B4: organising animals and plants

• Blood


  A key part of how multicellular organisms in animals transport substances around their body
• Blood

  • Contains red blood cells, platelets, and plasma
• Red blood cells

  Doughnut-shaped cells that make up 40-45% of blood
• Platelets

  Cells that cause blood to clot, making up 1-2% of blood
• Plasma


  The liquid component of blood that makes up around 50% of blood, transporting substances
• White blood cells

  Cells that fight infections, making up around 1% of blood
• Blood circulation

  1. Arteries take blood away from the heart

  2. Capillaries connect arteries and veins, allowing diffusion

  3. Veins take blood back to the heart
• Arteries

  • Thickest blood vessels, adapted to handle high blood pressure
• Veins

  • Contain valves to prevent backflow of blood due to lower pressure
• Capillaries


  • Incredibly thin, allowing easy diffusion of substances
• Double circulatory system

  Blood enters the heart twice - once to the lungs to become oxygenated, then back to the heart to be pumped around the body
• Blood flow through the heart

  1. Enters through vena cava into right atrium

  2. Passes through valve into right ventricle

  3. Pumped to lungs via pulmonary artery

  4. Returns oxygenated from lungs via pulmonary veins

  5. Enters left atrium, then left ventricle

  6. Pumped around body via aorta
• Heart

  • Left side is thicker to pump blood further around the body
• Heart beats around 2 billion times in a lifetime
• Pacemaker


  Artificial device that sends electrical impulses to regulate heartbeat
• Artificial heart


  Completely replaces the natural heart, used as a last resort
• Plant organ systems


  • Leaf
• Leaf structure

  • Waxy cuticle on upper surface
  • Upper epidermis layer
  • Palisade mesophyll layer (photosynthesis)
  • Spongy mesophyll layer (gas exchange)
  • Lower epidermis with stomata
• Xylem

  Transports water and minerals up from roots
• Phloem


  Transports products of photosynthesis, can also transport minerals
• Factors affecting plant water loss

  • Wind
  • Heat
• Plant adaptations to reduce water loss

  • Fewer leaves
  • Waxy coatings
  • Stomata closing when not photosynthesizing
• Potometer

  Device used to measure plant transpiration and water uptake
• Double Circulatory System

  Blood is pumped to the lungs by the right side of the heart and blood is pumped to the body by the left side of the heart