CORE PRACTICAL 8

Question 1

What is core practical 8? (1)

Answer 1

investigate factors affecting water uptake by plant shoots using a potometer.

Question 2

what is the first step of this practical? (1)

Answer 2

Lay the capillary tube and rubber connector under water and fill both parts. .

Question 3

what is the second step of this practical? (2)

Answer 3

2. Carefully select a leafy shoot which has a stem as close in diameter to that of the rubber connector as possible. Keep the end of the shoot under water at all times while you select and trim it as necessary

Question 4

what is the third step of this practical? (1)

Answer 4

3. Quickly insert the shoot into the rubber connector, making sure the fit is as tight as possible. Carry out this step under water.

Question 5

what is the fourth step of this practical? (2)

Answer 5

4. Firmly clamp the capillary tube to the stand with the shoot at the top end. Place the bottom end of the capillary tube into the beaker of water. Two people may need to carry out this step to avoid the leafy shoot becoming detached.

Question 6

what is the fifth step of this practical? (2)

Answer 6

5. Smear petroleum jelly around the join between the shoot and the rubber connector to ensure an airtight seal. Dry the leaves by blotting them gently with paper towels.

Question 7

what is the sixth step of this practical? (4)

Answer 7

6. Leave the apparatus for 5 minutes to allow water to be drawn up into the end of the capillary tube. A small air bubble should be present at the end of the capillary tube from the time spent out of water in step 4. If there is no air bubble, the tube can quickly be removed from the water and a piece of paper towel can be used to soak a little water from the open end. When the tube is replaced in the beaker of water a small air bubble should be visible.

Question 8

what is the seventh step of this practical? (2)

Answer 8

7. Time the movement of this air bubble along the capillary tube for a set distance.
   Alternatively, measure the distance moved by the bubble in a set time. Record
   your results in a suitable table.