Photosynthesis

• Photosynthesis is a process that takes place in the leaves and more specifically in the subcellular structures called chloroplasts.
• Chlorophyll is a pigment that can absorb light, which it uses to convert carbon dioxide and water into glucose and oxygen.
• The equation for photosynthesis can be written as six CO2 molecules combining with six H2O molecules to make a single molecule of glucose, resulting in six O2 molecules.
• The reaction requires light energy for it to take place, and when energy from the surroundings is used to help a reaction take place, it is called an endothermic reaction.
• Energy is transferred from the environment to chloroplasts by light.
• The carbon dioxide diffuses into the leaves through the stomata and the water is taken up from the soil by the roots and then transported to the leaves via the xylem.
• The only product that the plants really want is the glucose, which they use for solar respiration, photosynthesis, and for making cellulose, starch, amino acids, and oils.
• Glucose is essential for plants' growth rate, which is often dependent on how fast they can photosynthesize.
• The glucose made during photosynthesis can be used for respiration but also can be stored as starch for later
• To get carbon dioxide for photosynthesis, it diffuses from the air into the leaves through the stomata
• For plants to get water for photosynthesis, the water diffuses from the soil into the root hair cells from osmosis
• Starch is a useful long-term molecules because:

  • It is insoluble in water
  • It can easily be broken down when needed
  • It is compact
• One use of glucose is to make amino acids. Plants need nitrate ions to make amino acids
• Glucose in plants can be used for:

  • respiration
  • stored as starch
  • make amino acids
  • make lipids, which store energy as fats and oils for later use
  • making cellulose for a strong cell wall
• during photosynthesis, photosynthetic organisms such as green plants and algae use energy from the sun or artificial sources to make glucose
• Some of the glucose is used to make larger complex molecules that the plants or algae need to grow
• Photosynthesis is an endothermic reaction, as energy is transferred from the environment during it
• equation for photosynthesis

  A) carbon dioxide

  B) water

  C) light

  D) chlorophyll

  E) glucose

  F) oxygen

  
• Photosynthesis happens in 2 main stages:

  1. energy transferred by light is used to split water into oxygen and hydrogen ions
  2. carbon dioxide then combined with hydrogen ions to make glucose