Biology Flashcards
How do dissolved substances move
Through diffusion and active transport
How does water move across borders
Osmosis
What is osmosis
Diffusion of water from a dilute to more concentrated solution through a partially permeable membrane that allows the passage of water molecules
What causes water to move in and out of the cells by osmosis
Difference in concentration inside and outside the cell
What do most soft drinks contain
Water
Sugar
Ions
Why do sports drinks contain sugar
To replace the sugar used in energy release during the activity
Why do sports drinks contain water and ions
To replace the water and ions lost through sweat
What happens if water and ions are not replaced
The ion/water balance is disturbed and the cells do not work as efficiently
What is active transport
When substances are absorbed against a concentration gradient using the energy from respiration
Many organisms are specialised for exchanging materials. How can the effectiveness of an exchange surface increase
Having a large surface area
Being thin - to create a short diffusion path
Having an efficient blood supply (in animals)
Being ventilated (in animals, for gaseous exchange)
Why are gas and solute exchange surfaces in humans and other organisms adapted
To maximise effectiveness
The size and complexity increases …
… The difficulty of exchanging materials
The surface area of the lungs are increased by…
… Alveoli
The surface area of the small intestine is increased by…
… Villi
How do villi absorb the products of digestion
By diffusion and active transport
What are the adaptations of villi
Large surface area
Extensive network of capillaries for absorption
Where are the lungs
In the upper part of the body (thorax)
Protected by the ribcage
Separated from the lower part of the body (abdomen) by the diaphragm
Why does the breathing system take air into and out of our system
So that oxygen can be diffused into the bloodstream
So that carbon dioxide can be diffused from the bloodstream into the air
How does air move into the lungs
The ribcage moves down and out
The diaphragm become flatter
What is ventilation
The movement of air in and out of the lungs
What do the roots absorb
Water and mineral ions
How does carbon dioxide enter plants
Through leaves
How is the surface area of leaves increased
It’s flattened shape and internal air spaces
What do stomata do
Obtain carbon dioxide from the atmosphere
Remove oxygen through respiration
Where is the main water loss in plants
In the stomata, in the leaves
When is evaporation faster
In hot, dry or windy conditions
How can the stomata help with excessive water loss
Close to prevent wilting as water is being lost faster than replaced by the roots
How is the size of stomata controlled
Guard cells that surround them
What does the circulatory system do
Transport substances around the body
What is the heart
An organ, mostly made up of muscle tissue that pumps blood around the body
What are the main chambers in the heart
Left atrium
Left ventricle
Right atrium
Right ventricle
Properties of arteries
Thick walls compared to the lumen
Thick layers of muscle to make them strong
Elastic fibres to allow them to stretch and bounce back
These carry blood away from the heart
Properties of veins
Thinner walls and often have valves to prevent back-flow of blood
These carry blood to the heart
When are stents used
When the arteries begin to narrow and restrict blood flow
What are capillaries
Thin-walled blood vessels that are involved in the exchange of materials at the tissues
Have permeable walls so substances can diffuse
Supply food and oxygen and take away CO2
Substances needed by the cell in body tissues pass …
…out of the blood
Substances produced in the cells pass …
… Into the blood, through the capillary walls
What is blood
A tissue
What does blood consist of
A fluid called plasma in which red blood cells, white blood cells and platelets are suspended
What does blood plasma transport
Carbon dioxide from the organs to the lungs
Soluble products of digestion from the small intestine to other organs
Urea from the liver to the kidneys
Hormones
Antibodies and antitoxins produced by white blood cells
What do red blood cells transport
Oxygen from the lungs to the organs
In the lungs, oxygen and haemoglobin come together to make
Oxyhaemoglobin
Where does oxyhaemoglobin split up
Organs (excluding the lungs) into oxygen and haemoglobin
What are white blood cells part of
The body’s defence system against microorganisms
What are platelets
Small fragments of cells
What do platelets help with
Blood to clot at the site of the wound
What are the separate transport systems in flowering plants
Xylem tissue
Transpiration stream
Phloem tissue
Xylem tissue
Transports water and mineral ions from the roots to the stem and leaves
Phloem
Carries dissolved sugars from the leaves to the rest of the plant, including the growing regions and storage organs
Waste products that have to be removed
Carbon dioxide
Urea
How is carbon dioxide produced and removed
Respiration
Via the lungs when we breathe out
How is urea produced and removed
In the liver by the breakdown of amino acids
In the kidneys, in urine which is temporarily stored in the bladder
What happens if the water and ion content is wrong
Too much water may move in and out of the cell and damage it
How do water and ions enter the body
When we eat and drink
How does a healthy kidney produce urine
Filtering the blood
Reabsorbing all the sugar
Reabsorbing the dissolved ions needed by the body
Reabsorbing as much water as the body needs
Releasing urea, excess ions and water as urine
How are people who suffer from kidney failure treated
Using a kidney dialysis machine
Having a healthy kidney transplanted
What does treatment by dialysis restore
The concentration of dissolved substances in the blood and has to be carried out at regular intervals
In a dialysis machine, a person’s blood flows through a …
… Partially permeable membrane
The dialysis fluid contains the same concentration of …
… Of useful substances in the blood. This ensures that glucose and mineral ions aren’t lost
What passes out of the blood and into the dialysis fluid
Urea
What happens in a kidney transplant
A diseased kidney is replaced with a healthy one by a donor
What is a problem with kidney transplants
The donor kidney may be rejected by the immune system unless precautions are taken
What are antigens
Proteins on the surface of cells
Why might the donor kidney be rejected
The recipient’s antibodies may attack the antigens on the donor organ as they do not recognise them as part of the recipient’s body
How do you prevent rejection of the transplanted kidney
Use a donor kidney with a ‘tissue-type’ similar to that of the recipient
Treat the recipient with drugs that suppress the immune system
What does sweating help to do
Cool the body
Why does more water have to be taken in as drink or in food when it’s hot
To balance the loss of water as when it is hot, more water is lost
What is body temperature controlled and monitored by
The thermoregulatory centre in the brain (hypothalamus)
How is the thermoregulatory centre of the brain adapted
By having receptors sensitive to the temperature of blood flowing through the brain
How is information about skin temperature given
Temperature receptors in the skin send information to the thermoregulatory centre
What is the blood glucose monitored and controlled by
The pancreas
What hormone does the pancreas produce
Insulin which allows the glucose to move from the blood into the cells
What is glucagon
Another hormone produced in the pancreas when blood glucose levels fall.
What does glucagon do
Converts glycogen into glucose and be released into the blood
What is Type 1 diabetes
A disease in which a person’s blood glucose concentration may rise to a high level because the pancreas does not produce enough insulin
How can Type 1 diabetes be controlled
Careful attention to diet, exercise and by injecting insulin
Why is more waste produced
Rapid growth in the human population and increase in standard living means
Waste may pollute
Water, with sewage, fertiliser or toxic chemicals
Air, with smoke and gases e.g. sulphur dioxide (acid rain)
Land, with toxic chemicals e.g. pesticides and herbicides, which may be washed from the land into the waterways
How do humans reduce the land available for other animals and plants
Farming
Building
Quarrying
Dumping waste
Effects of large-scale deforestation in tropical areas
Increased the release of carbon dioxide into the atmosphere (burning and activities of microorganisms)
More methane in the atmosphere from rice farms and cattle
Reduced the rate at which carbon dioxide is removed from the atmosphere and ‘locked up’ for many years as wood
Less biodiversity due to extinction
Deforestation has occurred so that
Crops can be grown from which biofuels, based on ethanol, can be produced
There can be increases in cattle and in rice fields to provide more food
What does the destruction of peat bogs and other areas of peat release
Carbon dioxide into the atmosphere
How can the efficiency of food production be improved
Reducing the number of stages in a food chain. At each stage in a food chain, less material and energy are contained in the biomass of the organisms
Restricting energy loss from food animals by limiting their movement and controlling the temperature of their surrounding
Why is it important to maintain fish stocks at a level where breeding continues
Certain species may disappear altogether in some areas
What play an important role in conservation of fish stocks
Net size and fishing quotas
Why is Fusarium useful
It helps produce mycoptotein
What is mycoptotein
A protein-rich food suitable for vegetarians
How is the fungus, Fusarium, grown
It’s grown on glucose syrup, in aerobic conditions and the biomass is harvested and purified
How is the heart a double pump
The blood goes around the body twice through the heart:
From the heart to the lungs (deliver CO2 and pick up O2/ gas exchange)
From the heart to the rest of the body
Left Atrium
Receives oxygenated blood from the lungs and pumps the blood to the left ventricle
Left Ventricle
Pumps oxygenated blood to the rest of the body
Right Atrium
Receives deoxygenated blood from the body and pumps this to the right ventricle
Right ventricle
Pumps deoxygenated blood to the lungs
Vena Cava
The main vein that carries deoxygenated blood from the body to the right atrium
Aorta
The main artery that carries oxygenated blood from the heart’s left ventricle away to the body
Pulmonary Vein
Carries oxygenated blood from the lungs to the left atrium
Pulmonary Artery
Carries deoxygenated blood away to the lungs from the right ventricle
Coronary artery
Supplies heart muscle cells with blood rich in oxygen and nutrient
How are blood vessels narrowed
Fatty deposits can be deposited and restrict the flow of blood
What can be done to widen blood vessels
Stents
Bypass
What are stents
Narrow mesh tubes inserted into blood vessels
How do stents work
Balloons inside the mesh tube are blown up, which expands the mesh tube
This restores blood flow
Transpiration
Movement of water from the roots (osmosis) through the xylem and out of the leaves (stoma)
What do vascular bundles consist of
Xylem tissue
Phloem tissue
Adaptations of alveoli
Increased surface area (for gas exchange) - maximises rate of diffusion Thin wall (1 cell thick) - flattened cell (even thinner), shortens diffusion pathway Dense blood supply - Take away the absorbed gases; maintains the concentration gradient Moist lining - Allows dissolved gases to diffuse
What happens when we inhale
Intercostal muscles contract Ribcage lifts up and out Diaphragm contracts Lung volume increases Pressure decreases Air flows into lungs
What happens when we exhale
Intercostal muscles relax Ribcage lowers and goes in Diaphragm relaxes Lung volume decreases Pressure increases Air flows out of lungs
How does light intensity affect the rate of transpiration
They’re in direct proportion until a certain point because by then all the stomata have opened
How does temperature affect the rate of transpiration
They’re in direct proportion.
The higher the temperature, the faster the water particles move -> evaporate faster -> increased rate of transpiration
How does wind speed affect the rate of transpiration
When air moves over a leaf, evaporated water molecules are removed.
Faster the air moves, more water removed
Increased diffusion of water out of the leaf
Increased rate of transpiration (high concentration gradient)
How does humidity affect the rate of transpiration
The more humid the air is, the more water there is in it
Water molecules will diffuse out less quickly, decreasing the rate of transpiration (low concentration gradient)
6 reasons why water and ions are important
Fluids protect organs (liquid buffer)
Fluids keep skin, mouth, lining of nose and lungs moist
Needed to regulate body temperature
Fluids lubricate joints
Reactants of respiration are dissolved in water and carried to muscle cells
Mineral ions cannot be used as they need to be dissolved in water
What changes happen in a cell during respiration
Oxygen (in) Nutrients (in) Water (in and out) Carbon dioxide (out) Energy creates heat in the cell
Factors that need to be controlled in the body
Body temperature Salt levels Amounts of nutrients Oxygen Waste (CO2 and urea) Water
Urea
Product of breakdown of protein
Excess amino acids cannot be stored -> amino acids broken down by liver -> urea
Removed by kidneys from the blood
Receptor cells
Cells that detect change in temperature
If the body temperature is too high
More sweat is produced by sweat glands
Blood vessels supplying capillaries of the skin dilate
How does sweat cool the body
Evaporation
Vasodilation
More blood flows through skin capillaries -> more heat is lost
If the body temperature is too low
Muscles contract quickly
Blood vessels supplying capillaries of the skin constrict
How does shivering warm us up
Increases rate of respiration -> some energy is transferred in respiration warming the surrounding tissue
Vasoconstriction
Less blood flows through the skin capillaries less heat is lost
Health risks associated with an unhealthy diet
Heart disease Diabetes (Type 2) Obesity Tooth decay Cancers (Bowel cancer) Eating disorders (anorexia)
Risk factor
Things that increase your chance of being ill
Identification of risk factors
Epidemiological studies (large sample of population studied) Looks for links between diet and health
Why do processed foods have high glucose levels
To improve the taste
Quickly absorbed into the blood stream
How does the body respond to the sugar high
Pancreas releases insulin
Glucose quickly removed from blood and absorbed by cells
Result of sugar highs
Energy boost becomes sugar low
Lack of concentration
Mood swings
Lack of concentration
Symptoms of diabetes
Feeling very thirsty Urinating frequently Feeling very tired Weight loss Muscle loss
Reasons behind fast increase in population after 1900
Improved diet
Better hygiene
Better healthcare
Lower infant mortality rate
What is biofuel made from
Natural products by anaerobic fermentation of the products or waste material by decomposers
Advantages of biofuel
Reduces use of fossil fuels
Carbon neutral
(Biogas/ alcohol) - produce no particulates
Disadvantages of biofuel
Destroys habitats
Extinction of species
Advantages of energy-efficient farming
Less energy is transferred out of the food chain, more energy available for humans to consume
Less labour intensive since animals are contained in a reduced area
Less risk of attack by predators
Low production costs
Disadvantages of energy-efficient farming
Inhumane technique
Greater risk of disease spreading through the animals (close together)
Lower quality of product
Tissue fluid
Water with dissolved oxygen and glucose surrounding the cells in our body
It’s squeezed out of the blood capillaries to supply the cells with everything they need
Why is exchanging substances harder in more complex substances
The place where the substances are needed ends up being a long way away from the exchange surfaces
Where are the alveoli
In the bronchioles, in the bronchi, in the lungs
Ventilators
Machines that move air into or out of the lungs
They help people who can’t breathe by themselves e.g. if they’re under anaesthetics, or have a lung injury or disease
‘Iron lung’
Giant cases from the neck to the abdomen, with only the patient’s head out
How did ‘iron lungs’ work
Air was pumped out of the case
Pressure dropped
The lungs expanded
Air was drawn into the lungs
Air pumped into the case had an opposite effect, forcing air out of the lungs
Problem with ‘iron lungs’
They could interfere with blood flow to the lower body
How do modern ventilators work
By pumping air into the lungs
This expands the ribcage - when they stop pumping, the ribcage relaxed and pushes back out of the lungs
Problem with modern ventilators
Can occasionally cause damage (e.g. burst alveoli) if the lungs can’t cope with the artificial air flow
What are phloem tubes made of
Columns of living cells with small holes in the ends to allow food to flow through
What are xylem tubes made from
Made of dead cells joined end to end with no end walls between them and a hole down the middle
Where do xylem tubes carry water and minerals
To the stem and leaves in the transpiration stream
What is transpiration caused by
The evaporation and diffusion of water from inside the leaves
Why is there a constant transpiration stream
Transpiration causes a slight shortage of water in the leaf so more water has to be drawn up from the rest of the plant to replace it
Therefore more water is drawn up from the roots
What are nephrons
Filtration units in the kidneys
What are bogs
Areas of land that are acidic and waterlogged
How is peat formed
Plants that live in bogs don’t decay when they die because of the lack of oxygen
The partly-rotted plans gradually build up to form peat
How are root hairs specialised
The cells on the surface of plant roots grow into long ‘hairs’ which stick out into the soil -> larger surface area
