CAPE BIOLOGY UNIT 2 - Circulation in Humans

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MRC Family School Biology CAPE Unit 2 Transport in Humans Name:___________________________________ 1.

Date:__________________________

The diagram below shows some blood cells that may be seen in a stained blood film when observed under a microscope.

A B

C

10 m

In the table below, name the cells A, B and C and give one function of each cell. Blood cell

Name of cell

One function

A

B

C (Total 6 marks)

2.

(a)

The table below refers to mammalian blood plasma and tissue fluid. If the statement is correct, place a tick ( ) in the appropriate box and if the statement is incorrect, place a cross ( ) in the appropriate box. Statement

Blood plasma

Contained in vessels Very low hydrostatic pressure Contains white blood cells 1

Tissue fluid

2 (3)

(b)

Most of the tissue fluid is reabsorbed into the blood in the capillaries. Suggest why this reabsorption is reduced in people whose diet is very low in protein. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… (2)

3.

The diagram below shows cross-sections of three different types of blood vessel, A, B and C.

A

B

5 m m

(a)

C

5 m m

0 .0 0 5 m m

Name the blood vessels A and B. A ............................................................................................................................... B ............................................................................................................................... (1)

(b)

State two ways in which blood vessel C is adapted to enable the formation of tissue fluid. 1 ................................................................................................................................ ................................................................................................................................... 2 ................................................................................................................................ ................................................................................................................................... (2)

(c)

Give one function of tissue fluid. ……………………………………………….……………………………………… (1)

(d)

When tissue fluid is not efficiently reabsorbed, it collects in tissues causing swelling (oedema). 2

3 Suggest one factor that could cause oedema. ……………………………………………….……………………………………… ……………………………………………….……………………………………… (1) (Total 5 marks)

4.

The diagram below shows the structure of the heart and some associated blood vessels.

(a)

Name the parts labelled A, B and C. A ................................................................................................................................... B ................................................................................................................................... C ................................................................................................................................... (2)

(b)

Describe how the structure of the left ventricle and the parts labelled B and C enable the left ventricle to carry out its function. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... 3

4 ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (4)

5.

The graph below shows changes in the blood pressure in the aorta and the left ventricle during two complete cardiac cycles.

(a)

On the graph, draw an arrow to show when the left atrioventricular (mitral) valve closes. (1)

(b)

Use the information in the graph to calculate the heart rate. Show your working.

Answer .................................. (2)

(c)

During the cardiac cycle, the pressure in the left ventricle falls to a much lower level than in the aorta. Suggest an explanation for this difference. ……………………………………………….……………………………………… ……………………………………………….……………………………………… ……………………………………………….……………………………………… ……………………………………………….……………………………………… ……………………………………………….……………………………………… 4

5 ……………………………………………….……………………………………… (3)

(d)

During the cardiac cycle, the pressure in the right ventricle rises to a maximum of about 3.3 kPa. Suggest reasons for the difference between this pressure and the maximum pressure in the left ventricle. ……………………………………………….……………………………………… ……………………………………………….……………………………………… ……………………………………………….……………………………………… ……………………………………………….……………………………………… ……………………………………………….……………………………………… ……………………………………………….……………………………………… (3)

6.

The graph below shows oxygen dissociation curves for haemoglobin at two different partial pressures of carbon dioxide.

(a)

(i)

From the graph, determine the percentage saturation of haemoglobin with oxygen at a partial pressure of oxygen of 4.2 kPa, at low and at high partial pressures of carbon dioxide. Low partial pressure of carbon dioxide ................................................................. 5

6 High partial pressure of carbon dioxide ................................................................ (1)

(ii)

High partial pressures of carbon dioxide are found in active tissues such as muscle. Suggest why the difference between the percentage saturation of haemoglobin at low and at high partial pressures of carbon dioxide is important for the functioning of such tissues. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... (3)

(b)

Describe how the carbon dioxide produced in tissues is transported in the blood to the lungs. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (5) (Total 9 marks)

7.

(a) Explain why the mammalian circulatory system is described as a closed double circulation. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ......................................................................................................................................[2] (b) Mature mammalian red blood cells have no nuclei. State one advantage and one disadvantage of this. advantage ........................................................................................................................ .......................................................................................................................................... 6

7 .......................................................................................................................................... disadvantage .................................................................................................................... .......................................................................................................................................... ......................................................................................................................................[2] (c) The changes in blood pressure in the right atrium are the same as those in the left atrium. The changes in blood pressure in the right ventricle are different from those in the left ventricle. Explain why this is so. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ..................................................................................................................................... [4] 8.

Explain what is meant by each of the following terms. (a)

The cardiac cycle ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (3)

(b)

Coronary circulation ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (3)

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