Prepared and compiled by:
Ridwan Abrar
Department of EEE, Bangladesh University of Engineering and Technology (BUET)
Special thanks to Mahmuda Hoque who did all the common questions section.
Shazina Shehreen helped with the preparation of the checklist (Have a check at it before
the main exams!)
List of Core Practicals
From Unit 1:
1. Use a semi-quantitative method with Benedict’s reagent to estimate concentrations of
reducing sugars and with iodine solution to estimate the concentration of starch, using
colour standards
2. Investigate the Vitamin C content of food and drink
3. Investigate membrane properties including the effect of alcohol and temperature on
membrane permeability
4. Investigate the effect of temperature, pH, enzyme concentration and substrate
concentration on the initial rate of enzyme-catalysed reactions
From Unit 2:
1. (i) Use a light microscope to make observations and labelled drawings of suitable animal
cells
(ii) Use a graticule with microscope to make measurements and understand the concept
of scale
2. Prepare and stain a root tip squash to observe the stages of mitosis
3. Use a light microscope to:
(i) make observations, draw and label plan diagrams of transverse sections of roots,
stems and leaves
(ii) make observations, draw and label cells of plant tissues
(iii) identify sclerenchyma fibres, phloem, sieve tubes and xylem vessels and their
location
4. Determine the tensile strength of plant fibres
5. Investigate the antimicrobial properties of plants, including aseptic techniques for the
handling of bacteria
Past Questions from the core practicals:
Unit 2, Topic 5:
Investigate the antimicrobial properties of plants, including aseptic techniques for the
handling of bacteria:
Q-1. Many bacteria are evolving resistance to antibiotics. Some plant extracts have antibacterial
properties and, in some cases, these extracts may be useful as antibiotics.
, Experiments were carried out to investigate the effect of extracts, from garlic and from nutmeg
plants, on the growth of bacteria.
(a)(i) The two plant extracts were prepared using the following method. Some plant material was
crushed and shaken with ethanol. Suggest two improvements that could be made to this
method. (2)
Answer:
i) Standardised crushing
ii) Standardised shaking
iii) Volume of alcohol/ concentration of alcohol
iv) Equal amount of plant material
(ii) The diagram below shows the effect of garlic extract on bacteria growing on agar plate.
Describe how you would prepare an agar plate that would produce this result, using a sterile
Petri dish, sterile nutrient agar, a pure culture of a suitable bacterium in a bottle and some garlic
extract. (5)
Answers:
i) Credit description of aseptic precaution e.g. flaming neck of bacteria bottle/ swabbing bench at
beginning/ sterilising {loop/spreader}/ using lit Bunsen flame at back
ii) any reference to reducing biohazard described e.g. pipette in a disinfectant/ autoclave used
eqpt./ swabbing bench at end/ appropriate taping of lid (i.e. not all round)/ eq
(iii) The effectiveness of the extract can be estimated by measuring the size of the clear zone.
Suggest an accurate method for finding the size of the clear zone in the diagram in (a)(ii).
Answers: Graph paper is placed on top of the Petri dish. The area of the clear zone is traced in
the graph paper. The number of squares inside the circle/ tracing area is counted. Any area
outside the clear zone needs to be deducted.
(b) The 100% garlic extract used was then diluted to produce 75%, 50%, 25% and 10%
solutions and the experiment repeated. The diameter of each clear zone was measured. The
results are shown in the table below.
Concentration of garlic extract (%) Diameter of clear zone/mm
0 0
10 0
25 0
Ridwan Abrar
Department of EEE, Bangladesh University of Engineering and Technology (BUET)
Special thanks to Mahmuda Hoque who did all the common questions section.
Shazina Shehreen helped with the preparation of the checklist (Have a check at it before
the main exams!)
List of Core Practicals
From Unit 1:
1. Use a semi-quantitative method with Benedict’s reagent to estimate concentrations of
reducing sugars and with iodine solution to estimate the concentration of starch, using
colour standards
2. Investigate the Vitamin C content of food and drink
3. Investigate membrane properties including the effect of alcohol and temperature on
membrane permeability
4. Investigate the effect of temperature, pH, enzyme concentration and substrate
concentration on the initial rate of enzyme-catalysed reactions
From Unit 2:
1. (i) Use a light microscope to make observations and labelled drawings of suitable animal
cells
(ii) Use a graticule with microscope to make measurements and understand the concept
of scale
2. Prepare and stain a root tip squash to observe the stages of mitosis
3. Use a light microscope to:
(i) make observations, draw and label plan diagrams of transverse sections of roots,
stems and leaves
(ii) make observations, draw and label cells of plant tissues
(iii) identify sclerenchyma fibres, phloem, sieve tubes and xylem vessels and their
location
4. Determine the tensile strength of plant fibres
5. Investigate the antimicrobial properties of plants, including aseptic techniques for the
handling of bacteria
Past Questions from the core practicals:
Unit 2, Topic 5:
Investigate the antimicrobial properties of plants, including aseptic techniques for the
handling of bacteria:
Q-1. Many bacteria are evolving resistance to antibiotics. Some plant extracts have antibacterial
properties and, in some cases, these extracts may be useful as antibiotics.
, Experiments were carried out to investigate the effect of extracts, from garlic and from nutmeg
plants, on the growth of bacteria.
(a)(i) The two plant extracts were prepared using the following method. Some plant material was
crushed and shaken with ethanol. Suggest two improvements that could be made to this
method. (2)
Answer:
i) Standardised crushing
ii) Standardised shaking
iii) Volume of alcohol/ concentration of alcohol
iv) Equal amount of plant material
(ii) The diagram below shows the effect of garlic extract on bacteria growing on agar plate.
Describe how you would prepare an agar plate that would produce this result, using a sterile
Petri dish, sterile nutrient agar, a pure culture of a suitable bacterium in a bottle and some garlic
extract. (5)
Answers:
i) Credit description of aseptic precaution e.g. flaming neck of bacteria bottle/ swabbing bench at
beginning/ sterilising {loop/spreader}/ using lit Bunsen flame at back
ii) any reference to reducing biohazard described e.g. pipette in a disinfectant/ autoclave used
eqpt./ swabbing bench at end/ appropriate taping of lid (i.e. not all round)/ eq
(iii) The effectiveness of the extract can be estimated by measuring the size of the clear zone.
Suggest an accurate method for finding the size of the clear zone in the diagram in (a)(ii).
Answers: Graph paper is placed on top of the Petri dish. The area of the clear zone is traced in
the graph paper. The number of squares inside the circle/ tracing area is counted. Any area
outside the clear zone needs to be deducted.
(b) The 100% garlic extract used was then diluted to produce 75%, 50%, 25% and 10%
solutions and the experiment repeated. The diameter of each clear zone was measured. The
results are shown in the table below.
Concentration of garlic extract (%) Diameter of clear zone/mm
0 0
10 0
25 0
