ecology Flashcards
what is the definition of a habitat
-environment in which an organism lives in
what is the definition of community
a community is the population of all different species that live in the same habitat
ecosystem defintion
both biotic and abiotic parts of an environment and how they interact.
what is the definition of a population
total number of organisms of the same species living in the same geographical area.
what do plants compete with each other for?
- light
- minerals
- water
- space
what do animals compete with each other for?
- food
- water
- mating partners
- territory
what is interdependance?
when all the different species of a community depend on each other.
how do plants rely on other living organisms
plants rely on bees to disperse their pollen
and rely on birds to disperse seeds in their faeces.
if a species disppears from a community, the whole community is affected. without bees what can happen to plants?
without bees lots of plants would be unable to reproduce as they would not get pollenated.
animals which feed on these plants, could run out of food and their populations would fall.
in most communities, populations of different species remain constant. what is this called
a stable community. a stable community is one where all species and environmental factors are in balance so that population sizes remain fairly constant.
biotic factors (living)
competition between species (one species outcompeting other so numbers are no longer sufficient enough to breed could lead to extinction)
availability of food
new predators arriving( prey population can fall or competition can compete with other predators)
new pathogens
abiotic factors
light intensity temperature moisture levels oxygen levels (for aquatic plants) carbon dioxide levels ( for plants) soil ph and mineral content wind intensity and direction
every food chain starts with a :
producer
what do producers do
synthesise complex molecules
producers source of biomass in all communities
glucose- biomass
primary consumers
primary consumers eat producers
secondary consumers
secondary consumers eat primary consumer
food chain
producer- source of all biomass in a community
biomass such as glucose passes down food chain to other organisms
producers synthesise complex molecueles
primary consumers eat the producer
secondary consumers eat the primary consumer
tertiary consumer- eats secondary consumer
what are consumers that kill and eat other animals called
predators
animal that is being eaten
prey
what can be represented by a food chain
feeding relationships within a community
all food chains begin with a producer
a produce synthesisises complex moclecules. producer usually green plant or algae which make glucose by photosynthesis
why is random sampling used
used to compare numbers of organisms in different areas
using a quadrat
a quadrat is a wooden or plastic square
place it on the ground
count numbers of organisms inside the quadrat
can be used to sample plants or slow moving animals
in random sampling where is quadrat placed
random sampling used to compare number of organisms in different areas
quadrat placed in random locations across the area. one way to do this could be to use random numbers to select different locations
count numbers of organisms in each quadrat
move quadrat to a different random location and count number of organisms over there.
do this until you have large number of random locations
how to make results more valid
place the quadrat a large number of times.
whats wrong with only placing the quadrat once
-might not give us a sample that represents the whole area accurately.
must place quadrat large number of times to get valid results.
total population size
total population size=total area/ area sampled x number of organisms of that species counted in a sample.
sampling along a transect line why is it used
used to investigate whether a number of species changes as we move across a habitat. transect- piece of rope or tape measure place the transect line so that it runs across habitat we are looking it. use a quadrat to count number of organisms at intervals on the transect.
we use sampling along A transect, to see
how numbers of species have changed as we move across a habitat
sand dune
species of plant we find on a sand dune change as we move inland from the sea.we can measure this using sampling along a transect.
first place a tape measure on the dune, runnning from the beach inland. now place first quadrat at start of transect and count different plants in the quadrat
move the quadrat closer in land by a set distance such as 2m count number of plants again. keep doing this as we move further inland.
why must we carry out the transect a number of times
to get valid results. move tape measure along and repeat whole process we can get valid data this way on how the number of species change across the dune.
why are all materials recycled
to provide building blocks for future organisms
what is the carbon cycle
the carbon cycle returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis
describe carbon cycle
carbon cycle starts with carbon dioxide in the atmosphere
the only way that carbon can enter the carbon cycle is by photosynthesis
in photosynthesis carbon is combined with water to make glucose
carbon dioxide returns back into the atmosphere by aerobic respiration
two key processes in the carbon cycle
photosynthesis brings carbon into the cycle
respiration returns carbon back to the atmosphere as carbon dioxide
explain each step of the carbon cycle
-plants and algae take in carbon dioxide from the atmosphere in photosynthesis.
carbon is used to make carbohydrates, proteins and fats which make up the cells of plants and algae
-the plants and algae respire, so carbon is released back into the atmosphere as carbon dioxide.
-plants and algae can be eaten by other animals
-these animals can be eaten by other animals
-at this point, the carbon that was in the plants has now become a part of the carbohydrates, fats and proteins in the cells of animals.
-the animals respire and some of the carbon is released back into the atmosphere as carbon dioxide.
-animals release waste products such as faeces.
and eventually all plants and animals die
-carbon in waste products and dead remains
-waste products and dead remains are broken down by decomposers such as bacteria and fungi.
-when these decomposers carry out respiration, the carbon in the waste and the dead remains is returned to the atmosphere as carbon dioxide.
why are decomposers extremely important
because they cycle materials through an ecosystem
as well as returning carbon to the atmosphere as carbon dioxide, they also release mineral ions into the soil.
under certain conditions sich as lack of oxygen, decomposers cannot function effectively. what happens if this happens
the carbon in the dead remains slowly converted to fossil fuels. over millions of years, large amount of carbon dioxide becomes trapped underground in fossil fuels. combusting fossil fuels releases huge amount of carbon dioxide back into the atmosphere.
describe the water cycle
- most water in the Earth is found in oceans. and this water is known as salt water.
- energy from the sun causes water to evaporate from the surface of the sea
- this water vapour travels into the air and cools down
- as it cools down, the water vapour condenses to form clouds
- water in the clouds falls to the ground as precipitation.
- precipitation also includes rain, snow, hail and sleet
- precipitation contains fresh water which does not contain any salt.
- once water hits the ground, it simply evaporates back into the atmo as water vapour.
- some of the water passes through rocks and forms aquifers
- alot of the water forms streams and rivers
- eventually, the water in the streams and rivers drains out back into the sea.
how do living organisms play a part in the water cycle
- ;living organisms such as plants take up water in the roots. the water passes through the xylem. the water passes out of the leaves through the stomata as water vapour. this is known as transpiration
- animals take in water through food and drink. water is released in urine, faeces and when they exhale.
what do pyramids of biomass represent
pyramids of biomass represent relative amount of biomass at each trophic level of a food chain
what is a trophic level
the trophic level of an organism is how many steps it is away from the start of its food chain
definition of biomass
biomass is amount of living or recently dead biological matter in an area. biomass is transferred from each trophic level to the level above it on the food chain.
producers transfer how much percent of incident light energy used for photosynthesis to produce biomass
1 percent
how much percentage of biomass from each trophic level is transferred to the level above it
10 percent
what factors cause the loss of biomass moving up the food chain
- used in life processes such as respiration
- not all the matter is eaten or digested some is egested as waste products
- some absorbed material is lost as waste eg water snd urea in urine
- energy is used in movement and to keep animals warm
- large mounts of gluocse are used in respiration
defnitions of terms in organising an ecosystem
biomass- amount of living or recently dead biological matter in an area. biomass is transferred from each trophic level to the level above it in the food chain,
food chain- shows feeding relationships within a community
food webs- organisms usually have more complex feeding relationships with more than one predator or more than one food source
predator- consumer that eats and kills other animals
-prey- eaten by predators
trophic level- trophic level of an organism is the number of steps it is from the start of the food chain.
a number of factors affect the rate of decomposition LIST And explain them:
temperature-chemical reactions work faster in warmer conditions. decomposition takes place faster in warmer conditions because enzymes work faster in higher temperature but temperature must not be too hot because then enzymes could denature and decomposers could die
water levels: the chemical reactions for decay require water. water also makes food easier to digest.
availability of oxygen- decomposers carry out aerobic respiration so requires good oxygen supply compost bins may have holes to allow oxygen to enter. gardeners may use forks to mix compost regularly
when biological material decays, compost is produced
what is used by gardners for
its used by gardeners and farmers as a natural fertiliser
to do this- they have to provide optimum conditions for decay, if more oxygen is available, they respire aerobically producing heat. the increased temperature increases the rate of decay so the compost is made quicker.
in the absence of oxygen, decomposers carry out anaerobic decay which produces methane’
the methane can be burnt as fuel- known as biogas
what are biogas generators used to produce
methane- require a temperature of 30 degrees so the microorganisms keep respiring it needs to be used immediately so cannot be stored as liquid.
what is a producer
green plant or algae synthesises complex molecules, and makes it own food by photosynthesis
what is a food chain
represents feeding relationships within a community
what is a consumer
organism that eats other organisms for food
what is a herbivore
organism that only eats producers (plants or algae)
what is a predator
predators are consumers that kill and eat other animals
what is a prey organism
organisms that are killed and eaten by other organisms.
what is an apex predator
carnivores without any predators
what proportion of biomass is transferred from each trophic level to the one above
approximately 10 percent
why is biomass lost between trophic levels (answer from spec)
not all matter ingested is absorbed some is egested as faeces
some absorbed material is lost as waste sich as carbon dioxide and water in respiration and water and urea in urine.
large amounts of glucose are used in respiration
energy lost due to movement
spec points about tranfer of biomass
Producers are mostly plants and algae which transfer about 1% of the
incident energy from light for photosynthesis.
Only approximately 10% of the biomass from each trophic level is
transferred to the level above it.
Losses of biomass are due to:
• not all the ingested material is absorbed, some is egested as faeces
• some absorbed material is lost as waste, such as carbon dioxide and
water in respiration and water and urea in urine.
what is the carbon cycle
process that retruns carbon from organisms to the atmosphere as carbon dioxide which can be used by plants
what is the water cycle
process that provides fresh water for plants and animals on land before draining into seas and rivers
what is a decomposer
organism that breaks down dead plant or animal matter
waste products and dead remains are broken down by decomposers.
decomposers are extremely important as they cycle materials through an ecosystem.
as well as returning carbon to the atmosphere as co2, they also release mineral ions in the soil.
what is the role of decomposition
returns carbon to the atmosphere and mineral ions to the soil from dead matter.
what factors affect rate of decay by decomposers
oxygen levels, moisture levels temperature and ph
what does anaerobic decay produce
methane
how can methane gas be used
can be burnt and used as a fuel biogas
what do trophic levels tell us
organisms position on a food chain
why is dry biomass more useful than wet biomass
because the moisture content of organisms canvary widely and produce inaccurate results
only 1 percent of light energy that falls on producers is absorbed and used for
photosynthesis to produce biomass
approximately 10 percent of biomass from each trophic level is transferred
to the level above it
efficiency of biomass
gain in biomass/ total biomass intake
what is meant by food security
having sufficient food to feed the population
what factors affect food security
1) increasing birth rates means more food is required
2) new pests and pathogens can destroy crops
3) conflicts in countries can affect availability of food and water
4) climate change can affect food production for example no rains causing crops to fail
5) changing diets in developing countries mean food resources which are already in low amounts become even more scarce as demand for them increases.
Biotic factors
biotic factors are living factors that can affect a community
availability of food-more food means organism can breed more successfully and therefore population can increase
competition- if one species is better adapted to the environment than another, then it will outcompete it until numbers of the lessdapated species are insufficcient to breed
new pathogen when a new pathogen arises, population does not have resistance so can be wiped out quickly
new predators- compete with existing predators cause prey population to fall
abiotic factors non living factors that can affect a community
light intensity- light is required for photosynthesis, the rate of photsynthesis affects the rate at which the plant grows plants can be food sources or shelter for organisms
temperature- affects the rate of photosynthesis
wind intensity and direction- wind affects rate of transpiration transpiration affects the temperature of the plant and the rate of photosynthesis as it transports water and mineral ions to teh leaves
carbon dioxide levels in plants- co2 affects the rate of photosynthesis in plants and also affects the distribution of prganisms as some organisms thrive in high co2 environments
oxygen leves in aquatic animals- most fish need a high concentration of oxygen inorder to survive
oxygen levels vary in water unlike in air
moisture levels- both plants and animals need water inorder to survive
soil ph and minerals
