# Experiments Unit 1

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• Created by: neet
• Created on: 20-12-12 19:52

## Measure Initial Rate of an Enzyme-controlled React

• Set up experiment for the breaking down of hydrogen peroxide into water and oxygen
• Measure (the volume) amount of oxygen given off in the first minute
• Divide the volume of oxygen produced by the time to get the initial rate of reaction
• More oxygen given off = faster initial rate of reaction
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## Effect of Caffeine on the heart rate of Daphnia

• Make up a range, atleast 5, of caffeine solutions with different concentrations and one control with no caffeine
• Transfer a Daphnia into the dimple of a cavity slide
• Place slide under microscope and focus on heart beating
• Count the number of heartbeatd in 10 seconds and multiply by 6 to give rate per min
• Repeat 10 times using same concentration but different Daphnia each time
• Keep other factors the same (e.g temperature and volume of caffeine solution)
• Repeat procedure with other concentrations
• Compare results by drawing a graph
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## Measure amount of vitamin C

• Make up several, atleast 6, vitamin C solutions of different concentrations
• Measure out a set volume of DCPIP into a conical flask
• Add one of the vitamin C solutions to the DCPIP, drop by drop, using a pipette
• Gently shake the conical flask for a set length of time after each drop
• When solution turns colourless, record the volume (no. of drops)
• Repeat experiment with the same solution twice more
• Find average of results
• Make sure other variables are kept constant (e.g temperature)
• Repeat procedure with each solution
• Use results to make a line graph showing calibration curve
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## Effect of temperature on permeability

• Cut 5 equal sized pieces of beetroot
• Rinse them to remove any pigment released during cutting
• Place the five pieces in five different test tubes each with 5cm^3 water
• Place each test tube in water bath at different temperatures e.g 10, 20, 30, 40, 50 for same length of time
•  Remove the pieces of beetroot so only solution is left
• Use colorimeter to calculate intensity of the solution

More light absorbed by colorimeter = More pigment released = Higher permeability

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## FINDINGS

Increasing temperature increases permeability

Temperatures below 0 degrees:

Permeability is high, phospholipids dont have energy so can't move very much, membrane is rigid, carrier proteins and channel proteins deform, ice crystals form and pierce membrane

Temperatures between 0 - 45 degrees:

Phospholipids gain more energy so they can move around more so become more permeable

Temperatures above 45 degrees:

Phospholipid bilayer startd to melt, water inside the cell expands putting pressure on the membrane, Channel proteins and carrier proteins deform so they can't control what enter or leaves cell

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