P2 required practicals
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How to investigate the effect of light in the growth of seedlings
• Set up 3 petri dishes containing cotton wool soaked in equal amounts of water • Put 10 seeds in each dish • Put the dishes in a warm place • Allow the seeds to germinate, water daily with equal amounts of water to each dish • Remove excess seedlings from any dish that has too many, to make sure all dishes have same amount of seedlings • Measure the height of each seedling in mm • Move 1 petri dish on a windowsill in full sunlight, one in partial light and the 3rd one in darkness • Measure the height of each seedling everyday for at least 7 days Record the heights in a table and calculate the mean height of the seedlings each day
How to measure the population size of a common species in a habitat (not random)
• Place a 30m tape measure across the habitat to form a transect line • Place the 1m^2 quadrat against the transect line so one corner of it touches the 0m mark on the tape • Count the number of the species in the quadrat • Record the number of species counted in a table • Move the quadrat 5m up the transect line and count the amount of species in the quadrat Calculate the mean number of population per m^2 Repeat moving the quadrat all the way up the transect line
How to measure the population size of a species in a habitat (random)
• Place 2 20m long tape measures next to each other at right angles • Use a random number generator to create points in the grid that has been created on the ground with the transects and place the quadrat at the point • Record the number of the species in the quadrat • Repeat for a total of 10 different points • To work out the total population do total area/area samples x number of organisms of that species counted in sample