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7 Cards in this Set
- Front
- Back
- 3rd side (hint)
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How do organisms exchange substances with their environment? |
-All organisms need to take in substances that they need from the environment and get rid of waste products. -The larger the organism, the smaller it’s surface compared to its volume. You can show this with surface area: volume. -In single-called organisms, gases and in dissolved substances can diffuse directly into or out of the cell across the membrane- due to large surface area compared to volume. -Multicellular organisms have small surface area compared to volume so need an EXCHANGE SURFACE for efficient diffusion and MASS TRANSPORT SYSTEM to move substances between the exchange surface and the rest of the body. |
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How does diffusion happen along the alveoli |
-Rate of diffusion depends on 3 main things: Distance (more quick if small distance), Concentration (move fast if big difference in concentration), Surface area (more quick if lots of area to diffuse across). -Gas exchange in mammals happens in the alveoli. The jobs of the lungs is transfer O2 and CO2, this is done with alveoli. Blood arrives from body with lots of CO2, which maximises concentration gradient. O2 diffuses out of the air in the alveoli and into the blood (high to low conc gradient). -The alveoli are specialised to maximise diffusion rate by having: a moist lining for dissolving gases, a good supply of blood to maintain conc gradients, very thin walls, enormous surface area. -Ficks law describes the rate of diffusion. Shows that rate of diffusion will double if surface are or difference in conc doubles or thickness of membrane halves. Rate of diffusion ‘is directly proportionate to’ surface area x concentration difference / thickness of membrane. |
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Blood |
RED BLOOD CELLS -Job of red bloods (erythrocytes) is to carry O2 from lungs to cells in body. Have biconcave disc to increase surface area for absorbing O2. Don’t have nucleus to allow more space for O2. Contains red pigment called haemoglobin which contains iron. In the lungs, haemoglobin binds to O2 to become oxyhemoglobin, in body tissues revers happens- oxyhemoglobin splits up into haemoglobin and O2 to realise O2 to cells. WHITE BLOOD CELLS -Phagocytes are white blood cells that can change chape to engulf bad microorganisms- called phagocytosis. Lymphocytes are white blood cells that produce antibodies against microorganisms, some also produce antitoxins to neutralise any toxins produced by the microorganisms. Do have nucleus. PLATELETS -Small fragments of cells, have no nucleus. Help the blood to clot. Lack of platelets can cause excessive bleeding and bruises. PLASMA -Carries almost everything. Red and white blood cells, platelets, nutrients like amino acids and glucose, CO2, Urea, hormones, proteins, antibodies and abut toxins produced by white blood cells. |
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What are the types of blood vessels? |
ARTERIES: carry blood away from heart. Heart pumps so the artery walls are strong and elastic. Walls are thick compared to lumen. Contain thick layers o muscle fro strength and elastic fibres to allow them to stretch and spring back. CAPILLARIES: Involved in the exchange of materials at the tissues. Arteries brain into capillaries. Are tiny/narrow so can get between gaps of cells- close to every cell to exchange substances. Have permeable walls so substances can diffuse in and out. Supply food and O2, and take away waste like CO2. Walls are only one cell thick which increases rate of diffusion. VEINS: carry blood to heart. Capillaries eventually join to form veins. Blood is at lower pressure so walls not so thick. Have bigger lumen to help blood flow despite low pressure. Have valves to stop back flow. |
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How does the heart work? |
-Mammals have a double circulatory system, as blood is pumped in 2 circuits. First deoxygenated blood is pumped to lungs and back to heart as oxygenated blood. Then it’s pumped round to the body and back as deoxygenated blood. -Parts of the heart: see hint for photo -Cardiac output is total volume of blood pumped by a ventricle every minute. Cardiac output = heart rate x stroke volume |
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What is respiration for and how does it work? |
-Respiration happens in every cell, process of transferring energy from the breakdown of organic compounds. Is an exothermic reaction. 2 types. -Aerobic:glucose + O2 > energy + CO2 + H2O Most efficient way of getting energy. -Anaerobic respiration: glucose > Lactic acid + energy. does use oxygen, happens when body can’t supply enough O2. Creates less energy as glucose is partially broken down and lactic acid is created- builds up in muscles and is painful and leads to cramp. Is broken down by O2. -Anaerobic respiration in plants is slightly different, produce ethanol rather than lactic acid. Glucose > ethanol + CO2 + energy. |
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Core practical: investigating respiration |
In aerobic respiration, organisms use up O2 from the air. By measuring the amount of O2 consumed by organisms in a given time, you can calculate their rate of respiration. See hint picture for instructions |
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