Biology Paper 2 IGCSE Edexcel Test
Questions and Correct Answers.
PH and enzyme function - Answer If too high or too low it can cause the enzymes to
denature but often the enzymes optimum PH is 7 (not in the stomach!!)
Calorimetry. What is it and how can you test for it? - Answer Calorimetry is the process of
burning food to see how much energy it contains. Weigh food sample and skewer on mounted
needle. Hold under test tube of water held with a clamp and set on fire. Continue to do this
until the food no longer sets on fire. Measure the temp of the water again.
Energy in food= - Answer Mass of water (in grams) x temperature change of water (in
degrees Celsius) x 4.2
Energy per gram in food= - Answer Energy in food / mass of food
How are root hair cells adapted - Answer Millions of hairs, big surface area for osmosis
Phloem - Answer Transport sugars such as amino acids and sucrose from the leaves to other
parts of plant.
Translocation - Answer The movement of food substances around the plant
Pepsin - Answer Break down proteins in the stomach. It works best at PH2
Turgid cells - Answer When a plan is well watered all it's cells draw in water by osmosis to
become plump and swollen
Turgor pressure is - Answer The contents of the cell push against the cell wall. It helps to
support plant tissue
Flaccid cells - Answer When there's no water in the soil so a plant starts to wilt and therefore
lose water and turgor pressure.
Why doesn't a plant loose its shape? - Answer It has inelastic cell walls to keep things in
position
Questions and Correct Answers.
PH and enzyme function - Answer If too high or too low it can cause the enzymes to
denature but often the enzymes optimum PH is 7 (not in the stomach!!)
Calorimetry. What is it and how can you test for it? - Answer Calorimetry is the process of
burning food to see how much energy it contains. Weigh food sample and skewer on mounted
needle. Hold under test tube of water held with a clamp and set on fire. Continue to do this
until the food no longer sets on fire. Measure the temp of the water again.
Energy in food= - Answer Mass of water (in grams) x temperature change of water (in
degrees Celsius) x 4.2
Energy per gram in food= - Answer Energy in food / mass of food
How are root hair cells adapted - Answer Millions of hairs, big surface area for osmosis
Phloem - Answer Transport sugars such as amino acids and sucrose from the leaves to other
parts of plant.
Translocation - Answer The movement of food substances around the plant
Pepsin - Answer Break down proteins in the stomach. It works best at PH2
Turgid cells - Answer When a plan is well watered all it's cells draw in water by osmosis to
become plump and swollen
Turgor pressure is - Answer The contents of the cell push against the cell wall. It helps to
support plant tissue
Flaccid cells - Answer When there's no water in the soil so a plant starts to wilt and therefore
lose water and turgor pressure.
Why doesn't a plant loose its shape? - Answer It has inelastic cell walls to keep things in
position
