Notesale: Turn your study into money

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Biology – Unit 2: Section 5 – Resources from Plants
Plant cell structure and plant stems
Organelles
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Cell wall
o Rigid that surround plant cells made by carbohydrate cellulose
o Supports the plant
Middle lamella
o Outer most layer of the cell
o Acts as an adhesive as it sticks the plant cells together which gives the plant stability
Plasmodesmata
o Channels in the cell walls which links the cells together
o Allows transport of substances and communication between cells
Pits
o Areas in the cell wall where the wall is very thin, this occurs in the same place on both of the
neighbouring cells
o Allows transport of substances between cells
Chloroplast
o Small, flattened structure with a double membrane
o Membranes inside called thylakoid membranes these are stacked up in some areas to form
grana, grana are linked together by lamellae which are thin, flat pieces of thylakoid
membrane
o Where photosynthesis occurs, some happens in the grana and some in the stroma (a thick
fluid found in chloroplasts)
Amyloplast
o Small organelles contained by a membrane, they contain starch granules
o Storage of starch grains and converting starch back to glucose when required
Vacuole and Tonoplast
o Vacuole is a compartment surrounded by a membrane called the tonoplast
o Contains the cell sap which is made up of water, enzymes, minerals and waste products
o Keep cells turgid which stops plants wilting
o Involved in the breakdown and isolation of unwanted chemicals in the call
o Tonoplast controls what enters and leaves the vacuole

Plant stems
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Xylem vessels
o Transport water and mineral ions up the plant and provide support
o Long, lube-like formed from dead cells joined together, the tubes are found together in
bundles
o They have a hollow lumen, no cytoplasm and have no end walls
o Walls are thickened with a woody substance called lignin which supports the plants
o Water and mineral ions move in and out of the vessel through pits in the walls where there is
no lignin
o Found mostly in the stem where that group together with other vessels to form vascular
bundles
Sclerenchyma fibres

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Function is to provide support
Made of bundles of dead cells
Hollow lumen and end walls
Cell walls are thickened with lignin and they have more cellulose than other plant cells
Along with the xylem vessels they found the vascular bundle

Practise questions
1
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3
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5
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a
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Identify the structures labelled X and Y
X is sclerenchyma fibres and Y is xylem vessels
b
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It also contains lignin in the walls, this helps to support the plant,
mineral ions and water which is transported by the xylem vessels have to travel through pits
in the wall where there is no lignin
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The sclerenchyma fibres are also made of dead cells joined end to end, again they have a
hollow lumen and end walls, cells walls ware thickened with lignin
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The xylem vessels and sclerenchyma fibres come together to from vascular bundles
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It has a coiled structure
which makes it compact so it was good for storage
 Amylopectin is a long, branched chain of alpha-glucose
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2
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2
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4
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6
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2
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Name the two polysaccharides that starch is made up from
Amylose and amylopectin
Compare the structure and function of starch and cellulose
Starch is made up from amylose and amylopectin, these are made from alpha-glucose
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Cellulose is
made up of beta-glucose and the chain are straight, around 50-80 of these chains join together with
hydrogen bonds to form microfibrils
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5
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Describe the arrangement of cellulose microfibrils in a plant cell wall, and explain how this
relates to the properties of plant fibres
The cellulose microfibrils are formed in a net-like arrangement meaning they give plant fibres
strength
b
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Their results are
displayed in the table on the right
a
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They
should add weights slowly until the fibres break and then record their maximum limit
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Variables such as temperature and humidity
must be kept the same to ensure the data is valid and safety measure such as goggles and
leaving an area clear for when the weight break through the fibres
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Based on information, which fibre would be more suitable to make a climbing rope? Explain
your answer
Fibre B, this is because it took the most weight before breaking showing it is the strongest
fibre, making it more safe to use for a climbing rope

Sustainability and plant materials
Sustainable practices don’t deplete resources
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Sustainability is about using resources that meets the present generations needs without making it
hard or difficult for future generations
To make products sustainably you have to use renewable resources
Renewable sources can be used but don’t run out e
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plants
In unsustainable practices the resources would eventually run out e
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fossil fuels

Plant fibres and starch contribute to sustainability
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Plant fibres
o Ropes and fibres can be made of plant fibres or plastic (oil) – plastic is stronger
o Using plant fibres are more sustainable as less fossil fuels are being used and plants can be
regrown
o Products made of plant fibres are biodegradable
o Plants are easier to grow and process rather than the expense of extracting fossil fuels, this is
better in developing countries as less expertise is needed and its cheaper
Starch
o Found in all plants – loads in potatoes and corn
o Plastics can be made of oil or plant based materials like starch – bioplastics
o Using starch is more sustainable as less fossil fuels are used and crops can be regrown
o Vehicle fuel can also be made of oil or starch e
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bioethanol

Waters and inorganic ions
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1
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3
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Water and inorganic ions are absorbed through the root and travel through the xylem
Is the plant doesn’t have the water or ion it will show deficiency symptoms e
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stunted growth
Water
 Needed for photosynthesis
 Maintains structural rigidity, transport materials and regulate temperature
Magnesium ions
 Needed for the production of chlorophyll for photosynthesis
Nitrate ions
 Needed for the production of DNA, proteins and chlorophyll
 Required for growth, fruit production and seed production
Calcium ions
 Important components in the cell wall
 Needed for growth

Plant mineral deficiencies
1
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3
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5
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g
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2
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4
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Made a solution from the chosen
ion and have it in three different concentrations, low, medium and high
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Keep all other variables such as temperature, sunlight and water the same
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Phase one
 Testing the drug on a small healthy group of individuals
 Done to find a safe dosage, side effects and how the body reacts
2
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Phase three
 Drug is compared to existing treatments
 Involved testing the drug on hundreds or thousands of patients
 They are split into two groups, one receives the new treatment and the other receives the
existing treatment
 Allows scientists to see if the new treatment is bigger

Placebos and double blind study designs
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Placebos
o Usually used in phase two
o One is given the substance and the other is given a placebo (inactive substance that looks the
same but doesn’t actually do anything
o Some show a placebo effect – show improvements because they believe they are getting the
treatment
o Allows scientists to see if the drug actually works (if it improves patients more than the
placebo does)
Double blind trial study
o Usually in phase two and three, neither the doctor nor patients know who’s been given the
drugs and who’s been given the placebo or old drug
o Reduces bias as the attitudes of the patients and doctors cant affect the results

Plants and antimicrobial properties
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Some plants have antimicrobial properties – this kill or inhibit the growth of organisms
1
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Plants should be the same
size so the amount of extract is the same
2
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4
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6
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8
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Evenly spread a sample of bacteria onto an agar plate
Dip discs of absorbent paper in the extracts, the absorbent paper has to be the same size
Do a control disc that is only soaked in ethanol
Place the discs on the agar plate and make sure they are evenly spread
Incubate the plate to allow the bacteria to grow
Where the bacteria can’t grow there’ll be a clear patch in the lawn of bacteria, this is the
inhibition zone
The size of the zone tells you how well the antimicrobial plant is working and how effective it is

Practise questions
1
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3
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5
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Too much of the drug poisoned the patient but too little
had no effect, therefore using trial and error he managed to find the correct quantity that had an
effect but wasn’t dangerous
Plant extracts have been used to relieve symptoms of many diseases
a
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Then you need to drain the solution and using a disc
of absorbent paper take a sample of the extract, this should be placed on a sample of
bacteria spread throughout an agar plate
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Incubate the plate to allow the bacteria to grow and check there is no
inhibition zone around the paper disc
b
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Describe this process
During clinical trials there is three phases of testing, the first phase consists of testing the
new drug on a small sample of patients, this is to check for side effects as well as to decide a
safe dosage and how the body reacts
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During this stage a placebo or
double blind trial may be used so they can see how well the new drug compared to the old
drug or a placebo without bias interference

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