Topic 8: Exchnage and Transport in Animals Flashcards
Describe the need to transport substances into and out of a
range of organisms, including oxygen, carbon dioxide, water,
dissolved food molecules, mineral ions and urea
Metabolism waste isexcreted - prevents accumulation -> problems.
OXYGEN is exchanged in the ALVEOLI by diffusion. It is needed for aerobic respiration
CARBON DIOXIDE is exchanged in the ALVEOLI by diffusion. It is a waste product of metabolism
WATER is exchanged in the nephron by OSMOSIS. It is needed for cell function
DISSOLVES FOOD MOLES are exchanged in the small intestine by diffusion. They are needed to make new substances/respiration
Mineral ions are exchanged by the small intestine by diffusion. It is Needed to make new substances
UREA is exchanged in the nephrons by diffusion. It is a waste product of metabolism (poison)
8.2: Explain the need for exchange surfaces and a transport
system in multicellular organisms including the calculation of
surface area : volume ratio
SINGLE-CELLED organisms have a large surface area to volume ratio.
Diffusion transports raw materials into their body across a membrane.
Enough substances are exchanged to supply the volume of the cell.
MULTI-CELLED organisms have a small surface area compared to volume (can’t rely on only diffusion)
Difficult to exchange enough substances to supply the volume across only the outer membrane
It’d take too long for substances to diffuse through outside cells to reach inside cells.
Multi-celled organisms need exchange surfaces and transport systems to move substances.
SURFACE AREA: VOLUME RATIO = surface area/volume.
BIGGER SA : V ratio -> more surface area per unit volume -> bigger cells have smaller SA:V ratios.
If TOO SMALL, cells can’t get enough raw materials fast enough - limit to cell size.
The greater the surface area, the more of a substance can diffuse into/out of it in a certain time but if a volume is too big the cell can’t fill up all of the materials needed quickly enough.
8.3: Explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries
LUNGS are adapted for efficient gas exchange by alveoli:
Having A MOIST LINING for dissolving gases, but also:
Million of tiny clustered alveoli -> their shape creating a large surface area for diffusion
-Capillaries (providing a large deoxygenated blood supply) and alveolus ventillation (providing lots of oxygen) maintain the STEEP CONCENTRATION GRADIENT, maximising the rate of diffusion.
Alveolus + capillary walls are 1 cell thick to minimise DIFFUSION DISTANCE
8.4B: Describe the factors affecting the rate of diffusion, including
surface area, concentration gradient and diffusion distance
SURFACE AREA:Greater the surface area, the more space for particles to pass through in a certain time. Overall rate increases.
CONCENTRATION GRADIENT: The steeper the concentration gradient, the more particles move down the gradient to the side where there’s less. Greater rate of diffusion
DIFFUSION DISTANCE:If a membrane is thicker, particles have further to diffuse. Rate of diffusion is slowed. - slower to get across.
8.5B: Calculate the rate of diffusion using Fick’s law:
Fick’s Law shows different variables affecting rate of diffusion.
RATE OF DIFFUSION: (Surface area x concentration difference) / Thickness of membrane.
Rate of diffusion is PROPORTIONAL to surface area + concentration difference.
Rate of diffusion is INVERSELY PROPORTIONAL to the membrane thickness.
8.6: Explain how the structure of red blood cells is related to its
function
have: A BICONCAVE shape, giving them a large SA:V ratio for oxygen to diffuse in/out.
NO NUCLEUS, allowing them to have more space for more haemoglobin to carry oxygen.
LOTS of haemoglobin (red pigment containing iron) that binds with oxygen in lungs: oxyhaemoglobin.
8.6: Explain how the structure of white blood cells is related to its
function
PHAGOCYTE WHITE BLOOD CELLS: change shape to surround and ingest pathogens then destroy them.(phagocytosis)
LYMPHOCYTE WHITE BLOOD CELLS: produce chemical antibodies attaching to foreign cells/pathogens and destroy them. Make ANTITOXINS which neutralise toxins made by pathogens
8.6: Explain how the structure of plasma in blood is related to its
function
PLASMA: liquid carrying hormones, proteins, antibodies + antitoxins.
Mainly suspends blood cells: red and white blood cells and platelets.
Also carries many dissolved substances: CO2, glucose, urea + amino acids.
8.6: Explain how the structure of platelets in blood is related to its
function
(tiny fragments of no nucleus cells) produce substances to clot blood at sites of injury.
Dries to make a scab and block wounds - stops too much blood loss and pathogens entering.
Without them, cuts could cause excessive bleeding/bruising.
8.7: Explain how the structure of the arteries is related to
their function
ARTERIES carry OXYGENATED blood away from the heart except the pulmonary artery.
THICK WALLS withstand SUDDEN PRESSURE INCREASES when the heart squeezes blood into arteries.
Thick layer of elastic and muscle fibres makes arteries stretch with high pressure + contract after stretching to make the blood flow smoothly.
explain how the structure of veins is related to their fucntion
VEINS carry DEOXYGENATED blood back towards the heart except the pulmonary vein.
VALVE stop blood flowing BACKWARDS so it returns the right direction to the heart. (Helps blood flow against gravity
THIN WALLS: blood is at low pressure - walls don’t need to be thick. Allows muscles to squeeze the veins + push blood along.
WIDE LUMEN: helps blood flow easily back to the heart despite low pressure.
explain howthe structure of capillaries are related to their function
CAPILLARIES exchange materials with body tissues.
They are VERY NARROW TUBES which helps them squeeze in gaps between cells and carry blood close to every cell.
ONE CELL THICK, PERMEABLE walls allow for faster diffusion of substance in/out - shorter distance.
8.8: Explain how the structure of the heart and circulatory system
is related to its function
VENA CAVA: brings DEOXYGENATED blood from the BODY.
PULMONARY ARTERY: carries DEOXYGENATED blood to LUNGS.
AORTA: carries OXYGENATED blood to the BODY.
PULMONARY VEIN: brings OXYGENATED blood from the LUNGS.
DEOXYGENATED blood the BODY enters the RIGHT ATRIUM through the VENA CAVA. ATRIA contract, forcing blood into the VENTRICLES via the TRICUSPID VALVE. VENTRICLES contract forcing blood in the PULMONARY ARTERY to the LUNGS.
OXYGENATED blood from the LUNGS enters the LEFT ATRIUM through the PULMONARY VEIN. ATRIA contract, forcing blood into the VENTRICLES via the BICUSPID VALVE. VENTRICLES contract forcing blood in the AORTA to the body.
VALVES stop BACKFLOW + make blood flow in the right direction.
The LEFT VENTRICLE WALL contains more MUSCLE so is thicker. It has to pump blood around most of the body. The RIGHT VENTRICLE only pumps blood to the lungs.
what type of reaction is cellular respiration
exothermic
explain why cellular respiration is an exothermic reaction
it releases energy for metabolic reactions including aerobic and anaerobic respiration
8.11: Core Practical: Investigate the rate of respiration in living organisms
1) Soda limes are added to two test tubes. This absorbs CO2 produced by respiring woodlice in the experiment.
2) Cotton wool placed above soda lime in each test tube. Woodlice are placed on top of cotton wool in one tube. Glass beads with the same mass as woodlice is placed in the control tube.
3) Respirometer is then set up to be connected to both tubes using manometers and a bung to prevent oxygen escaping.
4) Syringe is used to set fluid in manometer at a known level. The apparatus is then left in a water bath at 15 degrees Celsius for a set period of time
5) Air vol will decrease as woodlice take in oxygen to release CO2 (which is absorbed by soda lime). This decrease creates low pressure in tube, causing liquid in manometer to move towards the woodlice tube.
6) Distance moved by liquid in given time is measured. This can then be used to calculate the volume of oxygen taken in by woodlice per minute. The rate of respiration. cm^3 min^-1.
Repeat the experiment using different temperatures (control), allows you to see effect of temp on respiration.
Dependant variable - distance moved by fluid/time taken.
Independent variable - amount of woodlice, mass of tubes, CO2 concentration, volume of tube.
describe the double circulatory system that mammals have
- heart pumps blood around the body in 2 circuits
- int he first circuit (pulmonary circuit) the heart pumps deoxygenated blood to the lungs to take in oxygen and then return the pxygenated blood to the heart
- in the second circuit (systemic circuit) the heart pumps oxygenated blood to all the other organs of the body to deliver oxygen to body cells and then deoxygenated blood returns to the heart
write word and symbol equation for aerobic respiration
