Energy And Ecosystems Questions Flashcards
Explain why the biomass of the primary consumers is less than the biomass of the producers in most communities (3)
Loss of energy
By respiration
Less energy left to sustain higher level
Give two advantages of using an organic fertiliser such as farmyard manure (2)
Greater range of nutrients
Nutrients released slowly
Readily available
Improves soil quality
Give two advantages of using an inorganic fertiliser (2)
Known nutrient content
Fast acting
Nutrients distributed evenly
Easy to handle/store/transport
When measuring the effects of using manure or inorganic fertiliser, how should the control plot be treated (2)
Same as the other plots
But without fertiliser
Explain how large scale deforestation for agriculture would lead to a decrease in the diversity of organisms in the area (2)
Removal of forests removes ecological niches/food sources/habitats
Reduces number of species that can exist in that area
Explain how large scale deforestation could increase the concentration of CO2 in the atmosphere in the area (2)
Reduce amount of CO2 used in photosynthesis
Increase amount of CO2 produced in combustion
Explain how large scale deforestation could decrease the concentration of CO2 in the atmosphere in the area (2)
Less respiration
By plants/decomposers
What is the name of the group of organisms that feeds on dead material (1)
Decomposers/detritus feeders
Give three explanations for the difference between the amount of solar energy reaching the primary producers and the energy in the biomass of the primary producers (3)
Light reflected
Light misses chlorophyll
Respiration by primary producer
Inefficiency of photosynthesis
Explain the change in the mass of the crop produced in a field when the fertiliser increase from 0kg to 20kg (2)
Replaces nutrients removed
Fertiliser provides nitrate needed for protein production
As more fertiliser added there is more growth
Explain why the mass of crop produced stays the same when more than 40kg of fertiliser is added (2)
Plants already have enough nitrate
Another factor is limiting growth e.g. Light
Keeping cattle indoors in barns leads to a higher efficiency of energy transfer. Explain why (1)
Less energy lost in maintaining body temperature
In the previous year, field A had been used for grazing cattle. Field B had been used to grow the same crop as this year. When no fertiliser was added, the mass of crop from field A was higher than from field B. Explain this difference (2)
Because cattle produced manure (organic fertiliser)
In field B crop used nutrients last year
Explain two advantages and one disadvantage of an inorganic fertiliser such as sodium nitrate compared with an organic fertiliser such as manure (2)
(+) Easy to handle/store/transport
(+) known chemical content
(+) releases nutrients quickly
(-) leads to eutrophication
(-) does not add to soil structure
Insecticides are pesticides which kill insects. A low concentration of insecticide was sprayed on the leaves of rose plants to kill greenfly which were feeding on the plants. Ladybirds eat greenfly. One month after spraying, the concentration of insecticides in the tissues of ladybirds was found to be higher than the concentration sprayed on the rose plants. Explain why (3)
Greenflies take in small amount of insecticides from leaves
Ladybirds eat large numbers of greenflies
Leads to bioaccumulation
Two methods, chemical and biological control, have been used to reduce the numbers of spotted knapweed plants. Explain how chemical control leads to plant numbers decreasing then increasing again. (1)
Number of plants drops because of spraying of insecticide then rises because insecticide washed away
Explain why spotted knapweed plants were never completely eliminated when using chemical control (2)
Some parts of plants not sprayed
Plant may be resistant to spray
Explain why the spotted knapweed were never completely eliminated when using biological control (2)
Biological control never eats all the plants
As weeds diminish so do control agents
Explain how including leguminous plants in a crop rotation reduces the need to use artificial fertilisers (2)
Contain nitrogen fixing bacteria in roots so don’t need fertiliser
Nitrogen containing compounds added to the soil when plant dies
Application of very high concentrations of fertiliser to the soil causes plants to wilt. Explain why (2)
Lower water potential in the soil
Prevents roots from taking up water
The mean temperature is highest in July. The gross productivity of the plants in a field was highest in July. Explain why (2)
High temperature allows enzymes to work faster
Photosynthesis reactions are faster
Give the equation that links gross productivity and net productivity (1)
Gross productivity = net productivity + respiratory losses
A horse was kept in a field from March to October. During the summer months, the horse was able to eat more than it needed to meet its minimum daily requirements. Suggest how the horse used the extra nutrients absorbed (1)
Stored as fat
Used for growth/movement/reproduction
The horse’s mean energy expenditure was higher in March than August. Suggest why (2)
More heat energy lost
Maintain body temperature
By respiration
Explain how the use of insecticides may poison the animals at the top of the food chain (2)
It accumulates in tissues
Becomes concentrated higher up the food chain (bioaccumulation)
Suggest one advantage of leaving a strip of bare ground between the hedgerow and the field (1)
Prevents pest organisms from teaching crop plants
Prevents herbicides from reaching hedgerows
Enables machinery to manoeuvre without damaging crop
After harvesting the crop, the farmer digs the unwanted stems and roots into the soil. Explain how the nutrients contained in these plant parts become available for use by other organisms (4)
Decomposers
Produce nitrogenous waste
Nitrates taken up by plants
Organisms respire and produce carbon dioxide
Used by plants in photosynthesis
Suggest two advantages of processing waste in anaerobic digesters rather than in open ponds (2)
Gases not released
Conditions can be controlled
Products can be collected
Open ponds associated with health risk/environmental damage/eutrophication
An anaerobic digester, used for processing waste, has a cooling system. Without this cooling system the disgusted would stop working. Explain why (2)
Respiration causes temperature increase
Enzymes would be denatured
Over application of fertiliser increases the rate of leaching. Explain the consequences of leaching of fertiliser into ponds and lakes. (3)
Increased algae - algal bloom
Light blocked out
Plants can’t photosynthesise so die
Bacteria breakdown dead organisms
Bacteria use up
Give one advantage of using natural frillier rather than an artificial one (1)
Increases organic content of soil
Wider range of elements
Less leaching
The percentage of barnacles in the diet of a starfish is much higher than the percentage of energy they provide. Suggest an explanation for this difference (1)
Low digestability/not all eaten
Suggest why the rapid rate of reproduction of a producer is essential to sustain the food chain (2)
To replace population so they don’t become extinct
To supply energy to next tropic level
To make up for energy loss between tropic levels
Not all light energy entering the leaves of an oak tree is used in photosynthesis. Give one reason for this (1)
Light is wrong colour
Does not hit chlorophyll molecule
Wavelength of light
Give two ways in which energy is lost between tropic levels (2)
Energy lost in respiration
Lost to decomposers
Not all eaten
Small amount lost as heat
Explain the roles of decomposers and nitrifying bacteria in converting nitrogen in organic compounds in sewage into a soluble inorganic form (3)
Decomposers convert nitrogen into ammonium
Nitrifying bacteria convert ammonium to nitrate
Via nitrite
Describe the part played by nitrogen fixing bacteria in the nitrogen cycle (2)
Convert nitrogen into ammonium
Add available nitrogen to an ecosystem
The partial pressure of oxygen int eh blood or two groups of fish was monitored. Explain why changes in water temperature might lead to unreliable results (1)
Variation in temperature will affect the solubility of oxygen/rate of respiration/use of oxygen by cells/gas exchange
The partial pressure of oxygen int eh blood or two groups of fish was monitored. The results of the two groups were compared using a statistical test. Suggest a null hypothesis that could be tested (1)
There is no difference between the partial pressure of oxygen in the two groups
Explain why it is important to use a statistical test in analysing the results of an investigation (2)
Results may have been due to chance
Statistical test allows us to determine the probability of this
Allows us to accept or reject null hypothesis
The concentration of ions in a sample of leaves was measured. These leaves were then fed to woodlice. The concentration of lead ions in the leaves was 908 but the concentration in the bodies of the woodlice was 132. Suggest what happens to most of the lead ions in the leaves eaten by the woodlice. (1)
Not absorbed from gut
Excreted
The concentration of ions in a sample of leaves was measured. These leaves were then fed to woodlice. The concentration of copper ions in the leaves was 52 but the concentration in the bodies of the woodlice was 1130. Explain this difference (2)
Woodlice eat large amounts of leaves
Copper accumulates in body
Some species of plants are tolerant to arsenic. What caused the allele for tolerance to first arise (1)
Mutation
Give two functions of phosphates in plant cells (2)
A component of nucleic acids
Phospholipids
ATP
Suggest why purple loosestrife became a pest when introduced to the USA but is not a pest in Europe (2)
No competition in US
No organisms to eat it is US
Environmental factors are more favourable
When treated with insecticide, the fire ant population decreases rapidly, remains low and stable for a while and then begins to increase agin. Explain why (3)
Most fire ants killed
Some survive because some are resistant
Insecticide does not reach all individuals
Survivors reproduce
Give the advantages and disadvantages of using biological control (6)
(+) specific to one pest
(+) only needs one application
(+) keeps pest population low
(+) pests do not develop resistance
(-) doesn’t get rid of pest completely
(-) may become a pest itself
(-) slow acting
Residual food intake (RFI) is the difference between the amount of food an animal actually eats and its expected food intake based on its size and growth rate. Explain the advantages to farmer of having cattle with a low RFI (2)
Reduced cost
More growth rate with same amount of food
Residual food intake (RFI) is the difference between the amount of food an animal actually eats and its expected food intake based on its size and growth rate. When RFI is calculated, low values are negative. Explain why (1)
Amount of food taken in is less than expected
Residual food intake (RFI) is the difference between the amount of food an animal actually eats and its expected food intake based on its size and growth rate. Scientists have developed a standard procedure for combating RFI in cattle. They control two factors. Explain why they need to control the type of food (2)
May vary in protein content
May affect growth
Residual food intake (RFI) is the difference between the amount of food an animal actually eats and its expected food intake based on its size and growth rate. Scientists have developed a standard procedure for combating RFI in cattle. They control two factors. Explain why they need to control environmental temperature (2)
Temperature will affect heat loss
Need to maintain/regulate body temperature
More energy can be used for growth
Residual food intake (RFI) is the difference between the amount of food an animal actually eats and its expected food intake based on its size and growth rate. Cattle with a low RFI have a lower mean rate of methane production. Selectively breeding cattle with a low RFI may help to limit global warming. Explain how (2)
Produce less methane
Methane linked to greenhouse effect
Methane is produced by anaerobic microorganisms in the soil. Scientists found that rice fields that are not flooded do not produce large amounts of methane. Suggest why (2)
Not flooded aerobic conditions (less oxygen)
Not flooded less active anaerobic microorganisms
Dead leaves contain starch. Describe how microorganisms make carbon in starch available to plants (2)
Extracellular digestion
Starch to monosaccharides
Produce CO2 from respiration
Describe how and explain why the efficiency of energy transfer is different at different stages in the transfer (6)
Some light energy is reflected
Respiratory losses
Loss as heat
Efficiency of photosynthesis in plants is low
Efficiency lower in older animals
Carnivores use more of their food than herbivores
Efficiency of transfer to producers greater than transfer to consumers
Explain how intensive rearing of domestic livestock increases net productivity (4)
Slaughtered while young so more energy transferred to biomass
Fed on controlled diet
Movement restricted so less respiratory loss
Kept inside so less heat loss
Genetically selected for high productivity
