Transport systems

• What process allows unicellular organisms to exchange substances with their environment?


  Diffusion, osmosis, and active transport through the cell membrane.
• Why don't unicellular organisms require specialized transport systems?


  They have a large surface area relative to their volume, making diffusion sufficient for their needs.
• What is the main reason multicellular organisms need transport systems?


  Their multiple cell layers make diffusion alone too slow to supply all cells.
• What does the circulatory system transport in animals?


  It carries essential substances in the blood to meet the organism's needs.
• What are the main transport systems in plants, and what do they carry?

  The xylem (transports water and minerals) and the phloem (transports sugars and amino acids).
• What is the primary function of xylem vessels in plants?


  To transport water and mineral ions from roots to other parts of the plant.
• What role does the phloem play in plants?


  It transports sucrose and amino acids from the leaves to other parts of the plant.
• How do root hair cells increase water and mineral absorption?


  By having a large surface area that facilitates efficient uptake of water (by osmosis) and minerals (by active transport).
• Describe the pathway of water through a plant, starting from the root hair cell.


  Root hair cell → root cortex cells → xylem → leaf mesophyll cells.
• What is transpiration in plants?


  The loss of water vapor from plant parts above ground, primarily leaves, through evaporation and diffusion.
• How does increased air movement affect transpiration?


  It increases transpiration by removing water vapor near the leaf surface, creating a gradient for more water to diffuse out.
• What is the relationship between humidity and transpiration?


  Higher humidity reduces the rate of transpiration because it lowers the diffusion gradient of water vapor.
• How does temperature impact the rate of transpiration?


  Higher temperatures increase transpiration as water molecules gain more kinetic energy and evaporate faster.
• Why does light intensity affect transpiration?


  Increased light intensity causes more stomata to open for photosynthesis, allowing more water to diffuse out.
• What are the four main components of blood?

  Red blood cells, white blood cells, platelets, and plasma.
• What is the primary role of red blood cells?


  To carry oxygen to respiring cells throughout the body.
• How is plasma significant in blood transport?


  Plasma transports substances such as carbon dioxide, digested food, urea, hormones, and heat energy.
• What shape are red blood cells and why is it beneficial?


  Biconcave discs, which increase the surface area for oxygen diffusion and allow more room for hemoglobin.
• What do platelets do in the blood?


  Platelets help blood clot to prevent excessive bleeding after injury.
• What are the two main types of white blood cells?


  Phagocytes and lymphocytes.
• How do phagocytes protect the body?


  By ingesting pathogens through a process called phagocytosis, where they engulf and digest pathogens.
• What is the role of lymphocytes in immune response?

  They produce antibodies specific to antigens on pathogens, marking them for destruction.
• What is phagocytosis?


  The process by which phagocytes detect, engulf, and digest pathogens.
• How do antibodies work against pathogens?


  They bind to specific antigens on pathogens, making it easier for other immune cells to identify and destroy them.
• How can a bubble potometer be used to measure the rate of transpiration?


  By tracking the movement of an air bubble in a tube as water is taken up by a plant cutting, indicating the amount of water lost through transpiration.
• What are platelets and their role in blood clotting?


  Platelets are cell fragments that play a vital role in blood clotting and forming scabs. When the skin is broken, platelets arrive to stop bleeding by triggering a series of reactions in the blood plasma to form a clot.
• How do platelets contribute to the formation of a blood clot?


  Platelets release chemicals that convert soluble fibrinogen proteins into insoluble fibrin. This fibrin forms a mesh across the wound, trapping red blood cells to form a clot, which eventually dries and hardens into a scab.
• Why is blood clotting important for the body?


  Blood clotting prevents excessive blood loss and protects the wound from bacterial infection until new skin forms, providing essential protection and healing.
• Describe the general structure of the heart.


  The heart is a double pump with the left side pumping oxygenated blood to the body and the right side pumping deoxygenated blood to the lungs. A septum separates the two sides, ensuring proper blood flow direction.
• Why is the left ventricle's wall thicker than the right ventricle’s?


  The left ventricle has a thicker muscle wall because it pumps blood at high pressure to the entire body, requiring more force than the right ventricle, which only pumps blood to the lungs.
• What is the function of the coronary arteries?


  Coronary arteries supply oxygenated blood to the heart muscle, providing the oxygen and glucose needed for aerobic respiration, essential for continuous muscle contraction.
• How do heart valves function in blood flow?


  Valves in the heart prevent the backward flow of blood, ensuring it moves in the correct direction from atria to ventricles and then out to the arteries.
• Outline the pathway of deoxygenated blood through the heart.


  deoxygenated blood enters the right atrium via the vena cava, flows through the tricuspid valve into the right ventricle, and is pumped through the pulmonary artery to the lungs for oxygenation.
• Outline the pathway of oxygenated blood through the heart.

  Oxygenated blood returns to the left atrium via the pulmonary vein, passes through the bicuspid valve into the left ventricle, and is then pumped out through the aorta to the body.
• What is the purpose of the septum in the heart?


  The septum separates the right and left sides of the heart, preventing the mixing of oxygenated and deoxygenated blood.
• What is heart rate and how is it measured?


  Heart rate is the number of heartbeats per minute (bpm). It can be measured by counting pulses in arteries.
• What role does the pacemaker play in the heart?


  Located in the right atrium, the pacemaker is a group of cells that sends electrical impulses to regulate the heart’s rhythm, coordinating contractions of the heart muscle.
• How does exercise affect heart rate?


  Exercise increases heart rate as muscle cells require more oxygen and glucose for energy, and the heart pumps faster to deliver these and remove waste products like CO₂.
• Why does heart rate remain elevated after intense exercise?


  Post-exercise, heart rate stays high to continue supplying oxygen to break down lactic acid accumulated from anaerobic respiration.
• What is coronary heart disease (CHD)?

  CHD occurs when fatty deposits, mainly cholesterol, build up in coronary arteries, narrowing the lumen and restricting blood flow, which can lead to angina or a heart attack.