PAPER 2 practicals

Question 1

Aim, method, variables and results of Dehydrogenase activity in chloroplasts?

Answer 1

• Aim is to measure enzyme activity via the reduction (gaining of hydrogrn) of DCPIP during photosynthesis
• Method is to isolate chloroplasts, add DCPIP, expose to light, monitor DCPIP colour change (blue to colurless) using colorimeter over time.
  Variables: IV: Light itnensity, temp, chloroplast conc DV: Rate of DCPIP reduction CV: Volume of chloroplast suspension
  Results: Rate of DCPIP reduction will correlate with dehydrogenase activity

Question 2

Aim, method, variables and results of respiration in single celled organisms

Answer 2

• AIm is to measure respiration rate by CO2 production or oxygen consumption
• Using a respirometer with yeast in glucose solution, measure volume change or gas release over time.
• Variables: CV: Rate of oxygen production, IV: Amount of glucose DV: Rate of respiration
• Results: respiration rate indicated by gas volume or pressure changes

Question 3

Aim, method, variables, results of Simple Animal Responses

Answer 3

Aim: Observe and quantify responses to stimulus such as (phototaxis or chemotaxis)
Method: Place organism in controlled arena with stimulus and record movement to record taxis or kinesis
Variables: DV: Rate of movement CV: Temperature, time allowed for response IV: Stimulus type/amount
Results: Taxis or Kinesis according

Question 4

Quadrats and transects

Answer 4

• Quadrats 1x1m area count individuals and a mean.
• Multiply by area.
• Regular transects, regular intervals and patterns
  Transects/Mark Capture Release
  Sample 1xSample 2/Marked in second sample