Progress Check

Questions on Transport in Animals

1. What is the job of platelets?

2. Why do red blood cells lack a nucleus?

3. Why do veins have valves?

4. What blood vessel carries blood from the heart to the lungs?

5. Why is the right side of the heart coloured blue in the diagram?

6. Some people have a defect in the bicuspid valve. Explain why this can lead to a build up of blood in the blood vessels of the lungs.

Answers

1. To clot the blood.

2. To fit more haemoglobin in and so carry more oxygen.

3. To stop the blood flowing backwards as the pressure is low.

4. Pulmonary artery.

5. It contains deoxygenated blood (which is dark red, not blue).

6. When the left ventricle contracts some of the blood goes back into the left atrium rather than out into the aorta. This causes a backlog of blood in the veins coming back from the lungs.

Questions on Transport in Plants

1. In which direction in a plant stem does water and minerals move?

2. What is translocation?

3. Where in a plant root is xylem found?

4. What is the function of root hair cells?

5. Why is it impossible for plants to prevent all water loss from the leaves?

6. What causes stomata to close when a plant wilts?

Answers

1. Up, towards the leaves.

2. The movement of dissolved food through the phloem.

3. In the centre, in a star shape.

4. To increase the surface area for water absorption.

5. Because carbon dioxide must be allowed in for photosynthesis.

6. The guard cells lose water by osmosis and so the cells become flaccid, straightening up and closing the pore.

Questions on Digestion & Absorption

1. Why does bread start to taste sweet if it is chewed for several minutes?

2. What is the function of the gall bladder?

3. What are the products of fat digestion?

4. Why is fructose used in sweets rather than glucose?

5. The lining of the stomach is protected by mucus. Why does it need to be protected?

6. People who have coeliac disease may have many of their villi destroyed. What effect might this have on the process of absorption? Explain your answer.

Answers

1. The starch is being digested into the sugar maltose by amylase.

2. To store bile.

3. Fatty acids and glycerol.

4. It is sweeter so less is needed.

5. So that the acid does not damage it and the protease does not digest it.

6. Slows down the rate of absorption as there is a smaller surface area.