Biology Experiments

Question 1

How do you test leaves for starch?

Answer 1

• burn leaf in water for 2 minutes to kill it
• heat in ethanol within water bath until it turns green
• rinse in cold water and place on tile
• add 5-10 drops of iodine
• —> blue/black starch is present

Question 2

How do you demonstrate that carbon dioxide is required for photosynthesis?

Answer 2

seal the leaf in a bag with soda lime

Question 3

How do you demonstrate that water is required for photosynthesis?

Answer 3

seal the leaf in a bag with silica gel

Question 4

how do demonstrate light is required for photosynthesis?

Answer 4

change distance of light from leaf

Question 5

how do you demonstrate chlorophyll is required in photosynthesis?

Answer 5

heat in ethanol

Question 6

What would be the CORMS for testing the sensitivity of skin?

Answer 6

C - distance between pins 
O - human
R - three times for each area
M - distance between pins in mm 
S - organism, sharpness of pins

Question 7

How would you test the rate of photosynthesis and the effect of light intensity in elodea?

Answer 7

• place elodea in water
• use the distance of a lamp as a measurement of light intensity in cm
• count the number of bubbles per minute for each intensity
• repeat three times for each intensity

Question 8

What are the colour changes in hydrogen carbonate indicator and why is it used?

Answer 8

alkali - purple
neutral - red
acid- yellow

changes very quickly/change in surroundings doesn’t have to be drastic

good for measuring carbon dioxide concentration

Question 9

How would you investigate gas exchange in plants?

Answer 9

• place leaf in hydrogen carbonate solution in a test tube
• measure colour change in darkness, high light, and controlled normal
• results -
dark - CO2 conc. goes up —> yellow
normal - CO2 conc. stays same —> red
light - CO2 conc. goes down —> purple

Question 10

How do you investigate the rate of transpiration in reference to temperature?

Answer 10

• set up a potometer
• heat the potometer with three temperatures
• choose a bubble and measure how far it moves in one minutes in mm
• repeat three times for each temperature

Question 11

How do you measure the energy content of food?

Answer 11

• set food alight with water directly above it
• measure the temperature change of the water after it is done burning
(vol of water)x(Δt)x(4.2)
• energy content = ————————————-
mass of food