B1.4 PHOTOSYNTHESIS

• why are plants and algae called autotrophs?

  they make their own food. they make complex molecules that can be used as an energy store from simple molecules, such as carbon dioxide and water.
• what are the reactants of photosynthesis?

  light energy, water and carbon dioxide.
• how can glucose be used by a plant?

  as a source of energy in cellular respiration or to make more complex molecules that are used to help the plant grow.
• what is another word for autotrophs?

  producers
• photosynthesis can be defined as the process by which plants manufacture carbohydrates from raw materials using energy from light.
• what are the products of photosynthesis?

  glucose and oxygen
• where does photosynthesis take place and why?

  chloroplasts because they contain chlorophyll to help absorb as much light energy as possible.
• what type of reaction is photosynthesis?

  endothermic
• stage 1 of photosynthesis

  energy transferred from light is used to split water into oxygen gas and hydrogen ions.
• stage 2 of photosynthesis

  carbon dioxide gas taken from the atmosphere then combines with the hydrogen ions to make glucose.
• what happens if there is low temperature?

  not enough kinetic energy in the particles, meaning that carbon dioxide and water move through a plant slowly, resulting in fewer successful collisions occurring over a period of time.
• what happens if the temperature is too high?

  • the kinetic energy increases, increasing the likelihood of collisions between reactants and enzymes, increasing the rate of photosynthesis
  • enzymes can be denatured, reducing the rate of photosynthesis
• the more light that a plant recieves, 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
• • 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