bio - exchange + transport in animals (8)

• Transport of substances in and out of organisms is necessary for life and prevents accumulation.
• Cardiac output equals stroke volume times heart rate.
• Plants take in co2 and give o2 through photosynthesis, also need to take in dissolved nutrient and material, molecules + water from the soil + air.
• Root hair cells take up water and nutrients from soil, have a large surface area and thin walls, facilitating quicker diffusion.
• Walls of nephrons in the kidney are thin and large, efficiently reabsorbing substances, water/glucose.
• Small intestine cells have projections called villi where digested food is absorbed over the membrane of these cells into bloodstream.
• Leaves allow co2 to diffuse through the stomata for photosynthesis while o2 and water vapour leave through them.
• Having an efficient blood supply creates a steep concentration gradient, facilitating diffusion.
• Multicellular organisms have a small surface area to volume ratio, so they can't rely on diffusion alone unlike single-celled organisms and have several adaptations.
• Larger organisms have a smaller surface area to volume ratio as they have a large volume but relatively small surface area.
• The greater the surface area to volume ratio, the better adapted the organism is for diffusion.
• In the lungs, oxygen is transferred into the blood and co2 goes into the lungs, taking place across the surface of millions of air sacs called alveoli, surrounded by blood vessels with thin walls, providing a short diffusion pathway, and are arranged in clusters, maintaining a large surface area.
• Factors affecting diffusion include concentration gradient, temperature, and surface area of the membrane.
• The rate of diffusion is calculated by the formula: (surface area x concentration difference)/thickness of membrane.
• Plasma is the liquid that carries components of blood (rbc, wbc, platelets, glucose, amino acids, co2, urea, hormones, proteins, antibodies + antitoxins).
• Rbc carry oxygen from lungs to rest of body, have a concave disk shape providing a large surface area, and contain pigment haemoglobin - oxyhaemoglobin (for oxygen to bind).
• Wbc are part of the immune system and have a nucleus.
• There are several types of wbc, one produces antibodies against microorganisms, another engulfs and digests pathogens, the other produces antitoxins - neutralises toxins produced by microorganisms.
• Platelets help the blood clot form at the site of a wound that then dries and hardens to form a scab which allows new skin to grow underneath while preventing microorganisms from entering, and are small fragments of cells with no nucleus.
• Muscle layers help vessels endure pressure created by heartbeat.
• The structure of heart includes muscular walls, which are strong and can withstand heartbeat, and a wall of the left is thicker to pump blood to body.
• Capillaries are 1 cell thick, providing a short diffusion pathway and permeable walls, allowing substances to move across them.
• Coronary arteries cover heart to provide it's own oxygenated blood supply.
• Valves prevent backflow of blood.
• The natural resting heartbeat is 70 beats per min and is controlled by a group of cells found in right atrium, which provide stimulation through small electrical impulses.
• The core practical involves setting up an apparatus consisting of two tubes, one containing the living organisms and the other with glass beads to act as a control.
• Atria and ventricles in heart contract.
• Aerobic respiration occurs when there is sufficient oxygen and it is mostly happens in the mitochondria, resulting in c6h12o6 + o2 = co2 + h2o.
• Ox blood circulates through pulmonary veins, left atrium, mitral valve, left ventricle, aortic valve, aorta to body.
• Lumen (tube in which blood flows through) is wide to allow low pressure blood flow through.
• The heart is an organ in the circulatory system that carries oxygen/nutrients to all of body and removes waste.
• Respiration is exothermic as energy is transferred to the environment.
• The heart pumps blood around body in double circulatory system, which consists of two circuits.
• The reduction of volume in the tube increases pressure causing the coloured liquid to move.
• Capillaries allow blood to flow very close to cells to enable substances to move between them.
• Veins carry blood towards heart.
• Muscle layers are strong and elastic.
• Arteries carry blood away from heart.
• Valves in heart ensure blood doesn't flow backwards.
• The distance moved by the liquid in a given time provides the volume of oxygen taken in by the insect per minute.