B7 Ecology Flashcards
Explain how abiotic and biotic factors can cause an uneven dispersal of plants
Abiotic: lack of light in certain areas like due to a tree means less photosynthesis so less glucose and less proteins meaning less growth. Trees may absorb more nutrients and water so less growth there for other plants
Biotic: More insects in certain areas meaning more plants are eaten there so less plants
How should the student decide where to place the quadrat and why?
Use a random number generator to generate random coordinates to achieve randomness
Describe how carbon is cycled through living organisms
- Green plants absorb CO2 through the stomata for photosynthesis to make glucose for growth and storage as starch
- Animals eat the green plants and so take in the CO2 to use the carbon compound to make other carbon compounds
- CO2 is released during respiration in animals (but also plants)
- When animals die they release CO2 as they are decayed by microorganisms thet respire and release CO2 into the atmosphere
Give 5 abiotic factors
- light intensity
- temperature
- oxygen levels
- carbon dioxide levels
- mineral ion levels
What three factors do plants compete for?
- light
- water
- space
How can you use a quadrat to make valid conclusions?
Repeat at different random locations
Why has deforestation increased? (2)
- provide land for cattle for agriculture
- grow crops for biofuels to provide fuel
Why does total biomass decrease along the food chain? (3)
- lost in faeces - egested so not all absorbed
- excreted in urine
- used in respiration which releases CO2
Plan an investigation to estimate population size of a plant species
- use of quadrat of area eg 1m×1m
- quadrats are placed randomly using a random number generator to find random coordinates
- count number of plants (in each quadrat)
- repeat, using a large number of quadrats
- calculate mean per quadrat
- calculate area of field area of field (length × width)
- population = total area/area sampled x species counted
Explain the advantage of making crops resistant to herbicides
Only weeds are killed but crops are not killed. This means there is less competition, like for light and water, so crops have a higher yield as can photosynthesise more.
What are 3 features organisms have to aid their survival?
- structural
- functional
- behavioural
What are functional adaptations of animals in hot deserts?
Stay in cooler conditions/ sweat less so lose less water because little water is available in deserts, energy stores last longer
What is the purpose of a fat store?
Insulation
Energy store that can be metabolised
What is the purpose of a hard mouth?
Avoids damage when eating hard foods
Why is rate of decomposition slower in waterlogged compost heaps
Waterlogged means less oxygen for decomposers so less aerobic respiration meaning less energy so decomposers work less efficiently. This also means temperature may not be as warm so enzymes not working at optimal conditions.
Describe a peat bog
Acidic, waterlogged with low levels of oxygen that act as ‘carbon sinks’ (store carbon)
What is peat used for?
- agriculture for cheap compost/fertilisers
- burned for fuel
Explain how draining peat bogs contributes to global warming
The draining of water allows air (and oxygen) to return to the soil
This allows microorganism to carry out aerobic respiration and decay the organic matter
This releases CO2 which is a greenhouse gas (especially because peat bogs are known as ‘carbon sinks’ that store carbon) and so contributes to global warming
Give 4 ways humans have adapted to increase production of food
- cleared land for agriculture - farming
- using fertilisers
- pesticides and herbicides
- genetic modification
A large amount of untreated sewage entered the river. Many fish died. Untreated sewage contains organic matter and bacteria.
Explain why many fish died
- bacteria decay organic matter by digestion and bacteria respire aerobically
- bacteria use up oxygen so lowers oxygen concentration, meaning fish have less oxygen
- reduced energy supply causes death of fish
Give two reasons why species counted with quadrat are not valid
- quadrat too small/sample size too small - use more quadrats
- not representative
‘Light intensity affects the number of dandelion plants that grow in an area.’ Plan an investigation to test this hypothesis.
- transect along an ecological gradient with different light intensities
- use a large number of quadrats along transect at regular intervals, using continuous sampling
- for each quadrat count number of dandelions and record
- for each quadrat measure light intensity (with a light probe)
- compare data from different light intensity
How do microorganisms help cycle materials and how this benefits plants.
- Break down large molecules to small molecules by secreting enzymes and respiration which releases carbon dioxide and energy for other processes such as active transport
- Release mineral ions eg nitrate and magnesium ions
- Plants take in carbon dioxide through diffusion by stomata for photosynthesis producing glucose required for growth which helps make amino acids
- Plants take in ions through roots by active transport for amino acid and protein production and chlorophyll synthesis
Why do micro-organisms decay faster in higher temperatures?
More energy so enzyme activity is higher, faster reactions
