Biology Unit 3 Flashcards
How is the glucose for the fermentation obtained?
Sugar cane juices can be used and glucose can also be derived from maize starch by the action of carbohydrase
What about the conditions of a biogas generator has to stay the same and why?
Must be kept at a constant temperature to keep the bacteria respiring
What is a digester / generator?
The simple fermenter that makes biogas
Describe the biogas generator
There is an inlet for waste material
The inside of the generator is has gas at the top and waste at the bottom of the container
There is an outlet at the top for the biogas and an outlet at the bottom for the by-products
What is fermentation?
When bacteria or yeast break down substances like sugar using anaerobic respiration
What is the composition of biogas?
70% methane and 30% carbon dioxide
What is done to the ethanol after being formed?
It is distilled to separate it from the yeast and remaining glucose before it’s used
What are 6 main advantages of biofuels?
They are carbon neutral because the carbon dioxide released into the atmosphere was taken in by plants which lived recently
Not much sulphur dioxide or nitrogen oxide is produced so there is less acid rain
Methane is given off from untreated waste, this is stopped by making it into biofuels
The raw material is cheap and available
The digested material is a better fertiliser than the undigested material
Biogas generators act as waste disposal systems
What is a batch generator?
A generator that makes biogas in small batches
They are manually loaded with waste which is left to digest and the by-products are cleared away at the end of each session
What is the main disadvantage of biogas?
It needs too high a pressure so it can’t be stored as a liquid so it has to be used straight away
How is ethanol made as a biofuel?
Yeast makes ethanol (along with carbon dioxide and energy) by breaking down glucose by anaerobic respiration
What is gasohol?
A mixture of ethanol and petrol that can be used by adapted cars
What are the 2 specific ways that biogas is made?
Bacteria can ferment plant and animal waste containing carbohydrates
Sludge waste from places like sewage works and sugar factories are used to make biogas on a large scale
How is biogas made?
Anaerobic fermentation of waste materials
What is the main way that biofuels are made?
Fermentation
What are the 4 factors to consider when designing a generator? (Explain each factor)
Cost (continuous generators are more expensive because everything has to be mechanically pumped in and removed
Convenience (batch generators are less convenient because they always have to be filled, emptied and cleaned manually)
Efficiency (the gas must be produced at 35% to get the fastest gas production)
Position (the waste will smell during delivery meaning the generator must be away from homes and close to the waste source)
What are the by-products of biogas generation used for?
Used to fertilise crops and gardens
What are the 2 types of biogas generators?
Batch generators
Continuous generators
What is a continuous generator?
They make biogas all the time
Waste is continuously fed in and biogas is produced at a steady rate
What is the purpose of the breathing system?
To get oxygen into the body and to get carbon dioxide out of the body
Describe the process of breathing in and breathing out
Breathing in happen when the intercostal muscles and diaphragm contract decreasing the pressure drawing air in
Breathing out is the opposite
What is the risk of artificial ventilators?
If the lungs can’t cope with the artificial air flow, damage like burst alveoli can occur
Describe where air goes after being breathed in
Air goes through the trachea which splits into 2 tubes called bronchi which split into even more smaller tubes called bronchioles and finally into small bags called alveoli where the gas exchange takes place
What is ventilation?
The movement of air into and out of the lungs
What is the thorax?
The upper part of the upper body which is separated from the abdomen by the diaphragm
What are artificial ventilators?
Machines that move air (often with extra oxygen) into or out of the lungs by pumping air
They help people who can’t breathe for themselves
What is the purpose of the lungs?
To transfer oxygen to the blood and to remove waste carbon dioxide from it
Why do some of the water molecules involved in osmosis go towards the high concentration region?
The water molecules move about randomly and sometimes deflect off another water molecules at the right angle so that it passes into the high concentration region
However, the net movement of the water molecules is towards the low concentration region
What are guard cells?
Cells that control the size of the stomata
They control the amount of water lost and make it equal to the amount of water coming into the plant through the roots
How is osmosis used in the human body?
So that water or solutions can travel into and out of cells
What is a partially permeable membrane?
A membrane with very small holes in it so that only small molecules like water can pass through
What decides if osmosis causes the water to go into or out of the cell?
If the cell is short of water, the concentration of water outside the cell will be higher so osmosis will bring water into the cell
If the cell has too much water, the opposite will occur
What is diffusion?
Where substances move from an area of high concentration to an area of low concentration without the input of energy
What are root hairs?
Tiny hairs that stick out of the sides of the roots of s plant so that the roots have a larger surface area so that they absorb more mineral ions and water
What do alveoli and villi have in common?
They are both exchange surfaces
Describe the process of gas exchange
Oxygen in the alveoli diffuses into the capillary network to get into the bloodstream
Carbon dioxide in the blood passes the alveoli and diffuses into them so that it can escape
In terms of diffusion, why are leaves flat?
To increase the area of the exchange surface making diffusion more effective
What are villi and how do they work?
Tiny hair-like projections on the inside of the small intestine that increase the surface area of the small intestine massively
The digested food is absorbed by the villi and it passes into the capillary network inside the villi
What is osmosis?
The movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of low water concentration
What is an exchange surface?
What the substances need to pass through
Describe how the digested food travels from the small intestine to the capillary network
There is a higher concentration of nutrients in the blood than in the small intestine meaning the nutrients are actively transported from the surface of the villi to the capillary network inside
Describe how the minerals and water get from the soil into the root hairs
The concentration is higher inside the plant so active transport has to be used to get the minerals and water into the root hairs
Active transport requires energy from respiration to work though
What are the 2 ways that diffusion is used in plants?
Carbon dioxide diffuses through the stomata into the plant
Oxygen diffuses out of the plant through the stomata
What is active transport?
Where substances move from an area of low concentration to an area of high concentration because another substance is carrying it
Active transport requires energy
What are the 3 ways in which substances move around living organisms?
Osmosis
Diffusion
Active transport
How do we restrict energy lost by farm animals?
Some animals can be intensely farmed meaning they are kept close together indoors
Why does growing crops instead of having grazing animals increase food production?
The crops are a stage lower than the farm animals in the food chain meaning that there is more energy and biomass in the crops than in the animals
What are the 2 problems with distributing food over long distances?
Can be expensive and bad for the environment
Fossil fuels are used and carbon dioxide is released, adding to global warming
What has to be supplied to the fungus?
Oxygen (fungus respires aerobically)
Nitrogen (as ammonia)
Other minerals
What is the disadvantage of mycoprotein?
Food made by microorganisms does not sound very appetising
Which type of fungus in the main source of mycoprotein?
Fusarium
What are the 2 effects of overfishing?
Less fish for us to eat
Food chains are affected and some fish species will go extinct
What are the 5 arguments against intensive farming?
The environment of intensive farming can be considered as cruel to the animals
Crowded conditions allow an easy spread of a disease
To prevent disease, animals are given antibiotics and humans eat those animals and so antibiotics will be less effective in the future
Animals need to be kept warm to prevent heat loss. This uses fossil fuels
Fish stocks are getting low but fish is a commonly used food in intensive farming
What are the effects of fishing quotas?
Limits number and size of fish being caught in certain areas
Prevents certain species from being overfished
What are the 2 ways that fishing stocks are maintained?
Fishing quotas
Net size
What is mycoprotein?
Protein made by fungi
How and why are the fermenters sterilised?
Fermenter and incoming nutrients are sterilised by steam and heat because other microorganisms that could grow must be prevented
What is sustainable food production?
Using resources exactly as fast as they renew to make sure there is never a decline in the amount of resources
Apart from increasing food production, what is the other use of mycoprotein?
A meat substitute in vegetarian meals such as Quorn
Why does reducing the number of stages in a food chain increase the efficiency of food production?
In a food chain, there is less energy and biomass every time you move up a stage
What are the effects of changing net size?
A larger mesh size allows unwanted fish to pass through the net and for younger fish to escape so that they can reach breeding age
What is the other advantage of intense farming?
It is cheaper for the farmer and the consumer
How does intense farming increase food production?
Saves the animals from wasting energy on movement and stops them from giving out as much energy as heat
They will grow faster on less food
Give 2 reasons that we don’t just grow crops since they are more efficient
People need a varied diet in order to keep healthy
Some land is unsuitable for crops but suitable for farm animals
What are the 3 ways that the efficiency of food production can be improved?
Reducing the number of stages in a food chain
Restricting energy loss by farm animals
Developing new food sources like mycoprotein
Give 4 advantages of mycoprotein
Protein can be rare in developing countries, mycoprotein helps
Mycoprotein grown in a fermenter is very efficient
Microorganisms grow very quickly and don’t need much space
Microorganisms can feed on waste material
How is the fungus grown?
Grown in fermenters with glucose syrup as a food source
What hapoens when we destroy peat bogs?
The peat fully decomposes when the bogs are drained which releases carbon dioxide into the atmosphere
What is peat actually made from?
Mostly carbon
This is why peat bogs reduce the amount of carbon dioxide in the atmosphere
Where are the 3 places where carbon dioxide can be sequestered?
Oceans, lakes and ponds
Plants and trees
Peat bogs
What is the greenhouse effect?
When greenhouse gases like carbon dioxide and methane trap heat from the sun in the atmosphere and re-radiate it in all direction including the planet
What 2 things does scientific evidence need to be so that it is considered valid?
Covers a wide enough area
Covers a long enough time scale
Why does deforestation cause there to be more methane in the atmosphere?
Cattle produce methane and the main reason for deforestation is to clear space for cattle to be farmed
Why does deforestation cause less carbon dioxide to be taken in?
Less trees are using carbon dioxide in photosynthesis
What are peat bogs?
Areas that are acidic and waterlogged so that plants living in them don’t fully decay when they die because there’s not enough oxygen
The partly-rotted plants build up to form peat
What are the 4 ways that scientists measure the effects of global warming?
Satelites to monitor snow and ice cover
Satelites to measure temperature of sea surface
Temperature and speed of ocean currents are measured
Automatic weather stations are constantly recording atmospheric temperatures
Why does deforestation cause there to be more carbon dioxide in the atmosphere?
Carbon dioxide is released when trees are burned
Microorganisms feeding on bits of dead wood release carbon dioxide as a waste product of respiration
What are the 4 problems caused by deforestation?
More methane in the atmosphere
More carbon dioxide in the atmosphere
Less carbon dioxide taken in
Less biodiversity
What is the advantage of the greenhouse effect?
At night, without the greehouse effect, there would be nothing to keep the heat in and it would be very cold
What is global warming?
A type of climate change where the Earth is gradually heating up because of the greenhouse effect
What are the 6 things that result from global warming?
Seawater expands so sea level rises
Ice melts (sea level rises even more)
Changed weather patterns including an increase in hurricanes
The distribution of many species will change according to the changes in temperature
Biodiversity is reduced as some species will become extinct
Migration of species to different areas of the world
What are the 3 reasons for deforestation?
To get wood for building materials
To clear land for farming
To produce paper from wood
What is biodiversity?
The variety of different species in a habitat
The more species, the greater the biodiversity
What does sequestered mean?
When a substance like carbon dioxide is locked up in natural stores
What is deforestation?
The cutting down of trees on a large scale
Describe the process of ultrafiltration
A high pressure is built up that squeezes the water, ions, urea and sugar out of the blood and into the Bowman’s capsule
The membranes between the blood vessels and the Bowman’s capsule act like filters so that larger molecules like protein and blood cells can’t get through
What are the 2 ways that people with kidney failure can be treated?
Dialysis machine doing the job of a kidney
Kidney transplant
Describe how a kidney dialysis machine works
The blood goes into the machine and the waste products diffuse into the dialysis fluid
The exchange surface is not permeable by the larger molecules
Why are kidney transplants sometimes rejected?
The foreign antigens of the kidneys are attacked by the antibodies of the patient (their immune system is rejecting it)
What are the 3 phases of filtration in the kidneys?
Ultrafiltration
Reabsorption
Release of wastes
What are the 2 disadvantages of kidney dialysis?
There is a 3 hour session of dialysis 3 times a week
Dialysis can cause blood clots and infections
What happens if the kidneys are not functional?
Waste substances will build up in the blood and there will not control of the levels of ions and water
What is the dialysis fluid made from and why?
It is a fluid that has the same concentration of ions and glucose as healthy blood so that ions and glucose are not lost from the blood
What are the 2 ways that we overcome kidney transplant rejection?
A donor with a similar tissue type to the patient is chosen (tissue type is based on antigens)
Drugs are given that suppress the immune system so that the kidneys are not attacked
Describe the release of wastes
The remaining substances continue out of the nephron, into the ureter and down to the bladder as urine
What are nephrons?
The filtration units in the kidneys
Describe the process of reabsorption
As the liquid flows along the nephron, useful substances are absorbed back into the blood
These are: all sugar (active transport), required ions (active transport) and required water
Describe the journey of glucagon and how it works
It is secreted by the pancreas and travels with the blood to the liver
It makes the liver turn glycogen into glucose meaning that the blood glucose level is increased
Describe the journey of insulin and how it works
It is secreted by the pancreas and travels with the blood until it reaches the liver
It causes the liver to turn glucose into glycogen causing blood sugar to decrease
Give 2 reasons that the new method of getting insulin is better
Human insulin does not have any side-effects where animal insulin does
No animals are killed in the new method
When is insulin used?
When blood glucose level is too high
What is the other way that ions can be removed from the body?
In sweat
When is glucagon used?
When the blood glucose level is too low
What are the 3 important substances that sports drinks contain and why?
Water and ions replace those lost in sweat
Sugar can be used in respiration to give the body more energy
How is the body temperature measured by the brain?
The thermoregulartory centre in the brain has receptors that are sensitive to the temperature of the blood that is passing by it
In which 3 ways is the amount of water regulated?
Liquids consumed
Amount sweated out
Amount excreted by the kidneys into the urine
What are the 3 ways that water is lost from the body?
Urine
Sweat
Breathed out air
What 3 things happen when the body is too cold?
Hairs stand up to form an insulating layer of air
No sweat is produced
Blood vessels constrict so that the blood is further from the surface
Describe the journey of urea in the body
It is produced by the liver as a waste product
It is released into the blood by the liver
The kidneys filter it out of the blood and it is stored as urine in the bladder and it is excreted
What are the 3 simple ways of controlling type 1 diabetes?
Eating less simple carbohydrates
Regular exercise
Injecting insulin (insulin therapy)
Why can’t insulin be taken in a pill?
The enzymes in the stomach would destroy it before it could reach the bloodstream
What are the 2 hormones that control blood sugar?
Insulin
Glucagon
What is type 1 diabetes?
A condition where the pancreas produces little or no insulin meaning the blood sugar level is too high
What are the 6 things that need to be controlled?
Body temperature Water content Ion content Blood sugar Carbon dioxide Urea
What are the old and new ways of getting insulin for patients?
The old way was to extract it from the pancreases of pigs and cows
The new way is to make human insulin with genetic engineering
What 3 things do kidneys do?
Remove urea from the blood
Adjust ions in the blood
Adjust water content in the blood
What is homeostasis?
The maintenance of a constant internal environment
What is the more difficult way of removing type 1 diabetes?
A kidney transplant
What 3 things happen when the body is too hot?
Hairs lie flat
Sweat is produced by sweat glands and is evaporated from the skin
Blood vessels dilate so that the blood flows closer to the surface of the skin
What is done if a transplant is rejected?
Immunosuppresive drugs are taken which are expensive and can have serious side-effects
Why does the body keep body temperature at 37 degrees?
It is the optimum temperature for enzymes
If someone sweats a lot, how will their urine be different?
Less urine will be produced but it will be more concentrated
This is because there is less water available that can make it more dilute
How do the kidneys adjust the ion content?
Excess ions that would upset the balance of the ions and water are removed by the kidneys and added to the urine to be excreted
Why does transpiration happen?
The way that leaves are adapted to perform photosynthesis means that water is lost through the stomata as a side-effect of photosynthesis
What is transpiration?
The loss of water from the plant which is caused by evaporation and diffusion of water from inside the leaves
What are the 2 types of plant vessel?
Xylem
Phloem
What do xylem tubes do?
They carry water and minerals from the roots to the stem and leaves in the transpiration stream
What is xylem?
Made of dead cells joined end to end with no end walls between them and a hole down the middle
What do phloem tubes do?
They transport food substances made in the leaves to growing regions and storage organs of the plant
The transport is in both directions
How are the effects of transpiration counterbalanced?
The water is replaced by the steady stream of water from the xylem vessels
What is the transpiration stream?
The continuous cycle of water evaporating off the leaves and being replaced by the roots at the sane rate as it is lost
What is phloem?
It is made from columns of living cells with small holes in the ends to allow food substances to pass through
What is the heart a double circulatory system?
One circuit goes around the body and one goes from the heart to the lungs and back
What are the 3 properties of capillaries?
Arteries branch into capillaries and capillaries join back up into veins
They carry blood very close to every cell in the body to exchange substances with them
They have thin, permeable walls so that substances can diffuse in and out
What is the disadvantage of stents?
The arteries can narrow again and drugs must be taken to stop blood clotting on the stents
What are the 3 different types of blood vessel and what are their basic functions?
Arteries carry blood away from the heart
Veins carry blood to the heart
Capillaries are involved in the exchange of materials and split off from the arteries and veins
What do red blood cells do?
They carry oxygen from the lungs to every cell in the body
What are the 3 properties of veins?
They carry blood back to the heart at low pressure
They have thinner walls and larger centres than arteries because the pressure is lower
They have valves to stop blood flowing in the wrong direction
What are stents?
Tubes that are inserted into arteries to keep them open and unblocked to strongly lower the risk of coronary heart disease
What is artificial blood?
A temporary blood substitute that can keep someone alive until they have a blood transfusion
What are the 4 components of blood?
Red blood cells
White blood cells
Platelets
Plasma
What are artificial valves?
Mechanical replacements for valves in the heart
What is the most commonly used chemical for artificial blood?
A salt solution like saline
What don’t red blood cells have a nucleus?
So that more oxygen can be held as there is more space without the nucleus
What are valves and where are they found in the circulatory system?
They stop blood from flowing in the wrong direction
They are found between each atrium and ventricle and before the pulmonary artery and the aorta
What is coronary heart disease?
When the arteries are blocked up by fatty deposits
Why do red blood cells have a concave shape?
So that the surface area is larger meaning that oxygen is absorbed better
What is the main advantage of replacing a damaged heart with an artificial heart?
It can’t be rejected by the immune system because it is mechanical
What is the purpose of the circulatory system?
To get food and oxygen to every cell in the body and to carry waste products to where they can be removed
What is unusual about heart diagrams?
The left of the diagram is the right atrium and ventricle and vice versa
What is haemoglobin?
A red pigment in red blood cells that combines with oxygen in the lungs to form oxyhaemoglobin
In body tissues, oxyhaemoglobin is split back into its constituents
What 5 things does the plasma carry? (not including cells, platelets or oxygen)
Glucose Amino acids Carbon dioxide (waste) Urea (waste) Hormones
What 3 things do white blood cells do?
They can change shape to engulf microorganisms
They can produce antibodies and antitoxins to fight microorganisms
They can detect unfamiliar microorganisms with the antigens on their surface
How the atria and ventricles pump the blood around the circulatory system?
They are made from muscle tissue that contracts which pumps the blood
Describe what happens to the blood in the heart
It comes into the vena cava, and is pumped through the right atrium, right ventricle and out of the pulmonary artery to be oxygenated
It comes back into the heart via the pulmonary vein and is pumped through the left atrium, left ventricle and out through the aorta to the rest of the body
What is the plasma?
A liquid that contains everything carried by the blood that is not oxygen including the cells and platelets themselves
What are the 3 properties of an artery?
They are made from thick layers of muscle to make them strong and elastic fibres to allow them to stretch
Their walls are very thick
They pump blood away from the heart at high pressure
What are platelets?
Fragments of cells that help the blood to clot at wounds
What is the disadvantage of artificial valves?
The surgery needed to insert them is very large and dangerous and there can be problems with blood clots
