b4 - community level systems

what is an ecosystem

all living organisms and physical conditions in an area

what is a habitat

the area in which organisms live in

what is a community

the organisms that live in an ecosystem

what is a population

the total number of organisms of each species

what are producers

organisms that create their own food through photosynthesis

what are consumers

organisms that eat other organisms for energy

what are decomposers

consumers that feed on dead or decaying material

what is each step of a food chain called

a trophic level

what is a prey

an organism eaten by another organism

what is a predator

an organism that eats another organism

what is a herbivore

a consumer that only eats plants - primary consumer

what is a carnivore

a consumer that only eats other animals - secondary consumers

what is an apex predator

a tertiary consumer that is a prey to none

what are biotic factors (3)

living factors - competition for food, mates, space

what are abiotic factors (4)

non living factors - light intensity, moisture level, soil ph, temperature

what do plants need to survive (5)

light, space, water, carbon dioxide, minerals

what do animals need to survive (5)

space, food, water, mates, shelter

what is interdependance

how different organisms depend on eachother in a community

what is predation

relationship between a predator and prey

what is a mutualistic relationship

when both organisms benefit from the relationship

what is a parasitic relationship

when only one organism benefits from the relationship - host suffers and the parasite benefits

why is all the energy from the sun not transferred to chemical stores in plants (3)

some reflected - only 1% converted, limited by temperature or water availability, energy lost in respiration

what ways are biomass lost between animals (5)

respiration, movement, not all eaten, egestion, excretion

what is egestion

material that cannot be digested is removed from the body

what is excretion

waste products after digestion are removed from the body

what is the efficiency of biomass transfer formula

( biomass available after transfer / biomass available before transfer ) x 100

what percentage of the atmosphere is nitrogen

80%

what do organisms use nitrogen for

making DNA and proteins when it is in nitrate form

explain the nitrogen cycle (8)

1. nitrogen exists as nitrates dissolved in water in soil

2. the solution is taken up by roots and nitrates are used to make proteins

3. nitrogen compounds are passed onto animals when plant is eaten

4. nitrogen enters soil again through excretion

5. when the animal dies, compounds are broken down by decomposers and released into the soil as ammonia

6. nitrifying bacteria converts ammonia back into nitrates in the soil

7. denitrifying bacteria sometimes releases nitrogen into the air

8. nitrogen-fixing bacteria in legumes combine nitrogen and oxygen in the air to form nitrates

key feature of denitrifying bacteria

they are anaerobic so perform bestin water-logged soil

key feature of nitrifying and nitrogen-fixing bacteria

they are aerobic so do well in warm environments with lots of oxygen

what are the steps of the water cycle (6)

evaporation / transpiration, condensation, cooling, precipitation, percolation

what is the difference between interspecific and intraspecific

interspecific - competition between different species

intraspecific - competition within a species

what does repeatable mean

you can repeat the experiment and get the same results

what does reproducible mean

someone else can perform the experiment and achieve the same results

what is the carbon cycle

the process in which carbon is cycled through the atmosphere, animals, plants and the earth

explain the carbon cycle (5)

1. carbon dioxide is removed from the atmosphere through photosynthesis and stored in plants as glucose

2. when animals eat plants, the carbon is transferred and used to produce fats and proteins

3. when organisms respire, carbon in food is converted into chemical stores and released as carbon dioxide

4. when organisms die they are broken down by decomposers which release it as carbon dioxide

5. when fossil fuels are combusted, carbon stored in it is released into the atmosphere as carbon dioxide

what is glucose

a simple starch used to make complex carbohydrates allowing growth

how do atmospheric carbon dioxide levels vary

carbon dioxide is only removed during the daytime as light is needed for photosynthesis

deforestation and combusting fossil fuels increases the release of carbon dioxide

what are decomposers

microorganisms that decay material at a microscopic level into nutrients that can be recycled (chemical)

what are detritivores

small animals that break down material into small pieces creating a larger surface area for decomposers to work on (physical)

what are examples of detritivores

earthworm - leaves

woodlouse - wood

maggots - animals

how do decomposers release material (3)

1. they release enzymes which break down substances in the organic matter

2. they absorb the soluble nutrients into their body for growth and an energy store

3. some nutrients are released into the soil

what factors increase the rate of decomposition

warm temperatures

moist environments

aerobic conditions