These eight questions move from naming to data and explanation. Write your answer before you open the explanation.
The lessons are in transport in plants. Record your slips in the mistake log and paper-error review.
Questions
1. Name the tissue that carries water upwards and the tissue that carries sugar. (2 marks)
Answer
Xylem carries water and minerals upwards. Phloem carries sugar, mainly sucrose.
2. Explain how a root hair cell is suited to absorbing water. (2 marks)
Answer
It has a long thin extension that gives a large surface area. The cell sap has a lower water potential than the soil water, so water enters by osmosis.
3. State what transpiration is and name the structures that the water vapour leaves through. (2 marks)
Answer
Transpiration is the loss of water vapour from the leaf. It leaves through the stomata.
4. A shoot takes up 18 mm of water in 6 minutes. Calculate the rate of uptake. (2 marks)
Answer
18 ÷ 6 = 3 mm per minute.
5. The same shoot takes up 30 mm in 6 minutes when a fan blows on it. Calculate the rate and explain the change. (3 marks)
Answer
30 ÷ 6 = 5 mm per minute. The fan blows away water vapour near the stomata, which steepens the diffusion gradient, so transpiration is faster.
6. Explain why a plant may wilt on a hot, dry day even when the soil is wet. (3 marks)
Answer
Transpiration is fast because the air is dry and warm. Water leaves the leaves faster than the roots can supply it, so the cells lose turgor and the plant wilts.
7. Define translocation and give one example of a source and one sink. (3 marks)
Answer
Translocation is the movement of sucrose and other organic substances in the phloem. A leaf is a source. A root tuber or a fruit is a sink.
8. State two differences between xylem and phloem. (2 marks)
Answer
Xylem carries water upwards and its cells are dead and hollow. Phloem carries sucrose in both directions and its cells are living.
If you got these wrong
- Questions 1 to 3: revisit explaining water movement through a plant.
- Questions 4 to 6: work through interpreting transpiration data.
- Question 7: read explaining translocation.
- Question 8: see comparing xylem and phloem.
If the same type of error returns, a teacher can trace the cause quickly. See online one-to-one Biology tuition.