Respiration II Exps 19th oct

Question 1

a. Both exp.s were carried about at the same temp. Explain why.

Answer 1

a.
Temp affects enzymes so affects respiration.
OR
Temp. affects vol./pressure so affects readings.

Question 2

b. The level of coloured liquid in the right hand side of the manometer tube went down during exp. 1. Explain why.

Answer 2

O2 take up.
CO2 produced + absorbed by KOH
Dec. in vol./pressure

Question 3

6bii) Use the results to calc. the vol. of CO2 produced in exp. 1

6(c). The student repeated exp. 1 using seeds which were respiring anaerobically. What would happen to the level of coloured liquid in the right hand side of the manometer tube? Explain your ans.

Answer 3

6bii). 4cm^3

6(c).
- Remains the same
- no O2 uptake

Question 4

8) II. Explain why the bead of liquid moved along on the first exp. but not in the second exp.

Answer 4

1. I. Establish a steady resp. rate

II. -Temp. affects pressure
-allows equip. to stabilise

2. • First exp. O2 being used for resp. & CO2 produced by resp. absorbed by NaOH.
   • Therefore, overall less gas pressure so bead moves to left.
   • 2nd exp. same (can’t understand spelling) =1 therefore, no movement.

Question 5

8)III. Giving a reason for your choice, suggest a suitable control for these exps.

IV. The cross sectional area of the capillary tube was 1mm2, and the 10 blowfly larvae had a total mass of 0.5g. Calculate the rate of oxygen consumption of the blowfly larvae. Give your ans. in mm3 g-1 hour-1

Answer 5

III.
- dead blowfly/beads
- can’t respire/ vol. same

IV.
Moves 60mm in 5 mins
x12 (to set into hour)
Divide by 0.5 (set into grams)

Rate = 1440 mm3 g-1 hour-1

Question 6

(a) The changes in volume of gas in apparatus A and in apparatus B were calculated. Explain how the changes in volume in apparatus A and apparatus B could be used to find:

I) vol. of O2 used by the seeds
II) the vol. of CO2 sed by the seeds

Answer 6

I. Vol. decreases / change in A

II.
Vol. dec. in B
(O2 in- CO2 out)

Vol. change in A = A-B = 20-10