GCSE AQA Biology Combined Science Plant Tissues, Organs & Systems: A student used a potometer to in

Question

A student used a potometer to investigate the rate of water uptake in a plant shoot.

Figure 3 shows a potometer.

As the shoot takes in water the air bubble moves.

The rate of water uptake is the distance the air bubble moves in a given time.

This is the method used.

1. Place the potometer in moist air at 25 °C
2. Position the air bubble at 0 mm in the capillary tube.
3. Record the position of the air bubble in the capillary tube every minute for 5 minutes.
4. Repeat steps 2 and 3 with the potometer in different conditions.

Table 3 shows the conditions used.

Table 3

| Investigation | Conditions          |
|---------------|---------------------|
| A             | Moist air at 25 °C  |
| B             | Dry air at 15 °C    |
| C             | Dry air at 25 °C    |

After investigation A the air bubble had moved part way along the capillary tube.

Suggest how the student moved the air bubble back to 0 mm for the start of investigation B.

Capillary tubing is very narrow.

Explain why narrow tubing was used.

Figure 4 shows the results for investigation A.

The cross-sectional area of the capillary tube was 0.8 mm².

Calculate the rate of water uptake for investigation A in mm³/min.

Rate = ___________ mm³/min.

Table 4 shows the results from investigation B.

Table 4

| Time in minutes | Position of air bubble in mm |
|----------------|------------------------------|
| 0              | 0                            |
| 1              | 6                            |
| 2              | 16                           |
| 3              | 26                           |
| 4              | 30                           |
| 5              | 42                           |

Plot the data from Table 4 on Figure 4.

You should:

- draw a line of best fit
- label the line B.

Investigation C was carried out in dry air at 25 °C.

Draw a line on Figure 4 to show the results you would expect for investigation C.

Label the line C.

The investigations were carried out in daylight.

The air bubble would not move if the investigations were done in the dark.

Explain why.

A student used a potometer to investigate the rate of water uptake in a plant shoot - AQA - GCSE Biology Combined Science - Question 3 - 2019 - Paper 1

Worked Solution & Example Answer:A student used a potometer to investigate the rate of water uptake in a plant shoot - AQA - GCSE Biology Combined Science - Question 3 - 2019 - Paper 1