B4

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  • Created by: hols_
  • Created on: 01-10-15 17:02
The xylem and phloem form a....
Continuous system of tubes from roots to leaves called vascular bundles.
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Xylem transports?
Water and soluble mineral salts from the roots to the leaves (transpiration).
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Phloem allows the movement of?
Food substances around the plant (translocation), up and down stems to growing tissues and storage tissues.
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What are xylem vessels made from?
Dead plant cells and have hollow lumen, the cellulose cell walls are thickened with a waterproof substance.
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Phloem cells are...
Long columns of living cells.
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Why do root hairs have an enormous surface area?
For absorbing water and to increase the plant's ability to take up water.
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Transpiration is?
The diffusion and evaporation of water from inside a leaf. It causes water to be moved up xylem vessels and provides plants with water for cooling, photosynthesis & support, & brings minerals to the plant.
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The rate of transpiration is affected by?
Light, more light increases the rate of PS & transpiration, air movement, temperature, increases rate of PS, low humidity.
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Healthy plants need to balance the amount of water they take in and lose:
Water is absorbed by the plant by the root hair cells, which have a large surface area, the water then diffuses through plant up to the leaves, when it reaches leaves - can be lost by transpiration (evaporation).
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Two adaptations that reduce the rate that water is lost from leaves:
Waxy Cuticle on the surface of the leaf
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Why are essential minerals needed?
To keep plants healthy and growing properly. Plants absorb dissolved minerals in the soil through their roots.
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Why do farmers use fertilisers?
Even though minerals are naturally present in the soil, it is in low concentrations - fertilisers are needed to ensure plants get what they need to grow.
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Each mineral is needed for a different purpose...
Nitrates - to make proteins for cell growth, potassium compounds - for respiration and photosynthesis, phosphates - for respiration & cell growth, magnesium - for photosynthesis.
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What will happen if one or more of the essential minerals is deficient from the soil?
The growth of the plant will be affected.
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What is decay?
A process involving the breakdown of complex substances into simpler ones by microorganisms. The key factors in the process of decay are microbes, temp., oxygen and moisture.
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The rate of decay is affected by:
Changing temp. - microorganisms responsible for decay work best at around 40 degrees, amount of O2 - microorganisms' rate of activity increases as the amount of O2 in the air increases, Amount of water - prefer moist conditions.
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Earthworms, woodlice and maggots are known as detritivores, they feed on:
Dead organisms, decaying material produced by living organisms.
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How do detritivores speed up the processes of decay?
By breaking down detritus into small particles which have a large surface area. This makes it easier for decomposers to feed on.
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Microorganisms are used to break down?
Human waste in sewage treatment works, plant waste in compost heaps.
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Why can materials that can decay be recycled?
Because decaying materials release minerals back into the soil. Plants use these minerals to grow.
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Fungi are saprophytes...
They feed on dead organic material secreting enzymes onto the material and then absorbing the digested products. They are essential for decay.
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Food can be preserved by?
Removing the oxygen, warmth or moisture that the microorganisms need in order to grow and survive.
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Food can be:
Sealed inside sterile cans - this prevents entry of decomposers, kept at low temps. slows down reproduction of bacteria, pickled in vinegar - acid kills decomposers, preserved in sugar - removes water by osmosis, dried - reduces water.
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Intensive farming methods aim to?
Produce as much food as possible from the available land, plants and animals. These methods use chemicals like pesticides to kill pests that damage crops or livestock so more food is produced.
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Chemical methods farmers use?
Pesticides - used to kill pests, insecticides - used to kill insect pests, fungicides - used to kill fungi, herbicides - used to kill weeds which compete with crops for water & nutrients.
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Why does care need to be taken with pesticides?
They can harm other organisms, they can build up in food chains, harming animals at the top, some pesticides are persistent - they stay in the food chain for years.
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Intensive farming can?
Increase productivity by keeping animals in carefully controlled environments where their temp. is controlled and movement very limited.
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Examples of intensive farming:
Battery farming, glasshouses, hydroponics and fish farming.
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How does keeping animals warmed and penned up inside so they cannot move improve the energy transfer?
By reducing the amount of energy lost at each stage of the food chain. But it is very cruel and animals suffer with health problems as a result.
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Organic farming methods aim to?
Produce food without the use of chemicals, so minimising the impact on the environment.
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Organic farming methods include:
Using natural fertilisers like animal manure or compost, growing nitrogen-fixing crops, rotating crops to maintain soil fertility, avoiding chemical pesticides by weeding, varying seed planting times to discourage pests.
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Advantages of Organic farming:
Food crops and the environment are not contaminated with artificial fertilisers or pesticides, soil erosion is limited & fertility is maintained through the use of organic fertilisers, biodiversity is promoted because hedgerows are conserved.
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Disadvantages of Organic farming:
It is less efficient because some crops are lost to pests & diseases, It is expensive, more space is needed, organic fertilisers take time to rot and they don't supply a specific balance of minerals.
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What is hydroponics?
A way of growing plants without using soil, the plants are grown with their roots in a solution containing the minerals needed for growth. Most useful for greenhouses or areas which have very thin or barren soil.
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Advantages of hydroponics:
The mineral levels added to the solution can be carefully controlled & adjusted to the type of plant. There is a reduced risk of the plants becoming diseased.
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Disadvantages of hydroponics:
The plants have to be supported as they have no anchorage for their roots & expensive fertilisers are needed to supply the plant with minerals.
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What is biological control?
Farmers introducing a predator instead of using a pesticide, to reduce the numbers of pests.
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It is important to remember whilst using biological control...
The effect on the rest of the organisms in the food chain or web must be considered.
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Advantages of biological control:
Predator selected only usually attacks the pest, once introduce, the predator can have an impact over many years, the pest cannot become resistant to the predator, no need for chemical pesticides.
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Disadvantages of biological control:
The pest is reduced but is not completely removed, the predator may not eat the pest or it may even eat useful species, the predator may reproduce out of control, the predator may leave the area.
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Other cards in this set

Card 2

Front

Xylem transports?

Back

Water and soluble mineral salts from the roots to the leaves (transpiration).

Card 3

Front

Phloem allows the movement of?

Back

Preview of the front of card 3

Card 4

Front

What are xylem vessels made from?

Back

Preview of the front of card 4

Card 5

Front

Phloem cells are...

Back

Preview of the front of card 5
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