B2 Unit 2 - Organisms in the environment

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What is the equation for photosynthesis?
carbon dioxide + water ---( + light energy)----> glucose + oxygen
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What can photosynthesis be carried out by?
plants and algae
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What absorbs light energy from the sun?
Chlorophyll in the chloroplast
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What is the process of photosynthesis?
1) Carbon dioxide is taken in by the leaves and absorbed by the roots 2) the chlorophyll traps the light energy 3) this energy is used to convert the carbon dioxide into glucose
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What is oxygen released as?
a by-product of photosynthesis
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What is some of the glucose converted to?
insoluble starch for storage
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what substance is used to test for starch?
iodine
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where does the energy for photosynthesis come from?
the sun
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why would a lack of light slow down the rate of photosynthesis?
it provides the energy for the process
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why would the cold air slow down the rate of photosynthesis?
Enzymes do not work effectively in the cold
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what do we call things that slow down the rate of photosynthesis?
limiting factors
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what conditions does a plant need to be able to grow best?
enough light, carbon dioxide and water and are keot at a suitable temperature
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what is the independent variable?
the one being tested eg. concentration of CO2
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what is the dependent variable?
the one you measure eg. volume of oxygen produced
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why would the line on a graph increase to a certain point and then drop suddenly?
enzymes stop working and are destryed at a high temperature and the reaction stops completely
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what can the glucose in photosynthesis be used for?
- converted into soluble starch for storage - used for respiration - converted into fats and oils for storage - used to produce cellulose to strengthen cell walls - used to produce proteins
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what kind of ions do plants and algae need a supply of?
mineral ions eg. nitrate ions to produce protein
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where are nitrate ions absorbed from by plants?
the soil
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where are nitrate ions absorbed from for algae?
the water they live in
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how do plant growers try and give their plants the best conditions?
by controlling the environment
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what structures can be built to grow plants in an enclosed space?
greenhouses and polytunnels
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what factors have to be controlled in a greenhouse to improve plant growth?
temperature, light intensity, carbon dioxide levels
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what do living organisms form?
communities
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what can the relationships between communities be influenced by?
external factors
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what may affect ehe distribution of of organisms?
physical factors
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why is temperature a physical factor that may affect distribution?
eg. arctic plants are small which limits the number of plant eaters that can survive in the area
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why is the availability of nutrients a physical factor that may affect distribution?
most plants struggle to grow when mineral ions are in short supply and few animals will survive there
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whiy is the amount of light a physical factor that may affect distribution?
few plants live on the forest floor as the light is blocked out by the trees. shaded plants often have broader leaves or more chlorophyll
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why is the availability of water a physical factor that may affect distribution?
few will survive in the desert as there is little water there. when it does rain, plants grow, flower and seed very quickly to provide food for animals
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why is availability of oxygen a physical factor that may affect distribution?
water animals can be affected by lack of O2. some invertabrates can live with low O2 levels but most fish need high levels of oxygen dissolved in the water
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why is the availability of oxygen a physical factor that may affect distribution?
it will affect plant growth and consequently food for the animals
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what can quanative data be used to describe?
how physical factors might be affecting the distribution of organisms in a particular habitat
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how can quantative data be obtained?
random quantative sampling using a quadrat, sampling along a transect
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what is a quadrat?
a square frame made of metal or wood which may be subdivided into a grid
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what can quadrats be used for?
to estimate the number of (for example) the amount of daisies in the field
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why is sample size important?
in a large field random quadrats must be placed to ensure the sample is representative of the whole field
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what is an example usually given as?
mean per square metre
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is a transect random?
no
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how is a transect marked out?
a line is marked out between two points eg. from the top of a rocky shore down to the sea. a quadrat can be placed along the line every 5 metres and the organisms counted.
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what could also be measured at each quadrat of a transect?
physical factors
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why can investigstions about the distribution of organsims be difficult?
they are often done over a long period of time and not all variables can be controlled
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why is the time of day a controlled variable?
the investigation must be done at the same time of day even if it is two months later if possible.
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what does it mean if a measurement is repeatable?
the original experimenter repeats the investigation using the same method and equipment and obtains the same results
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what does it mean if the experiment is reproducible?
the investigation is repeated by another person or by using different techniques or equipment and obtains the same results
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why is sample size an important factor in order to get valid, repeatable and reproducible results?
if the sample is too small it may not be representative. the larger the sample size the more we can trust we can have in the data generated.
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Other cards in this set

Card 2

Front

What can photosynthesis be carried out by?

Back

plants and algae

Card 3

Front

What absorbs light energy from the sun?

Back

Preview of the front of card 3

Card 4

Front

What is the process of photosynthesis?

Back

Preview of the front of card 4

Card 5

Front

What is oxygen released as?

Back

Preview of the front of card 5
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Comments

Swallowtail

A good set of cards on photosynthesis, limiting factors and plant growth. This topic is common to most GCSE Biology specifications. Use these alongside a set of revision notes and a quiz for a complete package.

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