Making Use of Plants Flashcards
What are four examples of how humans use plants?
Clothing, rope, floor coverings and paper
What three properties do plant fibres have that make them useful?
They are long and thin, flexible, and strong
What is extraction of plant fibres also known as?
Retting
How are plant fibres retted mechanically?
By pulling out the fibres using a machine
How are plant fibres retted using chemical and enzyme digestion?
Cellulose is resistant whilst polysaccharides that hold the fibre together can be dissolved
How are plant fibres retted using caustic alkali?
To produce fibre pulps from trees, caustic alkali is needed
How are plant fibres retted using traditional heaps?
Stems are piled in heaps, allowing bacteria and fungi to naturally break down the fibres
What are mats of fibres used to absorb?
Heavy metals and also hydrocarbons from polluted water
What are biocomposites?
Plant fibres that are added to other materials
What is an example of a biocomposite?
Rapeseed fibres mixed with plastic
What are the advantages of biocomposites?
They are strong, renewable, more biodegradable and can be easier and safer to handle than artificial fibres
Plants have developed adaptations that provide ? ? to repel or even kill animals that feed on them
Chemical defences
How can a chemical prevent a plant being eaten?
A chemical that is distasteful or toxic is produced. If the animal takes a bite the taste is offensive and the animal is deterred from feeding further. If its chemical kills the predator the plant will avoid further attacks
How do the tannins in tea prevent insect attack?
They are bitter and ‘gum up’ the mouthparts of aphids
Why are pyrethrum plants so special?
They have no known pests or diseases
What chemicals do pyrethrum plants contain?
Pyrethrins
What are the chemicals in pyrethrum plants used for?
Insecticides, sprays for fruit and flowers, flea treatment and the reduction in tick infestation in cattle
What advantaged do the pyrethrum chemicals have?
They are unstable after spraying and rapidly decompose to harmless residues
What is an alternative to using pyrethrums?
Organic gardeners use chrysanthemums and marigolds as ‘companion’ plants - planted amongst vegetables , the act as a natural insect repellant
Where are toxic compounds sometimes stored in plants?
Hairs on the surfaces of plant leaves
Which two plants are known to be antimicrobial?
Mint and garlic
What does mint produce that is toxic to microbes and insects?
Menthol and carvone
What effect does mint have in humans?
A numbing effect hence it is used in toothpaste
What active ingredient does garlic have?
Allicin
What does allicin do? When is it produced?
Allicin interferes with lipid synthesis and RNA production. It is only produced when the plant is cut or damaged.
What is garlic known to kill? And why is this particularly beneficial?
Its known to kill campylobacter and helicobacter which causes intestinal infections, this is particularly important as some strains are resistant to widely used antibiotics such as penicillin
What does rosemary contain and what is it known to kill?
Rosemary contains volatile oils such as camphor and cincole, its known to kill E.coli
When does the embryo remain dormant until?
Conditions are suitable for restoring growth
How is the seed adapted to ensure protection of the embryo?
The testa is hard and indigestible so the seed doesn’t open until its ready
How is the seed adapted to aid dispersal?
The surrounding ovary develops into fruit which attracts animals that digest and excrete the seed, hopefully somewhere it can grow. Some seeds are easily dispersed because of their design e.g. dandelions. Some also have grips/claws that attach to animals fur
How is the seed adapted to provide nutrition for the new plant?
The endosperm contains lipid, protein and carbohydrate stores for the plant
Seed germination 1: The seed takes in water through?
A small pore in the seed coat
Seed germination 2: Absorbing water triggers?
Metabolic changes in the seed
Seed germination 3: Production of plant growth substances is switched on and ?
These cause the secretion of enzymes that mobilise the stored food reserves
Seed germination 4: Maltose and amylase ?
Break the starch down into glucose, which is converted into sucrose
Seed germination 5: Proteases break down ?
The proteins in to food stores to give amino acids
Seed germination 6: Lipase’s break down?
Stored lipids to give glycerol and fatty acid
Why is starch easy to extract from seeds?
Because it is stored in granules that don’t dissolve in water, but can be washed out
How is starch used in thickening?
When starch granules are heated in water they suddenly swell, absorb water and thicken the liquid. This is called ‘gelatinisation’ and is used in custard and wallpaper paste
What is the stiffening of cloth by starch known as?
SIzing
How is starch stiffened?
A starch mixture is gelatinised then cooled, allowing bonds to form between starch molecules, the addition of water reverses the stiffening. This reversal is called ‘plasticisation’
How is starch used as an absorbent?
If starch is chemically cross linked before its gelatinised then particles are formed which can be dried. When rehydrated these particles can take up large amounts of water
How can starch be transformed into foam?
If pressure is raised at the same time as boiling temperature in gelatinised starch then the starch forms a plastic mass. If the pressure is suddenly released then steam forms and the starch puffs into an expanded structure
What are the advantages of biodiesel?
It produces less sulphur dioxide than diesel and less CO2 when CO2 used by plants grown to produce it are taken into account
What is a brief definition of sustainability?
Sustainability is using materials which can be replaced
Why are oil-based products not considered to be sustainable? (3 things)
1) Burning of fossil fuels releases CO2
2) Oil reserves will run out (they aren’t renewable)
3) Plastics generate non-biodegradable waste
What are the problems associated with biodegradable packaging?
Most bacteria required for degradation requires oxygen so when biodegradable packaging is buried it doesn’t actually decompose. It can also generate methane
