paper one and two practicals

Question 1

investigating rate of respiration

Answer 1

1. Assemble the respirometer.
2. Add 5g of one organism to the boiling tube and replace the bung.
3. Place a drop of coloured manometer fluid in the open end of the respirometer.
4. Use a syringe to draw the fluid as far from the respirometer as possible and record its
   starting position.
5. Close the tap. Start the stop clock.
6. After five minutes, open the tap. Record the end position of the coloured liquid.
7. Repeat the process for the other organism.

Question 2

measuring the effects of exercise

Answer 2

1. Find the vertical scale by emptying the chamber, starting the kymograph and
   then forcing a known volume of air into the chamber. This measures the volume
   of gas in the chamber, and by reading the trace, the movement of the pen on the
   kymograph can be calibrated to the actual volume of air.
2. Find the horizontal scale by setting it to 1 mm per second, using the switch (or
   as close to 1 mm per second as possible). This is the speed at which the drum
   turns.
3. A trained member of staff can fill the spirometer with medical grade oxygen.
4. Disinfect the mouthpiece and attach it to the tube. Turn the tap so the tube is
   not attached to the spirometer..
5. Subject attaches the nose clip and breathes into the tube for a while to practice.
   When they are comfortable, start the datalogger/kymograph and turn the tap to
   attach the tube to the spirometer.
6. Subject takes one forced deep breath and then breathes normally into the
   spirometer for a duration of 5 minutes maximum

Question 3

investigating habituation to a stimulus

Answer 3

1. Dampen the cotton wool bud in distilled water.
2. Touch the snail between the eye buds with the cotton wool bud
3. Time the length of time it takes for the snail to emerge fully from its shell
   again.
4. Repeat for a total of ten touches.

Question 4

DAPHNIA PRACTICAL
why is daphnia selected as an organism to be used?
how does caffeine act in humans?
how is the control set up?
why should a cover slip not be used?
what is the purpose of placing cotton wool on the slide?

Answer 4

• they have translucent bodies so heart rate can be easily observed
• stimulant that increases heart rate by increasing the release of excitatory neurotransmitters
• replace caffeine solution with distilled water to measure the effect without caffeine
• to allow oxygen to reach the organism
• to restrict the movement of the organism

Question 5

what is the effect of temperature on membrane permeability

Answer 5

increasing temp increases membrane permeability as high temperatures denature membrane proteins.
this creates gaps in the membrane for the molecule to pass through

increasing temp also decreases the kinetic energy of phospholipids so they pack tightly together, restricting movement of molecules across the membrane

Question 6

what is the effect of increasing ethanol concentration on membrane permeability

Answer 6

leads to increased membrane permeability as ethanol ruptures the membrane to form gaps for molecules to pass through

Question 7

where in plant can cells undergoing mitosis be found

Answer 7

meristem tissue at shoot and root tips

Question 8

why is bacteria incubated at 25 degrees

Answer 8

to prevent the growth of pathogens which occur at higher temperatures

Question 9

what does the zone of inhibition indicate

Answer 9

it indicates the bacteria killed by the antibiotic. the larger the zone the more effective the microbial properties of the plant .

Question 10

what is a limitation of q10

Answer 10

it can only be used up to the optimum temperature

Question 11

rate of respiration practical
- control
- how do you use the volume of oxygen
- how can volume of co2 be found
- control variables

Answer 11

• replace organism with an inert object of the same mass
• measure distance moved by the dye, and use formula. volume = distance x pir2
  -two set ups one with soda lime and one without. calculate difference
  -mass of organism, temp, mass of soda lime

Question 12

effects of exercise practical
- respirometer function
- what happens to tidal volume, vital capacity, breathing rate and respiratory minute volume after exercise

Answer 12

• measures breathing rate and respiration
• tv increases, vc remains same, be increases, rmv increases