OCR GCSE BIOLOGY

• How does the temperature effect the rate of photosynthesis?

  At low temperatures, the enzymes work at a slower pace and at high temperatures the enzymes will denature- the rate of reaction decreases rapidly.
• What is the ideal temperature needed for photosynthesis?

  45 degrees.
• How does carbon dioxide effect photosynthesis?


  The amount of carbon dioxide will only increase the rate of photosynthesis up to a certain point. After reaching the point, carbon dioxide is no longer the limiting factor.
• How does light level effect photosynthesis?


  If the light level is raised, the rate of photosynthesis increases steadily to a certain point. Overall, it does not make much of a difference.
• What are the two main stages of photosynthesis?


  Energy transferred by light is used to split water into oxygen gas and hydrogen ions. Carbon dioxide then combines with the hydrogen ions to make glucose.
• What time of reaction is photosynthesis?


  Endothermic
• What is the balanced symbol equation for photo synthesis?

  
• Where does photosynthesis occur?


  Photosynthesis happens inside chloroplasts- they contain chlorophyll which absorbs the light.
• What is glucose used for in plants?


  Some of the glucose is used to make larger, complex molecules that the plants need to grow. These make up the organism's biomass.
• What happens during photosynthesis?


  Photosynthetic organisms (e.g green plants and algae) use the energy from the sun to make glucose.
• How are lipids broken down in the body?


  Lipids are broken down by enzymes in the small intestine.
• What do lipids contain?

  Carbon, Hydrogen and Oxygen atoms.
• What are lipids made up of (in regards to fats and oils)?

  Glycerol and 3 fatty acids.
• How are proteins broken down in the body?


  Proteins are broken down by enzymes in the stomach and small intestine.
• What are amino acids made of?

  Carbon, Nitrogen, Hydrogen and Oxygen atoms
• What are proteins made of?


  Proteins are polymers that are made up of long chains of monomers called amino acids.
• How are carbohydrates broken down in the body?

  Carbohydrates are digested/broken down by enzymes in the mouth and small intestine.
• How can polymer molecules be broken down back into sugars?

  When the chemical bonds between the monomers are broken.
• How are carbohydrates made?


  Monomers (simple sugars e.g glucose or fructose) can be joined together in long chains, polymers, to make large, complex carbohydrates.
• What are carbohydrates made up of?

  Carbon, Hydrogen and Oxygen.
• What is the equation for anaerobic respiration in plants and fungi?


  Glucose --> Ethanol + Carbon Dioxide.
• Why do plants sometimes have to resort to anaerobic respiration?

  If the soil is water-logged, plant root cells respire anaerobically as there is little to no oxygen.
• What is the word equation for anaerobic respiration in animals?


  Glucose --> Lactic Acid
• What is anaerobic respiration?


  'Anaerobic' means "without oxygen".
• What is the equation for aerobic respiration?

  Glucose + Oxygen --> Carbon Dioxide + Water
• What is aerobic respiration?


  Aerobic respiration is what happens when there's plenty of oxygen available. It is the most efficient way to transfer energy from glucose.
• How can cells respire?


  Cells can respire using glucose as a substrate, but organisms can also break down other organic molecules (e.g carbohydrates, proteins and lipids) to use as substrates for respiration.
• How is respiration controlled?

  Respiration is controlled by enzymes.
• What can effect the rate of respiration?

  The rate of respiration can be effected by temperature and pH.
• What type of reaction is respiration?

  Exothermic (because it transfers energy to the surroundings).
• How does substrate concentration effect the rate of reaction?

  The higher the substrate concentration, the faster the reaction but only to a certain extent.
• How does enzyme concentration effect the rate of reaction?

  Increasing the concentration of the enzyme increases the rate of reaction but in some cases there are more than enough enzyme molecules to deal with the available substrate, so adding more enzymes would have no further effect.
• How does pH effect enzymes?

  If the pH is too high or too low, it interferes with the bonds holding the enzyme together which changes the shape of its active state- causing it to denature.
• What is the optimum pH for enzymes?


  The optimum pH is often 7 but not always, e.g pepsin is an enzyme used to break down proteins in the stomach and it works best at a pH of 2.
• What is an enzymes optimum temperature?

  37 degrees (body temperature).
• How does temperature effect enzymes?

  A higher temperature increases the rate at first.
• What happens if an enzyme loses its shape?

  It cannot catalyse the reaction.
• What makes up a cell's metabolism?


  Respiration, photosynthesis and protein synthesis and these reactions need to be carefully controlled.
• How can you speed up the reactions which occur in a cell's metabolism?

  Usually, you can speed up the reaction by raising the temperature.
• How are enzymes specific?


  They have an active site where it joins on to its substrate. They all have their own specific substrate.