Biology B4

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Finish this sentence: Where a plant or animal lives is its...
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What makes up the 'Community'?
All the animals and plants living in an ecosystem
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Give a common example of an ecosystem
A garden
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What is the population?
The number of a particular plant or animal present in the community.
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Which ecosystems have good biodiversity, and why?
Natural ecosystems have good biodiversity because they have a large variety of plants and animals living there.
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Which ecosystems have poor biodiversity?
Artificial ecosystems such as fish farms have poor biodiversity.
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What can you use to map the distribution of organisms? Explain the process
You would use a transect line. A length of string is layed across an area such as a path or the shore. At regular intervals the organisms in the quadrat(s) can be counted for animals, or percentage cover for plants.
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How can the data you collect from using a transect line be displayed?
By a kite diagram
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What do humans do to artificial ecosystems?
They protect one species only, and remove any other organisms that they would compete with and lower the yield. THIS DOES NOT HAPPEN IN NATURAL ECOSYSTEMS!!
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What can transect lines show?
Zonation in the distribution of organsims
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What factors can cause zonation?
Abiotic factors (not biological), such as trampling near a footpath.
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What do food chains and webs show about plants and animals?
That they are interdependant, meaning they depend on eachother. This is because energy is being transferred from one organism to another.
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What two processes ensure the overall balance of gases?
Photosynthesis and respiration.
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Why are ecosystems mostly self supporting, but never completely?
Because they need the sun as an energy source
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How can population size be estimated?
By scaling up data from small samples
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What is the formula for population size using the capture-recapture method?
population size= (number in first sample x number in second sample) / number in the second sample previously marked.
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What assumptions have to be made when using the capture-recapture method to find population size?
There are no deaths, reproduction and movement of animals in and out of the area, that identical sampling methods are used for the two samples, and that the markings used do not affect the survival of the organism.
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What is the balanced symbol equation for photosynthesis?
6CO2 + 6H20 ---> 6O2 + C6H12O6
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Name four uses that simple sugars such as glucose have
They are used in respiration, releasing energy, converted into cellulose to make cell walls, converted into proteins for growth and repair, and converted into starch, fats and oils for storage.
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Why is starch used for storage and not glucose?
Because it is insoluble and does not move from storage areas. Unlike glucose, it doesn't affect the water concentration of cells and cause osmosis.
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Explain the TWO stage process of photosynthesis
Water is split up by light energy releasing oxygen and hydrogen IONS, Carbon dioxide gas combines with the hydrogen ions producing glucose and water
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What did Greek scienctists believe about plants?
That plants took minerals out of the soil to grow and gain mass.
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What did Van Helmont conclude from his experiment?
He experimented by growing a willow tree, and concluded that plant growth could not be due only to the uptake of soil minerals, it must depend on something else.
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What did Priestley's experiment show?
That plants produced oxygen.
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Describe a modern experiment thats proves the stages of photosyntheis
Using a green algae called Chlorella and an isotope of oxygen 18O, as part of a water molecule.
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What did this experiment show?
It shows that light energy is usd to split water, not carbon dioxide. The water is split up into oxygen gas and hydrogen IONS.
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What 3 things can increase the rate of photosynthesis?
More carbon dioxide, more light and a higher temperature which increases activity of the enzymes.
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When will photosynthesis take place?
During the daytime only, when there is light.
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When do plants respire, and what do they take in and then release?
Plants respire at all times by taking in oxygen and releasing carbon dioxide.
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Why can plant respiration only be noticed at night?
Because the rate of gas exchange in photosynthesis is larger than that of respiration, so you only notice it when photosynthesis is not being carried out.
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Finish this sentence: Since photosynthesis depends on light, temperature and carbon dioxide, a lack of one of these factors will.......
Limit the rate of photosynthesis. These are called limiting factors.
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What is special about cells in green leaves?
There are many different specialised cells
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Name the four layers of a green leaf
Cuticle (wax layer), upper epidermis, palisade layer, spongy mesophyll layer.
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How is the upper epidermis adapted for efficient photosynthesis?
It lacks chloroplasts so it is transparent, so there are no barriers to the entry of light.
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How is the upper palisade layer adapted for efficient photosynthesis?
This layer contains most of the chloroplasts as it will recieve the most light.
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How are the spongy mesophyll cells adapted for efficient photosynthesis?
They are loosley spaced so that diffusion of gases between cells and the outer atmosphere can take place.
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How does the arrangment of mesophyll cells improve efficiency?
It creates a large surface area/volume ratio so that large amounts of gases can enter and exit the cells.
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What makes up the palisade layer?
Palisade cells, green chloroplasts, and vascular bundle(s)
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What makes up the spong mesophyll layer?
spongy mesophyll cells, and airspace.
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What makes up the lower epidermis?
Stoma (pores) and guard cells.
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How are leaves adapted for photosynthesis? (cont. on next card)
They have a large surface area, they are thin so gases can difuse easily and light can get to all cells, they contain chlorophyll and other pigments so they can use light from a broad spectrum,
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They have a network of vascular bundles for support and transport of chemicals such as water and glucose, they have guard cells which control the opening and closing of stomata which regulates the flow of carbon dioxide and oxygen, as well as water.
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Why does having different pigments maximise the use of the sun's energy?
Because each pigment absorbs light on different wavelengths.
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What is diffusion?
Diffusion is the net movement of particles in a gas or liquid from an area of high concentration to an area of low concentration, resulting from the random movement of the particles.
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What does diffusion explain?
It explains how molecules of water, oxygen, and carbon dioxide can enter and leave cells through the cell membrane.
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Explain how carbon dioxide levels are increased in a plant cell through diffusion
If a plant cell is using up carbon dioxide, there is a lower cocentration of it inside the cell, so carbon dioxide will enter by diffusion.
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How are leaves adapted to increase the rate of diffusion of carbon dioxide and oxygen?
They usually have a large surface area, they have specialised openings called stomata which are spaced out, an have gaps between the spongy mesophyll cells.
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How can the rate of diffusion be increased?
A shorter distance for the molecules to travel, a steeper concentration gradient (greater concentration difference between the two areas), a greater surface area for the molecules to diffuse from or to.
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What is osmosis a type of?
It is a type of diffusion.
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What is required for osmosis to take place?
A partially-permeable membrane that allows the passage of water molecules but not large molecules like glucose.
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What is osmosis? Def.
Osmosis is the movement of water across a partially-permeable membrane from an area of high water concentration to an area of low water concenration.
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What do you need to know in order to predict the net movement of water molecules?
You need to know the different concentrations of water inside and outside the cells.
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What effect does the entry of water into a cell have on the walls?
It increases the pressure pushing on the wall, which is rigid and not elastic.
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What pressure supports the cell stopping it and the whole plant from collapsing?
Turgor pressure
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What happens when too much water leaves a cell?
It loses the pressure and therefore the plant wilts.
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Complete this sentence: A plant cell full of water is said to be...
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Complete this sentence: When the cell loses water, the cell contents ______ and become ___________ and the cell is called _______.
When the cell loses water the cell contents SHRINK and become PLASMOLYSED and the cell is called FLACCID.
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How do animal cells react to the loss and gain of water?
They will shrink and collapse when they lose too much water, and swell up when too much water enters.
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Why do animal cells swell and burst when too much water enters (lysis)?
Because they lack a supporting cell wall.
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How do animal cells show crenation?
When they lose too much water, they shrink into a scalloped shape.
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What are Xylem and Phloem made up of?
Specialised plant cells
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What do both tissues have in common?
They are both continuous from the root, through the stem and into the leaf.
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What do Xylem and Phloem cells form?
Vascular bundles in broadleaved plants
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What do Xylem cells do?
They carry water and minerals from the roots to the leaves, and are therefore involved in transpiration
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What do Phloem cells do?
They carry food substances such as sugars up and down stems to growing and storage tissues. This is called translocation.
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What are the Xylem cells called?
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Why are they called vessels?
Because they are dead cells, and lack of living cytoplasm leaves a hollow lumes.
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What makes Xylem cells so strong?
They have extra thickening of lignin.
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How are Phloem cells arranged?
They are arranged in columns and are living cells.
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What is transpiration?
Transpiration is the evaporation and diffusion of water from inside leaves.
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What are root hairs, and how are they adapted?
They are projections from root hair cells, and produce a large surface area for water uptake by osmosis.
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What does transpiration ensure?
It ensures that plants have water for cooling by evaporation, photosynthesis and support from cells' turgor pressure, and for transport of minerals.
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How is the rate of transpiration increased?
By an increase in light intensity, temperature and air movement, and a decrease in humidity.
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How is water loss reduced in a plant leaf?
It has a waxy cuticle covering the outer epidermal cells, and most of the stomata openings are situated on the shaded lower surface.
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What do the spongy mesophyll cells have to make sure photosynthesis is effective?
They are covered with a film of water in which the gases can dissolve. This water can therefore readily escape from the stomata.
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How does an increase in light intensity increase rate of transpiration?
The stomata will open, enabling fast exit and entry of gas.
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How does an increase in temperature increase rate of transpiration?
It causes an increase in the evaporation of water.
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How does a decrease in humidity increase rate of respiration?
It allows more water to evaporate
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How does an increase in air movement increase rate of respiration?
By blowing away air containing a lot of evaporated water.
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How does the stomata reduce water loss?
By having fewer stomata, smaller stomata, and the position and distribution of the stomata, particularly in the lower epidermis.
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What can the guard cells do to reduce water loss?
Change the size of the stomatal openings.
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Name 4 minerals that plants need
Nitrates, phosphates, potassium compounds, magnesium compounds
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What does a plant need nitrates for?
To mkae proteins for cell growth.
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What do plants need phosphates for?
They are involved in respiration and growth.
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What do plants need potassium compounds for?
They are involved in respiration and photosynthesis.
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What do plants need magnesium compounds for?
They are involved in photosynthesis.
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What do plants use nitrogen for?
To produce amino acids, to make different proteins.
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What do plants need phosphorus for?
It is used to make the plant's DNA and cell membranes.
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What do plants need potassium for?
It is used to help enzyme action in photosynthesis and respiration.
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What do plants need magnesium for?
It is used to make chlorophyll, which is essential for photosynthesis.
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What does a lack of nitrates cause?
Poor growth and yellow leaves.
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What does a lack of phosphate cause?
Poor root growth and discoloured leaves.
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What does a lack of potassium cause?
poor flower and root growth and discoloured leaves.
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What does a lack a magnesium cause?
Yellow leaves.
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How are minerals in the soil taken up by plants?
They are taken up by root hair cells by active transport. A system of carriers transport selected minerals across the cell membrane.
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What does active transport require?
energy from respiration
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What does active transport enable the root hairs to do?
Take up minerals that are in low concentrations in the soil, into the root hair cells with a high concentration of minerals.
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Name three examples of a detrivore
Earthworms, maggots and woodlice.
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Why are they called detrivores?
Because they feed on dead and decaying materials (detrius).
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How do detrivores increase the rate of decay?
By breaking up the detrius, which increases surface area, for further microbial breakdown.
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How can the rate of decay be increased?
By increasing temperature, the amount of oxygen, and the amount of water.
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What is the optimum temperature for bacteria? What will it increase?
37 degrees. It will increase rate of respiration.
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What is the optimum temperature for fungi? What will it increase?
25 degrees. It will increase rate of respiration.
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How will increasing the amount of oxygen increase the rate of decay?
Bacteria will use aerobic respiration to grow and reproduce faster.
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How will increasing the amount of water increase the rate of decay?
It will allow for material to be digested and absorbed more efficiently and will increase growth and reproduction of bacteria and fungi.
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Name an example of a fungus that feeds on dea and decaying material.
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What type of digestion do fungi use to digest and absorb food?
They use extracelluar digestion.
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Explain extracelluar digestion
Fungi produce enzymes to digest food outside their cells and then reabsorb simple soluble substances.
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What do food preservation methods reduce?
The rate of decay.
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How does canning reduce rate of decay?
Foods are heated to kill bacteria and then sealed in a vacuum to prevent entry of oxygen and bacteria.
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How will cooling foods slow the rate of decay?
It slows down bacterial and fungal growth and reproduction.
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How does freezing food reduce rate of decay?
It will kill some bacteria and fungi and slow down their growth and reproduction.
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How does drying food reduce rate of decay?
It removes all water and moisture so bacteria cannot feed and grow.
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How does adding salt and sugar decrease rate of decay?
It will kill some bacteria and fungi, as the high osmotic concentration will remove water from them.
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How does adding vinegar decrease rate of decay?
It will produce very acidic conditions, killing most bacteria and fungi.
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Name three different pesticides
insecticides, funicides, and herbicides
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What are the disadvantages of pesticides?
They can enter anf build up in food chains causing a lethal dose to predators, they can harm other organisms nearby which are not pests, some take a long time to break down and become harmless.
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What is the difference between normal an organic farming?
Organic farming doesn't use any pesticides or artificial fertilisers.
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What does it use instead of artificial fertilisers?
Manure, and compost, as well as crop rotation to avoid build up of crop pests.
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How do organic farmers replace nitrates in the soil?
By planting nitrogen fixing crops.
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What are the disadvantages of organic farming?
The crops produced are smaller and more expensive.
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Why do people still buy organic food if it is expensive?
Because they believe it tastes better and is more healthy for them.
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What is biological control?
It uses living organsims to control pests.
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Give an example of biological control
Using ladybirds to eat aphids which damage plants.
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How is biological control better than using pesticides?
Because it avoides the disadvantages of pesticides, and once introduced, they do not usually need replacing.
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What is a disadvantage of biological control?
The introduced species started eating useful organisms, leading to a rapid increase in their population, so they themselves become pests.
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How can biological control produce unexpected results?
Because you are introducing a species to kill another species, which can affect food chains.
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What is intensive farming?
Farming that makes use of pesticides and artificial fertilisers.
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What are the advantages of intensive farming?
It produces large crops yields very cheaply.
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What concerns are associated with intensive farming?
Concerns about animal cruelty, as animals are kept in small spaces, and the effects of extensive use of chemicals on soil structures and other organisms.
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How can plants be grown without soil?
Using Hydroponics.
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Explain the system of hydroponics
It uses a regulated recycling flow of aerated water containing minerals and is usually done in greenhouses.
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What is the most common crop from hydroponics?
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What are the advantages of using hydroponics?
You have better control of mineral levels and disease, many plants can be grown in a small space.
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What is a disadvantage of using hydroponics?
Because there is no anchorage for plants in water, artificial fertilisers are used.
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How does intensive farming improve the efficiency of energy transfer in food chains involving humans?
By reducing or removing competing organisms such as pests and weeds.
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What is battery farming?
Keeping animals inside sheds or farms.
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What are the advantages of battery farming?
They use less energy to keep warm and to move, and use more energy on growth (cattle) or egg production (hens).
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Other cards in this set

Card 2


What makes up the 'Community'?


All the animals and plants living in an ecosystem

Card 3


Give a common example of an ecosystem


Preview of the front of card 3

Card 4


What is the population?


Preview of the front of card 4

Card 5


Which ecosystems have good biodiversity, and why?


Preview of the front of card 5
View more cards


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