Topic 10 Flashcards
What’s an ecosystem
life supporting environment , includes all the organisms living in a particular area known as a community ,
Ecosystems can vary in size
What’s the biosphere
What’s a biome
The biosphere is all the areas of earths surface where living things survive
The biosphere is the largest ecosystem
a biosphere is split into biomes
What succession (there are 5 stages)
process by which communities of
animals and plants colonise an area and then
over time are replaced by more
varied communities.
What’s primary succession
This type of succession occurs where no life has
previously existed eg bare rock
What’s the first stage which is colonisation
These include algae, mosses and fungi , they penetrate the surface of bare rocks helping it to break into smaller grains
The second stage is pioneer
Decay adds to soil depth , decomposition
The third stage is herbaceous plants
Larger plants can grow due to soil depth and minerals
The forth stage is shrubs and bushes
Once the soil becomes deep enough larger plants can be supported , plant diversity increases
What’s the 5th stage which is climax community
As plant biodiversity increases, so does the diversity of animals that can be supported.
Eventually a climax community is reached where the
biodiversity is constant over time
What’s an artificial climax community
These are climax communities which are constant
and self-sustaining but not formed naturally
Lichens are organisms composed of a fungus and algae living together. Lichens colonise bare rock.
Explain how colonisation of bare rock by lichens can result in succession over long periods of time.
lichens are pioneer species (1)
• they break down surface of rocks to create soil (1)
• therefore other plants are able to {grow / be established) (1)
• death and decay helps to {create humus / recycle
minerals) (1)
• therefore providing niches for either plants or animals (1)
What are abiotic factors
Non-living elements of the habitat of an
organism.
Example: light, temperature, wind and
water availability, oxygen
availability, soil structure.
What are biotic factors
Living factors Plants
• Algae
• Fungi
• Herbivores
• Predators
Pathogens
How would abiotic factors effect a community : light intensity , enzymes , wind and water currents , o2 availability , ephadic factors
L - needed for photosynthesis, if there a low lvls plants must be adapted to low light lvls
T - effects enzyme controlled reactions in plants
W - water loss
O- need o2 to survive
E - relates to structure of soil. Sandy soil leaches minerals as water passes thru and drains quick , clay gets waterlogged and js difficult to drain
What are the effects of Biotic factors - predation
As prey pop incr more food for
the predators so predator population
grows too.
What are some density dependent factors
Biotic factors that effect a population
eg Predation , food source , space and competition , parasitism, Impact of the factor depends on
Impact of factor depends on how many organisms there are
in an area.
E.g. disease and parasitism.
The more individuals in an area
the more likely the disease is to
be transmitted between
individuals.
What are some density independent factors
Abiotic factors that Effect the pop regardless of its size / density
E.g. extremes of
temperature have the same
effect on all individuals
regardless of how many
individuals there are.
Climate weather natural disasters
What’s abundance
What’s distribution
The relative representation of species in a particular ecosystem compared to other organisms in the same habitat
Where are these specifies found and how they’re arranged (random, uniform or clumped)
What are limitations to quadratting
What 2 ways can quadrats be used
- It needs to be on flat land , the quad rates need to be spread randomly
- Random sampling (used to measure abundance of species, must be placed randomly to avoid bias, no abiotic factor monitored)
- Systematic sampling (measures the change in distribution of a species over a distance, measure change in abiotic factors , quadrats placed along tape at regular distances)
There are two types of competition between organisms;
; interspecific competition between individuals of different species and intraspecific competition between individuals of the same species.
What are limitations to the acfor scale
The limitations of this scale are:
1. It is subjective – 2 people would probably never come up
with the exact same scores, may classify same species differently
What’s a permanent quadrat
Left in place all of the
time. This means data
can be collected reliably
from the same place
through the seasons
2 types systematic sampling (not random)
- Line transects – A tape is stretched between two
points and every individual plant (or animal) that
touches the tape is recorded. - Belt transects – Two tapes are laid out and the ground
between them are sampled. Quadrats could be laid
out along a tape to form a belt transect.
Trophic lvls
Producers
Primary consumers
Secondary consumers
Tertiary consumers
Decomposers
Producers - make food
Primary - eat producers
Secondary - feed on herbivores (primary consumers)
Tertiary - feed om carnivores
Decomposes - final trophic lvl
Animals that rely on a single food source
Are very vulnerable bc if that food source runs out the population will decrease , which will effect the whole food chain
What’s a pyramid of biomass
Shows the combined mass
of all organisms in a
particular habitat.
Biomass normally
decreases at each trophic
level.
Is wet or dry mass better for measuring biomass
Dry bc wet is affected by transpiration , urinating
Compare pyramids of energy with pyramids of biomass
• Pyramids of numbers show the number of organisms at each trophic level.
• Pyramids of biomass show the total mass of living organisms at each trophic level.
2. Shape:
• Pyramids of numbers can have irregular shapes. For example, a single tree (producer) may support many herbivores, creating an inverted pyramid.
• Pyramids of biomass are usually pyramid-shaped because biomass decreases as you move up the food chain due to energy loss.
3. Accuracy:
• Pyramids of biomass are generally more accurate as they consider the actual mass of organisms rather than just their count.
• Pyramids of numbers can be misleading if the organisms vary greatly in size (e.g., one tree vs. thousands of insects).
pyramids of numbers
Pyramids of biomass
Pyramid of energy
Easiest to measure but least accurate representation
Doesn’t take into account the rate of production of biomass, shows combined biomass of organisms at different trophic lvls
Most accurate but difficult to measure
Why can some energy be lost at each trophic level
Undigested matter
Respiration
Waste products
gross primary productivity
The rate at which producers make organic material by photosynthesis
Units : kJm^-2 year ^-1
Net primary productivity
The energy that remains after the plant has used some for respiration , this is alw less than gpp as some energy is lost in plant respiration (rate r)
The energy in producers which transfers to the next trophic lvl
What’s the sum to work out gpp
Gpp = npp + r
R = respiration
What factors can affect NPP
Temperature, light intensity
Why may there be a loss in biomass between primary and secondary consumers
Losses from excretion,
Losses from respiration
Exam q- only a small percentage of light energy that falls on the green plants is used in photosynthesis, why would blue and red light be more useful to a plant than green light
- red and blue absorbed
- red and blue absorbed by chlorophyll
-green light reflected
What’s the nitrogen cycle
Nitrates in the soil taken up by plants to make amino acids and build proteins , animals take in these aa as they eat the plants , death and excretion , waste contains nitrogen , formation of ammonia , nitifrying bacteria converts ammonia back into nitrates
Nitrates in the soil are converted into nitrogen gas in the air by
Denitrifying bacteria found in soil
Nitrogen fixing bacteria
Lightening
Nitrogen gas turned into ammonia , nitrifying bacteria converts ammonia into nitrates , found in soil
High temps from lighting allow N2 and O2 to react forming nitrates
Why does the efficiency of energy transfer differ between tropic levels
Diff organisms use diff proportions of energy
Eg. Respiration for movement
And some material is lost as faeces
How can humans effect ecosystems
Climate change
Deception of biological resources, more ppl means more resources needed
Loss of biodiversity- climate change can cause this and overfishing
When you evaluate a study many factors need to be considered
- Is the study size sufficient , is the study reliable so other scientists can repeat it and gain similar results,
The study needs to have what
- Peer review
- Validity (keep the study heavily controlled
- Reliability- being able to repeat the results to gain consistent results
What is evidence used for climate change
Co2 lvls - incr co2 contributes to the green house effect
Temp records
Pollen in peat bogs - pollen grains are preserved in peat bogs and analysing pollen samples can tell us what plants were present at the time
Dendochronolgy - study of tree rings, size of tree rings are effected by temp
What effect does temp have on organisms
Change in temp, leads to disruption of hydrogen bonds holding tertiary structure of protein, a.s changes shape, substrate can no longer fit , less enzyme substrate complexes formed
What’s overfishing
What are the effects of overfishing
Fish are caught at a faster rate than they can reproduce, leading to a decline in fish populations
- Disrupts food chains - reducing fish population, means less food for primary secondary consumers
- Loss of biodiversity- some fish may become extinct
What’s conservation
Protecting an endangered species
What are some conservation agreements
Cities - countries sign up to a treaty allowing us to protect endangered species
Icun
cities can also prevent poaching
What’s a way to reduce global warming
Reforestation
Biofuels k
Reduction of co2 - eg reforestation increases the rate at which co2 is removed
Biofuels - growing plants to use as bio fuels which are carbon neutral , co2 released from burning the fuels is taken in by the plants thru photosynthesis
What are some effects of climate change
- Changes in rainfall patterns
- Changes in the distribution of species , moving to colder areas , competition
- Disrupted food cycles
- Changes to development - temp influences the sex ratio of males:females in a species
Standard
deviation
Looks at the spread/range of values
either side of the mean. Shows
degree of variation in the results
Spearman
rank
Looks for correlations between different
measurements from the same sample.
Compares the rank of two variables
(differences between the ranks).
Student t
test
Looks for significant differences
between 2 sets of data. Used to assess
whether differences in the means of
two groups are statistically significant.
Error bars show standard deviation
The spread of data around the mean value , the bigger the bars the higher the s.d and the more variety
- YOU MUST look at if they overlap , ALWAYS COMMENT ON THE ERROR BARS : IF THEY OVERLAP OR NOT, is there a statistically significant difference between the means or no?
If in the chi squired table the P value gets larger it shows
Vice versa
Probability that it’s just due to chance goes up (this is a bad thing for an experiment)
Happy it’s high except w kai
