Transport in humans

• What is the main reason unicellular organisms can rely on diffusion to survive?

  They have a large surface area to volume ratio (SA:V) which allows efficient diffusion.
• Why do multicellular organisms need a transport system?

  Because they have a smaller surface area to volume ratio (SA:V) which makes diffusion insufficient for nutrient and gas exchange.
• What are the four components of blood and their roles?

  • Red blood cells: transport oxygen
  • White blood cells: support the immune system and fight pathogens
  • Platelets: involved in blood clotting
  • Plasma: transports nutrients, waste products, and hormones

  
• How is a red blood cell adapted for its function?

  It contains hemoglobin, has no nucleus, is small and flexible, and has a biconcave shape to maximize surface area for oxygen absorption.

  
• What is coronary heart disease and why is it dangerous?

  Coronary heart disease occurs when arteries supplying blood to the heart become narrow or blocked, leading to heart attacks and strokes.

  
• What factors may increase the risk of coronary heart disease?


  Factors include smoking, lack of exercise, unhealthy diet, excessive alcohol consumption, high blood pressure, high cholesterol, obesity, diabetes, and family history.

  
• How does heart rate change during exercise and why?

  Heart rate increases during exercise to deliver more oxygen and nutrients to the muscles.
• How does adrenaline affect heart rate?

  Adrenaline increases heart rate by stimulating the heart to beat faster, preparing the body for heightened activity.
• What is diffusion?


  Diffusion is the movement of particles from an area of high concentration to an area of low concentration.
• How do arteries, veins, and capillaries differ in structure and function?

  • Arteries: Thick walls, carry oxygen-rich blood away from the heart.
  • Veins: Thinner walls, carry deoxygenated blood back to the heart, contain valves.
  • Capillaries: Tiny blood vessels, facilitate exchange of oxygen, nutrients, and waste products.

  
• What is the function of plasma in blood?


  Plasma transports carbon dioxide, digested food molecules, urea, hormones, and distributes heat.
• What are the main symptoms of coronary heart disease?

  Main symptoms include chest pain (angina), shortness of breath, pain in neck, shoulders, jaw, or arms, feeling faint, and nausea.

  
• What are the treatments for coronary heart disease?

  • Regular exercise
  • Stopping smoking
  • Medications
  • Angioplasty (balloons and stents)
  • Surgery

  
• Why is coronary heart disease dangerous?


  It can lead to heart attacks if arteries become blocked and can weaken the heart muscle, potentially causing heart failure.

  
• What is the function of the valves in the heart?


  Valves prevent the backward flow of blood.

  
• How does deoxygenated blood travel from the body to the lungs?

  Deoxygenated blood enters the right atrium from the vena cava, moves to the right ventricle, and is pumped into the pulmonary artery to the lungs.

  
• What is the heart made of?

  The heart is made of cardiac muscle.

  
• What is the difference between phagocytes and lymphocytes?

  Phagocytes engulf and destroy pathogens, while lymphocytes produce antibodies to protect the body from infection.

  
• What are memory cells?

  Memory cells are lymphocytes that recognize a pathogen and help the body respond more quickly upon re-exposure.
• Why do we feel ill for several days before getting better?

  It takes time to find the right lymphocyte and produce antibodies to fight the infection.

  
• What is the role of antibodies in the immune response?

  Antibodies attach to pathogens, clumping them together and signaling for their destruction.

  
• What is the function of lymphocytes in the immune system?

  Lymphocytes produce antibodies and antitoxins to neutralize toxins released by pathogens.

  
• What is the relationship between surface area to volume ratio (SA:V) and the rate of diffusion?

  • Higher SA:V leads to faster diffusion.
  • Lower SA:V leads to slower diffusion.
  • As organism size increases, SA:V decreases.
• What is the conclusion regarding SA:V and decolourisation time?

  The higher the SA:V, the less time it takes to decolourise; the lower the SA:V, the more time it takes.
• What is the method to investigate the effect of SA:V on diffusion?

  1. Change the surface area of the cube.

  2. Use agar as the medium.

  3. Repeat three times and find the average.

  4. Measure time taken to decolourise using a stopwatch.

  5. Keep concentration of hydrochloric acid constant.
• What is the method to investigate the effect of exercise on heart rate?

  1. Rest for 5 minutes to return to resting heart rate.

  2. Measure heart rate after sitting for 1 minute.

  3. Perform squats for 1 minute and measure heart rate.

  4. Repeat for jogging for 1 minute and measure heart rate.

  5. Find the average heart rate.
• How many sides does the heart have?

  The heart has two sides.
• What is the function of the ventricles in the heart?


  The ventricles pump blood to the entire body.

  
• Why is the wall of the left ventricle thicker than the wall of the right ventricle?

  The left ventricle pumps blood to the entire body, requiring more force, while the right ventricle only pumps blood to the lungs.
• What is the function of the hepatic portal vein?

  The hepatic portal vein carries blood from the gastrointestinal tract to the liver.

  
• What is the function of the renal artery?

  The renal artery carries oxygenated blood to the kidneys.

  
• What is the function of the renal vein?


  The renal vein carries deoxygenated blood away from the kidneys to the heart.

  
• What is the function of the pulmonary artery?

  The pulmonary artery carries deoxygenated blood from the heart to the lungs.

  
• What is the function of the pulmonary vein?

  The pulmonary vein carries oxygenated blood from the lungs to the heart.

  
• What is the function of the aorta?

  The aorta carries oxygen-rich blood away from the heart to various parts of the body.

  
• What is the function of capillaries?

  Capillaries deliver oxygen and nutrients to cells while removing waste products like carbon dioxide.
• What is the function of platelets?

  Platelets are involved in blood clotting, preventing blood loss and entry of pathogens.
• What is the role of phagocytes in the immune system?

  Phagocytes engulf and destroy pathogens by surrounding them and breaking them down with enzymes.

  
• What is the role of lymphocytes in the immune system?

  Lymphocytes produce antibodies and antitoxins to neutralize toxins released by pathogens.

  
• What is the definition of antigens?

  Antigens are markers on the surface of cells that trigger an immune response.