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GCSE Edexcel Biology B1 Flashcards

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Describe how you would investigate the effect of pH on amylase

1. Put drop of iodine solution in every well of a spotting tile 2. Use a bunsen burner to heat up a beaker of water to the optimum temperature of the amylase you're using 3. Add 3cm3 amylase and 1cm3 buffer solution with pH5 to a boiling tube. 4. Put boiling tube into beaker of water and wait for 5 mins 5. Next, use different syringe to add 3cm3 starch solution to the boiling tube 6. Immediately mix and start stop clock 7. Use continuous sampling to record how long it takes for amylase to breakdown all of starch by using a pipette to take a fresh sample from boiling tube every 30s and put a drop into a well on spotting tile. When iodine remains browney-roange, starch is no longer present. Repeat whole experiment with 4 different buffer solutions of different pH values to see how pH affects the time. CONTROL VARIABLES: concentration and volume of amylase and starch solutions, temp of reaction mixture.

Describe the adaptations of an egg cell

cell membrane that hardens and changes structure after fertilisation so only 1 sperm fertilises the egg. the cytoplasm contains necessary nutrients to nourish the growing baby until birth haploid nucleus- contains half the set of chromosomes as a normal body cell; fuses with sperm at fertilisation to produce a zygote with full set of chromosomes (diploid)

Describe the effect of temperature, pH and concentration on enzyme activity

temperature- increasing temp. increases activity however if it gets too hot, the enzyme will denature (the active site will change shape) (will have an optimum temperature, enzymes inside the body usually have an optimum temp. of around 37°C pH- if too high or low, the enzyme will denature, all enzymes have an optimum pH (a pH in which they work best at) substrate/enzyme concentration- higher the concentration, the faster the reaction as it's more likely to meet and react, only true up to a point though, as after, all the active sites are full and therefore there will not be any more reactions despite having a high concentration of enzymes/substrates.

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