Biology Required Practicals

Set of revision cards for GCSE Biology required practicals

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  • 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

Comments

Adam_S

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Really Helpful. Cheers :)

what_jack_revises

Report

cheers mate

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