⭐️SB8 - Exchange And Transport In Animals Flashcards
What waste product is removed by the kidneys and what is it?
Urea - a poison produced by breaking down amino acids
What substances are needed to produce new substances in the body
Dissolved food molecules and mineral ions
What properties must surfaces have to maximise rate of diffusion in an organism?
- must be thin so particles do not need to move very far
- must have a large surface area so there is more rook for particles to diffuse
Why do multicellular organisms have transport systems?
As it would take too long for materials to diffuse through cells on the outside of a tissue to reach cells on the inside
What is the transport system in humans?
A fine network of capillaries in the circulatory system which uses blood to transport substances to and from the cell
Describe the diffusion happening in the capillaries
What goes out?
What goes in?
- oxygen molecules diffuse out
- glucose molecules diffuse out
- carbon dioxide molecules overall move into the capillary down the concentration gradient
How are capillaries efficient at diffusing particles?
They are only one cell thick
What maintains the concentration gradient in a capillary?
The continual flow of blood
What is the surface area to volume ration and what does it mean?
The surface area / volume and so the bigger it is the more surface area something has
how does size of cells depend on SA:V ratio?
The larger the ratio the smaller the cells and so the smaller the ratio the larger the cells
What does it mean if an organ has a large SA:V ratio?
Then that organ moves substances into and out of the body
How does blood move through and alveolus?
- It enters from the rest of the body with a higher concentration of carbon dioxide and a lower concentration of oxygen
- There is a net movement of CO2 into the alveolus and out of the blood
- There is a net movement of oxygen out of the alveolus and into the blood
- Blood goes to the rest of the body with a lower concentration of carbon dioxide and a higher concentration of oxygen
How is an alveolus adapted to its function
- It has a one cell thick wall of alveolus
- it has a one cell thick wall of capillary
- it has a higher concentration of oxygen and lower concentration of carbon dioxide than blood to have more oxygen in the blood and less carbon dioxide
- its shaped a certain way so it has a larger surface area
What is concentration?
The amount of substance in a certain volume
How do you calculate concentration in g dm cubed?
Concentration = mass of solute (g) / volume of solution ( dm cubed)
What does it mean that particles in a solution move randomly in all directions?
It causes an overall net movement of the solute particles from higher concentration to lower concentration
What forms a concentration gradient? What is the link between greater difference in concentration and rate of diffusion?
The difference between two concentrations and the greater the difference between them, the steeper their concentration gradient and the faster the rate of diffusion
What is the relationship between rate of diffusion and difference In concentrations and how do you know this?
They are directly proportional to each other because on a graph the line goes through the origin so:
Rate of diffusion ∝ concentration difference
How is concentration gradient maintained in the lungs?
A good blood supply moves oxygen quickly out of the lungs so this keeps rate of diffusion high
How does surface area affect the rate of diffusion? Explain it
The rate of diffusion ∝ the surface area
As if surface area of a membrane is increased, there is more space through which particles can pass so rate of diffusion increases
How does distance effect the rate of diffusion and explain
Rate of diffusion ∝ 1 / thickness of membrane. This makes it inversely proportional because the slower particles have to diffuse the slower the rate of diffusion
What does fick’s law show?
The relashionship between the variables that affect diffusion:
Rate of diffusion ∝ surface area x concentration difference / thickness of membrane
Describe the flow of blood in the circulatory system
It flows away from the heart, into the arteries which divide into capillaries and form fine networks running through tissues. Blood then returns to the heart in veins
What are valves for?
To prevent blood flowing the wrong way
Explain the pulse you feel in the arteries
Its when the artery wall stretches due to sudden increase in blood pressure (not movement of blood)
What happens to artery walls after a sudden increase in pressure
They stretch and then muscle and elastic fibres cause them to contract again
Why does the artery stretch and contract?
So the blood flows more smoothly
What helps push blood along veins?
Muscles in the skeleton
For an artery,
Describe the Lumen, thickness of muscular wall, pressure and wether valves are present
- lumen is narrow
- has a thick layer of elastic and muscle fibres
- pressure is high
- has no valves
For a vein,
Describe the Lumen, thickness of muscular wall, pressure and wether valves are present
- lumen is wide due to a thin muscular wall which is flexible
- low pressure hence why the wall is thin
- contains valves
For capillaries
What process mainly happens in them and describe the Lumen, thickness of muscular wall, pressure and wether valves are present
Mainly diffusion occurs here,
- very narrow lumen
- thickness is only one cell thick to allow faster diffusion of substances in and out
- low pressure
- no valves
What is blood made up of
- Erythrocytes (red blood cells)
- platelets
- white blood cells
- plasma
Describe erythrocytes
- have a lot of haemoglobin which binds with oxygen in lungs and releases it in tissue
- have no nucleus so there’s space for haemoglobin
- have a biconcave shape for a large SA:V ratio to diffuse oxygen in and out
What is plasma?
A straw coloured liquid which carries dissolved substances like carbon dioxide, glucose and urea and is where erythrocytes and platelets and white blood cells are suspended
What are platelets?
Tiny fragments of cells that gave no nuclei and produce substances needed to clot the blood as a site of injury
Describe 2 types of white blood cells and what they do
There are lymphocytes which produce antibodies that stick to foreign cells and help digest them
There are phagocytes that surround foreign cells and digest them
When does a heart attack occur?
When blood stops flowing to muscles in parts of the heart damaging the muscles so the heart doesn’t pump properly
What are the four chambers in the heart?
Left atrium, right atrium, left ventricle and right ventricle
How does blood move through the heart?
- Deoxygenated blood from the rest of the body enters the superior vena cava on the right side of the heart
- then it goes to the right atrium
- then it goes to the right ventricle
- then it gets pumped out through the pulmonary artery to the lungs
- At the same time Oxygenated blood from the lungs goes through the pulmonary veins
- Blood goes to the left atrium
- Blood goes to the left ventricle
- It’s pumped out through the aorta which sends blood to the rest of the body
What do heart valves do? What do they cause?
Stop blood flowing the wrong way and when they shut they make the ‘lub-dub’ sound of a heart
Be able to label the heart
Check page 168 on diagram of heart to know where everything is
What does the aorta do?
Carries oxygenated blood to the rest of the body
What does the superior vena cava do”
Brings deoxygenated blood from the upper body
Where does the pulmonary artery go?
To the lungs to oxygenate the blood
What do the pulmonary veins do
Carry oxygenated blood from the lungs into the heart
What does the inferior vena cava do?
Brings blood from the lower body
What do tendons do?
Stop valves turning inside out
What is the difference between the left and right ventricle
The wall of the left contains more muscle and so is thicker
What is the septum In the heart?
Tissue that separates both sides of the heart
In each chamber is the blood oxygenated or deoxygenated?
Left atrium and ventricle deal with oxygenated blood and right atrium and ventricle deal with deoxygenated blood
How does the nervous system control the heart?
As impulses control the contraction and relaxation of muscles during each heartbeat
What is heart rate? Give units
The number of times a heart beats per minute in beats/min
What is the stroke volume? What’s the unit?
The volume of blood pushed into the aorta in each heartbeat measured in litres
What is cardiac output? Give a unit
Volume of blood pushed into the aorta each minute in litres per minute
How do you calculate cardiac output?
Cardiac output = stroke volume x heart rate
Why do fitter people have a slower heartbeat?
Because regular exercise increases the strength of heart muscle and ventricle size so the stroke clime will be bigger and the heart has to beat slower to achiever the same cardiac output as a less fit person
What does the body require an energy supply for?
Moving, keeping warm and producing and breaking down substances
What process is respiration?
Exothermic as some energy is transferred out of cells by heating hence why respiration can keep you warm
Where does aerobic respiration occur and what’s the word equation for it?
Occurs in the mitochondria and
Glucose + oxygen -> carbon dioxide + water
What are the aims of the circulatory system?
- to make sure cells have a good supply of oxygen from the lungs and glucose from the small intestines
- to make sure wastes are carried away from cells
How does glucose move?
It’s absorbed into the blood plasma from digested food in the small intestines
What part of the blood carries oxygen?
The erythrocytes
How does carbon dioxide move into blood?
From cells it enters into the plasma
What happens during exercise as tiny muscles need more energy?
- rate of respiration increases as muscle cells take more oxygen and glucose from the blood
- the heart beats faster to get more blood to the muscle cells
- you breath faster and deeper to increase the amount of oxygen diffusing into the blood in your lungs as this allows your lungs to excrete more carbon dioxide
When does anaerobic respiration increase?
During strenuous exercise when oxygen is used up faster than it is replaced
Where does anaerobic respiration occur?
In the cytoplasm
How is anaerobic respiration different to aerobic respiration?
- It does not require oxygen
- produces lactic acid
- releases less energy from glucose than aerobic respiration
- causes muscles to tire quicker
- releases short bursts of energy
What’s the word equation for anaerobic respiration
Glucose -> lactic acid
When is anaerobic respiration very useful?
Animals that may need to move fast and suddenly such as when sprinting away from a predator
Why do heart and breathing rates remain high after exercise?
As extra oxygen is needed to replace the oxygen lost from the blood and muscles and it release extra energy required to get rid of lactic acid
Explain why oxygen uptake increases as an athlete runs at faster speeds (2)
Muscles contract more so there us more aerobic respiration occurring
Explain how the higher cardiac output after 4 weeks of training increased the rate of aerobic respiration (2)
There is faster blood flow so there is more oxygen transported to muscle cells
Explain why the concentration of lactic acid changes while a person is running (3)
Aerobic respiration reaches maximum rate (1) as oxygen is not being supplied fast enough (1) so anaerobic respiration occurs (1)
A person was running for a certain period and then rested
Explain why the concentration of lactic acid in the blood changes while resting (3)
Because oxygen is now being used in aerobic respiration (1) causing the lactic acid to be broken down (1) and it decreases in concentration (1)
Why is a large surface area to volume ratio an advantage to an earthworm? (1)
As it can absorb more oxygen at a faster rate
Which type of enzyme digests fats? (1)
Lipase
Explain why dead plants decay faster in soil containing earthworms compared with soil containing no earthworms (3)
There is more oxygen in soil with earthworms (1) which causes higher aerobic respiration of bacteria or decomposers (1) that can decay the plant (1)
For the respiration practical,
what was the independent variable?
What was the dependant variable?
What were the control variables?
- The temperature
- distance moved by fluid
- mass of organisms, fluid and soda lime used
Give a word equation for anaerobic respiration in yeast
Glucose -> carbon dioxide + alcohol
Explain why exercise can’t be sustained when anaerobic respiration takes place in muscle cells
As not enough energy is being transferred (1) so the muscles stop contracting (1)
Give a way to increase blood flow
Increase Heart rate
