P5 Flashcards
Is it pure oxygen gas released in gas syringe ?
No , due to CO2 and water vapor from plant or microorganism respiration
How to get the rate of photosynthesis as volume of pure oxygen gas per unit time ?
volume of gas before adding oxygen absorbent - volume of gas after adding oxygen absorbent / Time
Plan an investigation to show that increasing light intensity increases rate of photosynthesis from plant
How to improve accuracy of the measurements?
- use colorimeter instead of judging color
- Use pH meter to measure the change in pH
How to get plant extract ?
- crush 20g of leaves to break cell using mortar and pestle
- Add 100 cm3 of alcohol to dissolve phospholipid bilayer using measuring cylinder
- filter to remove cell debris using filter paper
- evaporate excess alcohol by gentle heating for 1 min to concentrate the extract
How to immobilize the plant extract ?
- mix plant extract with sodium alginate using glass rod at low speed to have uniform mixture and avoid
damage of chloroplast - Titrate on CaCl2 solution using syringe to form Ca alginate beads \
- Remove beads using forceps immediately to avoid hardiness
- Wash beads with water to remove traces of NaCl
Plan an investigation to show that increasing light intensity increases rate of photosynthesis using immobilised beads
Why student should cut root before starting the experiment ?
- to fit to apparatus
- For less resistance to water molecules
- Dye molecules is large to cross cell membrane of root hair cells
How to calculate volume of water gained by the plant ?
- measure radius of capillary tube using ruler
- Measure the distance moved by dye (mm) x R = mm
How to get surface area of leaf ?
- using square grid count number of squares occupied by leaf full , more than half or half square
count it as 1 cm3 less than half dont count it
Plan an investigation to show that increasing light intensity increases rate of transpiration
HILLS REACTION
PLANT GROWTH
Serial dilution
simple dilution
How to prepare 1% sugar solution ?
use digital balance to measure out 1 g sugar and add 100 cm3 of distilled water using syringe
How you will make 200 cm3 of 5% sucrose ?
Prepare 1% of glucose solution using solid glucose
Dissolve 1g of glucose in 100cm3 water using syringe
Prepare 25% of sucrose solution as initial stock
dissolve 25g of sucrose in 100 cm3 water using syringe
Prepare 500 ml of 0.1% sucrose solution
Prepare 1 dm3 0.15 moldm3 of lactose ( molar mass of lactose = 342 )
Prepare 25 mmoldm3 of NaNO3 ( molar mass of NaNO3 = 85 )
Prepare 500 cm3 of 0.2 moldm3 urea ( molar mass of urea = 60.1 )
yeast respiration
There are two types of respirometer:
1 simple respirometer
2 complex respirometer
simple respirometer
Explain possible reason why the rate of respiration or Heart rate at the start of the experiment ( trial
1) was higher than remaining trials? ( 1 mark)
- As the organism was under stress and not left enough time for adaptation.
How student can measure the volume of oxygen gas consumed using simple respirometer ? (2 marks)
- Measure the radius of capillary tube using ruler
- Use formula: distance moved by colored liquid X 𝜋𝑟2= cm3
How you can calculate the rate of respiration as volume of oxygen gas consumed per unit mass of
organism ? (3 marks)
Volume of O2 gas ( distance moved by colored liquid X 𝜋𝑟2) / Time X Mass of organism = cm3/
min.g
Why the student divide the volume of oxygen gas consumed by the mass of organism ? ( 2 marks)
For fair comparison as the original masses of organisms used in investigation may be different.
How student can measure the rate of Co2 gas production using simple respirometer ? ( 2marks)
Way 1
Measure the difference in mass of soda lime before and after the experiment divide it by the time Using
digital balance and stop watch
Or
Way 2
Remove the soda lime Then measure the distance moved by colored liquid to the right then multiply it by
the area of the tube 𝜋𝑟2 and divide it by time