Practicals

Question 1

What are the key points for the J-tube experiment?

Answer 1

• Measure length of column of air
• Expel most of the water from the open end (by pressing syringe plunger)
• Draw up some concentrated Potassium Hydroxide into the capillary tube
• With end of the J-tube submerged in Potassium Hydroxide shuffle air column back and forth so that in comes in contact with glass wetted with KOH
• Remeasure the length of the column
• % CO2= change in length/ Original length x100
• Expel most KOH using syringe draw up pyrogallol, repeat shuffling of air column over pyrogallol wet on side of tubes
• %O2= change in length/original length x100

Question 2

What are the key points for the respirometer experiment?(with KOH present)

Answer 2

• Mark in U-tube moves because peas are respiring, (taking in O2 and producing CO2)
• the CO2 is absorbed by KOH
• The volume of air decreases
• Pressure decreases and mark moves towards peas
• Distance marker moves= O2 uptake
• Volume can be calculated using (Pie-r-squared x height) if diameter of tubing is known

Question 3

What are the key points for the respirometer experiment? (without KOH and calculating CO2 levels)

Answer 3

-Replace KOH with water
-Where mark ends is total respiration (e.g. -2cm)
-If the mark has moved -2cm then CO2 produced is
2+X= -2
X= -4

Question 4

Describe the bicarbonate indicator experiment

Answer 4

• Expose a normal tube, muslin wrapped tube and tinfoil wrapped tube to lamp for 12 hrs
• Colour of indicator at start of each is red
• Colour at end of 12hrs (Normal tube=purple red, muslin tube=red, tinfoil tube=orange yellow)

Question 5

Describe how the Audus apparatus works

Answer 5

• Set up lamp 10cm away from plant
• Make sure temperature is 20C in water bath
• Collect gas evolved in 10 minutes
• draw bubble into apparatus
• measure the length of the bubble
• Repeat with light source different lengths away
• Limitation=only can be done with amphibious plants

Question 6

Describe how to random sample

Answer 6

• Use quadrat
• Randomly distributed on area
• Estimate plant cover (%) inside quadrat
• Approx. 30 times
• Subjective

Question 7

Describe how to belt transect

Answer 7

• Mark out the line of transect
• Use a quadrat
• place CONTIGUOUSLY (end2end)
• Estimate frequency of plants in quadrats

Question 8

Describe how to line transect

Answer 8

• mark out the line of transect
• Measure what plants actually touch the line
• record data