1
Q
Is it pure oxygen gas released in gas syringe ?
A
No , due to CO2 and water vapor from plant or microorganism respiration
2
Q
How to get the rate of photosynthesis as volume of pure oxygen gas per unit time ?
A
volume of gas before adding oxygen absorbent - volume of gas after adding oxygen absorbent / Time
3
Q
Plan an investigation to show that increasing light intensity increases rate of photosynthesis from plant
A
4
Q
A
5
Q
How to improve accuracy of the measurements?
A
- use colorimeter instead of judging color
- Use pH meter to measure the change in pH
6
Q
How to get plant extract ?
A
- 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
7
Q
How to immobilize the plant extract ?
A
- 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
8
Q
Plan an investigation to show that increasing light intensity increases rate of photosynthesis using immobilised beads
A
9
Q
Why student should cut root before starting the experiment ?
A
- to fit to apparatus
- For less resistance to water molecules
- Dye molecules is large to cross cell membrane of root hair cells
10
Q
How to calculate volume of water gained by the plant ?
A
- measure radius of capillary tube using ruler
- Measure the distance moved by dye (mm) x R = mm
11
Q
How to get surface area of leaf ?
A
- 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
12
Q
Plan an investigation to show that increasing light intensity increases rate of transpiration
A
13
Q
HILLS REACTION
A
14
Q
PLANT GROWTH
A
15
Q
Serial dilution
A
16
Q
simple dilution
A
17
Q
How to prepare 1% sugar solution ?
A
use digital balance to measure out 1 g sugar and add 100 cm3 of distilled water using syringe
18
Q
How you will make 200 cm3 of 5% sucrose ?
A
19
Q
Prepare 1% of glucose solution using solid glucose
A
Dissolve 1g of glucose in 100cm3 water using syringe
20
Q
Prepare 25% of sucrose solution as initial stock
A
dissolve 25g of sucrose in 100 cm3 water using syringe
21
Q
Prepare 500 ml of 0.1% sucrose solution
A
22
Q
Prepare 1 dm3 0.15 moldm3 of lactose ( molar mass of lactose = 342 )
A
23
Q
Prepare 25 mmoldm3 of NaNO3 ( molar mass of NaNO3 = 85 )
A
24
Q
Prepare 500 cm3 of 0.2 moldm3 urea ( molar mass of urea = 60.1 )
A
25
yeast respiration
26
There are two types of respirometer:
1 simple respirometer
2 complex respirometer
27
simple respirometer
28
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.
29
How student can measure the volume of oxygen gas consumed using simple respirometer ? (2 marks)
1. Measure the radius of capillary tube using ruler
2. Use formula: distance moved by colored liquid X ππ2= cm3
30
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 ππ2) / Time X Mass of organism = cm3/
min.g
31
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.
32
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 ππ2 and divide it by time
33
How student can calculate the RQ using simple respirometer? ( 4 marks)
* Measure the radius of the capillary tube using ruler
* In presence of soda lime ( volume of oxygen)
* Measure the distance moved by colored liquid X ππ2 In absence of soda lime ( volume of Carbon
dioxide)
* Measure the distance moved by colored liquid X ππ2
* Divide the volume of carbon dioxide by the volume of oxygen gas consumed
34
How the student can measure the rate of anaerobic respiration using simple respirometer ? ( 3 marks)
* Add oxygen absorbent to absorb oxygen gas to maintain anaerobic respiration Allow organism to
respire anaerobically
* Measure the distance moved by colored liquid to the right in constant time.
35
Write a procedure a student can carry out to analyse the pigments present in different plants ?
36
disease detection and reaction time
37
disease analysis can be done by
urine test and blood test
38
urine test
39
blood test
40
color of urine
normally from light to dark yellow
41
orange urine
bacterial infection
42
red urnie
normal from menstruation or abnormal from virus infecting urinary system
43
clarity of urine
normally clear
44
turbid urine
something insoluble is produced in urine (proteins or cells)
45
odor and taste of urine
normally aromatic
46
sugary urine
glucose present
47
fruity urine
bacteria toxins is presen
48
Species gravity
: it has normal range but when something abnormal is produced in urine it increases the specific
gravity
49
Glucose test
* Benedict and Boil color changes from blue to green yellow orange or brick red ppt.
* Fehling A + B and Boil color changes from blue to green yellow orange or brick red ppt
* Dipstick
* Biosensor
50
Protein analysis
Biuret reagent
* Urine + NaOH + CuSo4
If protein presents then color changes from blue to purple. If protein absent then color remains blue.
51
Ketones analysis
Urine sample + ammonium Hydroxide + ammonium sulphate + sodium nitroprusside If ketones presents
color change from yellow to pink
If ketones absent color remains yellow
52
NaCl analysis
* add to urine sample excess silver nitrate
* ADD Fe 3+
* Silver nitrate is added to react with NaCl in urine
* Titrate with potassium thiocyanate
* Each drop will react with free silver nitrate remained unreacted
* After all silver nitrate reacted with potassium thiocyanate drops
* Excess potassium thiocyanate will react with Fe3+ ion giving red color
53
If urine sample contain high conc of NaC
will react with most of silver nitrate and leaves few molecules
of silver nitrate so it will take less number of drops to produce red color
54
Microscopical examination
Preparation of sample
dilute urine with water and mix well using glass rod
* Filter using filter paper to remove solid particles
* Drops of filtrate added to microscope slide to be viewed under microscope and examined for presence
of bacteria
55
blood analysis can be done by
Haemocytometer
56
Haemocytometer
1. It is a way for counting any substance present in blood that can be seen by light microscope
2. Use dye to stain dead cells using methylene blue and and distinguish it from unstained living cells
3. It is used to count number of RBCs in blood samples
4. It estimate an approximate number only not the actual
5. We should use x40 as objective lens
57
stepf of haemocytometer
1. Dilute sample with distilled water to avoid clumps of cells under microscope
2. Take a uniform blood sample after stirring well using micropipette and add it to counting grid slide
3. Count the average number of RBCs per square , includes the cells on top and left boundaries and exclude the cells
on bottom and right boundaries
4. Any overlapped cells count them by 2 cell only
5. To get the total number of cells multiply the average number of cells per square by the total volume and divide by the
given volume 1 square
58
Experiment to show the effect of sucrose concentration on change in length of plant tissue
59
Experiment to show the effect of NaCl on change in-angle of bending of plant tissue per unit time
60
density
61
Plan an investigation to show differences in stomata density on upper and lower surface of leaf
62
Inverstigate the effect of different types of antibiotic against bacteri
63
Mark release recapture method
1.Catch random sample from environment ( N1)
2.Mark the sample, and make sure that the marking is not harmful to organism
3.Release the marked sample to environment and Allow enough time for random mixing
4.recatch another random sample ( N2)
5.Count number of marked organisms in second sample (m2)
6.Make sure to avoid birth or death between two sampling times
7. Use the formula of Lincoln-Petersen index
64
random sampling
65
Systematic sampling
66
2 types of sampling
mobile and note mobile
67
mobile sampling
mark release recapture method
68
not mobile sampling
quadrats
69
quadrats
70
If index of diversity is 0.5 or greater
r it means the area has high biodiversity
71
If index of diversity is less than 0.5
it means the area has low biodiversity
72
Why area with pesticides has lower index of biodiversity
1. Pesticides kills pests so it decreases animal biodiversity
2. Pesticides are non specific and it may kill pollinators decreasing pollination so it will decrease
plant and animal biodiversity
73
What is the effect of the washing liquid on the cell membrane ?
it contains lipase and protease which will disturbs phospholipid bilayer and increase
membrane permeability
74
Why was the mixture heated ?
* To denature DNASE
75
Why was the beaker heated for few minutes at 60 C not 90 C and then immediately
cooled ?
heated at 60 to denature DNASE and avoid denaturing of DNA at 90 then cooled to
avoid denaturing of protease K that will be added in the next step
76
What type of enzyme would be needed to separate the DNA into smaller pieces ?
restriction enzymes
77
DNA amplification using PCR
1. Denature DNA by heating from 90 to 95 C to separate DNA double strands
2. Cool down the temperature to 65C then add a primer that will form hydrogen bonds
3. Then increase temperature to 72 C
4. Add optimum concentration of MgCl
5. Add taq polymerase and free nucleotides
6. Taq polymerase is heat stable so will not denture at high temperatures
78
Importance of PCR
1. DNA amplification
2. Identification of virus
3. Identification of mutations
79
What controls changes n temperature in PCR ?
* automatically controlled using thermal cycle
80
What are components of PCR ?
* DNA sample
* Primers
* Taq polymerase
* Free nucleotides
* MgC
A2 LEVEL 9700
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