Biogenetic

• absorbs the energy required for photosynthesis?

  Chlorophyll
• In what part of the cell does photosynthesis take place?

  Chloroplast
• What is the word equation for photosynthesis?

  Carbon dioxide + water ➔ glucose + oxygen
• What is the chemical symbol equation for photosynthesis?

  6CO2 + 6H2O ➔ C6H12O6 + 6O2
• Which type of reaction is photosynthesis?

  Endothermic process because it requires energy (from the sun).
• How do plants get the carbon dioxide required for photosynthesis?

  It diffuses from the air into the leaves via stomata
• How do plants get the water required for photosynthesis?

  It diffuses from the soil into the root hair cells by osmosis
• What makes starch a useful long term storage molecule?

  It is compact

  It is insoluble in water

  It can be easily broken down in when needed when photosynthesis isn't happening like in winter
• One use of glucose is to make amino acids.

  
  

  What else do plants need to make amino acids?

  Nitrate ions absorbed from soil
• What are the 5 main uses of glucose in plants?

  Cellular respiration - break down the glucose to release energy

  Make cellulose - which is used to make strong cell walls

  Make starch - which is used to store glucose for a later time

  Make amino acids - which are used to make proteins

  Make lipids - these store the energy as fats or oils for later use
• What is the role of chlorophyll?


  To absorb light energy for photosynthesis
• Why may plants produce insufficient chlorophyll?

  They lack the required nutrients

  They have a disease like Tobacco Mosaic Virus
• What factors effect photosynthesis

  Light intensity

  Carbon dioxide

  Temperature

  Chlorophyll
• Describe and explain how the rate of photosynthesis varies with temperature.

  At first the rate of photosynthesis rises with temperature as the particles have more energy and move more quickly. This means they can react more quickly and so the rate is higher.

  However, as temperature rises above the optimum temperature for the enzymes involved, the enzymes may start to break down. This decreases the rate until it falls to zero (when the enzymes are denatured).
• Farmers help plant photosynthesis?

  Farmers in cooler climates often use greenhouses. These help trap the heat energy from sunlight, and so increase the temperature. They also keep out pests which could otherwise damage the plants.

  
  

  Artificial lighting

  
  

  - paraffin heater it realises heat and also carbon dioxide

  
  

  - pump in co2

  
  

  Fertiliser

  
  

  Pesticides
• Method to investigating photosynthesis

  A lamp with an LED bulb is set up at different distances from the plant in a beaker of water:

  an LED bulb is best as this will not raise the temperature of the water

  sodium hydrogen carbonate (NaHCO3) is added to the water to supply the reactant carbon dioxide to the plant

  the light intensity is proportional to distance - it will decrease as the distance away from the bulb increases.
• What are the variables in investigating photosynthesis

  independent variable - distance from the light source/light intensity

  
  

  dependent variable - the number of bubbles produced per minute

  
  

  control variables - concentration of sodium hydrogen carbonate solution, temperature, using the same piece of pondweed each time

  
  

  Risk = Care must be taken when using water near electrical equipment. Ensure that your hands are dry when handling the lamp.
• Is respiration an exothermic or endothermic reaction?

  Exothermic because it involves the release of energy
• Give two examples of how cells use the energy from respiration.


  To combine small molecules to make larger molecules

  For muscle contraction

  Maintain body temperature
• What is metabolism?


  The combination of all chemical reactions in an organism
• What is glucose converted to during anaerobic respiration in animals

  Lactic acid
• What is the word equation for anaerobic respiration in plants and fungi?

  Glucose --> ethanol + carbon dioxide
• What are the two reasons animals cells prefer aerobic respiration to anaerobic respiration?

  Anaerobic respiration doesn't break down the glucose molecule completely, and so releases less energy than aerobic respiration

  
  

  Anaerobic respiration produces lactic acid which can damage cells and leads to an oxygen debt
• How exercise affects the body

  In order to move during exercise, we have to contract and relax our muscles.

  
  

  Muscular contraction requires energy though, which has to be released by cellular respiration.

  
  

  Most of the time cells carry out aerobic respiration, which is far more efficient but requires oxygen.

  
  

  This means that we have to pump oxygen around the body faster when we exercise.

  
  

  As a result we increase both our heart rate and our breathing rate.
• Which organ in the body removes the lactic acid from the blood.

  Liver where converted back to glucose
• Photosynthesis


  The process by which plants make glucose from sunlight
• Endothermic reaction


  Energy is transferred from the environment to the chloroplasts by light
• Photosynthesis

  Carbon dioxide + water → glucose + oxygen
• Factors affecting rate of photosynthesis

  • Temperature
  • Light intensity
  • Carbon dioxide concentration
  • Amount of chlorophyll
• Measuring oxygen production to calculate rate of photosynthesis


  1. Pondweed in test tube

  2. Capillary tube and syringe

  3. Lamp at measured distance

  4. Measure distance bubble moves to calculate oxygen volume

  5. Control variables except independent variable
• Limiting factor

  An environmental condition (such as light intensity) which, in low levels, restricts any increase in the rate of photosynthesis
• Graphs showing limiting factors

  • One line levelling off showing one limiting factor
  • Two lines showing two limiting factors
  • Three lines showing three limiting factors
• Farmers can use knowledge of limiting factors to enhance greenhouse conditions for greater rate of photosynthesis
• Inverse proportion


  Relationship where one factor increases as the other decreases
• Inverse square law

  Light intensity is inversely proportional to the square of the distance
• Uses of glucose from photosynthesis

  • For respiration
  • Converted to starch for storage
  • To produce fat or oil for storage
  • To produce cellulose to strengthen cell walls
  • Combined with nitrates to form amino acids and proteins
• Respiration


  The process of transferring energy from glucose so living processes can occur
• Exothermic


  Energy is transferred to the environment
• Types of respiration

  • Aerobic (with oxygen)
  • Anaerobic (without oxygen)
• Aerobic respiration


  Glucose + oxygen → carbon dioxide + water