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)
Why is some energy from photosynthesis not converted into biomass
Used in respiration
Lost in form of heat to the environment
How to calculate net primary productivity
NPP = Gross primary productivity - total amount of organic carbon that is respired
There are nine subspecies of giraffe. These subspecies evolved when populations of giraffe were separated for long time periods. Each subspecies has distinct coloured skin markings. Some biologists have suggested that up to six of these subspecies should be classified as different species.
Explain how different subspecies of giraffe may have evolved from a common ancestor.
Use information from the passage in your answer.
1) No interbreeding
2) Mutation linked to colours
3) Selection linked to colours
4) Adapted organisms breed
5) Change in allele frequency
What is an ecosystem
Dynamic systems made up of a community and all the non-living factors of its environment
What are the two major processes in ecosystems
the flow of energy through the system
The cycling of elements within the system
What is a population
Group of individuals of one species that occupy the same habitat at the same time and are potentially able to interbreed
What is the carrying capacity
The size of population of a species an ecosystem can support
What can the carrying capacity depend on
effect of abiotic factors
Interactions between organisms
What is a community
All populations of different species living and interacting in a particular place at the same time
What is a habitat
Place where an organism normally lives and is characterised by physical conditions and the other types of organisms are present
What is a microhabitat
Smaller units in a habitat with their own microclimate e.g. bloodworm living in mud at the bottom of a stream
What is an ecological niche
How an organism fits into its environment; where it lives and what it does there.
Including biotic and abiotic conditions to which the organism is adapted to
What are the abiotic factors
Temperature
Light
PH
Water and humidity
How is temperature a limiting factor
Each species has a different optimum temperature
Cold blooded animals need low temperatues, where enzymes work slowly and metabolic rate is reduced
If temperature is too high enzymes denature
Hot-blooded animals can maintain body temperature regardless of external temperature, but this uses energy
How is light a limiting factor
Rate of photosynthesis, for plant growth, spore and seed production
How is pH a limiting factor
Affects enzyme action
Each enzyme has optimum pH where it works most effectively
how is water and humidity a limiting factor
Humidity affects transpiration rates in plants and evaporation of water from animals bodies
How do mutations occur
changed to genes and chromosomes which may or may not be passed on to next generation
List two different selection pressures that limit the size of a population
1) availability of resources/competition over resources
2) predation/disease
3) temperature/weather conditions
4) natural disasters
Suggest why it is not possible for two different species to occupy the same niche
1) It would lead to interspecific competition
2) Where one species would eventually outcompete the other
Charles Darwin used the phrase “survival of the fittest” to support his theory of evolution through natural selection.
State the meaning of this phrase
1) Some individuals have more advantageous traits
2) Making them better adapted to their environment
3) They are more or less likely to survive
Explain how natural selection could result in evolution of a species of rabbit being resistant to a disease
1) Mutations generate variation in population
2) Rabbit may possess mutation that makes it more likely to survive
3) Rabbits that survive are more likely to reproduce and pass on their alleles to the next generation
4) Frequency of the advantageous allele will increase
Calculating percentage efficiency between trophic levels
(Energy in 2nd trophic level / energy in 1st trophic level) x 100
Why when a secondary consumer eats a primary consumer they do not gain all the energy
Some lost in excretion
Not all of organism is eaten/can’t physically digest all of it e.g. the bones
Heat lost from respiration
Factors that might cause the gorse to increase in biomass by different amounts each year include
Abiotic factors
(Such as) light OR rainfall OR temperature
Biotic factors
(Such as) competition from other plant species OR grazing by animals/insects OR pests/disease
