Question 

(a) Fig. 4.1 is a diagram of the heart. 

(i) Identify the parts labelled B, C and D in Fig. 4.1.

(ii) Describe the function of the structure labelled E.

(iii) The blood vessel labelled A is an artery. Describe the role of arteries in the circulatory system.

▶️Answer/Explanation

(i) B: septum, C: muscle / muscle wall, D: ventricles
(ii) Ensure one-way flow of blood.
(iii) Transport blood away from the heart.

(b) Name two of the main components of blood.

▶️Answer/Explanation

1: Red blood cells
2: White blood cells
(Other possible answers: platelets, plasma)

(c) A student measures their heart rate over a 24-hour period. Fig. 4.2 shows a graph of the results.

(i) Calculate the difference in heart rate between the minimum and maximum heart rate seen in Fig. 4.2.

(ii) At 10:00 hours the student attends a fitness class. Estimate the length of time of the fitness class.

(iii) At 18:00 hours the student was scared by a snake. Describe and explain the result seen at 18:00 hours in Fig. 4.2. Use ideas about hormones in your answer.

▶️Answer/Explanation

(i) 110 bpm
(ii) 4 hours
(iii) There is a rapid increase in heart rate (increase by 70 bpm or increase to 140 bpm) due to the release of adrenaline, which prepares the body for a “fight or flight” response.