer 21

phototropism
gravitropsim or geotropism

Question 22

Gibberellins are important in initiating :
Gibberellins can be used to:

Answer 22

seed germination

end seed dormancy
promote flowering
increase fruit size

Question 23

Ethene controls :
It is used in the food industry to control:

Answer 23

cell division and ripening of fruits
ripening of fruit during storage and transport.

Question 24

Auxins are used:

Answer 24

as weed killers
as rooting powders
for promoting growth in tissue culture.

Question 25

Why are some people against IVF:

Answer 25

The process of IVF often results in unused embyros that are eventually destroyed. Because of this, some people think it is unethical because each embryo is potentially a human life

The genetic testing of embryos before implantation also raises ethical issues as some people think it could lead to the selection of preferred characteristics, such as gender or eye colour.

Question 26

Describe a method for investigating the rate of plant growth responses

Answer 26

Place cotton wool in three petri dishes
Pour an equal volume of water into each petri dish
Evenly spread 10 seeds out in each petri dish
Place one petri dish in the dark, one in partial light and one in full light
Measure the height of the seedlings in each petri dish every day for 5 days

Question 27

control variables:

Answer 27

Volume of water in each petri dish
Type of seed / plant used
Number of seeds in each petri dish

Question 28

Independent variable is

Dependent variable is

Answer 28

light intensity

Height / growth of seedlings

Question 29

Why is it important to keep the number of seedlings in each petri dish the same:

Answer 29

Seedlings could compete with each other for light or water

Question 30

Describe the main sources of error

Describe how to improve the accuracy of the experiment

Answer 30

Measuring the height accurately as stems can be curved (dependent variable)

Repeat and calculate a mean

Question 31

Suggest an uncontrolled variable

Answer 31

Seedlings may have got light from different directions
Temperature could vary

Question 32

Describe how to improve the validity of the experiment

Answer 32

Using more seedlings and calculating a mean
Make sure light is coming from directly above
Grow the seedlings in temperature controlled greenhouse

Question 33

Describe how you could change the experiment to investigate something different:

Answer 33

Change the volume of water in each petri dish but keep the light intensity the same
Change the type of seed in each petri dish but keep light intensity the same
Change the number of seeds in each petri dish but keep light intensity the same

Question 34

Describe and explain how unequal distributions of auxin cause unequal growth rates in shoot tips and roots.

Include the 3 different examples

Answer 34

When a shoot is growing sideways, gravity produces an unequal distribution of auxin the tip, with more auxin on the lower side. This causes the lower side to grow faster bending the shoot upwards.

A root growing sideways will also have more auxin on its lower side. But in a root the extra auxin inhibits growth. This means the cells on top elongate faster and the root bends downwards.

When a shoot tip is exposed to light more auxin accumulates on the side that’s in the shade than the side that’s in the light. This makes the cells grow faster (elongate) on the shaded side, so the shoot bends towards the light

Question 35

How does the everyday use of hormones as weed killers has an effect on biodiversity

Answer 35

many cereal crops and grasses are narrow leaved plants. Most weeds are broad leaves plants. The amount of hormone weed killer absorbed by a plant largely depends on the surface area of the leaf so broad leaved weeds absorb much more than narrow leaved cereal or grass plants. As a result crop plants are mainly unaffected but the broad leaved weeds go into uncontrollable growth and die. Because these chemicals affect one type of plant and not another they are called selective herbicides.

Question 36

IVF stands for

Answer 36

in vitro fertilisation