Bio Practicals 2

Question 1

Model practical in algae balls

Answer 1

• IV-> distance of algal cells from lamp
• DV-> record of pH of surrounding solution
• CV-> mass of algal cells, time of practical, interval of distance

1. Add 10-15 algae balls to each bottle
2. Place a container algae balls at set distances from lamp; 0cm, 10cm, 20…
3. Add same volume of indicator solution to each bottle & replace the cap
4. Compare colour of each bottle to the pH chart to identify starting pH
5. Place tank of water between lamp & area you place your tubes
6. Cover 1 bottle with foil so it’s in dark closest to lamp
7. Turn on lamp & wait 60 mins
8. Compare colour of bottles with pH chart & record final pH
9. For each bottle calculate change in pH

Question 2

Light intensity on pondweed

Answer 2

• IV-> distance of pondweed from lamp
• DV-> bubbles produced in 1 min
• CV-> mass of pondweed, temperature, carbon dioxide concentration

1. Set up boiling tube with 49ml sodium hydrogen carbonate
2. Cute piece of pondweed to 8cm & insert into boiling tube
3. Place boiling tube into beaker of water
4. Place the lamp at 10cm away from the pondweed & count bubbles produced in 1 min
5. Repeat for other distances

Question 3

Investigating transpiration rate

Answer 3

• IV-> time
• DV-> distance moves by bubble along capillary tube
•CV-> temperature, air flow, supply of water

1. Record place of air bubble at start of experiment
2. Start time
3. Record position of air bubble after time is up
4. Divide distance by time (transpiration)

Question 4

Respiration

Answer 4

1.Measure 10 ml of soda lime into boiling tube. Use cotton wool to protect you & organism
from soda lime.
2. transfer small organisms (e.g. maggots or meal worms) in weighing boat into tube
3.Insert bung & capillary tube into
boiling tube
4. Set up control tube without small
organisms.
5. Place both tubes in rack that is slightly tilted at an angle in the water bath at set temperature.
6. Wait for 5 min for organisms to adjust to temperature
7. Add coloured liquid to end of capillary tube & mark starting position.
8. Time for 5 mins & mark position of coloured liquid again.
9. Measure distance travelled.
10. Repeat at different temperatures Use same number of small
organisms each time.