Topic 8 - Exchange And Transport In Animals Flashcards
What is the word equation for aerobic respiration?
Glucose + Oxygen -> Carbon Dioxide + Water
What adaptations of surfaces ensure quick diffusion?
Surfaces are thin so that particles don’t need to diffuse very far.
They have a large surface area so that there is more room for particles to diffuse.
What is the surface area to volume ratio?
Surface Area/Volume
What does a larger surface area mean?
The larger a cells surface area, the more of a substance can diffuse into (and out of) it in a certain time.
Where are Oxygen and Carbon Dioxide exchanged?
In the alveoli
Where and how are Oxygen and Carbon Dioxide exchanged?
By diffusion in the alveoli.
Direction of diffusion
^ - diffusion of Carbon Dioxide.
V - diffusion of Oxygen
Factors that affect the rate of exchange:
Surface area
Diffusion distance
Concentration gradient
How is surface area for exchange maximised in the lungs?
They have millions of alveoli. Each alveolus is closely linked with many capillaries.
Complete the sentence - The _________ the diffusion distance, the faster the rate of exchange.
Shorter
How are the alveolus and capillary adapted to reduce diffusion distance?
The capillary wall and alveolus walls are both one cell thick.
Complete the sentence - the greater the difference in concentration along the path of diffusion, the _______ the rate of diffusion
Faster
How does air being breathed in/out of the lungs help maintain a high concentration gradient?
Air in the alveolus is continually replaced with fresh air that has less carbon dioxide and more oxygen.
How does blood flowing continually through the capillaries help maintain a high concentration gradient?
Blood coming into the lungs has a higher carbon dioxide concentration and lower oxygen concentration than blood leaving the lungs.
Function of red blood cells -
Carries oxygen around the body
Function of white blood cells -
Fight disease
Function of platelets -
Carries substances around the body
Function of plasma -
Helps to clot blood
What do arteries do?
Carry blood away from the heart.
What do veins do?
Carry blood (mostly deoxygenated) back to the heart.
What do capillaries do?
Carry blood through tissues and organs.
Pressure in the arteries -
Higher than in other blood vessels.
How is the structure of arteries adapted to these pressures?
Thick, elastic, muscular walls stretch as blood arrives from the heart.
The relaxation of the muscle helps to reduce variation in blood pressure and make blood flow smoothly.
Blood pressure in veins -
Lower than in other blood vessels
How is the width of veins adapted to help blood return to the heart?
The width of veins allows blood to flow more easily along the vessel.
What do veins have along their length?
Valves
How do valves help blood flow in veins when muscles contract?
When the muscles contract, blood is pushed through the valve towards the heart.
How do valves help blood flow in veins when muscles relax?
When the muscles relax, the valves close, stopping the blood flowing back away from the heart.
How is capillary structure adapted to the function of exchange?
The capillary wall is one cell thick -> substances in blood are very close to cells -> the distance for diffusion with cells is as small as possible.
What does the right side of the heart do?
Pumps deoxygenated blood to the lungs to collect oxygen.
What does the left side of the heart do?
Pumps oxygenated blood brought back from the lungs around the body.
How does muscle tissue allow the heart to do its job?
Different thickness of tissue to pump different blood pressures when a muscle contracts
Why is the thickness of the muscle tissue not the same in all parts of the heart?
Blood needs to be pumped for different distances e.g to the lungs
State what heart valves do and how they work.
They are the structure in veins that prevent the backflow of blood. When the muscle relaxes, they close. When the muscle contracts, they open
What structure holds the flaps of the heart valves in position?
Tendons
What causes each heartbeat?
Contraction and relaxation of cardiac muscle controlled by impulses from the nervous system.
Heart rate definition -
The number of times the heart beats in a minute.
Stroke volume definition -
The volume of blood pushed into the aorta in each beat (litres)
Cardiac output equation -
Stroke volume x heart rate
Why do fitter people have larger stroke volumes?
Regular exercise increases the strength of heart muscle and ventricle size. So, fitter people often have bigger stroke volumes, and their hearts can beat more slowly to achieve the same cardiac output as a less fit person.
3 reasons why organisms need energy?
To drive the chemical reactions needed to keep organisms alive.
For cell division.
To move molecules against concentration gradients in active transport
When a reaction gives out energy it is ____________
Exothermic
Aerobic respiration word equation
Glucose + Oxygen -> Water + Carbon Dioxide (+ Energy)
Aerobic respiration symbol equation
C6H12O6 + 6O2 -> 6H2O + 6CO2 (+ Energy)
Where does aerobic respiration occur?
The mitochondria
Process of anaerobic respiration
During exercise, your muscles need more energy -> rate of aerobic respiration increases.
Your heart beats faster and deeper.
Oxygen in this process is used up faster than it is replaced -> increases rate of anaerobic respiration in the cytoplasm
Equation for anaerobic respiration
Glucose -> Lactic Acid
Why is soda lime used?
To absorb any carbon dioxide produced by the respiring organisms
Why must soda lime be handled carefully?
It is corrosive
What variables need to be controlled during the investigation?
The type of organism used, volume of soda lime, number of organisms
Ethical and safety issues with using living organisms
Well being and safety of organisms as they could die or become distressed
Why do the tubes containing the organisms need to be left in a water bath for 5 minutes before the rate of oxygen consumption is measured?
So the organisms can acclimatise to the new temperature outside of their natural environment
How can the distance that the coloured liquid moves be
used to determine the rate of oxygen uptake?
- The distance the coloured liquid moves is due to the decrease in the volume of the air in the test tube.
- which is due to CO2 being absorbed by soda lime.
- Which is due to the organisms removing oxygen from the test tube and adding CO2 to the air during respiration.
- The distance moved by the liquid in a given time is measured and used to calculate the volume of oxygen taken in per minute (you can calculate the gradient to find this). This gives you the rate of respiration in cm^3/min
Fick’s law
Rate of diffusion ∝ (surface area x concentration difference) / thickness of membrane
