Practical investigation- Respirometer

Question 1

what is a respirometer

Answer 1

apparatus used to measure the rate of respiration of living organisms by measuring the rate of respiration by measuring rate of oxygen and co2

Question 2

a respirometer usually has two tubes, what is in the two tubes

Answer 2

Tube 1- will have some organisms

Tube 2- will have an object of the same mass

Question 3

the apparatus is left for 10 minutes, why

Answer 3

so equillibrium is reached

respiration rate is stabilised

Question 4

what is the role of the syringe in the respirometer

Answer 4

the syringe can be depressed to restart the experiment when wanted, pushing it to balance the fluids in the manometer

Question 5

what is important to record of the syringe when you begin the experiment

Answer 5

Its important to record at which mark the syringe is at the beginning.

Question 6

why are the measurements;
oxygen g-1 h-1

Answer 6

Oxygen- volume of oxygen in what is being measured

g-1: this would be the mass of the organism being tested

h-1: measuring time

Question 7

what solutions are used in the compensating chamber

Answer 7

sodium hydroxide or potassium hydroxide

Question 8

an organisms will be placed on a platform in the compensating chamber to avoid it falling in the chemical. What is the name given to the platform

Answer 8

Guaze platform

Question 9

what is the role of the sodium hydroxide or soda lime in the compensating chamber

Answer 9

absorbs carbon dioxide which is released in respiration.

Allows us to measure the o2 absorbed .

Question 10

after time, the pressure in the chamber with the organisms in will exert less pressure, why is this

Answer 10

Because the organisms will absorb the oxygen in the tube, and the carbon dioxide is absorbed by the sodium hydroxide. Therefore less particles means less pressure

Question 11

Why will the manometer fluid rise when the organism has been left to respire for a while

Answer 11

Because as they respire, o2 and co2 is being absorbed, therefore a reduction in pressure in the one chamber causes the liquid to rise in the manometer

Question 12

what is the equation for respiration

Answer 12

02 + c6h12o6 = co2 + h20 + atp

Question 13

when setting up the apparatus, the taps must be kept open. Why

Answer 13

Because it enables air in the apparatus to connect with the atmosphere

Question 14

Due to the apparatus being in a water bath, it allows us to also use it to measure temperature. What is important to do before changing temperatures

Answer 14

It is important to leave apparatus and organisms to adjust to new temperatures.

Question 15

when testing the effect of temp on respiration. What knowledge can you apply to a hypothesis

Answer 15

You can link knowledge of enzymes to the effect of temp. E.g. 40+ will denature enzymes

Question 16

what type of equipment does the apparatus sit in

Answer 16

A temp controlled water bath

Question 17

how do you reset the respirometer when measuring the effect of temperature

Answer 17

Allow air to re-enter the tubes via the screw cap and reset the manometer fluid using the syringe

Change the temperature of the water bath and allow the tubes to acclimate

then close the screw clip to begin the experiment

Question 18

what part of the apparatus do you need to look at to measure the volume of oxygen absorbed

Answer 18

use the manometer reading to calculate the change in gas volume in a given time, y cm3 min-1

Question 19

what must you do to the organisms before placing them in the apparatus

Answer 19

measure their mass