gcse biology

Required Practicals

There are a number of Required Practicals you will carry out in GCSE Biology, and you should familiarise yourself with them. You can find videos of all of them, and lots of other information here:

PAPER 1:

RP1: MICROSCOPY

Use a light microscope to observe, draw and label biological specimens.

Calculations: Magnification = size of image Ă· real size of object

RP2: MICROBIOLOGY

Investigate the effects of antiseptics or antibiotics on bacterial growth using agar plates and measuring zones of inhibition.

Independent Variable: Type of antibiotic/antiseptic
Dependent Variable: Area of zone of inhibition
Control Variables: Temperature
 Species of bacteria
Calculations: Zone of inhibition = π r² 

RP3: osmosis

Investigate the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue.

Independent Variable: Concentration of salt/sugar solution
Dependent Variable: Percentage change of mass in plant tissue
Control Variables: Size of potato chips
 Volume of salt/sugar solution
Calculations: % change in mass = change in mass Ă· original mass

RP4: food tests

Use qualitative reagents to test for a range of carbohydrates, lipids and proteins.

Starch: Iodine (brown to black)
Sugar: Benedict's Solution + Heat (blue to green/yellow/red)
Proteins: Biuret Solution (Blue to purple)
Lipids: Sudan III (Brown to red stained layer)

RP5: enzymeS

Investigate the effect of pH on the rate of reaction of amylase enzyme.

Independent Variable: pH
Dependent Variable: Time taken for iodine to remain brown
Control Variables: Volume of amylase solution
 Concentration of amylase solution
 Temperature

RP6: photosynthesis

Investigate the effect of light intensity on the rate of photosynthesis using an aquatic organism such as pondweed.

Independent Variable: Distance of pondweed from lamp
Dependent Variable: Volume of oxygen produced
Control Variables: Temperature
 Carbon dioxide levels

PAPER 2:

RP7: REACTION TIME

Plan and carry out an investigation into the effect of a factor on human reaction time.

Independent Variable: Caffeine levels
Dependent Variable: Reaction time
Control Variables: Age of participants
 Light levels

RP8: plant responses

Investigate the effect of light or gravity on the growth of newly germinated seedlings.

Independent Variable: Light
Dependent Variable: Height of seedlings
Control Variables: Species of plant
 Number of seedlings
 Volume of water

rp9: FIELD INVESTIGATIONS

Measure the population size of a common species in a habitat. Use sampling techniques to investigate the effect of a factor on the distribution of this species.

Independent Variable: Distance from object
Dependent Variable: Number of particular plants
Control Variables: Time sampled
 Sampling method (must be random)
Calculations: Area = length x width

rp10: DECAY

Investigate the effect of temperature on the rate of decay in fresh milk by measuring pH change.

Independent Variable: Temperature
Dependent Variable: pH
Control Variables: Volume of milk
 Volume of lipase enzyme
 Concentration of lipase enzyme