Required practical

Question 1

Looking at cells under the microscope

Answer 1

• Clip slide onto the stage
• Start with the lowest power lens
• Focus the microscope using the coarse focus
• Adjust the focus with the fine focus
• Move to a higher power lens and repeat
• Draw the cells

Question 2

Osmosis in plants

Answer 2

1. Cut up a potato into identical pieces. Weigh the piece, then place them into beakers containing different sugar (or salt) solutions.
2. The sugar solutions should range from pure water to concentrated sugar with some in between concentrations eg. 0-1 mol/dm3
3. Leave the potatoes in the solutions for one day
4. Take out and dry the potato pieces. Weigh the potato pieces. Calculate the percentage change in mass.

Question 3

Osmosis in plants results

Answer 3

• Potato chip in water: water has entered the potato chip = increased size and mass
• Potato chip in concentrated water: water has left = decreased in size and mass

Question 4

Food test

Answer 4

Iodine turns black = starch is present
Benedict’s solution turns orange = sugar is present
Biuret turns purple = protein is present
Ethanol turns cloudy = fat is present

Question 5

pH and enzyme activity

Answer 5

• Place single drops of iodine in every well of a spotting tile
• Place amylase into the test tube
• Add buffer solution to the test tube
• Drop the mixture on the first drop of iodine, repeat every two minutes

Question 6

pH and enzyme activity results

Answer 6

Orange = starch has been broken down the enzyme works
Black = starch present the enzyme is not working

Question 7

Light intensity affect the rate of photosynthesis (seaweed)

Answer 7

Independent variable: Distance of lamp from pondweed
Dependent variable: Number of bubbles per minute
Control variable: Temperature, species of pondweed