Ecology Part 1 Flashcards
Suggest why the mark-release-recapture method can produce unreliable results in very large lakes
Less chance of recapturing fish
Succession occurs in natural ecosystems. Describe and explain how succession occurs.
1) Colonisation by pioneer species;
2) Pioneers change the environment to make it less hostile
3) more suitable for new species
4) Previous species out-competed.
5) increasing biodiversity
6) climax community is reached
Describe how you could estimate the size of a population of sundews in a small marsh [5 marks]
1) Divide area into squares/sections
2) Use random coordinates/place quadrats at regular intervals
3) Count percentage cover in each quadrat
4) Calculate the mean number of sundews
5) Mean number of plants per quadrat multiplied by number of quadrats in marsh
Suggest and explain how digesting insects helps the sundew to grow in soil with very low concentrations of some nutrients.
1) Digestion/breakdown of proteins
2) Provides amino acids
Describe how you would determine the mean percentage cover for beach grass on a sand dune.
1) Randomly determining position (of quadrats)
2) Large sample of quadrats
3) Divide total percentage by number of quadrats
Dengue is a disease. One method used to try to reduce transmission of this disease is the Sterile Insect Technique (SIT). This involves releasing large numbers of sterile (infertile) male A. aegypti into the habitat.
(a) Explain how using the SIT could reduce transmission of dengue.
1) Compete (with fertile males) for resources
2) Do not reproduce
Describe how the mark-release-recapture method could be used to determine the population of A. aegypti (a mosquito) at the start of the investigation.
1) Capture count, mark and release
2) Wait for mosquitos to disperse before collecting second sample
3) Collect and count second sample, which were marked and total amount
4) number in first sample × number in second sample divided by number of marked in second sample
Give two features of a climax community
1) Same species present over long time
2. Abiotic factors constant over time
3. Populations stable (around carrying capacity)
Suggest an explanation for the effect size when non-native species were introduced to communities.
1) Non-native species out-competes native
2) Some native species become extinct
Describe how you would investigate the effect of an invasion by a non-native species of plant (a biotic environmental factor) over many years on the abundance of a native species of plant in a community.
1) Set up grid system with coordinates
2) Place large number of quadrats at randomly selected coordinates
3) Count percentage cover of native plant in quadrats
4) Repeat at same time each year
Give two ways in which plants use molecules produced during photosynthesis
1) sugars -> reactant in respiration
-> energy storage
-> converted to cellulose for cell walls
-> converted to lipids for cell membranes
-> converted to amino acids for protein synthesis
Define the term biomass
Total mass of living material in a specific area at a specific time
State why dry biomass is a more accurate measurement than wet biomass
Organisms contain different amounts of water in tissues
Dry biomass enables comparisons to be made between different organisms, eliminating difference in water content in tissues
How would an organism’s dry biomass be calculated
1) Removing water by heating in oven at low temperature to avoid burning
2) Until mass stops decreasing and remaind constant
What is the name of the process by which you convert solar energy into GPP
Photosynthesis
The process of converting solar energy into GPP is not 100% efficient
Suggest one reason why this might be the case
1) not all wavelengths of light are absorbed
2) some light passes through leaves
3) not all light falls on chloroplasts
4) other factors may be limited (CO2)
