b2

•  Xylem tissue

  water and mineral ions from the roots to the stems and leaves. hollow tubes strengthened by lignin adapted for the transport of water in the transpiration stream.
• The role of stomata and guard cells

  control gas exchange and water loss.
• Phloem tissue

  transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage- translocation .tubes of elongated cells. Cell sap can move from one phloem cell to the next through pores in the end walls.
• Lung structure (overall)

  
• How is carbon dioxide transported in the body

  plasma
• how does increased temperature denature an enzyme

  High temperatures start to break the bonds holding the enzyme together 

  This causes the enzyme and it's active site to change shape

  This means the enzymes active site will no longer be complementary to the substrate 
• Which structures help to minimise water loss?

  Waxy cuticle

  Guard cells that close stomata
• If there is plenty of water in the leaf,

  guard cells become turgid, which opens the stomata. This allows carbon dioxide to enter the leaf, but also allows water to escape. 
• At night time there is no light for photosynthesis, so plants don't need to absorb carbon dioxide. This means they can close their stomata and conserve water.
• glucose


  • grind up food

  • mix with water

  • add Benedict’s (reagent / solution)

  • heat mixture (≥ 65 °C)

  • in a water bath

  • turns (brick) red / orange / brown / green / yellow
• starch


  • add iodine (solution)

  • turns black
• protein


  • grind up food

  • add Biuret

  • turns purple
• Advantages of statins

  easy to take

  decrease blood cholesterol

  slow down build-up of fatty materials in arteries

  maintain blood flow to heart muscle cells

  low cost (compared to stent operation)
• Disadvantages of statins

  side effects of drug e.g muscle pain

  effects take time

  needs to be taken long term

  might forget to take
• Advantages of stent

  blocked artery is held open

  blood flow to heart muscle cells is increased

  will remain in place for a long time

  immediate effect

  rapid recovery from operation
• Disadvantages of stent

  risk of infection from operation

  risk of surgery eg heart attack

  risk of blood clot
• Describe how water is transported from the soil to the atmosphere through a plant (4)

  absorbed from soil by osmosis through root hair cells (1)

  travels through xylem vessels to the leaves (1)

  lost through stomata to atmosphere (1)

  driven by evaporation (1)
• Explain two ways sieve tube cells are specialised for their function. (4)

  have pores in the end walls (1)

  so dissolved sugars can move from cell to cell (1)

  no nucleus (1)

  so maximises space for movement of dissolved sugars (1)
• What does the structure of the companion cells suggest about the process that moves dissolved sugars through the phloem tissue?

  process uses ACTIVE TRANSPORT (1)

  because cells have many mitochondria (1)
• Describe why it is important that dissolved sugars are moved both upwards and downwards in a plant.

  sugars are made in the leaves by photosynthesis (1)

  all cells need sugar for respiration (1)

  sugars transported to meristems for growth / cell division / mitosis (1)

  sugars transported for storage as starch / fat / oil (1)
• How the human circulatory system is adapted to supply oxygen to the tissues

  1. Double circulatory system (higher blood pressure and flow)

  2. Heart muscle cells contract to pump blood with long protein filaments that slide

  3. Heart pumps blood -> pulmonary artery -> O2 diffuses from alveoli air

  4. Pulmonary vein -> heart muscles -> aorta -> body

  5. O2 carried by RBC (haemoglobin binds to O2, no nucleus to maximise space)

  6. Arteries -> oxygenated blood to tissues SO respiration (energy)

  7. Thin walls -> easy diffusion in cells

  8. Large SA:V capillaries maximises exchange
• How the human circulatory system is adapted to remove waste products from tissues

  1. Waste products removed in blood plasma

  2. Back to heart via VEINS- valves stop blood back flow

  3. Cardiac output affected by adrenaline
• Double circulatory system has higher blood pressure and flow
• Heart muscle cells contract to pump blood with long protein filaments that slide
• Heart pumps blood -> pulmonary artery -> O2 diffuses from alveoli air
• Pulmonary vein -> heart muscles -> aorta -> body
• O2 is carried by RBC (haemoglobin binds to O2, no nucleus to maximise space)
• Arteries carry oxygenated blood to tissues for respiration (energy)
• Thin walls allow easy diffusion in cells
• Large SA:V capillaries maximise exchange
• Waste products are removed in blood plasma
• Blood flows back to heart via VEINS, with valves to stop back flow
• Cardiac output is affected by adrenaline
• how to move air bubble back to 0 in potometer experiment?


  opened and closed the tap to allow water to enter from reservoir
• Why is the capillary tube narrow in the potometer?

  Air bubble moves further in a given time

  so the resolution is improved
• Why is there no transpiration in the dark


  No light so no photosynthesis

  Stomata are closed as no carbon dioxide is needed

  No transpiration as water cannot leave via stomata
• give three differences between transpiration and translocation stream

  • transpiration involves xylem AND translocation involves phloem
  • transpiration transports water and minerals / ions AND translocation transports dissolved sugars
  • transpiration moves substances upwards and translocation moves substances upwards and downwards
• What changes does stomata undergo at different times?

  • AT MIDNIGHT- stomata almost closed because there is no light for photosynthesis so closing stomata reduces water loss
  • AT MIDDAY-stomata open widest as maximum light intensity for photosynthesis to take in more carbon dioxide for photosynthesis
• Capillaries carry blood through the body tissues, allowing oxygen, nutrients, and waste products, to be exchanged between tissues and the blood.
• arteries have a relatively narrow lumen, which keeps the blood pressure high