Practicals

Question 1

What is the aim of the cheek cell slide practical?

Answer 1

Use microbiological techniques to prepare and view cheek cell slides.

Question 2

List the equipment for cheek cell slides.

Answer 2

Cotton bud, disinfectant, microscope slide, cover slip, mounted needle, methylene blue, light microscope.

Question 3

Outline the method to prepare cheek cell slides. - 10 steps

Answer 3

Add methylene blue to slide.
Swab cheek with cotton bud.
Dab bud in dye, then place in disinfectant.
Lower cover slip carefully to avoid air bubbles.
Blot excess stain.
Set on microscope stage.
Start with x10 objective lens.
Adjust coarse/fine focus.
Switch to high power (x40), focus again.
Identify & draw 3–4 cells.

Question 4

Give a risk for the cheek cell slides practical

Answer 4

Methylene blue is an irritant. Avoid contact with skin.

Question 5

What is the aim of food tests practical?

Answer 5

Test for starch, reducing sugars, lipids, and protein in food samples.

Question 6

Equipment list for food tests.

Answer 6

Iodine, Benedict’s solution, Biuret reagent, ethanol, spotting tile, test tubes, sugar paper, water bath, pipettes, beaker.

Question 7

How is starch tested?

Answer 7

Add iodine to food sample in test tube.
If starch present, turns brown → blue-black.

Question 8

How is reducing sugar tested (Benedict’s test)?

Answer 8

Add Benedict’s solution to food.
Heat in water bath.
Brick red precipitate = sugar present.

Question 9

Describe the emulsion test for lipids.

Answer 9

Add ethanol to food sample.
Add water.
White emulsion = lipids present.

Question 10

What is the sugar paper method for lipids?

Answer 10

Rub sample on paper, allow to dry. Translucent spot = lipids.

Question 11

Describe the Biuret test for protein.

Answer 11

Add Biuret solution.
Shake and wait.
Blue → purple = protein present.

Question 12

Name one source of error and one safety precaution for food test using Biuret.

Answer 12

Error: Subtle colour changes if low concentration.
Safety: Biuret = corrosive. Use goggles.

Question 13

What is the aim of the sampling techniques practical?

Answer 13

Compare biotic and abiotic factors in different habitats.

Question 14

What equipment is used in this practical?

Answer 14

Quadrat, tape measures, pen, paper, soil pH kit, thermometer, umbrella, random number generator.

Question 15

Describe method 1 (random sampling). - sampling techniques

Answer 15

Use random coordinates to place quadrat.
Count target species.
Repeat 10 times.
Estimate population size using:
    (Total area ÷ quadrat area) × mean per quadrat.

Question 16

Describe method 2 (along transect).- sampling techniques

Answer 16

Lay tape from tree into open area.
Place quadrat at 0 cm.
Count plant species.
Test abiotic factor (e.g. pH, light).
Move 5 m, repeat.
Repeat until end of line.

Question 17

Describe method 3 (insects). - sampling techniques

Answer 17

Place umbrella under branch.
Shake.
Count and identify insects.
Release them.

Question 18

Name one source of error and one risk for sampling techniques

Answer 18

Error: Only one transect = unreliable.
Risk: Insect stings or plant allergies.

Question 19

What is the aim of the Enzyme-Controlled Reactions (Catalase) experiment?

Answer 19

Investigate enzyme-controlled reactions using catalase in potato.

Question 20

What is the independent variable in the Enzyme-Controlled Reactions (Catalase)

Answer 20

Hydrogen peroxide concentration.

Question 21

What is measured? - Enzyme-Controlled Reactions (Catalase)

Answer 21

Volume of oxygen released.

Question 22

Describe the method. - Enzyme-Controlled Reactions (Catalase)

Answer 22

Label tubes with H₂O₂ %s.
Cut equal potato pieces.
Add to H₂O₂ in flask with bung.
Collect gas in measuring cylinder.
Record oxygen after 5 mins.
Repeat for each %.

Question 23

How do you calculate rate of reaction?

Answer 23

Rate = volume of oxygen ÷ 5 (cm³/min).

Question 24

Give 2 controlled variables. - Enzyme-Controlled Reactions (Catalase)

Answer 24

Temperature, potato length.

Question 25

One risk in this practical? - Enzyme-Controlled Reactions (Catalase)

Answer 25

H₂O₂ is an irritant — wear goggles.

Question 26

Aim of this practical? - photosynthesis

Answer 26

Investigate how light intensity affects photosynthesis (pondweed).

Question 27

What is the dependent variable? - photosynthesis practical

Answer 27

Number of bubbles produced per minute.

Question 28

What is the method? Photosynthesis

Answer 28

Place pondweed in tube 10 cm from light. Add sodium hydrogen carbonate. Count bubbles in 1 min. Repeat at 20, 30, 40 cm.

Question 29

What is the equation for light intensity?

Answer 29

Light intensity = 1 ÷ distance²

Question 30

One extension for this practical? - photosynthesis practical

Answer 30

Test different pondweed species.

Question 31

One hazard? - photosynthesis practical

Answer 31

Hot lamp, allergy to pondweed.

Question 32

What is the aim? -Physiology, Responses, Respiration

Answer 32

Measure changes in pulse and breathing before/after exercise.

Question 33

How do you measure pulse rate?

Answer 33

Press wrist. Count beats for 1 minute. Exercise, then repeat.

Question 34

How do you measure ventilation rate?

Answer 34

Use spirometer and nose clip. Time 1 min, count breaths. Exercise, repeat measurement.

Question 35

One risk and one source of error? - Physiology, Responses, Respiration

Answer 35

Risk: Exercise may be unsafe for asthmatics. Error: Exercise intensity may vary by person.

Question 36

What is the aim of the microbiological techniques practical?

Answer 36

Investigate the effects of antimicrobial agents (using a plant extract) on microbial growth using aseptic techniques.

Question 37

Name 4 pieces of equipment used in the microbiological techniques practical.

Answer 37

Bacterial stock, petri dishes with growth medium, plastic spreader, syringes.

Question 38

What is the first step to maintain aseptic conditions in this practical?

Answer 38

Perform all steps near a Bunsen flame on a blue flame to prevent contamination.

Question 39

Perform all steps near a Bunsen flame on a blue flame to prevent contamination.

Answer 39

Use a syringe to transfer 0.1 cm³ of bacterial stock 10 cm above the agar.

Question 40

What is used to spread bacteria evenly on the agar?

Answer 40

A plastic spreader.

Question 41

What is done to the petri dish lid after spreading bacteria?

Answer 41

Place the lid on and dispose of the spreader safely.

Question 42

How is the petri dish divided and labelled?

Answer 42

Divide the base into 4 sections and label them; one section is used as control.

Question 43

How is the plant extract prepared?

Answer 43

Grind a plant using pestle and mortar, then add 10 cm³ of sterile water.

Question 44

How are paper discs prepared?

Answer 44

Soak sterile filter paper discs in the plant extract.

Question 45

How are the discs applied?

Answer 45

Place the discs on the labelled sections of the petri dish.

Question 46

What must be done after adding discs to petri dishes?

Answer 46

Incubate upside down for 48 hours.

Question 47

What is measured at the end of the experiment? - Microbiological Techniques

Answer 47

Diameter of the clear zone around each disc.

Question 48

What are 2 sources of error in this practical? Microbiological Techniques

Answer 48

Petri dish contamination, irregular shape of clear zones.

Question 49

Name 2 safety precautions for this practical. Microbiological Techniques

Answer 49

Tie back hair near Bunsen flame; disinfect all surfaces after experiment.

Question 50

What is the aim of the osmosis practical?

Answer 50

Investigate osmosis in plant tissue by measuring change in mass of potato cylinders.

Question 51

What are 3 key pieces of equipment used?

Answer 51

Potato, sucrose solutions, electronic balance.

Question 52

What concentrations are the 7 sucrose solutions?

Answer 52

0.0M, 0.1M, 0.2M, 0.3M, 0.4M, 0.5M, 0.6M.

Question 53

What is the size of each potato cylinder used?

Answer 53

50 mm in length.

Question 54

How much solution is used per beaker?

Answer 54

50 cm³.

Question 55

How long are potato cylinders left in solution?

Answer 55

30 minutes.

Question 56

What is done after removing the cylinders?

Answer 56

Blot dry, weigh again, and record final mass.

Question 57

What calculation is performed at the end? - potato osmosis practical

Answer 57

Percentage change in mass = (final mass - initial mass) ÷ initial mass × 100.

Question 58

Give one source of error in the osmosis practical.

Answer 58

Potato pieces may have different water potentials depending on where cut.

Question 59

Name one risk and its precaution in this practical. - osmosis practical

Answer 59

Sharp tools (scalpel, cork borer) – handle carefully to avoid cuts.