nutrition

• Photosynthesis


  An endothermic reaction in which energy from sunlight is transferred to the chloroplasts in green plants
• Photosynthesis


  1. Energy from sunlight is absorbed by chlorophyll

  2. Green plants use this energy to make the carbohydrate glucose from the raw materials carbon dioxide and water

  3. Oxygen is made and released as a waste product
• Photosynthesis


  The process by which plants manufacture carbohydrates from raw materials using energy from light
• Plants


  • Autotrophs - they can make complex molecules (glucose) from simple molecules (carbon dioxide and water)
  • Producers - they can make their own food and so are the first organism at the start of all food chains
• Products of photosynthesis


  • Plants use the glucose they make as a source of energy in respiration
  • They can also use it to produce starch for storage, synthesise lipids for an energy source in seeds, form cellulose to make cell walls, and produce amino acids (used to make proteins) when combined with nitrogen and other mineral ions absorbed by roots
• Photosynthesis


  An endothermic reaction in which energy from sunlight is transferred to the chloroplasts in green plants
• Photosynthesis


  1. Energy from sunlight is absorbed by chlorophyll

  2. Green plants use this energy to make the carbohydrate glucose from the raw materials carbon dioxide and water

  3. Oxygen is made and released as a waste product
• Photosynthesis


  The process by which plants manufacture carbohydrates from raw materials using energy from light
• Plants


  • Autotrophs - they can make complex molecules (glucose) from simple molecules (carbon dioxide and water)
  • Producers - they can make their own food and so are the first organism at the start of all food chains
• The products of photosynthesis

  • Plants use the glucose they make as a source of energy in respiration
  • They can also use it to
  • Produce starch for storage
  • Synthesise lipids for an energy source in seeds
  • To form cellulose to make cell walls
  • Produce amino acids (used to make proteins) when combined with nitrogen and other mineral ions absorbed by roots
• lipids - long term energy source and provide insulation / protect organs. food with high percent of lipid contain a large amount of energy
• protein - needed for teeth and bones
• fibre - prevent constipation, gives the gut muscles something to push against (persistalis)
• calcium - required for grwoth and repair
• vitamin d - prevents rickets, helps absorb calcium and phosphate
• factors that affect diet: age groups (kids are actively growing)
• factors that affect diet: pregnancy, physical activity
• digestion: the process to break down large insoluble molecules such as carbohydrates, protein, lipids into smaller soluble molecules (glucose, amnio acids, fatty acids) that the body can use for life processes.(growth, repair, respiration)
• chemical digestion: enzymes produced by salivary glands, stomach lining, pancreatic juice and small intestine lining catalysed chemical reactions breaking down complex substances into simpler ones.
• balanced equation for photosynthesis: carbon dioxide + water -> glucose + oxygen
• balanced chemical equation for photosynthesis: 6CO2 + 6H2O -> C6H12O6 + 6O2
• carbon dioxide: diffuses into the leaf through the stomata
• water: taken up by the roots and transported through the xylem to the leaves
• glucose: used to make substances needed by the plant, used in respiration to release energy
• oxyegn - diffused out of the leave through the stomata, used in respiration
• factors affecting the rate of photosynthesis: light intensity, temperature, CO2 concentration, chlorophyll concentration
• Plants do not have unlimited supplies of their raw materials so their rate of photosynthesis is limited by whatever factor is the lowest at that time
• Limiting factor


  Something present in the environment in such short supply that it restricts life processes
• Main factors that limit the rate of photosynthesis


  • Temperature
  • Light intensity
  • Carbon dioxide concentration
• Although water is necessary for photosynthesis, it is not considered a limiting factor as the amount needed is relatively small compared to the amount of water transpired from a plant so there is hardly ever a situation where there is not enough water for photosynthesis
• Temperature


  The temperature of the environment affects how much kinetic energy all particles have
• Factors that can affect the rate of photosynthesis


  • Number of chloroplasts
  • Amount of chlorophyll in the chloroplasts
• Temperature affects


  The speed at which carbon dioxide and water move through a plant
• Lower temperature


  Less kinetic energy particles have, resulting in fewer successful collisions occurring over a period of time
• Increasing temperature


  Increases the kinetic energy of particles, increasing the likelihood of collisions between reactants and enzymes which results in the formation of products
• Higher temperatures


  Enzymes that control the processes of photosynthesis can be denatured (where the active site changes shape and is no longer complementary to its substrate)
• Light intensity

  • The intensity of the light available to the plant will affect the amount of energy that it has to carry out photosynthesis
  • The more light a plant receives, the faster the rate of photosynthesis
  • This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply
• Enzyme denaturation at higher temperatures


  Reduces the overall rate of photosynthesis
• Carbon dioxide concentration

  • Carbon dioxide is one of the raw materials required for photosynthesis
  • This means the more carbon dioxide that is present, the faster the reaction can occur
  • This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply
• Chlorophyll

  • The number of chloroplasts (as they contain the pigment chlorophyll which absorbs light energy for photosynthesis) will affect the rate of photosynthesis
  • The more chloroplasts a plant has, the faster the rate of photosynthesis
  • The amount of chlorophyll can be affected by:
  • Diseases (such as tobacco mosaic virus)
  • Lack of nutrients (such as magnesium)
  • Loss of leaves (fewer leaves means fewer chloroplasts)