Comment on a diagram comparing human populations in 1700 and 2010:
1700 has more mean children per woman
Role of microorganisms in producing nitrates:
Ammonium compounds are converted into nitrogen compounds
Explain why coastal waters are productive fishing areas
In coastal waters there are high levels of energy in the fish
The nutrients from their decay reach higher depths
More nutrients mean more food sauces for fish
High levels of nutrients e.g. nitrates are used by fish to make protein
Explanation of increase in diversity of birds as farmland was left to develop into woodland::
The trees support more species as food sources are higher
As birds changed the farmland into woodland ...
Birds may have adapted themselves
Comments on plant productivity of sun and shade plant:
CO2 taken in by plants is converted into carbon and passed on through each trophic level
The plant gets nutrients from soil for better growth, despite low light intensity
The sun plant will overshadow the shade plant so that the shade plant can receive a favoured low light intensity for ps
It respires less. This allows it more time to photosynthesise
The graph is less steep than the sun plant, indicating it relies less on light intensity for photosynthesis
Shade plant has a higher rate of photosynthesis in the dark
The shady plant has a higher rate of ps at low light intensities
It releases less CO2 at low light intensies to allow more for photosynthesis
Photosynthesis is more efficient at uptaking energy as it can do so at lower light intensities
Explanation of high frequency of HbC allele in areas where malaria occurs:
The HbC allele has developed a resistance to malaria
Selection pressure and adaptation introduced the HbC allele
As less people with HbC are killed by malaria there is less need for them to leave the area
Due to mutation HbA becomes HbC in order to survive
The HbC allele occurred to prevent malaria
People without the HbC allele are dead and cannot pass on the allele
The haemoglobin has changed via genetics from generation to generation
This is due to the malaria virus being non-resistant
Those with the HbC allele have a higher risk of survival
People reproduce in these small areas
This allele survived due to better adaptation
Why does respiration produce more ATP in the presence of oxygen rather than in its absence?
Oxygen is the final exceptor ... final terminator
With aerobic respiration you get to go further with one molecule of oxygen
Aerobic respiration is more efficient as less energy is lost as heat
Glycolysis can only occur without oxygen
Less ATP is used in aerobic respiration than in anaerobic, so more is left over after
Without oxygen, less electrons are converted into water
Ethanol is a store of ATP
Anaerobically water (H2O) is used which has half the oxygen content than an O2 molecule, which halves the rate of ATP production
Oxygen contains electrons which can release energy when moving through the electron transfer chain
If this did not happen then the electron would go back up the chain
It can use oxygen as the last receiver of the glucose molecule
Intraspecific competition by an introduced plant species:
It requires less oxygen to photosynthesise
Its a large plant and can eat other species
Economic consequence:
Destruction of tourist sights
Explanations why drying to constant mass provides a reliable estimate of biomass:
There would be no water or other elements that would add to the biomass
Samples were heated until the biomass was constant
Water levels vary within each plant
Regular weight checks show more accurate weights as short time gaps are used.
Reheating makes sure that temperature remained constant, so results were not due to temperature change.
Reheating and reweighing removes anomalous data
Heating burns all the fresh mass in the plant
This technique shows the true value of the plant
This means that anything that is not biomass has been released
It removes any molecules that may not be appropriate for the test
Reheating reduced the aquatic mass
This took into account the mass of the species rather than just the number
as water contains no energy
Comment on best concentration of biocide:
This concentration was best at not accumulating in the food chain
Advantages of fungus as biological control agent:
The fungus will recognise the Hydrilla
The fungus has not seen the other native species before so is less likely to attack them
In the Light Independent Reaction:
These TP molecules then break down into RuBP
A carbon molecule will be removed, producing 2 TP molecules
The LIR takes place in the dark as it does not require light to photosynthesise
As carbon from carbon dioxide binds with RuBP, oxygen is released
In this process, carbon is turned into glucose
Every six cycles this cycle produces something useful to plants
... using NHdp and ATP ...
This process is repeated 6 times for efficiency - on the 6th time TP is turned into glucose and RuBP
Human activities and global warming:
Burning fossil fuels release CO2 into the atmosphere which is a greenhouse gas
Burning fossil fuels release CO2 which was locked up in the fossils
CO2 is a greenhouse gas which increases the thickness of the ozone layer
The industrial revolution caused a sharp increase in the number of cars
Global warming is due to the increase of fossil fuels in the atmosphere
Humans have contributed to global warming by reproducing
So more CO2 is in the atmosphere where it prevents UV light from leaving the earth and warming it up
All of this increases the thickness of the atmosphere meaning light relecting off the surface of the earth can no longer escape
There are more people being born every year which increases CO2
Method of estimating number of bluebells in a small woodland:
The land used would be put on a grid
You must ensure samples are collected randomly
A computer could be used at random
You must find co-ordinates through random means
Use the mark-release-capture method
This way you can work out the estimated bluebells
This process should be repeated enough times to produce a running mean
Using the axis, visit all the co-ordinates
Count the number of daisies in the quadrat
Multiply your mean number of bluebells by the difference between your quadrat size and your woodland size
Divide all the amounts to get a mean total of the population
Now you can stop and use the data to run a statistical test to estimate the number of bluebells.
Why is the genetic code described as universal?
It's coded with one singular language by all species of animals and living organisms
Everyone uses the same four bases which form nucleotides
Each amino acid is the same in all organisms
The codes within amino acids apply to all living organisms
There are few exceptions. It is the same for all organisms
Because nearly everyone uses it in different countries
The whole world uses the same four bases to form triplets that code for amino acids
Consequences of base deletion
This would result in a completely different protein structure as it is made of one less and one different amino acid
When a base is deleted it causes genetic shift
Amino acids are coded for by multiple triplets
Due to the degenerative nature of the genetic code it may not be affected
An intron does not code for DNA
Turning of worms
A taxis is a movement towards a directional stimulus
Worms cultured at 17 °C would be better respiring at 17 °:C
Things you didn't know about nerve impulses
In a non-myelinated axon:
... the speed of the action potential is equal to the wavelength generated
... sodium ions must diffuse the entire length of the axon
... the impulses are allowed to jump
... there is more diffusion, which takes time
... energy escapes as it travels along
... the impulse is subjected to electrical resistance
... has one large node of ranvier
... impulse takes longer to travel past all the sodium/potassium pumps and gates
... impulse has to be passed through every cell
Myelinated axons:
... allow neurotransmitters to pass the synaptic gap faster
... have a greater O2 concentration
... have an electrical conductor made of Schwann cells surrounding their membrane
... sodium ions jump from node to node
... have a layer of fat which keep them warmer
... the impulses are more confined so less energy is lost
... as it is insulated the impulse cannot leave the axon
... reduces friction
... allows a myelin head to bind to it which moves the axon along
... the nerve impulse can jump between the non-myelinated parts of the myelinated axon
... has an insulating layer that prevents conduction of a nerve impulse
... schwann cells are insulators and electrical charge jumps through the sheath
... this allows action potentials to jump from one node of ranvier to others
... the electrical impulse travels directly down the axon and does not change course onto another neurone
- faster if it does not detour
... help reduce the loss of ions across the axon
... acts as insulator, reducing loss of charge
... impulse is more direct and so travels in a straighter line
... impulse only has to jump between axons, resucing the disruption of the impulse
... the mylon shief conducts energy so causes the pulse to jump from one unmylonated shief part to another
... myelin sheath presents a synapse in certain places. The action is greater than wave action.
... This is quicker than sending signals from one side of the axon to the other
... The schwann cells are raped around the axon
... allow statutory conduction
... The fatty coating attracts the impulse
Results may be different if the dementia did not involve loss of mental ability
The standard error bars do not overlap so the differences are statistically different
This will increase the number of eggs available to develop into follicles
The corpus lupus will not form
Phosphocreatine allows the actin sheet around the muscle to unwind, allowing the myelin head to cause a contraction
If a dog gets too warm its nose will start running
Carrier proteins on the cell surface will allow certain substance to travel in and out, due to their big size
... myocardial infraction ...
Enzymes become less efficient as people get older
Older people have thicker muscle fibres
Less anaerobic enzymes are available in the upper arm
Why are 2 carrier proteins needed in transporting a protein into the mitochondrial matrix?
Molecule is too large so must be grabbed at both ends
Comments on DNA probe technique with different genotypes
The alleles have different sequences of amino acids
The DNA base sequence (for the homozygote) was AA
Less DNA will attach to the probe so there will be less green lights
As DNA is double stranded, only one strand can have the allele A
Measurements to calculate rate of carbon dioxide production
Use a potometer to measure CO2 concentration
Measure the length of the part of the ecosystem
Before the experiment the plants should not have done any respiration - only photosynthesis
Why is there a delay between rise in photosynthesis rate and rise in respiration rate?
Photosynthesis has to drop past a certain point for respiration to occur
The tree must convert all of the light into ATP first
Takes time for oxygen to drop from the leaves
Photosynthesis and respiration cannot occur at the same time
Takes time for the gaseous to be exchanged
Delay is due to time
Continuous prose
Photosynthesis starts when light excites a chlorophyll molecule so much that its electrons leave the molecule all together
To regenerate RuBP the cycle must spin 6 times
Fish with a low affinity for oxygen require a high supply of oxygen in the water
All energy is recycled into the ground where it is used by organisms
In animals the nervous system transmits the sun's energy to chemical energy
The (light dependent) process will hydrolyse H2O
Water diffuses by osmosis out of the stomata and is evaporated by the sun's heat
Ectotherms move to the sun when they are cold
In organisms that are too hot, such as humans, the hair follicles relax
Plants open and close their stomata, insects open and close their spiracles, fish open and close their gills.
There is a loss of energy from sunlight to producers as not all waves of light can be absorbed
There is very little energy left by the time it reaches the tertiary level. For this reason tertiary consumers need to eat a lot of food.
The sun provides solar waves
Humans are not eaten by anything alive
To create heat from contraction of muscles shiving occurs
Producers make the light into glucose via photosynthesis, which can be used by other organisms
When light hits chlorophyll, electrons are omitted
.. The venal end of the capillary
Energy such as CO2 is released by saprobionts
Glucose is used to produce energy at the rate of 1:38
On the underside of a plant are stomata
Food is passed down from the mouth to the stomach where all food substances are broken down
Energy can be added to an ecosystem via fertiliser
In cold conditions vasoconstriction occurs so less blood is lost by evaporation
A food chain cannot support more than 2 consumers
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