Genetics, Populations, Evolution and Ecosystems Flashcards
define habitat
the place where an organism lives
define population
all the organisms of one species in a habitat
define community
populations of different species in a habitat make up a community
define ecosystem
a community, plus all the non-living conditions in the area in which it lives. ecosystems can be small or large
define abiotic conditions
the non-living features of the ecosystem, e.g temperature and availability of water
define biotic conditions
the living features of the ecosystem, e.g the presence of predators or food
define niche
the role of a species within its habitat, e.g what it eats, where and when it feeds
define adaptation
a feature that members of a species have that increases their chance of survival and reproduction
explain a niche a species occupies in its habitat
its biotic interactions- e.g the organism it eats, and those its eaten by
its abiotic interactions- e.g the oxygen an organism breathes in, and the carbon dioxide it breathes out.
does every species have the same niche?
no, every species has its own niche
what types of adaptations are there?
physiological; processes inside their body
behavioural; the way an organism acts
anatomical; structural features of their body
what are the benefits of an organism having better adaptations?
they are more likely to survive, reproduce and pass on the alleles for their adaptations, so the adaptations become more common in the population.
what are organisms adapted to?
both the abiotic conditions (e.g how much water is available) and the biotic conditions (e.g what predators there are) in their ecosystem.
describe an example of when hedgehogs have adapted to abiotic conditions
hedgehogs hibernate. and so they are able to lower their rate of metabolism (all the chemical reactions taking place in their body) over winter. this increases their chance of survival because they can conserve energy during the coldest months.
describe an example of when male frogs have adapted to biotic conditions
male frogs produce mating calls to attract females. this makes sure they attract a mate of the same species. this increases their chance of reproduction by making successful mating more likely.
what 2 factors causes population size to vary?
abiotic factors
biotic factors
define carrying capacity
the maximum stable population size of a species that an ecosystem can support.
what do abiotic factors include?
abiotic factors include the amount of light, water or space available, the temperature of the surroundings or the chemical composition of surroundings.
how do abiotic factors affect population size (include an example regarding temperature)
when abiotic conditions are ideal for a species, organisms can grow fast and reproduce successfully.
e.g when the temperature of a mammal’s surroundings is the ideal temperature for metabolic reactions to take place, they don’t have to use as much energy maintaining their body temperature. this means more energy can be used for growth and reproduction, so their population size will increase.
when abiotic conditions aren’t ideal for a species, organisms can’t grow as fast or reproduce successfully.
e.g when the temperature of a mammal’s surroundings is significantly lower or higher than their optimum body temperature, they have to use a lot of energy to maintain the right body temperature. this means less energy will be available for growth and reproduction, so their population size will decrease.
how do biotic factors affect population size
interspecific competition
intraspecific competition
predation
define and explain interspecific competition
interspecific competition is when organisms of different species compete with each other for the same resources.
interspecific competition between two species can mean that the resources available to both populations are reduced.
for example, if they share the same source of food, there will be less available to both of them. this means both populations will be limited by a lower amount of food. they’ll have less energy for growth and reproduction, so the population sizes will be lower for both species.
if two species are competing but one is better adapted to its surroundings than the other, the less well adapted species is likely to be out-competed.
define and explain intraspecific competition
intraspecific competition is when organisms of the same species compete with each other for the same resources.
the population of a species increases when resources are plentiful. as the population increases, there’ll be more organisms competing for the same amount of space and food.
eventually, those resources become limiting, where there isn’t enough for all organisms. the population then begins to decline.
a smaller competition then means that there’s less competition for space and food, which in turn is better for growth and reproduction, and so the population starts to grow again.
define and explain predation
predation is where an organism (the predator) kills and eats another organism (the prey). the population sizes of predators and prey are interlinked; as the population of one changes, it causes the other population to change as well.
explain how predation is shown through a graph
in a graph, as the prey population increases, there’s more food for predators, and so the predator population grows (there’s more food available). (shown through an accelerating line of prey and predators.)
as the predator population increases, more prey is eaten so the prey population then begins to fall. (shown through a decreasing line of prey.)
this means there’s less food for the predators, so their population decreases, and so on. (shown through a decreasing line of predators.)
when investigating populations experimentally, how are we supposed to take a random sample from an area we are investigating?
first we choose a small area within the area being investigated to sample.
the sample we choose, should be random. this is to avoid bias.
we can choose a random sample by dividing the area into a grid and using a random number generator to select coordinates.
we would then use appropriate techniques to take the sample of the population.
next we would repeat the process to reduce the likelihood of our results being down to chance.
what appropriate techniques are used to investigate non-motile organisms (organisms that don’t move; plants)?
quadrats and transects
what is a quadrat?
a quadrat is a square frame, usually divided into a grid of 100 smaller squares by strings attached across the frame.
where are quadrats placed?
quadrats are placed on the ground at different points within the area you’re investigating.
how is a quadrat used to measure the amount of species?
they are able to record the species frequency. how much quadrat covered by a species e.g 42 squares covered with species A means there’s 42% of that species.
what are transects?
they are lines used to help find out how plants are distributed across an area.
what is mark-release-recapture?
it is a method used to measure the abundance of more motile species.
what is the process of mark-release-recapture?
capture: we capture a small sample of a species using an appropriate technique.
mark: we mark them in a harmless way, e.g putting a spot of paint on them, or by removing a tuft of fur.
release: we release them back into their habitat.
we then wait a week, and take a second sample from the same population.
we count how many of the second sample are marked and use an equation to estimate the total population size.
what equation is used from mark-release-recapture to find out total population size?
the number caught in the first sample multiplied by the number caught in the second sample. then divide that value by the number marked in the second sample to give us the total population size.
when using the mark-release-recapture method, what 3 assumptions do we need to make?
1) the marked sample has had enough time and opportunity to mix back in with the population.
2) the marking hasn’t affected the individuals’ chances of survival (e.g. by making them more visible to predators), and the marking is still visible.
3) there are no changes in population size due to births, deaths and migration during the period of the study.
what is succession?
succession is the process by which an ecosystem changes over time.
the biotic and abiotic conditions change.
what are the two types of succession?
primary succession
secondary succession
what is primary succession? give an example
this happens on land that’s been newly formed or exposed. e.g. a volcano has erupted to form a new rock surface. there’s no soil or organic material to start with.
what is secondary succession? give an example
this happens on land that’s been cleared of all the plants, but where the soil remains, e.g. a forest fire or deforestation
explain the stages of primary succession
primary succession starts when species colonise a new land surface. seeds and spores are blown in by the wind and begin to grow. the first species to colonise the area are called pioneer species.
the abiotic conditions are hostile. only pioneer species grow because they’re specially adapted to cope with the harsh conditions.
the pioneer species change the abiotic conditions; they die and microorganisms decompose the dead organic material. this forms a basic soil.
this makes conditions less hostile, the basic soil helps to retain water, which means new organisms with different adaptations can move in and grow. these then die and are composed, adding more organic material, making the soil deeper and richer in minerals. this means larger plants like shrubs can start to grow in the deeper soil, which retains even more water.
some new species may change the environment so that it becomes less suitable for the previous species.
what is the difference between the stages of primary succession and secondary succession?
secondary succession happens in the same way as primary succession, but because there’s already a soil layer succession starts at a later stage; the pioneer species in secondary succession are larger plants.
what is the final stage of both successions?
the final stage is climax community.
what is climax community?
where the ecosystem is supporting the largest and most complex community of plants and animals it can. the ecosystem won’t change much more; it’s in a steady state.
define climatic climax
the climax community for a particular climate.
explain two examples of a climatic climax
in a temperature climate where there’s plenty of available water and mild temperatures, the climate climax will contain large trees because they can grow in these conditions.
in a polar climate there’s not much available water, temperatures are low and there are massive changes between the seasons. the climate climax contains only herbs and shrubs, but it’s still the climax community.
what is conservation?
conservation is the protection and management of species and ecosystems in a sustainable way.
define sustainable
it means that enough resources are taken to meet the needs of people today, without reducing the ability of people in the future to meet their own needs.
how can conservation sometimes prevent succession?
reaching climax community can have negative effects on habitats within stages of succession. within succession, the ecosystem becomes more and more complex. this in turn reduces the habitat of some species. and so conservation is needed to manage the succession.
why is there a need to manage the conflict between human needs and conservation?
to maintain sustainability of natural resources.
explain an example of managing human needs and conservation.
people may farm livestock in areas of vast wildlife however these livestock can overgraze the grasslands reducing wildlife. having a compromise or a conservation trust can help the people continue to make money from their land but also allow the area and its wildlife to be conserved.
give two examples of different conservation techniques
- endangered species being bred in captivity to increase its numbers and then returned back to the wild.
- having protected areas such as national parks and nature reserves to protect habitats. this restricts urban and industrial development as well as farming.
