B4 OCR GATEWAY GCSE

identify some abiotic components of an ecosystem

temperature, light intensity, ph of the environment, moisture content of the soil

What is abiotic?

non living chemical and physical factors

What is a biotic factor?

living components that affect the population of another organism or the environment

also is the interaction between living organisms

What is an ecosystem?

made up pf all the living organisms and physical conditions in an area

identify some biotic components of an ecosystem

plants, animals, decomposers.

How does light intensity affect communities

- light is required for photosynthesis

- the greater the light availability the greater success of a plant

- plants evolve to grow successfully in different light intensities

- example, in areas of low light there are often plants with larger leaves.

How does temperature affect communities

- temperature has it greatest effect on the enzymes that control metabolic reactions

- plants develop more rapidly in warmer temperatures as their metabolism will be faster

How does moisture level affect communities?

- for most plant and animal species, a lack of water leads to death

- a lack of water causes most plants to wilt because water is required to keep their cells turgid (turgid refers to cells or tissues that are swollen from water upake), which keeps plants upright.

- water is also required for photosynthesis

How does soil pH affect communities?

-the pH in soil can affect the biological activity in soil, and the availability of certain minerals

- some plant species grow better is acidic soils (below pH7),such as ferns whereas others grow better in alkaline soils (above pH7) such as cucumbers and cauliflower.

What do organisms use nitrogen to make

DNA, proteins

What do organisms use carbon to make

carb, fats, proteins, DNA

identify nutrients needed to be recycled in ecosystems

carbon, nitrogen, water

what is the importance of decomposition to the recycling of substances in an ecosystem

when decomposers are broken down in the soil, the nutrients go down in the soil the roots of the plants uses it in the production of their food make the nutrients available again

they recycle nutrients

recycle carbon returning it back to the atmosphere as carbon dioxide

recycle nitrogen returning it back to the nitrogen cycle in the form of ammonia

identify two decomposers

What are detritus

bacteria + fungi

Dead organic matter

What are some examples of detritivore and what material they break down

earthworm= leaves

woodlouse= wood

maggot= animal material

What are detritivores and what do they do

detritivores eat decaying matter and animal faeces (detritus)

small animals, they speed up decomposition by breaking down organic matter into very small pieces this creates a large surface area for decomposers to work on

How do decomposers release nutrients

Bacteria and fungi release enzymes which break down substances into organic matter.

They can then absorb the soluble nutrients into their bodies and use them for growth and as an energy store.

Many of the bacteria and fungi can be eaten by other organisms resulting in the nutrients being passed on. Some nutrients are released directly into the soil or the environment

Describe the nitrogen cycle

-nitrogen in the air is converted to nitrates by nitrogen fixing bacteria

- the water is taken up the roots (containing dissolved nitrates) and the nitrates are used to make proteins

- when the plant is eaten the nitrogen compounds are passed on to an animal

-animals release waste products, both plants and animals die

-nitrogen is in waste product and dead remains

- when the plants and animals die these compounds are broken down and released back into the soil as ammonia

(decomposing bacteria converts nitrogen into ammonia)

-nitrifying bacteria converts ammonia to nitrates

-nitrates is absorbed by the plants and the cycle continues

-some bacteria (denitrifying bacteria) breaks down nitrates back to nitrogen gas which returns to the air

What are nitrogen fixing bacteria?

convert nitrogen in the air to nitrates in the soil

What is the role of nitrogen fixing bacteria?

nitrogen fixing bacteria converts nitrogen into nitrates

what is the role of nitrifying bacteria

converts ammonia into nitrates

What is dentrification?

nitrates are broken down by denitrifying bacteria into nitrogen gas

describe the effect of temperature on the rate of decomposition

high temp prevent decomposition- destroy enzymes and proteins killing the micro organisms resposible for decomposition

low temp slow the rate of decomposition- slow the rate of reaction of enzymes prevent growth and reproduction of the micro organisms

explain why high temp prevent decomposition

high temp prevents decomposition because it destroys enzymes and proteins, killing the micro organisms responsible for decomposition

explain why low temp slow the rate of decomposition

low temp slow the rate of decomposition because it slows the rate of reaction of enzymes and will prevent growth and reproduction of micro organisms

describe the effect of oxygen availability on decomposition

lack of oxygen will slow or prevent decomposition

explain the effect of oxygen availability on decomposition

oxygen is needed for aerobic respiration so without oxygen micro organisms will die however some bacteria respire anaerobically

describe the effect of water content on decomposition

lack of water will slow or prevent decay

explain the effect of water content on decomposition

water is needed for transport and to support reactions inside micro organisms

decomposers need water to digest their food without water the micro organisms will die

What is the carbon cycle?

-carbon enters the atmosphere as carbon dioxide from respiration and combustion

-carbon dioxide is absorbed by producers to make glucose in photosynthesis

-plants respire, some of the carbon is released back into the atmosphere as carbon dioxide

-animals feed on the plant passing the carbon compound along the food chain

-animals respire so some of the carbon is released into the atmosphere as carbon dioxide

-the animals release waste products and plants eventually die

- decomposers break down the dead organisms and return the carbon in their body to the atmosphere as carbon dioxide

-in some conditions, decomposition is blocked

-if this happens the carbon in the dead remains can be converted to fossil fuels for combustion

What is the water cycle?

percolation: water falls down onto the ground water trickles through the soils and rocks

.plant absorb it leads to transpiration (the loss of water vapour from plants to the air )

surface run off into the ocean this leads to evaporation: heat from the sun heats the water(ocean) changing it from liquid to water vapour

Condensation: a moist air rises it cools. Water vapour condenses back into liquid water droplets producing clouds

as water droplets in clouds get heavier they fall as rain, snow, hail

what releases carbon dioxide into the atmosphere

respiration: all living organisms respire

decomposition

combustion

burning fossil fuels: fossil fuels are a store of carbon, when they burn this trapped carbon is released

What removes carbon from the atmosphere?

photosynthesis

what are abiotic factors which affect animal populations

water

oxygen

temperature

difference between food chain and a food web

food chain= shows the transfer of biomass from one organism to the other (transfers energy)

food web= a collection of food chains which are interconnected and interdependent

Define the term species

organisms that interbreed and produce fertile offspring

Define the term population

the total number of organisms of each species

Define the term ecosystem

the community of all living things and the habitat they live in

what is a communtiy

the organisms within the ecosystem

what are abiotic factors which affect plant populations

light intensity

temperature

water

identify equipment used to measure abiotic factors in an environment

light intensity= light meter

measure moisture= humidity sensor

measure PH= ph probe

temperature= thermometer

Name the types of biotic factors which affect populations

predation

parasitism

mutualism

competition

what are examples of parasites

tapeworm

fleas

What is paratism?

parasite which lives in or on a host which is harmed

What do animals need to survive?

food

water

space

mates

What do plants need to survive?

Light, space, water, minerals

What is Mutaulism?

both species benefit

what are examples of mutualism

oxpeckers and buffalo bees and flowers

Flowering plants provide bees with nectar and pollen, which will feed their entire colony. Bees provide flowers with the means to reproduce by spreading pollen in the process called pollination

relationship between oxpeckers and buffalos

the oxpeckers eat the parasites on the buffalos making them comfortable mutualistic relationship

what is a producer

An organism that makes its own foodplants

what is a primary consumer

An organism that eats producers/plants

What is a pyramid of biomass?

A representation of the total biomass at each trophic level

What is pyramid of numbers

shows the population at each tropic level. the producer in the food chain is placed at the base, with the next tropic levels placed above

- The bar width represent the number of organism present

The number of organisms in each trophic level is counted and presented in a pyramid of numbers.

Why are not all pyramids of numbers pyramid shaped

- does not take into account the size of the organisms present

how is biomass data collected

- scientist measure the average mass of these organisms and multiply it by the number of organisms present to calculate the total biomass at each tropic level

How to draw a pyramid of biomass

- find a midpoint on a graph or draw a line down the middle of the graph

- label the x-axis biomass and the units of the data you are using

- decide on a suitable scale that will allow you to draw each of the bars (decide what the little squares will be and then the medium squares, remember there are 5 little boxes in 1 medium box so for example if your little box is 20g/m3 your medium box will be 100)

- half the biomass so equal amount of both sides e.g. biomass of 880 440 would be at the other side of the line and 440 will be on the other side of the line

- draw on the rest of the trophic levels in order from bottom up. the bars should all be touching and each bar should be the same height

- label each trophic level

How is biomass lost?

some biomass is used in respiration

some biomass is used to provide energy for movement

some biomass is not eaten

biomass is lost in excretion

what is the equation to work out the efficiency of biomass

biomass available after transfer/ biomass available before the transfer X 100

biomass transferred to the next level/ biomass that was available at the previous level

Why are the number of trophic levels limited?

at each stage of a food chain the amount of energy transferred becomes less. not enough energy can be transferred to sustain life processes

there's not enough energy available

What is a habitat?

area in which organisms live

effect of light intensity on environment

the greater the light availability the greater the success of the plant

what is special about plants that grow in shadier areas

they've evolved to grow successfully in lower light intensity.

have large surface area in the leaves to allow them to trap the maximum amount of light that's present

effect of temperature on environment

temp affects the enzymes that control metabolic reactions

warmer temp aid rapid development in plants as their metabolic reactions happen faster

effect of moisture on environment

lack of water lead to death the plants will wilt as the cells are no longer turgid

effect of PH on environment

affects biological in soil and mineral availability

certain plants are adapted to grow in either acid and alkali conditions

which plants grow in acidic and alkaline conditions

acidic: ferns

alkaline: cucumber

4 things animals compete for

water, food, breeding partners, shelter

4 things plant compete for

water , light, minerals, space

What are saprophytes?

small animals- speed up decomposition by breaking organic material up into very small pieces

3 ways to increase the rate of decay

warm temp

moist --> water conditions

oxygen --> aerobic condition

how to calculate the rate of decay

change in mass/ time (day)

What are producers

organism that make their own food by photosynthesis they include all plants and algae

What are consumers?

Organisms that eat other organisms

What is the relationship between legumes and nitrogen fixing bacteria

some plants such as peas and beans (legumes) form a mutualistic relationship with nitrogen fixing bacteria

these bacteria live in their roots and combine nitrogen from the air with oxygen to form nitrates

these are then used by the plant

What are decomposers and 2 examples example?

micro organisms(bacteria and fungi) , they break down dead or decaying matter as their food source

gain their energy by feeding on dead or decaying material

What is the impact of volcanic activity on the carbon cycle

Volcanoes emit carbon dioxide in two ways: during eruptions and through underground magma

What is biomass and dry mass?

How would you get the biomass

The dry mass of all of the living organisms in an area

the mass of the organism with the water removed

take an organism and dry it what's left of it is the dry mass

What is egestion?

removal of undigested waste

What is excretion?

the process of removing waste from the body