B4

• What is the heart

  An organ which pumps blood around the body in a double circulatory pump
• Why is the heart known as a double pump?

  Blood enters the heart twice from one circuit around the body
• What is the route of a blood cell through the heart?


  Body > Vena Cava > Right Atrium > Right Ventricle > Pulmonary Artery > Lungs > Pulmonary Vein > Left Atrium > Left Ventricle > Aorta > Body
• What is the function of the left ventricle

  Pumps blood around the rest of the body
• What is the function of the Aorta

  Transport oxygenated blood from the body to the right atrium of the heart
• What is the function of the right ventricle

  Pumps blood to the lungs where gas exchange takes place
• What is the function of the Vena Cava

  Return deoxygenated blood from the body to the right atrium of the heart
• What is the function of the pulmonary artery

  Transport deoxygenated blood from the heart to the lungs
• What is the function of the pulmonary vein

  Transport oxygenated blood from the lungs to the heart
• How is resting heart rate controlled

  Group of cells known as a pacemaker
• Where is the natural pacemaker found

  Right atrium
• What are artificial pacemakers


  Electrical devices used to correct irregularities in the heart rate
• What is the function of the arteries

  Transport oxygenated blood under high pressure from the heart to the body
• How are the arteries adapted for their function

  Narrow lumen, thick elastic walls to withstand pressure
• What is the function of the capillaries

  Transport blood to cells
• How are capillaries adapted for their function

  One cell-thick so that blood cells can pass through them one by one

  Thin walls for a short diffusion pathway
• What is the function of veins

  Transport deoxygenated blood under high pressure from the body to the heart
• How are veins adapted for their function

  Thin walls and large lumen due to low pressure

  Valves to prevent backflow
• What is blood?


  A tissue made up of plasma in which red blood cells, white blood cells, and platelets are suspended
• What are the components of blood

  Plasma, Red blood cells, white blood cells and platelets
• What is the function of plasma


  Transport blood cells and different substances such as hormones around the body
• What is transported in blood plasma

  Carbon dioxide

  Urea

  Hormones

  Products of digestion
• What is the function of red blood cells

  Transport oxygen around the body
• What is the function of white blood cells

  Defend the body against infection
• How do WBC defend from infection?

  Phagocytosis

  Produce antibodies

  Produce antitoxins
• What is the function of the epidermal tissue

  Cover the leaf
• What is the function of the palisade tissue

  Absorb light for photosynthesis
• How is the palisade tissue adapted for its function

  They are close towards the upper surface of the leaf, packed with chloroplasts and are arranged closely together
• What is the function of the spongy mesophyll

  Gas exchange
• What is the function of the xylem

  Transport water and dissolved minerals around the plant
• How is the xylem adapted for its function

  Made of dead xylem cells, a hollow tube strengthened by lignin
• How is the spongy mesophyll adapted for its function

  Cells packed loosely to allow gaps between cells

  Cells are covered by a thin layer of water which gases dissolve in
• What is the function of the phloem 


  Transporting sugars around the plant
• How is the phloem adapted for its function

  The cells do not contain a nucleus and it is supported by companion cells

  The end of each cell has a sieve plate to allow free movement of substances from cell to cell
• What is the function of meristems


  Plant stem cells that differentiate into specialised cells throughout the life of the plant
• Where are meristems found in the plant


  Shoots

  Roots
• What are stomata


  Small pores on the underside of the leaf that allows gases such as oxygen, carbon dioxide, water vapour to diffuse in and out of the plant
• What is the function of guard cells

  Open and close stomata to control water loss
• What is the function of the roots

  Anchorage

  Absorption of water and mineral ions
• How are root hair cells adapted for their function

  Large surface area to increase rate of absorption

  Thin surface membrane for a short diffusion pathway

  Many mitochondria for active transport