1 markA student studied the different species of fish living in a small pond. Which of the following is not an example of an abiotic factor affecting this ecosystem?
pH level of the water in the pond
Light availability
Bacterial pathogens
Temperature
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1 markHow can farmers increase the transfer of biomass between trophic levels to increase agricultural yield?
| 1 | Using high-energy feed for livestock |
| 2 | Keeping livestock in smaller enclosures to limit movement |
| 3 | Using herbicides to kill weeds |
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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1 markNitrogen gas must be converted (fixed) into nitrate before plants can absorb it.
Which organism fixes nitrogen?
Crop plants
Decomposing organic matter
Denitrifying bacteria
Bacteria such as Rhizobium
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1 markWhat is the process by which producers convert organic carbon into CO2 in the atmosphere?
Combustion
Respiration
Photosynthesis
Movement
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1 markWhich of the following statement(s) about pioneer species is/are true?
| 1 | Pioneer species require nutrient-rich soil |
| 2 | Pioneer species are the first species to colonise a new habitat |
| 3 | Pioneer species can alter abiotic factors in an environment |
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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1 markA group of ecologists surveyed a meadow over the course of a year. They calculated the average biomass of grass in the study area and the biomass of snails that fed on the grass. They found that the average grass biomass was 50kg m-2 yr-1 while the biomass of snails was 0.1kg m-2 yr-1. What could account for this difference between the biomass of the primary producer and the primary consumer?
| 1 | The snails are not the only species feeding on the grass |
| 2 | The grass loses some energy through respiration and waste products |
| 3 | The snails lose some energy through respiration |
| 4 | The snails do not digest all of the grass biomass that they consume |
1 and 2 only
3 and 4 only
1, 2 and 3 only
1, 3 and 4 only
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1 markThe Net Primary Productivity of phytoplankton in an area of sea surface is 10,000 kJ m-2 yr-1. Of this, 3000 kJ m-2 yr-1 is ingested by zooplankton (primary consumers), of which 900 kJ m-2 yr-1 is lost through zooplankton respiration and 900 kJ m-2 yr-1 is lost through zooplankton faeces. What is the Net Productivity of the zooplankton and the efficiency of the energy transfer?
| Net Productivity of zooplankton (kJ m-2 yr-1) | Efficiency of Transfer (%) | |
| A | 3000 | 10 |
| B | 1200 | 12 |
| C | 2100 | 12 |
| D | 1200 | 10 |
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1 markThe surface of a pond receives 4,000,000 kJ m-2 yr-1, of which 1% is absorbed by the chlorophyll in the primary producers. The Net Productivity of Primary Consumers (NPPC) of the pond is 2000 kJm-2 yr-1. The Efficiency of Energy Transfer (EET) between the primary producers and primary consumers is 10%. What is the Net Primary Productivity (NPP) of the pond and what is the respiratory loss of the plants in a year?
Efficiency of Energy Transfer = (NPPC / NP of producers) X 100
| NPP (kJ m-2 yr-1) | Respiratory loss of plants (kJ m-2 yr-1) | |
| A | 40,000 | 2000 |
| B | 20,000 | 38,000 |
| C | 20,000 | 20,000 |
| D | 40,000 | 20,000 |
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1 markFigure 1 shows the atmospheric carbon dioxide levels measured at Mauna Loa in Hawaii. The graph shows oscillations in atmospheric carbon levels over the course of each year. These are driven by processes occurring only in the Northern Hemisphere. What is the best explanation for this oscillation?
The burning of fossil fuels by humans causes changes in atmospheric carbon dioxide.
There are seasonal changes in the balance between carbon dioxide fixed by plant photosynthesis and that released through plant respiration.
Organisms are more likely to die during the winter, releasing more carbon dioxide
Forest fires are more likely during the summer
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1 markA group of scientists wants to assess the population size of field mice in a meadow. What method should they use?
Divide up the sample area into a grid, and use a random number generator to select sample plots in which to assess mouse abundance using quadrats.
Capture mice using pitfall traps, mark captured individuals with non-toxic paint, release them and repeat the sampling the following week
Capture mice using non-harmful box traps, mark captured individuals with non-toxic paint, release them and repeat the sampling the following year.
Capture mice using non-harmful box traps, mark captured individuals with non-toxic paint, release them and repeat the sampling the following week.
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1 markThe nitrogen cycle involves a range of reactions and microorganisms.
Which of the following processes, A to D, usually occurs under anaerobic conditions?
Conversion of amino acids to ammonium compounds.
Conversion of urea to ammonium compounds.
Nitrification.
Nitrogen fixation.
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1 markWhich of the following bacteria, A to D, convert ammonium compounds to nitrites?
Azotobacter
Nitrobacter
Nitrosomonas
Rhizobium
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1 markAsh trees are common throughout the UK. They often grow in dense woodland.
Which of the following, A to D, is an abiotic factor that is likely to affect the growth of young ash trees?
the availability of light underneath larger trees in the wood
the availability of oxygen in the air
the presence of a pathogen that causes ash dieback disease
the species of bacteria present in the soil
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1 markA teacher wrote:
“A garden pond is a dynamic environment that is home to a variety of organisms. The temperature of the pond varies depending on the weather and the time of year, and this affects the populations of the species that live there.”
Which of the following terms applies to the teacher’s description of the garden pond?
a community
an ecosystem
a habitat
a niche
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Which of the following statements about ecosystems is not true?
An ecosystem is affected by biotic and abiotic factors.
An ecosystem is all of the organisms and habitats in a large area.
An ecosystem is dynamic.
There is a flow of biomass between trophic levels in an ecosystem.
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1 markThe first stage of primary succession is the pioneer community.
Which of the following statements about a pioneer community are correct?
| 1 | species produce large numbers of wind-carried seeds or spores |
| 2 | biomass is low |
| 3 | many species are lichens and mosses |
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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1 markThe graphs below show the density of two different plant species as proximity to the coast changes.
Which of the following statements correctly describes one aspect of the technique used to collect these data?
Quadrats were randomly placed using a random number generator and coordinates.
Larger quadrats were required for species A because their mean density was higher.
A belt transect has been used to allow calculation of density.
Abiotic factors were measured at every point of quadrat sampling.
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1 markDeep sea vents on the ocean floor are surrounded by unusual organisms such as chemosynthetic bacteria and eyeless shrimp.
Which of the following statement(s) about these ecosystems is/are true?
| Statement 1: | The temperature of the vents influences the organisms that live there. |
| Statement 2: | A predatory octopus would affect the balance of these organisms. |
| Statement 3: | The number of eyeless shrimp found at each vent is constant. |
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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1 markThe energy transferred from the sun to the grass in this food chain is 65 000 kJ m-2 year-1.
Using your knowledge of the efficiency of energy transfer in food chains, approximately how much energy is passed from the shrew to the owl in kJ m-2 year-1?
650 000
6 500
650
65
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1 markWhich option, A to D, would be the most appropriate unit for a measurement of the biomass of all the deciduous trees in a forest?
kg m-2 yr-1
kg m-3 yr-1
kg yr-1
kg m-2
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