Reasons why male and female life expectancies differ
Breast cancer is more popular than prostate cancer
Men have testicals (sic), women don't, and can obtain testicular cancer
Females are more health conscious ... as they put weight on more easily
Ammonification ...
... is the process where microorganisms convert the ammonium in plants into the soil
Bacteria feed on ammonium compounds, often dead
During nitrogen fixation, nitrifying bacteria convert nitrogen gas into ammonium ions
Ploughing ...
... would rotate the soil
spreads nitrate under the plants roots
stops nitrogen leaving to become nitrogen gas in the atmosphere
prevents water filling in the soil
would remove nutrients from the soil which would be needed for new crops
will dislodge the soil and weaken its strength
distributes the nitrates through the soil better therefore more denitrification occurs
breaks up the soil releasing glucose
When soil is aerated nutrients are added
Crop rotation ...
... allows plants to die and be decomposed
makes soil less hostile
If a pest is interested in a certain crop it will not return if it is not available
Different crops add different nitrates to the soil
It will take time for predators of the crop to find the field
Growing leguminous plants in alternative years mean more nitrogen is found in the soil
Nitrates formed from previous crops will remain in the soil to be used for the next crop
Explanation of decrease in gross productivity as woodland matures
Rate of growth begins to slow and so the plants and trees will expell less energy
More larger plants are producing energy
First 20 years of succession
Pioneer species have survival allele so environment is less hostile for them
After 100 years of succession
The community had become climaxed
Reasons for conserving woodlands
We can use woodlands to make vaccines
This maintains high gene pool for economic growth
To save habitats for human pleasure
so woodland does not get out of control
other species have the right to live on this plant as well
Explanation of no male tortoiseshell cats
Men only have one allele
The allele for fur is not usually present on Y
The Y chromosome is recessive
Males have an XY chromosome
So only one colour cat can be
Description of variations in genotype frequency due to selection
Over time the frequency of alleles will fall
[Suggest and (?)] Explain why rate of photosynthesis is low between light wavelength 525 & 575 nm
The temperature between 525nm and 575nm might not have been the optimum
This did not stimulate the electrons to leave the chloroplast
This could be due to the light bulb losing its power
Light needs to be able to enter the thylakoid membrane for pS to occur
Perhaps the light was coming in at an angle
This may not be the optimum temperature for enzymes
Light passed through and missed the chlorophyll molecules
It is not the wavelength for that colour of algal cells
This wavelength may not be accepted by chlorophyll
It must use the light independent reaction
The wavelength was the perfect size to reflect off the algae
This is due to a change in the pH conditions from the previous photosynthesis rate
At these wavelengths other cells which need light absorbed it more easily
Light does not enter the chlorophyll as easily and make contact with photosystem II
This wavelength of light is not within the green spectrum
This is not the best wavelength for photosynthesis
The leaves couldn't convert this wavelength of light into energy
The chlorophyll in the leaf may be less adapted to use this wavelength of light
These wavelengths may be the wrong size to be absorbed by the chlorophyll
The chlorophyll was unable to utilise the entirety of this wavelength
They get enough light in other wavelengths so there is no need to use that wavelength
These wavelengths may have been absorbed as heat
Another abiotic factor may have been a limiting factor e.g. carbon dioxide
This wavelength is obviously less intense than before 525 and after 575 PS would be less due to light intensity being a limiting factor
Perhaps this reached the light compensation point
Not optimal level of light intensity for pH build-up of photosynthesis
The wavelength could be mainly red or blue therefore they are reflected off the plant
Wavelength was not of the correct size and therefore frequency
Algal cells don't normally experience these waves of light
Comments on enzyme binding stages
The substrate shape will change
OAA is a non-competitive inhibitor, meaning it binds to anywhere on the enzyme except for the active site
This warps the active site so it becomes complimentary to acetylcoenzyme A
It binds to the active sight
Consequence of converting pyruvate to lactate
This process frees up phosphorous molecules
Consequence of converting lactate back to pyruvate
Pyruvate can enter the Krebs cycle, causing 38 ATP to be made
Climate change and soil salinity
Global warming will affect soil sanity
Climate change means some of the oceans will disso;ve
Crop growth problems in saline soil
It will lower the water potential of the soil so that it can no longer travel by osmosis
Water will want to stay in the saltier ground
This will lead to a decreased concentration of other things like water
Salt is insoluble and can therefore inhibit macronutrients from moving into the plant's root system
Osmosis can't occur
If the soil becomes too salty the pH will increase
This will result in plant cells becoming turgid
No osmosis takes place so nutrients aren't taken up
This causes osmotic lysis (cells fill with water and then burst)
The high volumes of soil salinity mean that the soil can't get rid of it so it remains in the plant
Higher salinity means less nutrients such as nitrates in the soil
Misinterpretation of the term isolated
The fungus was kept separate so it did not infect other plants
This decreases the risk of selecting from one anomalous cucumber
Evaluation of test results
The results showed a large standard error meaning they could do better
All the standard errors overlap so none of the results are significant
Standard errors overlap so significance is not different
All other treatments have less mean diseased plants
Why were weeds removed (in cucumber growth experiment)?
The weeds would take glucose out of the soil
Explanation of how different species of lizard evolved on Caribbean islands:
Certain phenotypes were favoured e.g. less fur in hotter regions
The islands budded off from the mainland
The Caribbean has evolved through speciation
Variety in the population can lead to mutations arising
Environmental changes led to a mutation in alleles
There may have been mutations to help the species to survive
It cannot produce offspring with the species it used to be apart of
Variation arises in the mutation in the genes or DNA
These organisms migrate to conditions they are better adapted for
Mutations between the different populations could have occurred
The characteristics which will be favourable on that island will be prominent
This would eventually lead to both species becoming so similar that they ended up being part of the same genus
The species from mainland USA may have come back to live with the newly evolved species, but ...
The lizard with the new allele reproduced and reduced the size of the gene pool
Mutation caused some advantageous characteristics to occur (caused by alleles)
Lizards that are mutated are better suited to the environment
Now the most favourable combination of alleles survive and reproduce
Species with alleles towards the extreme ends would survive
Variation occurs through mutation due to selection pressures
This narrows the gene pool
Description of the mark-release-recapture method to estimate the number of a species of lizard on a small island
Select a number of required lizards you wish to mark
The marking system should not make them any more of a threat to predators
After a period of time, random lizards would be caught
The amount marked symbolises the amount of lizards
Release any captured lizards of different species
Mark it inconspicuously so as not to make it vulnerable to pray
You would set up a study area where there is a definite boundary so that no organisms can enter or leave
Explanation of the variation in CO2 concentration in a tropical forest
CO2 is taken in through the stroma of the leaves
At low heights CO2 is higher
At greater heights it is colder so more respiration must occur to increase the heat
In the night there is no photosynthesis so plants must respire
It may be higher in the day as they respire at a faster rate to cool down and catch food
At night only the light independent reactions (respiration) occur
In the morning CO2 levels will be high due to a night of respiration
The concentration of CO2 will be lager during the day
At ground level CO2 is higher
Photosynthesis is lower at ground level
At low height there is more CO2 as heat is trapped
The tall trees are closer to the atmosphere
At higher points above ground the oxygen dissociation curve of organisms will move according to their surroundings
Over 24 hours it will be both light and dark for some time
As the day progresses the sunlight will travel higher up from ground level
At night time respiration occurs and light independent photosynthesis
Ps happens during the day, respn happens during the night
CO2 is taken up by chlorophyll in chloroplasts for photosynthesis
Below ground, less light is available therefore less photosynthesis