Coordination & Control – the Endocrine System (OCR GCSE Biology A (Gateway))

Higher Tier only

Carolina horsenettle is a weed that grows in crop fields in the USA.

New horsenettle shoots develop from buds on roots in spring. The shoots die in the autumn but the roots remain alive under the ground.

Effective weed control involves stopping seed production and killing the root system.

Selective herbicides are used to control Carolina horsenettle.

The best time to apply selective herbicide is when the horsenettle is actively growing between the bud and flower stage.

(i) Describe how a selective herbicide works.

[2]

(ii) Fig. 20.1 and Table 20.1 show information about four different herbicides A, B, C and D.

Fig. 20.1

Table 20.1

Carolina horsenettle is growing in a field with a crop and other broad-leaved weeds.
Evaluate the information on selective herbicides A, B, C and D.

Which selective herbicide would be best to use and when it should be applied?
Explain your decision.

Higher Tier only

(i) Describe one effect that gibberellin hormones have on plants.

[1]

(ii) A student investigates ripening in bananas.

The student keeps bananas in different conditions. After 1 week he decides if each banana was ripe or not ripe.

The results were difficult to interpret so he planned to develop the experiment.

He found a picture that he thought he could use.

Explain how this could help develop his experiment.

[2]

Higher Tier only

A process in cells is involved in producing a chemical that causes ripening of fruit.
Look at Fig. 20.2.

Fig. 20.2.

Use evidence from Fig. 20.2 to suggest what this process might be.

Plant hormones are involved in controlling some processes in plants.

Which processes in plants are controlled by plant hormones?

Tick (✓) three boxes.

A child sets up an experiment to grow grass seeds in a plastic cup.

The grass seeds in cup A are grown directly under a window.

The grass seeds in cup B are grown by a window to the side.

Look at the results.

The child’s older brother and sister try to explain what has caused the results.

They make different conclusions.

(i) Explain why the sister has given the better conclusion.

 [2]

(ii) Name the hormone that causes phototropism.

 [1]

(i) Different hormones control the human menstrual cycle.

Complete the sentences to describe how the menstrual cycle is controlled.

Use words from the list.

Each word can be used once, more than once, or not at all.

fetus    follicle    FSH    oestrogen    progesterone

The hormone released by the pituitary gland is called ..................................... .

This hormone acts on the ovary and causes the growth of a ..................................... .

The hormone that maintains the lining of the uterus is called ..................................... .

[3]

(ii)The table shows the concentration of oestrogen in the blood during the first 7 days of the menstrual cycle.

Put a  around the days below which show a steady increase in the concentration of oestrogen.  

  Days 1–4    Days 2–5    Days 3–6    Days 4–7

[1]

The lining of the uterus is shed during menstruation.

New cells are needed to replace the lining of the uterus.

Describe the processes that occur to make these new cells.

Hormones are used in some methods of contraception.

(i) Which two hormones are found in the most commonly used contraceptive pills?.

Put a  around the two correct answers.

FSH    Insulin    Oestrogen    Progesterone    Testosterone

[1]

(ii) How does the contraceptive pill containing the two hormones prevent pregnancy?

[1]

Contraceptive hormones can be used by women in different ways.

Method 1
One contraceptive pill is taken every day at around the same time of day for 21 days. Then no pill is taken for seven days.

Fewer than 1 in 100 women will get pregnant in a year if they use the contraceptive pill correctly. However, typically 9 in 100 women will get pregnant in a year.

Method 2
A contraceptive implant is a small flexible plastic rod containing hormones. It is inserted under the skin of a woman by a doctor or nurse. It is reversible and needs replacing after 3 years.

Fewer than 1 in 100 women using the contraceptive implant will get pregnant in a year.

Which method is more successful?

Evaluate the information to explain why.

Non-hormonal contraceptive methods have different success rates in preventing women from getting pregnant. 

(i) Suggest one reason why sterilisation is not widely used in couples without children.

[1]

(ii) The diaphragm is a circular dome made of thin soft latex with a flexible rim. It fits inside the vagina forming a seal.

Suggest how a diaphragm acts as a contraceptive.

[1]

(iii) The cervical cap is like the diaphragm but smaller. It fits over the cervix.

Explain why the success rate of the cervical cap would be lower than that of the diaphragm.

[2]

Higher tier content only

The graph in Fig. 21.1 shows how the level of progesterone changes during the menstrual cycle.

Fig. 21.1

(i) Draw another line on the lower graph to show how the level of oestrogen changes during the menstrual cycle.

[2]

(ii) Describe how oestrogen and FSH interact during the menstrual cycle.

[2]

Higher tier content only

Endometriosis is a condition where the cells that normally line the uterus (womb) can move to other parts of the body.

During the menstrual cycle the cells that have moved can react in the normal way to the hormones controlling menstruation.
This can cause a number of problems including fatigue and pain.

Explain what happens to the cells that have moved and how doctors could treat the condition using sex hormones.

Use the information from the graph in Fig. 21.1 and your own knowledge.

Higher Tier only

Adrenaline is an important hormone in the body. It helps to prepare the body for a ‘fight or flight’ response.

Sports injuries which involve cuts and bleeding are often treated with a dilute solution of adrenaline.

Explain why.

Higher Tier only

The graph shows how the lining of the uterus changes during the menstrual cycle and also shows the level of progesterone in the blood.

(i) Where in the ovary is progesterone produced?

[1]

(ii) Draw a line to continue the graph to show the levels of progesterone until day 28 (assume that an egg has not been fertilised).

[2]

Higher Tier only

(i) An egg develops in a follicle before ovulation. The follicle has a diameter  of 25 ×10^-3mm at the start. This follicle grows to 20mm in diameter just before the egg is released. 

Calculate the increase in size of the diameter of the follicle.

Give your answer to 2 decimal places.

Answer = ....................................... mm [3]

(ii) The failure of a follicle to increase in size can result in less production of oestrogen.
Explain what effect this may have on the uterus.

[1]

(iii) Explain how hormones can be used to treat infertility in women.

[3]

(iv) Infertility can also be caused by problems in the male.

Plasmin is a protease enzyme important in sperm movement.

Explain how changes to the structure of DNA could result in the plasmin enzyme being faulty.

[2]

Higher tier content only

Look at the diagram. It shows changes to the uterus lining during the menstrual cycle.

(i) Which hormone would peak at point X?

 [1]

(ii) Name two hormones that peak immediately before ovulation.

1 ....................................................................
2 ....................................................................

[1]

Higher tier content only

Explain how hormones can be used by women for contraception.

Which hormone works with insulin to control blood sugar levels in the body?

Tick (✓) one box.

Scientists are using human embryonic stem cells to grow cells to treat type 1 diabetes.

Explain why scientists use embryonic rather than adult stem cells.

Higher tier content only

Plant development is also controlled by hormones.

Describe one effect of gibberellins and one effect of ethene on plant development.

gibberellins ............................
ethene ......................................