B3 Flashcards
What is osmosis?
The movement of water molecules from region of high water concentration to a region of low water concentration across a semi-permeable membrane.
What will happen if the solution inside the cell is more concentrated than the solution outside of the cell?
It means that the solution outside of the cell will be more dilute than the inside of the cell, so the water will move into the cell by osmosis.
What will happen if the solution inside of the cell is more dilute than the outside of the cell?
Water will leave the cell and go into fluid outside of the cell by osmosis.
What is an exchange surface?
A surface that allows a dissolved substance to move through them. They have to allow enough of the dissolved substances through.
How are exchange surfaces adapted to maximise their effectiveness?
- Thin so substances only have a short distance to diffuse
- Large surface area- so lots of particles can diffuse through at once
- Exchange surfaces in animals- lots of blood vessels to get substances in and out of body quickly
Explain how leaves are adapted to maximise the amount of carbon dioxide that gets to their cells.
- Stomata- exchange surface under leaf- allows carbon dioxide to diffuse through the leaf into the cells (oxygen and water vapour diffuse out of leaf trough the stomata too)
- Guard cells- they open and close the stomata. If the plant is losing too much carbon dioxide than it is being replaced the guard cells will close the stomata, too much carbon dioxide and the guard cells will open stomata to release some of it.
- Flattened shape- increases surface area of exchange surface so more carbon dioxide can be absorbed by the leaves
- Walls of cells form another exchange surface and the air spaces inside of leaf increase the area of this surface so more CO2 gets into the cells
Name the main substances that diffuse out of leaves.
Oxygen and water vapour
What conditions does evaporation of water from leaves happen most quickly in?
Hot, dry and windy conditions
How does water vapour leave the leaf?
It evaporates from cells inside the leaf and then escapes by diffusion
What happens inside the lungs?
-Oxygen from the air is put into the bloodstream and gets rid of carbon dioxide from the blood. The oxygenated blood is sent to the heart to be pumped around the body
Where are the lungs located in the body?
Inside the thorax and protected by the rib cage.
How does oxygen get to the lungs?
- The air breathed in travels down the trachea, which then splits into tubes called bronchi
- Each bronchus goes into one of the lungs
- Then the bronchi splits into smaller tubes called bronchioles
- The bronchioles stop at small bags, called the alveoli, where gas exchange takes place.
Define ventilation.
The movement of air into and out of the lungs
How does the action of breathing in happen?
- The intercostal muscles and diaphragm contract which increases the volume of the thorax
- This decreases pressure in the lungs, drawing air in
How does the action of breathing out happen?
- Intercostal muscles and diaphragm relax which decreases the volume of the thorax
- This increases pressure in the lungs, forcing air out
Give four ways that the alveoli is ideal for gas exchange.
- Lots of small folded bags which increases surface area for gas exchange to happen-increases amount of gas exchange
- The walls of the alveoli are only one cell thick so it shortens the distance that gas has to diffuse across
- Surrounded by lots of capillaries which ensures a good blood supply. It takes oxygen away from the lungs quickly and helps to maintain the concentration gradient between the blood and air in alveoli.
- Each alveolus is well ventilated, removing carbon dioxide and replenishing oxygen levels- helps to maintain the concentration gradient between blood and air in the alveoli
What is an artificial ventilator?
A machine that moves air in and out of lungs
How does an artificial ventilator work?
It pumps air into the lungs and expands rib cage
When the pumping stops, the rib cage relaxes and pushes air back out of the lungs.
What are the advantages and disadvantages of an artificial ventilator?
+ It helps people who cannot breathe by themselves
+ It doesn’t interfere with the person’s blood flow
- It can cause damage if lungs cannot cope with the artificial air flow
Where are villi found?
Found inside the small intestine, which is covered in little tiny projections called villi.
How are villi adapted to absorbing nutrients?
- Increase surface area so digested food can be absorbed much quicker into the blood
- Have single layer of surface cells- shortens distance for molecules to diffuse
- Have good blood supply to assist quick absorption
What is active transport?
The absorption of substances against the concentration gradient (from low concentration to high)
How is active transport used in a plant?
It allows plants to absorb minerals ions from a very dilute solution, against the concentration. it is essential for growth.
How is active transport used in humans?
It allows nutrients to be taken into the blood, against the concentration gradient, so that the nutrients can travel around the body.
What are the two main differences between active transport and diffusion?
- Active transport works against the concentration gradient whereas diffusion does not
- Active transport requires energy from respiration to make it work whereas diffusion does not
What does the phloem do?
It transports food substances (mainly dissolved sugars), made in the leaves, to growing regions and storage organs of the plant. It transports food in both directions
What does the xylem do?
It carries water and minerals from the roots to the stem and leaves in the transpiration stream.
What is the phloem made up of?
Columns of living cells with small holes in the ends to allow food substances to flow through.
What is the xylem made up of?
Made of dead cells joined end to end, with no end walls and a hole down the middle.
What is transpiration?
The loss of water from the plant
What is transpiration caused by?
The evaporation and diffusion of water from inside the leaves
What does transpiration do?
Creates a slight shortage of water in the leaf, so more water is drawn up from the rest of the plant through the xylem vessels to replace it.
What is the transpiration stream?
The constant drawing up of water through the plant to replace the water lost by evaporation and diffusion. This means that the roots have to keep drawing up water to supply the plants with water. This causes a transpiration stream.
Why does water escape the leaves through the stomata?
Because there is more water inside of the plant than in the surroundings so diffusion takes place.
How are root hair cells adapted to increase the amount of water and minerals that they take in?
- They stick far out into the soil and are long and thin
- This gives the plant a bigger surface area to absorb more water and mineral ions from the soil
Explain why our circulation system is called a double circulation system.
Because it contains two separate circuits.
1st one: pumps deoxygenated blood to the lungs to take in oxygen before blood returns to the heart
2nd one: pumps oxygenated blood around the rest of the body. Here, the blood gives up oxygen and the deoxygenated blood returns to the heart and then to the lungs.
Describe the route the deoxygenated blood takes through the heart.
- Deoxygenated blood flows through the vena cava from the body
- Deoxygenated blood in vena cava travels into right atrium
- When right atrium contracts, deoxygenated blood is pumped through a valve into the right ventricle
- When the right ventricle contracts, blood is forced into the pulmonary artery which carries the blood to the lungs to become oxygenated
Describe the route the oxygenated blood takes through the heart.
- Oxygenated blood is pumped from the lungs into the pulmonary vein.
- Oxygenated blood is then carried to the left atrium
- When the left atrium contracts, the oxygenated blood is pumped into the left ventricle
- The left ventricle contracts, forcing the blood through a valve into the aorta
- The oxygenated blood from the aorta to the rest of the body, via the arteries.
What is the function of the arteries?
To carry the oxygenated blood away from the heart and to the rest of the body
What is the function of the veins?
To take blood from the lungs back to the heart
What are the features of the?
Thick muscle, elastic fibres and a small lumen
Why do arteries need muscular, elastic walls?
To withstand the high pressure of blood being pumped from the heart to the rest of the body. The elastic fibres allow the arteries to stretch and spring back
What are the features of the capillaries?
They are really tiny, are one cell thick and have permeable walls.
What is the function of the capillaries?
To carry blood to every cell in the body to exchange substances with them
Describe how the capillaries are adapted to their function.
- They are really small to get to every area and cell in the body to supply food and oxygen and take away CO2
- Have permeable walls so substances can diffuse in and out easier
- Are one cell thick to increase the rate of diffusion as substances have less distance to diffuse across.
What are the features of the veins?
They do not have very thick walls, have a bigger lumen and have valves inside of them
Explain why the veins have those three features.
- Not very thick walls because the blood is at a lower pressure when it is travelling back to the heart
- Bigger lumen to help blood flow back to the heart
- Valves to prevent back flow
What four things does the blood contain?
- Red blood cells
- White blood cells
- Platelets
- Plasma
What is the function of the red blood cells?
To carry oxygen from the lungs to all the cells in the body
How are red blood cells adapted to their function?
- Biconcave shape- larger surface area for absorbing oxygen
- No nucleus- more room to carry oxygen
- Contain haemoglobin- combines with oxygen in lungs
What is the product of haemoglobin and oxygen when they combine?
Oxyhaemoglobin
What is the function of white blood cells?
To defend against disease
How is a white blood cell adapted to its function?
- it engulfs bacteria
- it produces antibodies to fight bacteria
- produces antitoxins to neutralise toxins produce by bacteria
What is the function of the platelets?
To help blood clot
What are platelets?
Small fragments of dead cells that have no nucleus
Why is it important that the blood clots
To prevent excessive bleeding and bruising.
To prevent bacteria getting in the body through the wounds
What is plasma?
A liquid that carries:
- red blood cells, platelets and white blood cells
- nutrients (e.g glucose and amino acids) to cells
- urea from liver to the kidneys
- hormones
- antibodies and antitoxins produced by the white blood cells
Explain how artificial blood products keep people alive.
It replaces the lost volume blood and red blood cells. It gives the patient more time to produce new red blood cells to increase blood volume again.
What is artificial blood?
A blood substitute used to replace the lost volume of blood
What does an artificial heart do?
A mechanical device that pumps blood around the body if a person’s own heart fails
State one part of the heart that can be replaced with artificial parts, and give one potential complication.
A valve with an artificial valve. It can still cause problems with blood clotting
What does a stent do?
It causes a narrowing artery to open up again. This allows the blood flow to return to normal and decreases risk of strokes and heart attacks.
How is a stent placed in an artery?
A balloon is placed inside the stent and, when it is in the specific artery, the balloon is blown up to stretch stent and open artery up again. The balloon is removed and the stent is left in the artery.
What is the main advantage of an artificial heart?
It is not rejected by the immune system because it is made from metals and/or plastics so the white blood cells do not detect it as a foreign object
What are four disadvantages of an artificial heart?
- the heart could wear out or electrical motor could fail
- the blood still doesn’t flow through it as smoothly which can cause blood clots
- the patient will be required to blood thinners
- the surgery can lead to bleeding and infection
What is coronary heart disease?
A disease that is caused by the arteries getting blocked up with fatty deposits, which causes the arteries to narrow and restrict blood flow to the heart.
Define homeostasis.
The maintenance of a constant internal environment
State four things that the body needs to keep constant.
- Body temperature
- Blood glucose levels
- Water content
- Ion content
Where in the body is urea produced?
In the liver
How is water take into the body?
Through food and drink
Give three ways in which water is lost from the body.
- Sweat
- Breathing air out
- Urine
Explain why your urine is likely to be more concentrated on a hot day.
Hotter temperatures will cause the body to sweat more, so more water is lost through sweating than any other way. Therefore, there will be less water in the body to excrete so the urea and water solution will be more concentrated.
Explain why sugar doesn’t simply diffuse back into the blood from the nephrons.
- At first, water urea, ions and glucose are squeezed out of the blood into the Bowman’s capsule and then the membranes between the blood vessels act like filters.
- Big molecule stay in blood and the rest flow along nephron and the reabsorbed. All sugars are then reabsorbed into the blood using active transport.
Describe what happens when blood glucose levels get too high.
If blood glucose levels are too high, insulin is secreted by the pancreas. Insulin is then absorbed by the liver which triggers it to turn the glucose in the blood into glycogen. This can be stored in the liver, and so blood glucose levels will decrease.
Describe what happens when blood glucose levels get too low.
Glucogon is secreted by the pancreas. The glucogon triggers the liver to add more glucose into the blood so blood glucose levels increase again.
Which organ controls and maintains the blood glucose levels?
The pancreas.
How does the pancreas control and maintain blood glucose levels?
By releasing glucogon or insulin into the blood.
What are insulin and glucogon?
Hormones that control how much sugar is present in the blood.
What happens to waster after it leaves the nephron?
They continue down the nephron, into the ureter and down to the bladder as urine
How does the body stay warm on a cold day?
- hair stands up to trap insulating layer of air
- No sweat is produced
- Blood vessels supplying skin constrict to close off skin’s blood supply to reduce heat loss (vasoconstriction)
How does the body stay cool on a hot day?
- hair lies flat
- sweat produced by sweat glands- evaporation of sweat from skin removes heat
- blood vessels dilate so blood flows close to surface of skin (vasodilation)- makes it easier for heat to be transferred from blood to environment.
What are the three functions of the kidney?
- removal of urea from blood
- adjustment of ions in blood
- adjustment of water content in blood
How is the ion content in the blood kept at a normal level?
The kidney will remove excess ions as having the wrong amount can damage the cells. Ions are also lost by sweat but general balance is maintained by kidneys
Explain the process of renal dialysis.
- The patient’s blood flows alongside a selectively permeable barrier surrounded by dialysis fluid
- The membrane is permeable to things like ions and waste substances
- The dialysis fluid contains the same concentration of dissolved ions and glucose as the patient’s blood
- The useful ions and glucose will not be lost from blood during dialysis this way
- Only waste products, excess ions and excess water diffuse across the barrier
What happens if the kidneys do not work properly?
Waste substances build up in blood and they lose the ability to control water and ion levels in body.
What happens to the cell if there is too much water in it?
The cell will swell up and become turgid
What happens to the cell if there is too little water in it?
The cell crenates (shrivels)
What does a hypertonic drink contain?
A greater concentration of sugars and salts. It is used as a power drink to deliver glucose to the cells.
What does an isotonic drink contain?
It has roughly the same concentration sugar, salts for hydration and fuel replacement
What does a hypotonic drink contain?
It has a lower concentration of sugar and salts so is mainly used for hydration.
What is happening to the world’s population?
Currently rising very quickly
What is largely responsible for the increase in population?
- Modern medicine
- Farming methods
- Both have reduced people dying from disease and starvation
Name 3 stores of carbon.
- Oceans
- Green plants
- Peat bogs
Why is it important to have stores of carbon?
So CO2 is removed from the atmosphere
Define deforestation.
The cutting down of forests
Give three reasons why people are chopping down large areas of trees?
- To provide timber to use as a building material
- To clear more land fro farming
- To produce paper from wood
Explain the meaning of the term ‘biodiversity’.
The variety of different species living in a habitat so the more species the greater the biodiversity of that area.
List the four main problems that deforestation can lead to.
- More methane in the atmosphere
- More carbon dioxide in the atmosphere
- Less carbon dioxide being taken in by the trees and plants fro photosynthesis because there are less of them
- Less biodiversity
How could growing rice contribute to global warming?
- Rice is grown in warm, waterlogged conditions. This is an ideal environment for decomposers, who produce methane and so more is released into the atmosphere
How is peat formed?
- Plants that live in bogs do not decay fully when they die because there is not enough oxygen.
- The partly-rotted plants gradually build up to form peat
Describe one way that scientists collect data about climate change.
Satellites:
- used to monitor snow and ice cover
- used to measure the temperature of sea surface
- temperature and speed of ocean currents are monitored for any changes
- automatic weather stations are constantly recording atmospheric temperatures
Does fermentation involve anaerobic or aerobic respiration?
Anaerobic respiration
What are the two main components of biogas?
Methane (70%) and carbon dioxide (30%)
What is meant by sustainable food production?
Having enough food without using the resources faster than they renew
What are fishing quotas and how do hey help conserve our fish stocks?
- They place limits on the number and size of the fish that are allowed to be caught in certain areas.
- This prevents certain species from being overfished
Describe how enforcing a net size limit helps to conserve fish stocks.
- The holes in the net will be made bigger, depending on what is being fished, to prevent the number of unwanted and discarded fish. It also means that the younger, smaller fish will be able to escape and grow, allowing them to reach breeding age. In turn, this will ensure that the species will be carried on and not have a risk of being endangered or extinct.
How are the humans impacting the environment in terms of waste?
Waste we produce is causing more harmful pollution:
- sewage and toxic chemicals from industry can pollute lakes, sewers and oceans, affecting plants and animals that rely on them for survival
- we use toxic chemicals for farming, bury nuclear waste underground and dump household waster in landfill sites
- smoke and gases released into the atmosphere can pollute the air
Describe how carbon dioxide is contributing to global warming.
Energy from the sun is usually radiated back out of the Earth’s atmosphere and only some of it is retained in the Earth’s atmosphere. However, the increase in CO2 in the atmosphere is creating a layer around the Earth and trapping more of the Sun’s energy inside the Earth’s atmosphere. This is called the greenhouse effect, which is what is causing the Earth’s temperature to rise.
How is deforestation contributing to less biodiversity?
The cutting down of forests has destroyed many species’ habitats and so they have nowhere to live anymore. This causes them to die because they are not adapted to the drastic change in environmental conditions so biodiversity is reduced.
What are the consequences of global warming?
- As sea gets warmer, it expands, causing sea level to rise
- Higher temperatures cause the ice to melt which further increases sea levels
- Changing weather patterns- warmer sea could mean more hurricanes
- Distribution of wild animal and plant species may change
- Biodiversity could be reduced if species are unable to survive a change of climate
- Changes in migration patterns
How can fuels be made?
By fermentation
How is ethanol made?
Through the anaerobic fermentation of sugar
How is biogas made?
Through the anaerobic fermentation of waste material
Why do biogas generators need t be kept at constant temperatures?
To ensure that the conditions are right for microorganisms to respire and cause a reaction
What are the two types of biogas generators?
Batch generators and continuous generators
What are small biogas generators used for?
- Make biogas in small batches
- Used to make enough gas for a village or family to use
- Manually loaded with waste
What are continuous generators used for>
- Make biogas all the time
- Waste is continuously fed in and biogas is produced at a steady rate
- more suited to large-scale biogas projects
What does a simple biogas generator need?
- an inlet for waste material
- an outlet for digested material to be removed
- an outlet so biogas can be piped where it is needed
What four factors should be considered when desigining a generator?
- Cost
- Convenience
- Efficiency
- Position
State the effects of biogas fuels?
- greener alternative
- do not produce significant amounts of sulfur dioxide/nitrogen oxides
- methane, given off by untreated waste, means that burning it to make biogas is environmentally better
- raw material is cheap[ and readily available
- biogas generators act as waste disposal system
How can the efficiency of food production be improved?
- Reduce number of stages in food chain- means more energy is given to humans
- Restricting the energy lost by farm animals- intensively farming animals means they use less energy because thy don’t move about and they don’t give out as much heat energy- animal will grow faster on less food
What is mycroprotein?
A protein from fungi.
What is the main source of mycroprotein?
Fusarium
How is mycroprotein produced?
- Fungus grown in fermenters using glucose syrup (obtained by digesting maize starch with enzymes)
- Fungus respires aerobically
- Important to prevent other microorganisms growing in fermenter so it is initially sterilised using steam
- The mycroprotein is then harvested and purified
What are the advantages of mycroprotein?
+ gives developing countries a good source of protein
+ microorganisms grows very quickly and does not need much space
+ feed on waste materials that would be wasted otherwise
What are the disadvantages of intensive farming?
- forcing animals into uncomfortable conditions is cruel
- crowded conditions increases risk and spread of disease
- animals given antibiotics regularly to prevent disease but bacteria could become immune and be harmful to humans as well
- fossil fuels are used to keep the animals warm so they do not lose too much heat
What are the problems with food distribution?
- Expensive
- Bad for environment-food miles
- Planes, ships and trucks burn fossil fuels and release CO2 into atmosphere, contributing to global warming
What is crenation?
The shrinking of an animal cell by osmosis.
What is lysis?
The bursting of animal cell by osmosis
