Transport

• Explain the adaptations and role of red blood cells

  - biconcave shape: large surface area:volume ratio to maximise diffusion of oxygen in and out.

  - no nucleus: more space for haemoglobin

  - carries oxygen around body by allowing hemoglobin to bind
• Explain the appearance and role of white blood cells

  - large

  -have a nucleus

  - fight pathogens and disease in the body
• Define platelets and their role

  Small fragments of cells

  - clot the blood and form scabs to prevent bacteria entering
• Define plasma and its role

  Liquid part of the blood

  - transports CO2, glucose, hormones, urea
• What is the role of phagocytes?

  Ingest pathogens (non-specific immune response)
• What is the role of lymphocytes?

  Produce antibodies and antitoxins (specific immune response)

  - antibodies: complimentary to antigens on surface of pathogen, attach to antigens to enhance activity of phagocytes.

  - antitoxins: neautralise toxins produced by a bacteria
• How are memory cells helpful?

  They produce larger quantities of antibodies in a much shorter time
• How do vaccinations work?

  By introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies, and kill the pathogen, making it unable to grow or divide
• Describe the role and appearance of arteries

  Carry oxygenated blood at high pressure from heart to organs

  - small lumen: maintain high blood pressure

  - thick walls: withstand high pressure
• Describe the role and appearance of of veins

  Carry deoxygenated blood at low pressure from organs to heart

  - large lumen: reduces resistance to blood flow under low pressure

  - thin walls: maximize blood flow for effective return

  - valves: prevent backflow as it is under low pressyre
• Describe the role and appearance of capillaries

  Huge network that links arteries and veins

  - narrow, thin walls: short diffusion distance for glucose and oxygen
• How are water and minerals in the roots transported to the leaves?

  Root hair cells absorb waster by osmosis

  Water moves up the Xylem - transpiration by active transport

  Continuous tube made of dead cells and thick walls made of lignin

  Moves in 1 direction
• Describe the role of xylem

  Transpiration

  Transports water and minerals from root to plant

  Moves in 1 direction

  Made of dead cells

  Continuous tube - thick walls made of lignin
• How are sucrose and amino acids transported around the plant?

  Phloem - translocation

  Non-continuous (sieve) tube - has pores (semi-permeable)

  Made of living cells

  Moves in 2 directions

  Thin walls made of cellulose
• Adaptation of root hair cells that increases absorption of water and mineral ions

  Long 'hairs' for Large surface area - increase rate of absorption
• Define transpiration

  Loss of water from the surface of plant
• Why is evaporation faster when stomata are open?

  Air spaces between mesophyll cells and stomata creates a large surface area from which diffusion of water vapour out of stomata
• State 4 things that control rate of transpiration

  Temperature

  Light intensity

  Wind speed

  Humidity
• Describe how temperature affects rate of transpiration

  When hotter, particles have more kinetic energy and collide more often, so transpiration occurs faster as water molecules evaporate from mesophyll cells and diffuse away faster
• Describe how light intensity affects rate of transpiration

  Guard cells are responsive to light intensity - light causes stomatal pores to open for photosynthesis so water can be lost
• Describe how wind speed affects rate of transpiration

  Good air flow removes water vapour from the air surrounding the leaf, which creates a concentration gradient between the leaf and air, increasing water loss.
• Describe how humidity affects rate of transpiration

  When the air is saturated with water vapour, the concentration gradient between the leaf and air is weaker, so less water is lost.
• Why do unicellular organisms (amoeba) not have exchange surfaces such as roots/root hairs or transport systems such as xylem/phloem?

  They have a very large surface area:volume ratio, where the distance between the surface to the centre of the organism is small

  They don't have special exchange/transport systems as diffusion, osmosis, active transport through the cell occur at a sufficient rate
• Why do large multicellular organisms have exchange/transport systems?

  They have a small surface area:volume ratio, where the distance between the surface to the centre o the organism is long

  So, diffusion cannot occur at a sufficient rate
• How is coronary heart disease caused?

  Layers of fatty material/plaque build up inside coronary arteries

  Coronary artery narrows restricting blood flow (less elastic and cannot stretch to acc. Blood)

  This blockage leads to cells unable to respire aerobically

  Heart attack

  
  

  - lack of exercise: exercise reduces blood pressure and strengthens the heart
• How does high cholesterol (obesity) increase risk of coronary heart disease/heart attack?

  Speeds up the build up of fatty plaques in arteries, leading to blockages
• How does smoking increase risk of coronary heart disease/heart attack?

  Chemicals in smoke increase plaque build up and blood pressure
• Explain the differences between the left and right ventricle wall

  Left wall - thicker, more muscle, more pressure: pump blood all around body
• role of phloem

  • transport food in leaves to the rest of the plant
  • both directions
  • made o living cells with small pores (sieve tube) to allow cell sap through.
  • it is called translocation
• how are arteries adapted?

  • elastic and strong walls: pump blood at high pressure
  • small lumen, thick walls
• how are capillaries adapted?

  • thin walls: increases rate of diffusion by decreasing the distance
  • permeable walls: substances diffuse in and out
• how do stents lower the risk of heart attack in people with coronary heart disease?

  stents are tubes that are inserted inside arteries, to keep them open to make sure blood can pass through to the heart muscles and keep the heart beating.

  this is because with coronary heart disease, the coronary arteries get blocked by layers of fatty material, causing the arteries to narrow, restricting blood and oxygen flow
• loudspeaker

  • alternating current passes through the coil of the loudspeaker, creating a changing magnetic field around the coil