Anna Hollywood
Flashcards by Anna Hollywood, updated more than 1 year ago
Anna Hollywood
Created by Anna Hollywood over 6 years ago


GCSE Biology (B4) Flashcards on B4, created by Anna Hollywood on 11/09/2013.

Resource summary

Question Answer
Name 4 ways that organisms can be collected Nets, pooters, pitfall traps and quadrats
Using a quadrat, how can we make the estimation size as reliable as possible? - Take as many quadrats as possible - Distribute as widely as possible - Sample randomly
What's a line transect? It can show us the change in abundance and distribution of species over a set distance. We do this by placing the quadrat along set distances of the line and seeing what's in each one
What are the sorts of observations we can make from a line transect? - Biodiversity - Plant height in each quadrat - Level of cover of grass/soil/leaves etc - Level of light intensity -Level of oxygen - Level of temperature - Numbers of a specific species
Name 2 species that you could collect in a pooter - Spider - Ant
Explain the mark-release-recapture technique - Mark the animal - Release it back in its natural environment - Leave it then recapture it - Use the formula to calculate pop size
What are the problems with the mark-release-recapture technique? -The pop size could've changed through death, birth, natural disaster or migration
What are the different ways of tagging an animal? - using a tag - markings/scars/features
What's the equation for working out the population size? (no. 1st sample x no. 2nd sample) / no. marked animals in 2nd sample
What's zonation? Zonation is where different species are found in different bands of a habitat, this can be down to physical factors (such as exposure on a sea shore)
How can zonation be shown? On a kite diagram
What is the balanced symbol equation for photosynthesis? 6CO2 + 6H2O ---> C6H1206 + 6O2
What did the ancient Greeks discover about photosynthesis? Scientists in ancient Greece believed that plants gained mass only by taking in minerals from the soil. They would not have tested this idea.
What did Van Helmont discover about photosynthesis? He grew a willow tree in a weighed amount of soil. After five years, he discovered that the willow tree weighed about 74 kg more than it did at the start. As the weight of the soil had hardly changed, van Helmont concluded that plant growth cannot only be due to minerals from the soil. He thought that the extra plant material had come from the water alone.
What did Priestley discover about photosynthesis? He put a mint plant in a closed container with a burning candle. The candle flame used up the oxygen and went out. After 27 days, Priestley was able to re-light the candle. This showed that plants produce a gas that allows fuels to burn. This gas is oxygen.
What's the glucose used for in plants? respiration, converted into cellulose (to make cell walls), proteins (for growth and repair), starch, fats and oils (for storage)
Why is starch used for storage? - Because it's insoluble and doesn't move from storage areas. Unlike glucose, it doesn't affect the water concentration of cells and cause of osmosis
How can radioisotopes be used to determine the source of the oxygen release? One of these experiments involves an isotope of oxygen, 18O. The more common isotope of oxygen in water or carbon dioxide, 16O, can be replaced by 18O. The transfer of these 18O atoms into other substances can be traced. The results were: Plants watered with water containing 18O atoms release oxygen gas containing 18O atoms Plants supplied with carbon dioxide containing 18O atoms do not release oxygen gas containing 18O atoms This shows that the oxygen gas produced by photosynthesis comes from water and not carbon dioxide.
What are chloroplasts? Chloroplasts contain chlorophyll which give the leaf it's green pigment and absorb the light for photosynthesis
leafcrosssection.gif (image/gif) 0000.png (image/png)
What are the adaptations of upper epidermis? Transparent so light can pass through to the palisade layer
What are the adaptations of palisade mesophyll layer? Most chloroplasts found here
What are the adaptations of spongy mesophyll layer? It contains air spaces, allowing gases to filter through the layer with ease. This means they have a large area for gas exchange.
What do stoma do? They are the little holes in the lower surface that let gases in and out and allow transpiration to happen
What the adaptations of the network of vascular bundles (veins)? To support the leaf, and to transport water and carbohydrates
What are the adaptations of the guard cells? To open and close the stomata depending on the conditions
What are the three limiting factors of photosynthesis? light intensity, carbon dioxide concentration and temperature
Light intensity Without enough light, a plant cannot photosynthesise very quickly, even if there is plenty of water and carbon dioxide. Increasing the light intensity will boost the speed of photosynthesis.
Carbon dioxide concentration Sometimes photosynthesis is limited by the concentration of carbon dioxide in the air. Even if there is plenty of light, a plant cannot photosynthesise if there is insufficient carbon dioxide.
Temperature If it gets too cold, the rate of photosynthesis will decrease. Plants cannot photosynthesise if it gets too hot. If you plot the rate of photosynthesis against the levels of these three limiting factors, you get graphs like the ones above. In practice, any one of these factors could limit the rate of photosynthesis.
What does xylem transport in a plant? Water and minerals from the roots to the leaves - this is called transpiration
What does phloem transport in a plant? Sugars (made in the leaf from photosynthesis) to other areas of the plant needing it for growth or storage - called translocation
What type of cells of xylem Vessels that are made up of dead cells leaving a hollow lumen
How does transpiration work? Water on the surface of spongy and palisade cells (inside the leaf) evaporates and then diffuses out of the leaf. This is called transpiration. More water is drawn out of the xylem cells inside the leaf to replace what's lost. As the xylem cells make a continuous tube from the leaf, down the stem to the roots, this acts like a drinking straw, producing a flow of water and dissolved minerals from roots to leaves. Factors that speed up transpiration will also increase the rate of water uptake from the soil. When water is scarce, or the roots are damaged, it increases a plant's chance of survival if the transpiration rate can be slowed down. Plants can do this themselves by wilting, or it can be done artificially, like removing some of the leaves from cuttings before they have chance to grow new roots.
What are the factors that affect transpiration rate? Light, wind, temperature, humidity
What happens when there's an increase in light (in terms of transpiration)? More light = increase in transpiration The stomata (openings in the leaf) open wider to allow more carbon dioxide into the leaf for photosynthesis
What happens when there's an increase in wind (in terms of photosynthesis)? Increase wind = increase in transpiration Water vapour is removed quickly by air movement, speeding up diffusion of more water vapour out of the leaf
What happens when there's an increase in temperature (in terms of photosynthesis)? increase temp = increase transpiration Evaporation and diffusion are faster at higher temperatures
What happens when there's an increase in humidity (in terms of photosynthesis)? increase humidity = DECREASE transpiration Diffusion of water vapour out of the leaf slows down if the leaf is already surrounded by moist air
What's diffusion? The net movement of particles from a high concentration to low concentration.
How do you calculate the rate of diffusion? Rate of diffusion (is proportional to) (concentration yield x surface area) / thickness of membrane
Name 5 things that cells exchange with their environment through diffusion Carbon dioxide, oxygen, glucose, water and lactic acid
How can leaves adapt to increase the rate of diffusion? - Large S.A to V.R - Stomata - Gaps between the spongy mesophyll layer
How can the rate of diffusion be increased? - Shortening the distance - Steepening the concentration gradient - Increasing the surface area
What is osmosis? The net movement of water particles form a high (dilute) to a low (concentrated) concentration, across a partially permeable membrane
What would happen if you put a plant cell (with a 5% solution in it) into a solution of 1%? What would happen with an animal cell? Water moves in the cell and it becomes fat and turgid (pushes against the inelastic cell wall). In an animal cell it would burst (lysis)
What would happen if you put a plant cell (with a 5% solution in it) into a solution of 8%? What would happen with an animal cell? Water leaves by osmosis and the cell becomes flaccid. The animal cell wrinkles and starts to crenate.
What would happen if you put a plant cell (with a 5% solution in it) into a solution of 20%? What would happen with an animal cell? Water leaves by osmosis and cell membrane tears away from cell wall. In an animal cell it will be fully crenated and would have PLASMOLYSED.
What can help reduce the rate of decay? Food preservation
What is active transport? Used to make the particles move from a low to high concentration. Active transport needs extra energy from respiration. It needs protein carriers. It occurs in the root hair cell as it needs to be able to take in nutrients from the soil.
What are the 7 ways of preserving food? Canning, cooling, freezing, drying, adding salt/sugar/vinegar
Name 4 plant minerals and their uses - nitrates to make protein and ensure cell growth - phosphates which are involved in respiration and growth - potassium compounds which are involved in respiration and photosynthesis - magnesium compounds for photosynthesis
How does canning help preserve foods? The food is heated to kill bacteria then sealed in a vacuum to prevent oxygen or bacteria entering
What does nitrogen from nitrates produce? amino acids
How does cooling help preserve foods? It helps slow down bacterial and fungal growth and reproduction
What does phosphorous from phosphates produce? DNA and cell membranes
How does freezing help preserve foods? It will kill some bacteria and fungi and slow down their growth and reproduction
What does potassium from potassium compounds produce? Helps enzyme action
How does drying help preserve foods? It removes water so bacteria cannot feed and grow
What does magnesium from magnesium compounds produce? Chlorophyll
How does adding salt/sugar help preserve foods? It will kill some bacteria and fungi, as the high osmotic concentration will remove the water from them
What does magnesium from magnesium compounds produce? Chlorophyll
How does adding vinegar help preserve foods? It will produce very acidic conditions killing most bacteria and fungi
What does a lack of nitrates cause? Poor growth and yellow leaves
What is intensive farming? Farming that tries to produce the maximum amount of food per given space of land. This began after a population rise after WW2
What does a lack of phosphate cause? poor root growth and discoloured leaves
List 4 chemicals that farmers can use to kill unwanted organisms - Pesticides - Herbicides - Insecticides - Fungicides
What does a lack of potassium cause? poor flower/root growth and discoloured leaves
List 4 ways that farmers can increase food production - Glasshouses:for growing crops out of season - Hydroponics:futuristic farming involving growing plants without soil and spraying them with mineral solution, meaning you can grow many plants in one space - Fish farming:fish are bred and reared in cages - Battery farming:breeding chickens in cages
What does a lack of magnesium cause? yellow leaves
Explain how pesticides can build up and the problem caused If they get into lakes/rivers then they can get into our water supply and therefore our food chains. Pesticides are also poisonous so it can be dangerous to our health
What are detritivores? Animals that feed on dead and decaying material such as maggots woodlice and worms
Name 2 plants that can be grown by hydroponics Lettuce Tomato
How do detritivores increase the rate of decay? By breaking up the detritus (so increasing the surface area for further microbial breakdown)
Give 2 advantages of using hydroponics - Plants can be grown in 'soilless' areas - The technique gives better control of the minerals needed by the plant
How else can the rate of decay be increased? By increasing the temperature, the amount of oxygen and water
Give 2 disadvantages of using hydroponics - There is no support for the plant so you have use tray/frame - There is no soil to hold and store minerals so fertilisers need to be added constantly as dissolved minerals
What's the optimum temperature for bacteria and for fungi? 37 degrees and 25 degrees. having the optimum temperature will increase their rate of respiration
Explain 3 reasons as to why intensive farming is efficient - High yield: maximum production and use of pesticides (less food is lost) - Low cost production: maximum output achieved from available land and fertilisers used increase plant growth - Less labour intensive: due to artificial chemicals and machines
Why is it good for bacteria to have an increase in oxygen? so the bacteria will be able to use aerobic respiration to grow and reproduce faster
What is an organic farmer? They don't use intensive farming and they don't aim for the highest population yield but for smaller amounts of healthy, organic food
What will increasing the amount of water do in terms of bacteria and fungi? It will allow for material to be digested and absorbed more efficiently and will increase their growth and reproduction
List 3 things that organic farmers don't use on their land - Herbicides - Fungicides - Insecticides
What is a saprophyte? An organism, such as a fungus, that feeds on dead and decaying material
How do fungi digest food outside their cells? What's this type of digestion called? They produce enzymes to digest the food then they reabsorb the simple soluble substances. This type of digestion is called extracellular digestion.
What is biological control? They introduce a natural predator of the pest which kill/eat the pest/s. An example of this is adding ladybirds to your crops to kill the common pest, the greenfly/aphid
Why does biological control not always work? - The predator might not eat the pest - The predator may eat useful organisms - The predator population may grow out of control - Adding predators may disrupt the food web
List 4 other organic methods - Manure/compost (adds minerals) - Weeding - Crop rotation - Planting in timed batches
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