SB6

• what is the photosynthesis word equation? glucose + carbon dioxide -> oxygen + glucose
• What type of reaction is photosynthesis?

  Endothermic
• What is the symbol equation for Photosynthesis?

  6CO2 +6H20 ----> C6H12O6 + 6O2
• Why is photosynthesis important?

  Glucose and things made from it are energy stores.

  When animals eat plants they store the energy.
• Why do plants need glucose?

  So plants can respire
• How do plants store glucose?

  Some glucose can be stored in starch. the starch can be broken down into sucrose
• What is a stomata?

  Pores on the surface of plant leaves that allow for gas exchange.
• Stomata allow carbon dioxide into the leaf. The stomata are opened and closed by guard cells.
• The flow of different gases into and out of a leaf is an example of gas exchange.
• A factor that prevents a rate increasing is a limiting factor
• What are the laws of limiting factors?

  When a process depends on two or more factors the rate of that process is limited by the factor which is in short relationship.
• How do you work out rate?

  change in pH/ Time (in hours)
• What is the need for water in plants

  Carry mineral ions

  Keeps cells rigid and prevents wilting

  Cooling the leaves

  Photosynthesis
• The root hair cells are an extensions of the cell that provide a large surface area for absorbing water and minerals. The cell also have thin cell walls so that the flow of water into the cells is not slowed down.
• what happens in the diffusion of water?

  The particles move from a high to low concentration and the water diffuses into the cell walls of the plant roots.
• Osmosis is when water moves from a region of high water concentration to a region of low water concentration through a semi-permeable membrane.
• Active transport is when a substance is moved from a low concentration to a high concentration against a concentration gradient
• The flow of water unto a root, up the stem and out the leaves is called transpiration.
• Any factor that reduce the concentration of water molecules outside the stomata will increase transpiration
• Sucrose is translocated in the sieve tubes of the phloem tissue.
• Companion cells actively pump sucrose into or out of the sieve cells that form the sieve tubes.
• Photosynthesis occurs during the day and respiration occurs at night using the energy it made during the day.
• Plants can reduce water loss by trapping water vapour close to their leaves which slow down the rate of diffusion out of the leaves.
• A stimulus is a change in the environment that causes a response by an organism.
• Responding to a stimulus by growing towards or away from it is called a tropism.
• A tropism caused by light is a phototropism
• A tropism towards a stimulus is a positive tropism
• Plant shoots are positively phototropic
• Plant roots are negatively phototropic
• Plants respond to stimuli using plant hormones. Positive phototropism is caused by plant hormones called auxins.
• Where are auxins produced?

  In the tips of a shoot, where they cause elongation of the cells.
• What is Gravitropism?

  It is growth towards the direction of gravity
• In roots, auxins cause cells to stop elongating and this causes positive gravitropism.
• Selective weed killers contain artificial auxins to kill specific plants.
• Plant hormones called gibberellins are naturally released a seed to start germination.
• Photoperiodism is the response of an organism to the number of daylight hours in a day.
• Some fruits are transported/stored when they are unripe and ripened when they need to be using ethane a gas. during which, starch is broken down.