ecology stuff Flashcards
advantages generally
less competition
features of succession that would bring about an increase in the index of diversity
Initial environment is hostile as few organisms adapted, these organisms change the environment pioneer speices, more niches more habitats allowing other organisms to become established
two reasons why a species of seed did not grow succesfully in a climax community
too little food in seeds to become established, not enough light for psynth or small size
how to use a transect to get a MEAN percentage cover( to get a mean you flipping repeat it)
Create a grid by placing 2 transect tape measures at right angles, use a random generator to produce coordinates. Place quadrats at coordinates and estimate percentage cover of…
Reapeat many times. calculate mean percentage cover by adding up all the percentages and dividing them by the number of quadrats.
Total population = Average number per quadrat × Total area/Area of quadrat.
explain how something has evolved
geographical isolation, seperate gene pools, variation occurs due to mutations, different selection pressures pass on alleles due to mutations and this leads to an increased allele frequency of that gene
how to do mark release recapture- how to estimate the pop of anguirelas angathon
capture the organisms in a safe way, leave sufficient time for them to distribute randomly within the population, collect a second sample and count the number of marked invididuals. population=number in first sample times second sample/ number of marked individuals in the second sample
can mutations spread to other insects
no because mutations are random and only the rate of them can be affected by the environment, different species do not interbreed to produce fertile offspring, so mutations cannot be passed from one species to another.
anything about why something is high frequency
the people with that allele reproduce and over many generations it becomes the most common gene in the gene pool
benefits of woodlands
protects niches and habitats, conserves endangered species, reduces global warming, sources of medicine, reduces erosion
why do scientists measure the o2 produced to measure the rate of psynth
faster oxygen production means that more made in the ldr which means that more psynth occurs as o2 is a waste product
limits of transect lines
may avoid certain areas.
describe how you would determine the mean percentage cover for beach grass on a sand dune
randomly determine coordinates, large sample size and then divide total percentage by the number of quadrats
explain the decrease in gross productivity as the woodland matures
less light more competition for light, reduced psynth
succession, why does biomass increase
pioneer species, less hostile conditions, increase in niches or animals or whatevre
Explain the increase in the diversity of birds as the woodland developed.
greater variety of plants, more food sources, more habitats and niches
explain why co2 uptake is a measure of gross productivity
as it shows productivity minus respiration
explain how the shade plant is better
adapted than the sun plant to growing at low light intensities.
has lower respiratory losses
Greater (net) productivity of glucose used / more
Use the information in the graph and your knowledge of net productivity to explain
why biomass shows little increase after 100 years.
Net productivity = gross productivity minus respiratory loss;
2. Decrease in gross productivity
Explain why the scientists sterilised the surfaces of the seeds and grew them in soil that had been heated to 85 °C for 2 days.
To kill any bacteria on surface of seeds or in soil
2. So only the added fungus has any effect.
Explain why it was important that the soil contained no mineral ions useful to the
plants.
So that only type of fertiliser affects growth
Suggest what the scientists should have done during the drying process to be sure that all of the water had been removed from the plant samples.
Weigh samples at intervals during drying;
2. To see if weighings became constant
Can you conclude that the insect pest resistant to Bt toxin found in the years 2002
to 2005 was the same insect species? Explain your answer.
graph shows number of specices not the name of the species
There was a time lag between the introduction of Bt crops and the appearance of
the first insect species that was resistant to the Bt toxin.
Explain why there was a time lag.
Initially one / few insects with favourable mutation / allele;
2. Individuals with (favourable) mutation / allele will have more offspring;
3. Takes many generations for (favourable) mutation / allele to become the
most common allele (of this gene).
what is meant by uniformally distributed
equally spread number of organisms in a region
Use the letters A, R and S to write an equation showing how proportional sampling
is used to estimate the total size of a population, P. Show your working.
p= AS/R
How do the assumptions made in proportional sampling differ from those
made in mark-release-recapture?
No assumption that organisms are uniformly distributed;
Size of total area sampled not required;
Give one assumption about the animals caught that is made in both methods
We assume the animals are from the same population
The ecologists captured insects from a number of sites on the island. Suggest how
they decided where to take their samples.
Draw grid over (map of) area;
- Select squares / coordinates at random.
Suggest the advantage of using the fluorescent powder in this experiment.
Only glows brightly with UV, so doesn’t make insects more visible;
2. So doesn’t affect / increase predation;
Use the information provided to suggest one way in which the method used by the
ecologists might have caused the increase in their estimates of the size of the insect
population.
Scientists removed large numbers of insects (which were not returned)
from same area / same population;
2. Affecting ratio of marked to unmarked.
p values
greater than 5 percent due to chance when its >0.05 not <0.001 which is likely that it is not due to chance and the results are significant
Suggest how this student would obtain data to give a more precise value for the
index of diversity of this habitat.
Take more samples and find mean;
2. Method for randomised samples described.
describe how you would use quadrats to determine whether a particular species has a clustered or random distribution
use of random numbers to place quadrats, individuals counted and if little variation then random, if large variation clustered
advantages generally
less competition
standard answer for succession
intial environment hostile, these pioneer species change the environment, more niches or habitats, allows other organisms to become established
as age of trees increase why does less light pen
as trees block sunlight
quadrat investigation
Set up grid system with coordinates;
- Place large number of quadrats (at coordinates) selected at random;
- Count number of / estimate percentage cover of native plant in quadrats;
- Repeat at same time each year (for many years);
2 reasons why a plant can become dominant
outcometes other plants, less predators, ideal niche, better competes for abiotic resources
2 reasons why a plant can become dominant
outcometes other plants, less predators, ideal niche, better competes for abiotic resources
2 economic consequences for the spread of hydrilla
cost of removal, cost of restoring habitat,
why reheating and weighing till they found a constant mass of plant is good
to remove water content as plants each contain a diff amount of water
why is uniformly distributed plants a good thing
less comeptition for water or nutrients
why is the climax community the most stable
more species present, more complex food webs
explain what limits the size of a population in a climax community
named nutrient availability;
- numbers of producers providing energy (for a food chain) / light intensity affecting the rate of photosynthesis;
- disease killing (weaker) members of species / predation described;
- space for nest building / niches;
- competition for a named limited resource / (intra and interspecific) competition explained;
explain succession
species with the largest population initially are the pioneer species. This dies and decomposes creating increased soil depth and adding nutrients into the soil. The change in ABIOTIC conditions allowed the next species to colonise and outcompete beach grass. Less hostile conditions created. This adds more humus content to the soil increasing soil depth further. Further improves conditions for the climax community to colonise and increase in numbers outcompeting the other species.
why conservation is important
Conserving / protecting habitats / niches;
2. Conserving / protecting (endangered) species / maintains / increases
(bio) diversity;
3. Reduces global warming / greenhouse effect / climate change / remove /
take up carbon dioxide;
4. Source of medicines / chemicals / wood;
5. Reduces erosion / eutrophication.
How do the assumptions made in proportional sampling differ from those
made in mark-release-recapture? and give one made in both
In mark–release-recapture
1. No assumption that organisms are uniformly distributed;
2. Size of total area / size of sampled region not required;
Marking point 1 or marking point 2 do not have to start with
the same technique
In this case, allow difference by implication i.e. do not
penalise if the two techniques are not compared
2
(ii) Animals are from / all part of the same population
