Bio B2

• diffusion

  movement of cells from high concentration to low concentration
• factors affecting diffusion:

  • concentration gradient
  • temperature
  • surface area of the membrane
• osmosis

  the movement of water from a low concentration to high concentration through a semi-permeable membrane
• active transport

  the movement of particles from low concentration to high concentration

  AGAINST the concentration gradient
• cells specialise by differentiation: a process that involves the cell gaining new sub-cellular structures in order for it to be better suited to its role
• cells can either differentiate once early or have the ability to differentiate their whole life

  these are called stem cells
• types of stem cells:

  • embryonic stem cells
  • adult stem cells
• what does the circulatory system do?

  carries oxygen and nutrients to every cell in the body and removes the waste products
• the heart pumps blood around the body in a double circulatory system
• deoxygenated blood flows into the right atrium and then into the right ventricle
• oxygenated blood flows into the left atrium and then into left ventricle
• arteries carry blood AWAY from the heart
• veins carry blood TOWARDS the heart
• capillaries allow the blood to flow very close to cells to enable substances to move between them
• red blood cells contain haemoglobin

  haemoglobin is a red protein that combines with oxygen to allow for transport
• transpiration is the loss of water from the leaves of a plant through the stomata
• water travels up the xylem from the roots into the leaves of the plant that had been lost due to transpiration
• water is taken up through the root hair cells

  these are specialised cells with a large surface area to absorb water via osmosis
• guard cells open and close the stomata
• factors that affect water uptake:

  • light intensity
  • temperature
  • wind
  • humidity
• translocation is the movement of food from the leaves to the rest of the plant
• mitosis

  a type of cell division that results in two identical daughter cells

  used for growth and repair
• • xylem is a tissue consisting of dead cells that transport water and dissolved minerals
  • phloem is a tissue consisting of living cells specialised for transport