b7 Flashcards
give three environmental factors that affect plant growth.
- light intensity
- soil ph
- water or moisture
to investigate decay of milk, how does the student keep milk at a constant temperature?
place in water bath
when investigating decay of milk, what product makes ph decrease?
lipids break down into fatty acids
why would different types of milk have different rates of decay?
- different concentration or type of lipid
- different concentration or type or sugar
- different type of bacteria present
what two types of organisms cause decay?
- bacteria
- fungi
give three environmental factors needed for decay
- oxygen
- water
- temperature
what is the main gas found in biogas?
methane
why would a farmer spread dead plant material onto his fields?
used as fertiliser as it contains mineral ions so plants grow faster
why is a large surface area to ratio volume an advantage to respiring organisms?
can absorb more oxygen in a given time
why is it advantageous to place quadrats at random positions when sampling fields?
- to avoid bias
- more representative
- there is an uneven distribution of dandelions
when investigating decaying milk, why should you sterilise the flask before adding milk?
to kill bacteria in flask so only microorganisms in the milk cause the results
how could students sterilise a flask in a school lab?
heating to over 100°C
when investigating decay of milk, why is there a lid on the top of the flask?
to prevent microorganisms entering from the air
what’s the advantage of using a pH meter instead of universal indicator paper?
more accurate and precise
during the first few days of decay, why is rate of decay low?
too few bacteria
when sampling a field, what is tape measure used for?
to measure the area of field
why might a farmer be against using anaerobic decay in a compost bin?
- produces methane
- which is a greenhouse gas so causes global warming
what is meant by biodiversity?
the variety of all the different species of organisms on earth or in an ecosystem
give two uses of peat taken from peat bogs
- compost / fertiliser
- burned as fuel
why is the use of peat harmful to the environment?
decay/ burning of peat releases carbon dioxide which is increasing global warmint
why is the use of antibiotics in farming a threat to human life?
- antibiotics in animal faeces flows into rivers
- bacteria in water become antibiotic resistant
- sone of these bacteria are human pathogens
- so human diseases can not be cured as they are antibiotic resistant
give three reasons why deforestation occurs.
to clear land for…
- mining
- to raise cattle (agriculture)
- building
- paper
what is the order of living things?
- organism
- population
- community
- ecosystem
what do animals compete for?
- food
- territory
- mates
what do plants compete for?
- sunlight
- water
- nutrients
what are extremophiles?
organisms with adaptations that allow them to survive in extreme conditions of salt temperature and pressure
how do you calculate efficiency with biomass?
(energy for growth/ energy supplied) *100
how do you work out an estimate for population size?
(total area/ area sampled) * total number of plants counted
which is faster, anaerobic or aerobic decay?
aerobic decay
what are four advantages of biodiversity?
- useful substance for medicines
- preservation of species
- interruption of food chains
- loss of environmental indicators
why has the human population increased quickly?
- medicine and technology
- no natural predator
- abundance of food
what is eutrophication?
a sudden and dramatic increase in nutrients due to human activity causing a disruption to food chains
explain why many fish died after untreated water enters a river (5)
- bacteria decay organic matter
- by digestion
- and respire aerobically
- which lowers oxygen concentration in water
- so reduced energy supply causes death of fish
what is food security?
a measure of having enough food to feed a population
give three ways biomass is lost
- inedible parts
- faeces
- respiration
how would scientists selectively breed cattle that makes large volumes of low fat milk? (4)
- find female with lowest fat in milk and highest milk yield
- find male whose female offspring have highest milk yield and lowest fat in milk
- cross the best female with the best male
- select best offspring from each generation and repeat for several generations
describe how ancestors of modern lemurs may have evolved into a different species (speciation) (5)
- isolation of different populations
- habitat variation between lemur populations
- genetic variation or mutation in each population
- better adapted survive and reproduce and pass on favourable allele to offspring
- eventually cannot produce fertile offspring with other populations
plan an investigation to investigate the size of the population of ragwort on a field(6)
- use 0.5m by 0.5m quadrat
- quadrats placed randomly usint random coordinates from a calculator
- use large number of quadrats (over 10)
- count number of plants in each quadrat
- calculate mean per quadrat
- determine area of field
- population= mean per m^2* area of field
how do fishing quotas help return fish stocks to a sustainable level?
- fewer fish caught
- remaining fish can reproduce
