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GCSE Biology > Paper 1 practicals > Flashcards

Paper 1 practicals Flashcards

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1
Q

What microscope is used in school practicals?

A

Optical microscope

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2
Q

What is the stage of a microscope?

A

Centre of the microscope where the microscope slide is place

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3
Q

What is below the stage?

A

Lamp, where light from the lamp passes through the microscope slide.

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4
Q

What is above the stage?

A

3 objective lenses

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5
Q

What is above the objective lenses?

A

Eye piece where you look through, it has a magnification of 10x

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6
Q

What are on the side of the microscope?

A
  • coarse focusing dial

- fine focussing dial

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7
Q

Process of using a microscope?

A
  1. Place slide into stage using clips to hold it in place
  2. Select lowest objective lens , usually 4x
  3. Position the lens so it almost touches the microscope slide. To do this slowly turn the coarse focussing dial
  4. look down through eye piece lens
  5. Turn coarse focussing dial slowly , to increase the distance between objective lens and the slide , until cells come into focus
  6. use fine focusing dial to bring the cells into clear focus
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8
Q

How to calculate magnification?

A

Magnification of eye piece lens x magnification of objective lens

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9
Q

Problem with optimal microscopes?

A

Limited detail, only the cytoplasm , nucleus and cell membrane

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10
Q

What happens when a plant cell is placed into water?

A

Water will move into it through osmosis

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11
Q

What will happen if a plant cell is placed into a dilute solution?

A

Water will move out of it by osmosis and the cell will shrivel up

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12
Q

Process of investigating osmosis in vegetables?

A
  1. Peel potato , skin can effect osmosis
  2. Use cork borer to produce 3 cylinders of potato, make them all the same diameter
  3. Use scalpel to trim cylinders to the same length (around 3 cm)
  4. Measure length and mass of cylinders
  5. Place each cylinder into a test tube
  6. First test tube add 10cm^3 of 0.5 molar sugar solution. Second add 10cm^3 of 0.25 molar sugar solution. Third add 10cm^3 of distilled water
  7. Leave potato overnight to allow osmosis to take place
  8. Remove potato cylinders and gently roll them on paper to remove surface moisture
  9. Measure the mass and length of cylinders to find difference
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13
Q

Why is distilled water used instead of tap water?

A

Distilled water contains no dissolved substances, which could effect the rate of osmosis

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14
Q

How to work out percentage change?

A

Change in value/original value X100

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15
Q

How to prepare a slide a microscope slide?

A
  1. Place a drop of water on the slide
  2. using forceps remove thin layer of onion
  3. Place the specimen on the slide gently
  4. Using a pipette add 2-3 drops of stain , e.g iodine to specimen
  5. slowly at a 90 degree angle , lower the cover slip to cover the specimen . Avoid air bubbles.
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16
Q

What are we investigating the osmosis practical?

A

In this experiment, you can investigate the effect of glucose solution on plant tissue using a potato

17
Q

What are we investigating in the microscopy experiment?

A

Using a microscope to look at onion skin cells and estimate their size.

18
Q

What are we investigating in the food tests?

A

We are identifyinh the main foods groups using standard food tests.

19
Q

How do we prepare for the food tests?

A

Step 1: grind or crush the food sample using a pestle and mortar
Step 2: add the sample to a test tube containing water or ethanol and shake.
Step 3: filter the mixture to remove any solids.

20
Q

What test for starch?

A

Iodine

21
Q

What tests for protein?

A

Biuret solution

22
Q

What test for fat?

A

Ethanol

23
Q

What test for sugars?

A

Benedict solution

24
Q

How to test for starch?

A

Iodine test for starch , yellow -red iodine solution turns blue -black if starch is present

25
Q

How to test for sugars?

A

Benedict solution, blue benedicts oslution turns brick red on heating if a sugar such as glucose is present.

26
Q

How to test for protein?

A

Biuret test, blue biuret reagent will turn purple if protein is present

27
Q

How to test for lipids?

A

Ethanol tes, ethanol added to a solution gives cludy white layer if a lipid is present . Ethanol is highly flammable and harmful.

28
Q

Safety precautions with the food tests?

A

Biuret solution is corrosive. Wear chemical and splash proof eye protection.

29
Q

What are we investigating in the ‘effect of ph on enzymes ‘ practical?

A

How the ph effect the time taken for enzyme to digest starchs

30
Q

What is used in the reaction to test ph?

A

Reaction is followed by testing with iodine solution. If there is any unreacted starch present , it will react with iodine to give a boue-black colour. When the reaction is complete there will be no colour change.

31
Q

What equipment is needed for photosynthesis experiment?

A 
Boiling tube
Pond weed
Led light source
Ruler
Funnel
32
Q

Why is an Led light source used for photosynthesis experiment?

A

Not much heat is used by LED . Too much heat would effect the experiment

33
Q

Method for photosynthesis experiment?

A
  1. Boiling tube 10 cm away from LED light source
  2. Fill boiling tube with sodium hydrogen carbonate solution(releases CO2 needed for photosynthesis)
  3. put piece of pond weed into boiling tube with cut end at the top.
  4. Leave for 5 minutes to acclimate to conditions in boiling tube.
  5. Count number of bubbled produced in one minute
  6. Repeat 2 more times and calculate mean
  7. Repeat steps from 20cm,30cm ,40cm
34
Q

Problems with photosynthesis required practical?

A
  • bubbles could be too fast to count

- bubbles could differ in size

35
Q

How to make the photosynthesis experiment more efficient ?

A

Place pondweed under a funnel and catch bubbles in measuring cylinder . Use measuring cylinder to measure the volume of the bubbles.

36
Q

What is the inverse square law?

A

Describes the graph that shows the photosynthesis experiment. If double distance , number of bubbles per minute falls by a factor of four

GCSE Biology (20 decks)

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