exchange and transport 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 is excreted which prevents accumulation and problems, to distribute
essential molecules effectively
oxygen - for aerobic respiration, exchanged in cells and environment by diffusion
carbon dioxide - waste product, exchanged in cells and environment by diffusion
water - taken up by cells in osmosis
dissolved food molecules and mineral ions - are diffused along with water in animals by osmosis
urea - diffused from cells to the blood plasma for removal of the body by the kidneys
Explain the need for exchange surfaces and a transport system
in multicellular organisms including the calculation of surface
area : volume ratio
multicellular organisms- have a smaller surface area compared to their volume, making it difficult to exchange enough substances to supply their entire volume across their outside surface alone, so they need an exchange surface for efficient diffusion and a mass transport system to move substances between the exchange surface and the rest of the body
- calculation - area : volume
-area = length * width
-volume = length *width *height
Explain how alveoli are adapted for gas exchange by diffusion
between air in capillaries
- moist lining for dissolving gases
- good blood supply to maintain concentration gradients
- very thin walls to minimise distance that gases have to move
- large surface area
Explain how the structure of the blood is related to its function: red blood cells (erythrocytes)
-biconcave shape to give a large surface area to absorb oxygen
- no nucleus = more room to carry more oxygen
- haemoglobin (red pigment) containing iron
- in lungs haemoglobin binds to oxygen to become oxyhaemoglobin. in body tissues the reverse happens (to release oxygen to cells)
Explain how the structure of the blood is related to its function: white blood cells (phagocytes and lymphocytes)
- phagocytes = white blood cells that change shape to engulf unwelcome microorganisms (phagocytosis)
- lymphocytes = produce antibodies against microorganisms and some produce antitoxins to neutralise toxins in them
- with an infection = white blood cells multiply to fight it
Explain how the structure of the blood is related to its function: plasma
- liquid that carries everything in the blood
ex
- red and white blood cells and platelets
- glucose and amino acids, from digestion from gut to cells of body
- carbon dioxide from organs to lungs
- urea from liver to kidneys
- hormones and proteins
- antibodies and antitoxins produced by white blood cells
Explain how the structure of the blood is related to its function: platelets
- small fragments of cells, no nucleus
- help blood clot (to stop microorganisms getting in and blood pouting out)
(lack of platelets can cause excessive bleeding and bruising
Explain how the structure of the blood vessels is related to their
function
arteries = carry blood away from heart
- strong and elastic walls as heart pumps blood at high pressure
- capillaries = involved in exchange of materials at the tissues
- veins = carry blood to heart
Explain how the structure of the circulatory system is related to its function
- pumps blood in double circulatory system
- first - deoxygenated blood to lungs to take oxygen
- second - oxygenated blood around all other organs to deliver oxygen
- oxygenated blood returns to heart
Explain how the structure of the heart is related to its function
- valves prevent backflow of blood
- left ventricle has thicker wall - needs more muscle to pump blood around whole body at high pressure, right only pumps to lungs
- major blood vessels - vena cava, pulmonary artery, pulmonary vein, aorta
- chambers - right and left atrium and ventricle
- right atrium, deoxygenated blood from body through vena cava
- this blood moves through right ventricle to lungs via pulmonary artery
- left atrium gets oxygenated blood from lungs through pulmonary vein
- this blood, left ventricle to whole body via aorta
Describe cellular respiration
- exothermic reaction which occurs continuously in living cells to release energy for metabolic processes, including aerobic and anaerobic respiration
compare the process of aerobic and anaerobic respiration
aerobic - oxygen
anaerobic - no oxygen, transfers less energy - less efficient, glucose partially broken down, produces lactic acid
Core Practical: Investigate the rate of respiration in living
organisms
- woodlice, water bath, respirometer
- measures amount of oxygen consumed by organism in a given time get/= rate of respiration
- this experiment allows you to measure effect of temp. on rate of respiration of the woodlice
- soda lime granules to 2 test tubes, soda lime absorbs co2 from respiring woodlice
- cotton wool above soda lime, woodlice on cotton wool in one tube, glass beads with same mass as woodlice in control tube
- set up respirometer
- syringe sets fluid in monometer to a known level
- leave for time in water bath to 15 degreesC
- during this - decrease in volume of air in test tube with woodlice, woodlice use up oxygen in tube as they respire (co2 produced is absorbed by soda lime to not affect experiment)
- decrease in volume reduces pressure in tube - coloured liquid in monometer to move to test tube with woodlice
- distance moved by liquid in given time is measured
- this can be used to calculate volume of o2 taken in by woodlice per minute = rate of respiration - repeat steps with water bath at different temps to see how changing temp. affects rate
- treat organisms ethically (don’t leave in respirometer for too long)
how to calculate heart rate
cardiac output = stroke volume times heart rate
Explain how alveoli are adapted for gas exchange by diffusion
by air in the lungs
air in the lungs
-millions of alveoli (air sacs) where gas exchange takes place
- blood arriving to the alveoli has just returned to the lungs from the rest of the body so not much oxygen but lots of carbon dioxide
- which maximises the concentration gradient - for the diffusion of both gases
- oxygen diffuses out of the air in the alveoli (high conc) and into the blood (low conc)
