Coronary heart disease can lead to the narrowing of coronary arteries, reducing blood flow to the heart muscle cells.

Table 1 shows how the percentage of the coronary artery's cross-sectional area that remains open affects the blood flow rate.

Table 1

Cross-sectional area open (%)	Blood flow rate ( $cm3/min\text{cm}^3\text{/min}$ )
100	200
80	140
60	80
40	36
20	8

Describe the trend shown in Table 1 between the open cross-sectional area and the blood flow rate.

Calculate the percentage decrease in the blood flow rate when the open cross-sectional area of the artery is reduced from $100%100\%$ to $60%60\%$ . Show your working.

Assuming the change in blood flow rate is linear between an open area of $20%20\%$ and $40%40\%$ , estimate the blood flow rate when the open cross-sectional area is $30%30\%$ . Show your working.

Coronary heart disease can lead to the narrowing of coronary arteries, reducing blood flow to the heart muscle cells.

Table 1 shows how the percentage of the coronary artery's cross-sectional area that remains open affects the blood flow rate.

Table 1

Cross-sectional area open (%)	Blood flow rate ( $cm3/min\text{cm}^3\text{/min}$ )
100	200
80	140
60	80
40	36
20	8

Describe the trend shown in Table 1 between the open cross-sectional area and the blood flow rate.

Calculate the percentage decrease in the blood flow rate when the open cross-sectional area of the artery is reduced from $100%100\%$ to $60%60\%$ . Show your working.

Assuming the change in blood flow rate is linear between an open area of $20%20\%$ and $40%40\%$ , estimate the blood flow rate when the open cross-sectional area is $30%30\%$ . Show your working.

2.2 Animal tissues, organs and organ systems

Question 20

Markscheme

2.2 Animal tissues, organs and organ systems

Question 20

Markscheme

2.2 Animal tissues, organs and organ systems

Question 20

2.2 Animal tissues, organs and organ systems Questions

2.2 Animal tissues, organs and organ systems

Question 20

2.2 Animal tissues, organs and organ systems Questions