Organising Animals and Plants

• What is blood made up of?

  Based on a liquid called plasma (55%) carrying red blood cells (45%), white blood cells and platelets (<1%)
• What is the importance of plasma? (4)

  1) Plasma transports all of the blood cells around the body and some other substances

  2) Waste CO2 produced by the cells carried to the lungs

  3) Urea formed in liver from the breakdown of excess proteins is carried to the kidney where it is removed from the blood to form urine

  4) Small, soluble products of digestion pass into plasma from small intestine and are passed to individual cells
• Why are red blood cells important?

  They pick up oxygen from the air in your lungs and carry it to your cells where it is needed
• What are the adaptations of red blood cells (3)

  1) Biconcave shape gives them increased surface area to volume ratio for diffusion

  2) Packed with haemoglobin that binds to oxygen

  3) No nucleus making more space for oxygen
• How are white blood cells different to red blood cells? (3)

  1) Bigger

  2) Fewer

  3) They have a nucleus
• What are the 2 types of white blood cells?

  Lymphocytes - form antibodies against microorganisms like forming antitoxins against poisons made by microorganisms

  Phagocytes - Engulf and digest invading viruses and bacteria
• Why are platelets so important?

  Help the blood to clot at the site of a wound
• How does clotting work?

  Enzyme controlled reaction that converts fibrinogen into fibrin which produces a network of protein fibres that capture lots of red blood cells and more platelets to form a jelly-like clot. The clot dries and hardens to form a scab protecting the new skin and stopping bacteria from entering
• What are the 3 main types of blood vessels?

  Arteries, veins, capillaries
• What is the function of arteries and how are they suited for this function?

  Carries bright-red oxygenated blood from heart. The arteries stretch as blood is forced through them then go back to shape (pulse). They have thick walls containing muscle and elastic fibres and relatively small lumen ensuring this pressure is maintained as the blood is transported around the body.
• Why is it bad if an artery is cut?

  The arteries are under pressure so if they are cut they spew blood every time the heart beats
• What is the function of veins and how are they suited for this function?

  Carries purple-red, deoxygenated blood to the heart. They have thin walls and valves that will close to prevent backflow of blood where the blood will be squeezed back to the heart by contraction of the skeletal muscles and a large lumen allowing more blood to flow with less vessel resistance
• What is the function of capillaries and how are they suited for this function?

  They form a network of tiny vessels linking the veins and arteries. They are narrow with very thin walls which enables substances e.g., glucose, oxygen, to diffuse easily out of blood and into cells.
• What happens in the double circulatory system?

  One transport system carries blood from heart to lungs and back again allowing oxygen and CO2 to be exchanged with the air in the lungs. The other transport system carries blood from heart to all other organs and back again
• Why is a double circulatory system important? (2)

  1) Makes our circulatory system efficient

  2) Fully oxygenated blood can be sent to different parts of the body at high pressure so more areas of the body can receive fully oxygenated blood quickly
• Why are coronary arteries important?

  They supply the muscles surrounding the heart with oxygenated blood
• Describe what happens in the atria of the heart

  Deoxygenated blood enters right atrium by the vena cava. Oxygenated blood enters the left atrium by the pulmonary vein. The atria contract forcing blood down into the ventricles. Valves close to prevent the blood from going out the heart
• Describe what happens in the ventricles of the heart


  Right ventricle forces deoxygenated blood out the pulmonary artery to the lungs. Left ventricle pumps oxygenated blood around the body through the aorta.
• Why is the muscle wall of the left ventricle thicker than the right ventricle?


  Allows the left ventricle to develop the right pressure needed to force the blood through the arterial system all over the body. If the right ventricle had high pressure it would damage the delicate capillary network where gas exchange takes place
• What is coronary heart disease and what is it often caused by and what can it cause?

  When the coronary arteries narrow. Usually caused by the buildup of fatty material on the lining of vessels leading to the reduction of bloodflow to the heart muscles possibly causing heart pain/attack or death
• Explain is a solution to coronary heart disease

  Stents - metal mesh placed in artery. Balloon is used to open up blood vessel and then deflated and removed but the stent remains in place holding the blood vessel open
• What are the pros and cons of stents?


  Pros:

  - Can be done without general anaesthetic

  - Many stents release drugs to prevent clotting

  
  

  Cons:

  - Expensive
• What is a substitute for stents when the arteries are too blocked?

  Bypass surgery where doctors replace the arteries with veins
• What are the pros and cons of bypass surgery?

  Pros:

  - Helps with badly blocked arteries where stents cannot help

  
  

  Cons:

  - Expensive

  - Comes with the risks of general anaesthetic
• What are statins?

  They reduce the amount of bad cholesterol (LDL) in the blood and slows down the rate at which fatty material is deposited in the coronary arteries
• What are leaky valves and what can they lead to?

  Over time, valves may become stiff and not open fully leading to breathlessness or possibly death
• What is a solution to leaky valves?

  Mechanical valves made from titanium and polymers or biological valves from animals like pigs and cattle.
• What are the pros and cons of mechanical valves?


  Pros:

  - Last a very long time

  
  

  Cons:

  - Take medicine for life to prevent blood clotting around it
• What are the pros and cons of biological valves?

  Pros:

  - No medicine required

  
  

  Cons:

  - Lasts from 12-15 years
• What is a natural pacemaker?

  Group of cells in the right atrium that maintain the rhythm of a healthy heart. If it stops working properly, the heart rate could be too slow causing the person to not get enough oxygen and if it's too fast then the blood can't pump properly
• What is an artifical pacemaker?

  Electrical device sending strong, regular electric signals to the heart stimulating it to beat properly and are often very sensitive to the body's needs
• What are the pros and cons of an artifical pacemaker?

  Pros:

  - Only 20-50g

  - Increase quality and length of life

  
  

  Cons:

  - Regular medicine checkups needed
• Why are temporary hearts needed?

  They support the natural heart until a donor can be found as the donor needs to match the tissue which takes a long time
• What are the pros and cons of an artifical heart?

  Pros:

  - Gives people a relatively normal life whilst waiting for the heart transplant

  - Can give a diseased heart a rest so that it can recover

  
  

  Cons:

  - Requires a lot of machinery to keep them working

  - Risk of the blood clotting in the heart which can lead to death
• What happens in the gas exchange system when we breathe in?

  1) Atmospheric air at higher pressure than chest so it is drawn into the lungs

  2) Intercostal muscles relax

  3) Increased volume means lower pressure in the chest

  4) The ribs move up and out and the diaphragm flattens
• What happens in the gas exchange system when we breathe out?

  1) Pressure in chest is higher than outside so air is forced out the lungs

  2) Intercostal muscles contract

  3) Decreased volume means higher pressure in the chest

  4) The ribs fall and the diaphragm moves up
• Why is oxygen able to continually diffuse into the bloodstream?

  Oxygen-rich air moves into the lungs when we breathe in and this maintains a steep concentration gradient with the blood
• How is the alveoli adapted for its functions? (3)

  1) Spherical shape so large surface area to achieve effective diffusion of the oxygen and carbon dioxide

  2) Rich supply of capillaries maintaing a concentration gradient in both directions

  3) Thin alveolus walls giving a short distance between air and the blood to make diffusion easy
• What are the layers of the leaf? (4)

  Upper epidermis - covers surface and protects it and secretes a waxy substance that waterproofs the surface of the leaf

  Palisade mesophyll - contains lots of chloroplasts

  Spongy mesophyll - contains some chloroplasts and contains lots of big air spaces and a large surface area to make the diffusion of gases easier

  Lower epidermis - where most of the stomata are and the guard cells control the opening and closing of the stomata
• What is the purpose of the phloem?

  Transports sugars from the leaves to the rest of the plant e.g., growing areas of the stem or the roots where the sugar is needed to make new plant cells. It is also transported to the storage organs where it provides an energy store for the winter.