transportation systems

• red blood cells contains haemoglobin, which is a protein that carries oxygen around the body.
• haemoglobin contains lots of iron.
• when haemoglobin and oxygen combine, it makes oxyhaemoglobin.
• red blood cells have no nucleus to create more space for haemoglobin.
• red blood cells have a biconcave disc shape to maximise surface area for oxygen to be absorbed
• red blood cells are small and flexible, allowing them to easily pass through capillaries.
• plasma is a liquid that contains dissolved substances and proteins and carries blood cells
• Transpiration is the loss of water through the stomata from the leaf. Water is needed for photosynthesis which is needed for plants to survive.
• Open stomata allow water to evaporate out, while allowing carbon dioxide in which is needed for photosynthesis.
• Water comes into the plant from soil by osmosis through the root hair cells.
• Water vapour diffuses through the air spaces in the spongy mesophyll, then out of the stomata.
• Guard Cells


  open in the daytime to allow carbon dioxide to come in. happens when they are turgid.
• Guard Cells


  close at night time/ high temps because there is no sunlight and no water moving into the guard cells, making them flaccid.
• Factors affecting the rate of transpiration

  Light intensity :

  an increase in light intensity increases the rate of transpiration because it increases the rate of photosynthesis.
• Factors affecting the rate of transpiration

  Temperature:

  evaporation is faster at higher temperatures
• Factors affecting the rate of transpiration

  Wind/Air movement:

  removes any water vapour at the stomata and allows more water to evaporate.
• Factors affecting the rate of transpiration

  No humidity/ Dry conditions:

  evaporation takes place quicker in dry conditions.
• Xylem - transports water and mineral ions from the roots to the leaves.

  • are dead
  • long tubes
  • thick walls with lignin
  • end walls have broken down.
  • no nucleus, vacuole, cytoplasm, or chloroplast. --> makes it easier for water and mineral ions to get through.
• Phloem - transports sugars and amino acids from the leaves to the rest of the plant.

  1. end plates have holes, called sieve plates.
  2. allows sugars to move (translocation)
  3. are alive
• transpiration is the loss of water through the stomata in the leaves.
• water evaporates at the stomata
• Adhesion


  as water molecules are attached together by adhesion, they are pulled up as temperature/wind pulls them up, to evaporate out of the stomata. the water molecules are in the xylem
• The guard cells control the size of the opening of the stoma. They do this by changing shape. When the guard cells become turgid, the stoma opens. When the guard cells lose water, the stoma closes.
• Arteries


  have thick walls with lignin to avoid any bursts due to the high pressure. carry blood AWAY from the heart. elastic fibres allow them to stretch.
• Veins


  carry blood TOWARDS the heart. has a wide lumen to allow low-pressure blood to go through. have valves to make the blood flow in the right direction, to prevent backflow of blood.
• Capillaries 


  are very close together to allow substances to move quickly between capillaries. are one cell thick to have a large surface area to volume ratio which increases the rate of diffusion so the substances diffuse more effectively. permeable walls so substances can move quickly