7.1 Animal Hormones

Higher Tier only

Thyroxine is a hormone that affects metabolic rate.

State which gland in the human body releases thyroxine.

(1)

Higher Tier only

A patient visited their doctor complaining about fatigue and feeling depressed about their recent weight gain.

The doctor weighed them and took a sample of blood for analysis.

The results are shown in Figure 1.

Figure 1

Describe what the results show in relation to the normal (reference) values.

(4)

(ii)

Explain why the doctor performed these particular blood tests.

(2)

(iii)

Based on the blood result for thyroxine, the doctor diagnosed hypothyroidism which is an underactive thyroid gland. 

Explain why an underactive thyroid could cause this patient to feel tired and have an increased body mass.

(4)

Higher Tier only

Explain why adrenaline is known as the ‘flight or fight’ hormone.

The menstrual cycle is regulated through the action of several hormones. 

Figure 1 shows the changes in hormones oestrogen and progesterone over the 28 day period of the menstrual cycle. It also shows the changes that occur in the uterus lining throughout that time.

Figure 1

Explain the reasons for the decrease in the thickness of the uterus lining shown between days 0 and 3.

(2)

Describe and explain the relationship between the concentration of oestrogen in the blood and the thickness of the uterus lining between days 7 and 14.

(3)

Explain how a pregnancy could be avoided by tracking the menstrual cycle accurately. 

During puberty reproductive hormones cause secondary sex characteristics to develop.

In girls, the menstrual cycle also begins.

Name the event that occurs around day 14 of the menstrual cycle

(1)

(ii)

The menstrual cycle is regulated through the action of several hormones.

State which hormones are produced mainly in the ovaries.

(2)

During sexual intercourse sperm cells are deposited in the vagina and pass through the cervix to the uterus and oviducts.

(i)

State which event could likely take place if sexual intercourse occurred around the time of ovulation.

(1)

(ii)

Describe what is meant by the term 'contraception'

(1)

(iii)

Explain how two different barrier methods of contraception work

(3)

Higher Tier only

Figure 1 shows the fluctuations in four hormones involved in the menstrual cycle.

Figure 1

Line A in Figure 1 represents LH (Luteinising hormone) which is released from the pituitary gland.

State which target organ LH acts on.

(1)

(ii)

State which other hormone involved in the control of the menstrual cycle is released by the pituitary gland.

(1)

(iii)

Explain how the four hormones represented in Figure 1 interact to control the menstrual cycle and ovulation.

(6)

A study was carried out to investigate the effectiveness of different methods of contraception in females.

Figure 1 shows the number of pregnancies in four sample groups of 100 women.

Each group used a different form of contraception.

Figure 1

Describe the pattern shown by the data in Figure 1

(4)

(ii)

The diaphragm (or cap) is known as a barrier method of contraception.

Name a barrier method of contraception that can be used by males.

(1)

(iii)

Calculate the percentage success rate for each method of contraception tested in the study.

(4)

Higher Tier only

A woman wishes to have a child with her partner but has been unable to fall pregnant naturally.

Her doctor diagnoses ovulatory disfunction and prescribes the drug clomifene.

Explain how clomifene therapy helps women who cannot conceive naturally.

(3)

(ii)

Clomifene would not be suitable in all cases of infertility. In vitro fertilisation (IVF) is often used.

Describe two scenarios when IVF could be recommended over clomifene therapy.

(2)

(iii)

Clomifene therapy and IVF are all forms of Assisted Reproductive Technology (ART).

State which important issues should be considered by couples starting on a course of treatment with ART.

(3)

Higher Tier only

The graph in Figure 2 shows how infertility and the likelihood of a woman falling pregnant change with age.

Figure 2

In 1975 the average age for a woman from the UK to have her first child was 26.4 years.

In 2019, the average age had risen to 30.2 years.

Discuss the impact of the increase in the average age of women having their first child. Use information from the graph to answer the question.

Higher Tier Only

Figure 1 shows the concentration of the hormones oestrogen and progesterone in the blood of women of different ages.

Figure 1

Use information from Figure 1 to explain why women over the age of 50 are less likely to ovulate.

(2)

(ii)

Use information from Figure 1 to explain why women are less likely to menstruate after the age of 60.

(2)

(iii)

Explain how clomifene therapy may increase the chance of a woman over the age of 50 becoming pregnant.

(2)

(iv)

The hormone progesterone is produced by the

(1)

Higher Tier Only

Explain how the release of adrenaline can result in the improved performance of an athlete.

Methods of contraception include use of hormones and barrier methods.

(i)

Which form of contraception is a barrier method?

(1)

State why a barrier method of contraception may be used in addition to a hormonal method.

  (1)

The combined contraceptive pill contains the hormones oestrogen and progesterone.

(i)

State the endocrine gland that releases oestrogen.

(1)

(ii)

Explain how high levels of oestrogen and progesterone in the combined contraceptive pill work together to prevent pregnancy.

(4)

Hormones can also be used to treat infertility.

Explain how clomifene therapy and IVF can improve female fertility.