Animal Hormones (Edexcel GCSE Biology)

Adrenaline and thyroxine are two important hormones produced by the human body.

Explain why they are classified as hormones.

State which body system releases hormones

Figure 1 shows a list of hormones in the human body.

Figure 1

(i) Complete the empty cells in Figure 1 by identifying the endocrine gland that releases each hormone.

(3)

(ii) State which hormone controls the development of male secondary sexual characteristics.

(1)

Like the nervous system, the endocrine system is a regulatory system and they share some common features such as sending a message as shown in Figure 2.

Figure 2 

Higher Tier only

(i) Thyroxine is a hormone that affects metabolic rate.

State which gland in the human body releases thyroxine.

(1)

(ii) Explain how negative feedback controls thyroxine levels.

(6)

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

(i) 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

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

(2)

(ii) 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 characteristiacs to develop.

In girls, the menstrual cycle also begins.

(i) 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

(i) 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

(i) 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.

(i) 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

(i) 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)

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

  (1)

Higher Tier Only

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)

Higher Tier Only

Hormones can also be used to treat infertility.

Explain how clomifene therapy and IVF can improve female fertility.

Higher Tier Only

(i) Women with the condition known as polycystic ovary syndrome (PCOS) do not ovulate regularly.

Women with PCOS can be treated using clomifene therapy.

Clomifene therapy stimulates the production of FSH.

Name the endocrine gland that produces FSH.

(1)

(ii) During this therapy, a woman takes a clomifene tablet each day for the first five days of her menstrual cycle.

Describe the changes that would happen inside the ovaries during the first five days of this treatment.

(2)

(iii) Which hormone causes ovulation?

(1)

(iv) During clomifene therapy, the woman has a blood test on day 20 of the menstrual cycle.

The blood test shows a high level of progesterone.

Explain the cause of this high level of progesterone on day 20 of the menstrual cycle.

(2)

Hormones are also used as a method of contraception.

Explain why taking high levels of oestrogen and progesterone in the combined contraceptive pill reduces the chance of pregnancy.

The female population of Britain is 32.6 million.

The percentage of this population taking the combined contraceptive pill is 13.2 %.

The combined pill is 98.8 % effective.

Calculate the maximum number of females taking the combined contraceptive pill who could become pregnant.

Figure 1 shows the usage of different forms of contraception in four groups of 100 women.

Each group used a different form of contraception.

Figure 1

Evaluate the effectiveness of the different methods of contraception shown in Figure 1.

Explain which method(s) of contraception would help to prevent the spread of sexually transmitted diseases. 

Explain how contraceptive pills can be used to reduce fertility.

Intra-Uterine Devices (IUDs) are devices that are placed into the uterus to help prevent pregnancy.

There are two main types, plastic IUDs that release progesterone and copper IUDs. Figure 2 shows how many days menstrual bleeding occurs post implantation with either copper or progesterone-containing IUDs.

Figure 2

Explain why there are differences in the number of days of menstrual bleeding between the two devices.

Higher Tier Only

The hormones FSH and LH are used in IVF.

Explain the use of FSH and LH in IVF. 

Higher Tier Only

A private fertility clinic undertook an 'in house' scientific study to investigate the success of IVF treatment in their patients. Two cohorts of women were included in the study, one group were under 40 years of age and the other group was over 40 years of age. The results of the study are shown in Table 1.

Table 1

Calculate the percentage chance that a 45 year old woman would have successful IVF treatment.

Higher Tier Only

Based on their study (described in part b), the fertility clinic published an advert claiming that their clinic was more successful than the UK national average. Figure 6 shows the information published.

Figure 6

Evaluate the validity of their claim (use the data in Table 1 to support your answer).

Higher Tier Only

Adrenaline is commonly known as the 'fight or flight' hormone, but adrenaline is also released in many other situations such as undertaking dangerous activities or running a race.

Explain why the release of adrenaline can be advantageous to a competitive athlete. 

Higher Tier Only

Adrenaline can be used in some medical emergencies, such as anaphylaxis (potentially lethal allergic reaction) or to reverse cardiac arrest (heart attack).

Suggest why adrenaline is useful in trying to restore heart function. 

Higher Tier Only

Explain the homeostatic mechanisms involved in the control of metabolic rate.

Higher Tier Only

The hormone thyroxine contains iodine within its chemical structure.
Iodine is an essential nutrient in the diet as it cannot be synthesised by the human body.

Suggest the effect of a deficiency of dietary iodine on the human body.

Higher Tier Only

The following hormones are involved in the menstrual cycle:

• Follicle stimulating hormone (FSH)

• Luteinising hormone (LH)

• Oestrogen

• Progesterone

Draw an annotated graph showing how the levels of the above hormones change throughout the menstrual cycle.

Higher Tier Only

Suggest how oestrogen functions in both positive and negative feedback within the menstrual cycle.

Figure 1 shows changes in the thickening of the uterus wall lining in two women X and Y.

 Figure 1

Suggest why the thickness of the uterus wall lining is different between the two women.

Higher Tier Only

Explain how the levels of LH and progesterone will differ between the women X and Y during the next calendar month (assume a normal menstrual cycle for woman Y).