Biology paper 2 Flashcards
what is an individual
a single organism
what is a population
all the organisms of one species in a habitat
what is a community
all of the organisms of different species living in a habitat
what is an ecosystem
a community along with all the non-living (abiotic) conditions
what is the order of an ecosystem
individual
population
community
ecosystem
what is interdependence
organisms depend on each other for things like food and shelter in order to survive and reproduce meaning that a change in the population of one species can have huge knock on effects for other species in the same community
what is mutualism
a relationship between two organisms from which both the organisms benefit
what is an example of mutualism
bees and flowering plants - when bees visit flowers to get nectar, pollen is transferred to their bodies. The bees then spread the pollen to other plants when they land on their flowers. The bees get food and the plants get help reproducing
- coral and algae
- nitrogen fixing bacteria and the root nodule of leguminous plants
- cleaner fish and shark
- ox and ox pecker
what is parasitism or non-mutualism
a feeding relationship where the parasite benefits from living on and feeding on the host
parasites live very closely with host species and the parasite takes what it needs but the host doesn’t benefit
- fleas and mammals
- headlice and humans
- tape worm and humans
how are headlice adapted to live a parasitotic relationship with humans
they suck blood out of our heads to grow
they have sharp claws and mouth to pierce skin
how are tape worms adapted to live parasitotic relationship with humans
live inside our intestines to absorb nutrients
flattened bodies to increase SA for absorption
suckers to attach to small intestine wall
what abiotic factors affect communities
abiotic - non-living
- temperature
- amount of water
- light intensity
- levels of pollutants
what biotic factors affect communities
biotic - living
- competition
- predators
how can we study the distribution of small organisms in an area
using a quadrat
- place quadrat randomly in first sample area (use random number generator to pick coordinates)
- count organisms in quadrat
- repeat above lots
- work out the mean number of organisms per quadrat within the first sample area (total number of organisms/ number of quadrats)
- repeat steps 1-4 in the second sample area
- compare the two means
how can we study distribution along a gradient
using a belt transect - sometimes abiotic factors will change across a habitat and this change is known as a gradient and the number of organisms along this gradient may change
- mark line in area you want to study
- collect data along line using quadrats placed next to each other
- count all the organisms your interested in
- repeat several times and find the mean number of organisms or mean percentage cover for each quadrat
- plot graph to see if changing abiotic factor is correlated with distribution change
what is an organisms biomass
the mass of a living material that makes up an organism
why doesn’t all energy pass along the food chain
energy is used by organisms at each stage to stay alive i.e in respiration but a lot of the energy is transferred to the surroundings by heat
this energy isn’t stored as biomass so it isn’t transferred to the organisms in the next trophic level its ‘lost’ to the food chain
energy that does get stored as biomass doesn’t all get transferred to the next trophic level either because not all of an organism gets eaten and all the bits that do get eaten are not necessarily digested and is lost from the food chain in faeces
what is the equation for efficiency of energy transfer between trophic levels of a food chain
(energy transferred to the next level / energy available at previous level) x 100
what is biodiversity
the variety of living organisms in an ecosystem
discuss fish farming
- in areas of open water
- reduce biodiversity in the surrounding area
- food added to nets to feed fish
- huge amounts of waste produced which could leak into open water causing eutrophication and death of wild fish
- breeding ground for large number of parasites
- disease spreads easily
- predators and other wild animals can become trapped in the net and die
- farmed fish can escape into the wild and cause problems for wild populations of indigenous species
what is a non-indigenous species
a species that doesn’t naturally occur in an area
they can be introduced intentionally (e.g for food and hunting) or unintentionally (e.g as stowaway in international cargo)
why can the introduction of non-indigenous species reduce biodiversity
- compete with indigenous species and sometimes out-compete them so the species decrease and die out reducing biodiversity
- sometimes bring new diseases to a habitat killing species
how can we conserve and maintain biodiversity
reforestation:
- high biodiversity because wide variety of trees and plants
- provide food and shelter
- carefully planned to maximise positive effects and minimise bad ones
- plant variety of trees because more biodiversity then a single type of tree
conservation schemes:
- protect biodiversity by preventing species from dying out
- protect habitats
- protect species in safe areas like zoos and do captive breeding programmes
- use of seed banks to store and distribute the seeds of rare and endangered plants
what are the benefits of maintaining biodiversity
- protecting the human food supply
- ensuring minimal damage to food chains
- providing future medicines
- cultural aspects
- ecotourism
- providing new jobs
what is food security
food production must increase at the same rate as population growth
what biological factors are affecting the level of food security
increasing consumption of meat and fish and increasing animal farming
environmental changes caused by human activities
sustainability
new pests and pathogens
how are materials constantly recycled in an ecosystem
- living things made of elements taken from environment
- turned into complex compounds
- elements passed along food chains
- waste products and dead organisms broken down by decomposers and returned to soil and air to be used again
when does a drought occur
when there isn’t enough precipitation meaning there isn’t enough fresh water for drining
what is desalination
producing potable water from salt water
thermal desalination is where the salt water is boiled in a large enclosed vessel so the evaporates. the steam rises to the top and travels down a pipe to the top of the vessel and condenses back into pure water
how is reverse osmosis used as a method of desalination
1) salt water is first treated to remove solids before being fed at a very high pressure into a vessel containing a partially permeable membrane
2) the pressure causes the water molecules to move in the opposite direction to osmosis from low to high
3) as the water is forced through the membrane, the salts are left behind, moving them from the water
what is a decomposer
decompose proteins and urea and turn them into ammonia
ammonia forms ammonium ions in solution that plants can use
what is nitrifying bacteria
turn ammonia in decaying matter into nitrites and then into nitrates
what is nitrogen fixing bacteria
turn atmospheric N2 into ammonia which forms ammonium ions
what is denitrifying
turn nitrates back into N2 gas. this is of no benefit to living organisms and often happens in water-logged soils
where does nitrogen fixing bacteria live
some live in the soil but others live in nodules on the roots of legume plants
when these plants decompose the nitrogen stored in them and in their nodules is returned to the soil
nitrogen ions can also leak out of the nodules during plant growth
the plants have a mutualistic relationship with the bacteria - the bacteria get food (sugars) from the plant and the plant gets nitrogen ions from the bacteria to make into proteins
why does the amount of nitrates in the soil decrease over time
like all plants crops take up nitrates from the soil as they grow but crops are harvested rather than being left to die and decompose so the nitrogen they contain isn’t returned to the soil so overtime it decreases leading to poor crop growth and deficiency diseases
how can farmers increase the amount of nitrates in the soil
crop rotation - different crops are grown each year in a cycle which includes a nitrogen-fixing crop that puts nitrates back into the soil
fertilisers - spreading animal manure or compost on fields recycles the nutrients left in plant and animal waste and returns them to the soil through decomposition. Artificial fertilisers containing nitrates can be used but are expensive
what are indicator species of water pollution
stonefly larvae and freshwater shrimp = positive
blood worms and sludge worms = negative
what are indicator species of air pollution
bushy and crusty lichen = positive
blackspot fungus on rose leaves shows low level of sulphur dioxide = positive
more lichen further away from city centre because less pollution and sulphur dioxide
how can you find out pollution in an area
- count indicator species
- dissolved oxygen meters
- chemical test
- electronic meters and laboratory tests
what does the rate of decay depend on
- temperature speeds up rate of enzyme controlled reactions to a point
- water content, a high level is faster because the organisms involved need it to survive and carry out biological processes
- oxygen for aerobic respiration of microorganisms
how can we preserve foods
- vacuum
- fridge
- cans sealed and sterilised
- drying food and adding salt
what does the pancreas secrete
insulin which is used to regulate the blood glucose level
what does the thyroid gland secrete
produces thyroxine, TSH and TRH which is involved in regulating things like the rate of metabolism, heart rate and temperature
describe the difference between hormones and neurones
neurones
- fast action
- short time acting
- act in precise area
hormone
- slower action
- long time acting
- act in general way
what happens if blood glucose concentration is too high
insulin is secreted by the pancreas
glucose moves from blood into liver and muscle cells
what happens if blood glucose concentration is too low
glucagon is secreted by the pancreas and glucose is released from the liver into the blood
why does the level of blood glucose concentration change in the first place
- eating foods containing carbohydrates puts glucose into the blood from the small intestine
- the normal metabolism of cells removes glucose from the blood
- vigorous exercise removes much more glucose from the blood
- excess glucose can be stored as glycogen in the liver and in the muscles
