9 (ecosystems + material cycles) exam qs

• What is a tapeworm an example of?

  Parasite
• How are tapeworms adapted to live in a human intestine?

  There are suckers on the head so that it attaches to the intestine, they have a very long and thin shape meaning they have a large surface area for absorption and the skin of them is resistant to enzymes.
• Explain the relationship between the tube worms and the chemosynthetic bacteria:

  Chemosynthetic bacteria live in the gut of the tube worms and the bacteria convert hydrogen sulphide compounds into food for tube worms. They have a mutualistic relationship
• What is the process of ammonia in soil turning into nitrates in soil?

  Nitrification
• Explain how plants use nitrates from the soil:

  The root hair cells of the plants would absorb mineral ions (nitrates) from the soil which are used to make protein for growth
• Describe how the over-use of nitrate fertilisers can cause eutrophication:

  The nitrates will flow into the water making algae grow rapidly meaning underwater plants can't photosynthesis which means the plants die and decomposers break them down
• Leguminous plants such as beans + peas have bacteria growing inside nodules on their roots. Explain the relationship between this bean plant and the bacteria growing in the root nodules:


  Bacteria use nitrogen to make ammonia and nitrates for plants to use. This is called mutualism or symbiosis.
• NItrates can be produced by soil bacteria. How can soil bacteria produce nitrates?

  Decomposers break down dead matter in the soil into ammonia. This is converted into nitrates by nitrifying bacteria.
• Name a type of bacteria that reduce the nitrate content of soil:

  Denitrifying bacteria
• What do plants use nitrates to make?

  Proteins
• Name the process by which bacteria release carbon dioxide into the atmosphere:

  Respiration/Decomposition
• The carbon dioxide concentration changes during each year. Suggest why the carbon dioxide concentration changes during a year.

  Seasonal changes - more fossil fuels may be burned during winter and there would be more photosynthesis in the summer
• Carbon is present in a wide variety of compounds in the carbon cycle. Describe how carbon is cycled in the environment.

  Photosynthetic plants remove carbon dioxide from the atmosphere to make glucose. Animals will eat the plants which contain carbon and they will eventually die due to microbial action releasing carbon dioxide. Also, combustion of fossil fields will release carbon dioxide into the atmosphere.
• The woodlice move quickly on the light squares and slow down on the dark squares. All woodlice show this behaviour. What is this type of behaviour?

  Inherited
• Squirrels were observed to urinate regularly on particular trees. The trees on which they are urinated are marked on the map with an X. How does this behaviour benefit the squirrels?

  The squirrels are marking their territory using chemical markers which reduces conflict and competition
• What is operant conditioning?

  Random behaviour that is reinforced and specific
• Suggest 2 ways in which energy can be lost between trophic levels:

  Respiration, excretion, movement, not all eaten
• Suggest how a farmer rearing chickens could limit energy loss from chickens:

  Keeps them in a warm environment which restricts their movement
• Examples of parasites:

  Mistletoe
• Peas and beans are known as legumes, they form a mutualistic relationship with the bacteria in their roots. Explain the importance of this relationship to the legumes:

  Bacteria provides nitrates for the plants by nitrogen-fixation which provides protein for plant growth
• Explain how a quadrat could be used to sample the population of clover in a 500m2 field:

  Take the mean number of clovers in like 10 quadrants. Say you counted 50, divide this number by 10 (5). Then do 5 x 500.
• How can leguminous plants such as clover be used to reduce the amount of artificial fertilizers?

  The clover could be used in crop rotation where a field is planted with clover at intervals. The clover will have colonies of nitrogen-fixing bacteria that will produce nitrates, increasing the fertility of the soil and negating the use of artificial fertilisers.
• The survival of some organisms may depend on mutualism. Explain using 3 examples of how some organisms benefit from mutualism:

  Nitrogen-fixing bacteria - have a relationship with leguminous plants as they fix nitrogen for the plant to use and obtain nutrition from the plant and are protected from the environment. Chemosynthetic bacteria - have a relationship with tube worms, the bacteria produce chemicals for the tubeworms while the tubeworm protects from heat. Cleaner fish - have a relationship with ocean species as they eat the dead skin and parasites on the large fish - prevent disease
• What is an indicator species for clean air?

  Lichen
• What is an indicator species for clean water?

  Stonefly
• What is an indicator species for polluted water?

  Sludgeworms
• Describe how scientists can use plant breeding programmes to produce maize plants with larger cobs:

  Select the cobs with the more desired characteristics and collect seeds from plants with larger cobs and then cross breed the selected cobs and plant seeds together and repeat. (Selective breeding)
• Explain how use of pesticides may benefit maize production:

  Will reduce number of pests and reduce damage to maize increasing yield
• What is the microorganism used as a vector to produce transgenic plants?

  Agrobacterium
• What are the advantages of biofuel?

  Removes carbon dioxide when growing crops, less use of fossil fuels, is renewable
• What are the disadvantages of biofuel?

  Reduced food production, takes up plant, reduced biodiversity
• Describe the processes that return carbon dioxide back into the atmosphere:

  Respiration in animals, respiration in plants, decomposition
• How can water pollution be observed (polluted water)?

  Blood worm and sludge worm presence indicates high water pollution
• How can water pollution be observed (clean water)?

  Freshwater shrimp and stonefly presence indicates low water pollution
• How can air pollution be observed?

  If blackspot fungus is found growing on roses, the air is unpolluted
• What is the difference between specific types of lichen?

  Certain types can survive in polluted areas so depending on the type found, the pollution level of air can be assessed
• What type of species would be most likely to be found near a coal-burning power station?

  Species tolerant to oxides of sulfur as sulfur dioxide gas is given off
• Auxins cause the shoot fo a plant to grow towards light in a process called?

  Positive phototropism
• Fruit ripening is one use of plant hormones. Describe the other uses of plant hormones in crop production:

  They can be used as selective weedkillers to allow broad leaved plants to grow uncontrollably and die while narrow leaved plants and crops are left unaffected - auxins or gibberellins. Can be used as rooting powders, a large number of plants can be produced from the same plant and there is no need to wait for plants to grow from seeds - auxins. Can be used for seedless fruit productions so the fruit will develop but the seeds inside won't - gibberellins.