Biology Required Practicals
Set of revision cards for GCSE Biology required practicals
5.0 / 5 based on 6 ratings
- Created by: Will Lang
- Created on: 10-09-17 11:07
Investigating plant and animal cells
Equipment:
- onion
- knife
- forceps
- slide
- coverslip
- iodine solution
Steps:
- Peel off a layer of onion and place it on a microscope slide. Add a drop of iodine solution and cover with a cover slip
- Adjust the coarse adjustment knob until the cells come into focus and rotate the objective lens so that it is the most powerful
- Draw the cells seen and label with structures and magnification. Repeat for more animal and plant cells
1 of 10
The effects of antibiotics on bacteria
Variables:
- Control - antibiotic concentration and time taken soaking the discs
- Independent - type of antibiotic
- Dependent - Area around each disc that is clear of bacteria
Hazards:
- Use aseptic techniques to sterelise equipment (pass innoculating loop through a flame)
- Wash hands before and afterwards
Steps:
- Soak 3 filter discs in different antibiotics for equal amounts of time and place them on the agar jelly in the petri dish
- Secure the lid (not fully) and label with antibitoics used and pathogen.
- Incubate the petri dish at 25 degrees for 48 hours (any higher=dangerous pathogen growth)
- Measure area of clear zone and record results in a table
- Spray all surfaces with disinfectant and use a strong soap to wash your hands
2 of 10
Effects of concentrations of sugar solution
Variables:
- Control - temperature, time cylinders are in solution for and volume of solution
- Independent - sugar solution concentration
- Dependent - mass of potato
Tips:
- If there is a change in mass, they have gained or lost water by osmosis
Steps:
- Use a cork borer to cut out 4 potato cylinders of equal size and measure the size and mass of each one
- Measure 10cm^3 of 4 concentrations of sugar solution into a boiling tube and add the potatoes
- Leave for 30 minutes and measure the new mass after blotting with a towel (remove excess water)
- Record results in a table
3 of 10
Effect of pH on rate of reaction of amylase
Variables:
- Control - temperature, concentration and volume of starch and amylase
- Independent - pH
- Dependent - time taken for starch to be digested
Steps:
- Add a buffered pH solution, starcha and amylase to a test tube in a water bath at 37 degrees
- Start the stop watch and mix using a glass rod
- Every 30 seconds, add a drop of mixture to iodine solution to test for starch (turns black if present)
- Keep on removing mixture until the iodine turns orange (starch not present). This is the time taken for the starch to be fully digested
- Repeat the experiment with different pH values
Tips:
- Leave solution to reach 35 degrees before adding amylase to the starch
4 of 10
Test for lipids, carbohydrates and proteins
Steps:
- Grind up food using a pestle and mortar
- Add Benedict's solution and heat in a water bath for two minutes
- If sugar (carbohydrates) is present, the food will turn red
- Grind up food using a pestle and mortar
- Add iodine solution
- If starch (lipids) is present, the food will turn blue-black
- Grind up food using a pestle and mortar
- Add biuret reagent
- If protein is present, the food will turn purple
5 of 10
Investigate light intensity on photosynthesis
Variables:
- Control - piece of pondweed, temjperature and carbon dioxide concentration
- Independent - light intensity (distance from light source)
- Dependent - number of bubbles per minute
Steps:
- Place a boiling tube containing sodium hydrogen carbonate solution at 10cm from the light and place a beaker containing water inbetween to prevent heat from affecting the rate
- Record the number of bubbles coming out of the pondweed in a minute. Repeat again for this distance to back up the results
- Repeat these steps with the pondweed at 20cm away, 30cm and 40cm.
Tips:
- The smaller the distance, the higher the light intensity = higher rate
6 of 10
Investigate human reaction time
Variables:
- Control - age, mass and sex of the subjects
- Independent - whether the subject has had caffeine or not
- Dependent - distance the ruler travels
Steps:
- Have hand hanging over the table with a partner holding a ruler vertically with the end between your thumb and finger
- Partner drops the ruler without saying. Try and catch it as quick as possible
- Record the number on your ruler that the top of your thumb is at and the time taken to catch it
- Repeat the test several times to record multiple lengths and times
- Repeat these steps for people who have drunk cola/coffee (caffeine) to compare reaction times
Tips:
- It is hard to control the variables for this experiment
7 of 10
Effect of light or gravity on plant seeds
Variables:
- Control - number/type of seeds, soil type and volume of water
- Independent - position of holes in container
- Dependent - Direction in which seedlings grow in
Steps:
- Take 4 small plastic boxes and place one hole on a side. The holes must be in the same place and have the same size
- Put soil in containers and plant 10 cress seeds in each
- Put a lid on and put the containers in even lighting with holes pointing in different directions
- Water the soil and leave for several days
- Measure the height the plants have grown every day for the duration of the experiment
- Record results
Tips:
- Make sure the room is evenly lit with no windows
8 of 10
Population size of a species in a habitat
Hazards:
- Wash hands after work
Steps:
- Randomly throw the quadrat to the ground
- Count number of individual plants in the quadrat
- Repeat this process several times to calculate the mean number of plants per 1m^2
- Measure area of whole habitat and multiply number of plants in 1m^2 by the whole area
- This is the population size in this habitat
Tips:
- Make sure the quadrats are placed at random
- More samples taken = improved accuracy for the estimate of the population size
9 of 10
Investigate effect of temperature on rate of decay
Steps:
- Take a sample of fresh milk
- Place in a test tube and cover the lid
- Place in a water bath at a certain temperature
- Measure the pH at certain intervals across the course of the test
- Repeat the test with the water bath at different temperatures
- Record results
Tips:
- pH can be measured using universal indicator paper or a pH probe connected to a data logger
- The more decayed the milk is, the lower the pH level
10 of 10
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