GCSE OCR Gateway Biology 4.2 Respiration: 20 (a) (i) Adrenaline is produce

Question

20 (a) (i) Adrenaline is produced by the body and prepares it for vigorous exercise.

Complete the sentences about adrenaline.

Adrenaline is a hormone made by **endocrine** **glands**.

Hormones are **chemical** messengers that travel in the blood.

(ii) Explain how two changes caused by adrenaline prepare muscles for exercise.

1. **Respiratory passages dilate/widen to provide the muscles with (more) oxygen**.

2. **Increased heart rate/blood pressure to provide the muscles with (more) oxygen/glucose**.

(iii) Explain how muscle cells get the energy needed to work during exercise.

**Cellular respiration** supplies ATP.

(b) The heart pumps blood through two systems:

A pulmonary circuit that goes to and from the lungs.
A systemic circuit that goes to the rest of the body and back to the heart.

(i) Which chamber of the heart receives blood from the pulmonary circuit?

**Left atrium**.

(ii) Which structure in the heart controls the direction of blood flow between the left atrium and left ventricle?

**Bicuspid** valve.

(iii) Which tissue in the wall of the heart contracts to pump the blood?

**Cardiac muscle**.

(c) Desert marathons take place in extreme heat. High external temperatures can cause dehydration.

Explain the changes shown by the graphs in Fig. 20.1 and Fig. 20.2.

**Increased heart rate to supply the muscles**.
**Body temperature compared to normal hydration**.

Suggest what an athlete could do in advance to minimize the effect of these challenges during a desert marathon.

1. **Drink enough fluids (before desert marathon)**.  
2. **Condition body by increasing daily heat exposure**.  
3. **Gradually increase the exercise intensity/duration each day**.

20 (a) (i) Adrenaline is produced by the body and prepares it for vigorous exercise - OCR Gateway - GCSE Biology - Question 20 - 2021 - Paper 1

Worked Solution & Example Answer:20 (a) (i) Adrenaline is produced by the body and prepares it for vigorous exercise - OCR Gateway - GCSE Biology - Question 20 - 2021 - Paper 1

Adrenaline is a hormone made by:

Hormones are:

Explain how two changes caused by adrenaline prepare muscles for exercise.

Explain how muscle cells get the energy needed to work during exercise.

Which chamber of the heart receives blood from the pulmonary circuit?

Which structure controls the direction of blood flow between the left atrium and left ventricle?

Which tissue in the wall of the heart contracts to pump the blood?

Explain the changes shown by the graphs in Fig. 20.1 and Fig. 20.2.

Suggest what an athlete could do in advance to minimise the effect of these challenges during a desert marathon.

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