1. Energy transfer from forests is disrupted when trees are removed, impacting soil stability, carbon dioxide levels, biodiversity, and rainfall patterns. Deforestation harms local ecosystems.
2. Chemical insecticides accumulate in ladybird bodies through eating greenflies and cannot be excreted, increasing their numbers. Biological control using ladybirds is more stable as numbers fluctuate less with seasons and plants.
3. Two plant species interact through competing for limited resources like light or nutrients. Heather provides nitrogen fixing bacteria that stimulates spruce growth while inhibiting heather.
This document discusses several topics related to agriculture and ecology:
1. Deforestation can lead to soil erosion, increased carbon dioxide levels, and loss of biodiversity.
2. Using chemical versus biological pest control methods: chemicals fluctuate over time but biological controls are more constant; chemicals may not reach all plants.
3. Interspecific competition was shown between spruce and heather over light and nutrients; spruce grows better when heather is controlled.
4. Speciation occurs when populations become isolated and develop differences over time due to varying environments and natural selection, allowing them to breed but not mix ecologically. Increased diversity supports more niches and food sources.
5. Beach
1. Organic nitrogen is converted to ammonium compounds by decomposers and then to nitrates by nitrifying bacteria for uptake by plant roots. Nitrogen-fixing bacteria convert nitrogen to compounds used by legumes, reducing the need for fertilizer. Shorter food chains produce greater fish yields due to less energy loss between trophic levels.
2. Random quadrats are used to sample plant diversity. Heather affects diversity by providing habitat. Nitrogen is used for non-photosynthetic plant parts and eaten by grouse. Younger plants are more productive. Enzymes are proteins that catalyze reactions without being used up.
3. Earthworm taxonomy is given. Enzymes are not
1. Nitrogen cycles through ecosystems via organic compounds, ammonium, nitrites, and nitrates due to the actions of saprophytic bacteria and nitrifying bacteria. Nitrogen-fixing bacteria in root nodules of legumes convert nitrogen to organic compounds that fertilize the plant.
2. Decomposer bacteria release ammonia and nitrifying bacteria convert it to nitrites and nitrates via nitrification. There is competition between microbes for these nitrogen sources.
3. The document outlines scientific marking schemes for content, breadth, relevance, presentation, and use of technical vocabulary. It provides example questions and marking schemes related to ecology, biogeochemical cycles, microbes, and earthworm
Hydrogen sulfide as multifunctional gaseous moleculeUpasana Mohapatra
1. Hydrogen sulfide (H2S) functions as a signaling molecule in plants, modulating physiological processes like photosynthesis, senescence, and stress tolerance.
2. H2S is endogenously produced through enzymes in plants and its concentration increases under stress conditions like drought, salt, and pathogens.
3. Studies with transgenic Arabidopsis plants and H2S treatments showed that H2S activates stress-related genes, antioxidants, and compatible solutes to protect plants against abiotic and biotic stresses.
The document discusses pesticide laws and regulations, pesticide safety equipment, pest-related turf problems, turfgrass diseases, annual grasses and broadleaf weeds, turfgrass insects, and insect control. Key points include that a pesticide license is required to apply restricted pesticides, records must be kept for 5 years, pesticides must be EPA registered and properly labeled, and integrated pest management involves identifying pests and life cycles and using cultural, biological, or chemical controls as needed.
1. The document describes a system designed to meet the basic needs of a family of four living in the tropics. The system generates fuel gas from bacterial fermentation of urine and feces. It uses solid waste from the fermenter as fertilizer and grows leguminous plants such as beans and peanuts. Fish that feed on algae are stocked in the pond rather than carnivorous fish.
2. Candidates were asked questions about various parts of the system. For example, how the nitrogen cycle makes nitrogen in urine and feces available to plants, the advantages of growing legumes, and the benefits of stocking the pond with algae-feeding fish rather than carnivorous fish.
Thermus aquaticus gen. n. and sp. n., a nonsporulating extreme thermophileJosé Luis Moreno Garvayo
Thermus aquaticus is a newly isolated thermophilic bacterium that is widespread in aquatic thermal environments. It is a non-sporulating, nonmotile rod that forms yellow pigmentation and large spheres. Isolates have been obtained from hot springs in Yellowstone National Park and California between 40-79°C, as well as from man-made thermal habitats like hot tap water distant from natural springs. The organism is an aerobic obligate with optimal growth at 70°C and generation time of 50 minutes.
This document discusses several topics related to agriculture and ecology:
1. Deforestation can lead to soil erosion, increased carbon dioxide levels, and loss of biodiversity.
2. Using chemical versus biological pest control methods: chemicals fluctuate over time but biological controls are more constant; chemicals may not reach all plants.
3. Interspecific competition was shown between spruce and heather over light and nutrients; spruce grows better when heather is controlled.
4. Speciation occurs when populations become isolated and develop differences over time due to varying environments and natural selection, allowing them to breed but not mix ecologically. Increased diversity supports more niches and food sources.
5. Beach
1. Organic nitrogen is converted to ammonium compounds by decomposers and then to nitrates by nitrifying bacteria for uptake by plant roots. Nitrogen-fixing bacteria convert nitrogen to compounds used by legumes, reducing the need for fertilizer. Shorter food chains produce greater fish yields due to less energy loss between trophic levels.
2. Random quadrats are used to sample plant diversity. Heather affects diversity by providing habitat. Nitrogen is used for non-photosynthetic plant parts and eaten by grouse. Younger plants are more productive. Enzymes are proteins that catalyze reactions without being used up.
3. Earthworm taxonomy is given. Enzymes are not
1. Nitrogen cycles through ecosystems via organic compounds, ammonium, nitrites, and nitrates due to the actions of saprophytic bacteria and nitrifying bacteria. Nitrogen-fixing bacteria in root nodules of legumes convert nitrogen to organic compounds that fertilize the plant.
2. Decomposer bacteria release ammonia and nitrifying bacteria convert it to nitrites and nitrates via nitrification. There is competition between microbes for these nitrogen sources.
3. The document outlines scientific marking schemes for content, breadth, relevance, presentation, and use of technical vocabulary. It provides example questions and marking schemes related to ecology, biogeochemical cycles, microbes, and earthworm
Hydrogen sulfide as multifunctional gaseous moleculeUpasana Mohapatra
1. Hydrogen sulfide (H2S) functions as a signaling molecule in plants, modulating physiological processes like photosynthesis, senescence, and stress tolerance.
2. H2S is endogenously produced through enzymes in plants and its concentration increases under stress conditions like drought, salt, and pathogens.
3. Studies with transgenic Arabidopsis plants and H2S treatments showed that H2S activates stress-related genes, antioxidants, and compatible solutes to protect plants against abiotic and biotic stresses.
The document discusses pesticide laws and regulations, pesticide safety equipment, pest-related turf problems, turfgrass diseases, annual grasses and broadleaf weeds, turfgrass insects, and insect control. Key points include that a pesticide license is required to apply restricted pesticides, records must be kept for 5 years, pesticides must be EPA registered and properly labeled, and integrated pest management involves identifying pests and life cycles and using cultural, biological, or chemical controls as needed.
1. The document describes a system designed to meet the basic needs of a family of four living in the tropics. The system generates fuel gas from bacterial fermentation of urine and feces. It uses solid waste from the fermenter as fertilizer and grows leguminous plants such as beans and peanuts. Fish that feed on algae are stocked in the pond rather than carnivorous fish.
2. Candidates were asked questions about various parts of the system. For example, how the nitrogen cycle makes nitrogen in urine and feces available to plants, the advantages of growing legumes, and the benefits of stocking the pond with algae-feeding fish rather than carnivorous fish.
Thermus aquaticus gen. n. and sp. n., a nonsporulating extreme thermophileJosé Luis Moreno Garvayo
Thermus aquaticus is a newly isolated thermophilic bacterium that is widespread in aquatic thermal environments. It is a non-sporulating, nonmotile rod that forms yellow pigmentation and large spheres. Isolates have been obtained from hot springs in Yellowstone National Park and California between 40-79°C, as well as from man-made thermal habitats like hot tap water distant from natural springs. The organism is an aerobic obligate with optimal growth at 70°C and generation time of 50 minutes.
This document contains information about nitrogen cycling in soil and forests. It discusses:
1. The roles of decomposers and nitrifying bacteria in breaking down organic matter and converting ammonia to nitrates.
2. How burning forests releases more carbon dioxide into the atmosphere since trees are no longer removing carbon through photosynthesis.
3. Various factors that allow hardwood trees to regenerate more easily than softwoods in areas where forests have been cleared, such as competition for light, temperature and moisture regulation, and nutrient recycling.
This mark scheme provides guidance to examiners on how to award marks for answers on a biology exam. It shows the requirements to receive marks and gives examples of acceptable answers. While it does not discuss the examiners' meeting, it should be used along with the question paper and examiner report to ensure consistent marking. Cambridge will not discuss the specific details of the mark scheme.
FATE OF HERBICIDE IN SOIL by Pravir pandeyPravir Pandey
The document summarizes the fate of herbicides in soil after application. It discusses various processes that affect herbicide activity including degradation through biological, chemical and photodecomposition, as well as transfer processes like adsorption, leaching, volatility and runoff. Factors that influence these processes include environmental conditions, soil properties, herbicide formulations and application methods. The degradation of herbicides renders them inactive while transfer processes may remove herbicides from the application site.
This document contains an answer scheme and summary for an IB ESS grade 11 summative assessment from September 2012. It provides the marking criteria for questions about estimating population size, food chains, and biomagnification up the trophic levels. The key points assessed include appropriate sampling methods, representing trophic interactions in diagrams, explaining energy losses between levels, and defining producers and top carnivores.
This mark scheme provides guidance to examiners on how to award marks for the Biology exam. It shows the requirements for each question and lists acceptable answers. The mark scheme should be used along with the question paper and examiner report to ensure marks are awarded consistently. Cambridge will not discuss the mark scheme further, but has published it to aid teachers and students.
The document contains mark schemes for International GCSE Biology exam papers from June 2003. It provides the answers and number of marks awarded for multiple choice, short answer, and extended response questions on topics including the kidney, eye structure, plant transport, and ecology. The mark schemes also show the level of detail or reasoning required to earn each mark.
This document contains an answer scheme for an end of semester test in Grade 11. It provides the questions asked in the test and the marking scheme for student responses. The test covered topics related to population ecology, including predator-prey interactions, food webs, methods for estimating population sizes, biodiversity indices, and energy flow through ecosystems. The summary provides the essential information while being concise.
MULTIFACETED POTENTIAL OF EICHHORNIA CRASSIPES (WATER HYACINTH) LADENED WITH ...Dr Varruchi Sharma
Water hyacinth is an invasive aquatic plant that has spread widely and poses ecological issues. However, it also has potential value-added and therapeutic uses that could help address the invasion. It can be used for bioremediation to remove pollutants from wastewater. Its biomass can also be converted to biofuels like biodiesel and bioethanol, providing renewable energy. Additionally, extracts from water hyacinth have shown therapeutic effects, though more research is still needed to fully understand its medical applications. Utilizing water hyacinth for these beneficial purposes could help curb its invasion while providing useful products.
A trusted hat and two new shoes: Forages for Eco-efficiencyCIAT
This document provides information on CIAT's tropical forage research program including germplasm development, high value products, and integrating forages into smallholder crop-livestock systems. It summarizes outputs across various regions and describes benefits like improved livelihoods and environmental outcomes. Expertise within the program spans various disciplines including plant genetics, animal nutrition, and molecular biology.
This document contains a summary of a 40-mark exam on environmental management. It includes the following key points in 3 sentences:
The exam covered topics such as calculating percentages from data, interpreting graphs, sustainable charcoal production, shrimp farming impacts, and fish population management techniques. Questions addressed environmental monitoring of an oil pipeline project, impacts of oil extraction, and alternative energy sources for Ecuador. The summary provides an overview of the various sections and question topics assessed on the exam.
This document contains answers to questions about photosynthesis, reproduction in flowering plants, adaptations to habitats, ecosystems, human influences on the environment, and classification and variation from the Cambridge Checkpoint Science Workbook 3. The questions cover topics such as the process of photosynthesis, parts of flowers, dispersal of seeds, food webs, water and air pollution, intensive farming, and indicators of pollution. Diagrams, tables, and graphs are included as part of some answers.
The document discusses alternative pest management (APM) strategies that are ecologically sound and economically viable. It outlines APM principles and defines pests. It then discusses factors that affect pest populations and different pest management approaches like integrated pest management, ecological pest management, and alternative pest management which uses cultural, physical, mechanical, biological and botanical controls and avoids synthetic pesticides.
1. The document describes a system designed to meet the basic needs of a family of four living in the tropics. The system generates fuel gas from bacterial fermentation of urine and feces. It uses solid waste from the fermenter as fertilizer for crops and stocks the pond with fish that feed on algae rather than carnivorous fish.
2. The document discusses student responses to questions about the nitrogen cycle and leguminous plants. It notes confusion between nitrogen fixing and denitrifying bacteria. It also notes that students have difficulty with the sequence of changes in the nitrogen cycle and defining nitrogen compounds.
3. The document evaluates student essays on relationships between animals and plants. It finds the scientific
This document describes a system designed to meet the basic needs of a family of four living in the tropics. The system includes crop plants, solid and liquid waste, cattle, chickens, algae in a shallow pond, and fish. Urine, feces, and crop waste are recycled through various processes involving bacteria, plants, and animals to provide nutrients to crops and meet other needs in a sustainable cycle.
The document describes a system designed to meet the basic needs of a family of four living in the tropics. The system uses natural processes to cycle nutrients between different components. Urine and feces from humans and livestock are used to fertilize crop plants through the nitrogen cycle. A fermenter containing bacteria breaks down liquid waste, while solid waste is used directly as fertilizer. Algae in a shallow pond produce carbon dioxide and oxygen, and are eaten by fish which provide a source of protein. This sustainable system recycles resources to grow crops and raise animals.
Deforestation, especially in tropical rainforests over the past 60 years, has contributed to both local decreases in biodiversity and global climate effects. Deforestation and the burning of fossil fuels have increased carbon dioxide levels in the atmosphere and global temperatures. New ideas to address global warming include planting trees on farms to offset industry emissions by acting as carbon sinks, and reducing plowing which allows soil to store more carbon.
This document discusses exam responses on topics related to carbon and nitrogen cycling. It provides feedback on common mistakes and omissions in student answers. For example, many students stated carbon is converted to oxygen during photosynthesis rather than being used to produce organic molecules. The document also notes better responses incorporated appropriate scientific terminology and integrated knowledge from the passage with their own biological understanding.
1. Most candidates understood how species conservation could result from selective logging but had difficulty clearly expressing these ideas. Some incorrectly imagined minerals redistributing over long distances from unlogged to logged areas. Most recognized the importance of sufficient time for tree regrowth.
2. Many candidates confused fertilizers and pesticides. Most explained ladybird consumption of greenflies accumulating insecticide but some incorrectly suggested insecticide increasing from greenfly reproduction. Patterns of population changes were often described poorly.
3. Candidates correctly identified interspecific competition but had difficulty calculating growth rate differences between spruce and heather in a control experiment.
Large-scale deforestation leads to environmental problems like soil erosion and decreased biodiversity. Sustainable logging of tropical rainforest helps conserve the ecosystem by only removing mature trees from sectors in sequence, allowing regeneration. Integrated pest management uses both chemical and biological controls, along with other practices, to manage pests in a balanced way while reducing chemical use. Enhancing environmental conditions in greenhouses, like carbon dioxide levels and temperature, can increase crop yields. However, overuse of fertilizers can pollute water sources with nitrates.
This document contains summaries of exam responses on topics related to ecology and succession:
1) Many candidates incorrectly described industrial effluent or slurry spillage instead of the provided explanation of weathered rock for shoreline deposits. Few could apply knowledge of succession to explain climax communities.
2) Most calculated diversity indices correctly but responses varied in interpreting the results. Better responses recognized adaptations allowing Fucus spiralis to outcompete others in its habitat.
3) Some wrote too much about succession where not required, failing to distinguish key points about changes in species numbers and individuals. Most described pioneer species roles but some unnecessary detailed climax communities.
4) Many misinterpreted the provided graph and did
This document contains information about nitrogen cycling in soil and forests. It discusses:
1. The roles of decomposers and nitrifying bacteria in breaking down organic matter and converting ammonia to nitrates.
2. How burning forests releases more carbon dioxide into the atmosphere since trees are no longer removing carbon through photosynthesis.
3. Various factors that allow hardwood trees to regenerate more easily than softwoods in areas where forests have been cleared, such as competition for light, temperature and moisture regulation, and nutrient recycling.
This mark scheme provides guidance to examiners on how to award marks for answers on a biology exam. It shows the requirements to receive marks and gives examples of acceptable answers. While it does not discuss the examiners' meeting, it should be used along with the question paper and examiner report to ensure consistent marking. Cambridge will not discuss the specific details of the mark scheme.
FATE OF HERBICIDE IN SOIL by Pravir pandeyPravir Pandey
The document summarizes the fate of herbicides in soil after application. It discusses various processes that affect herbicide activity including degradation through biological, chemical and photodecomposition, as well as transfer processes like adsorption, leaching, volatility and runoff. Factors that influence these processes include environmental conditions, soil properties, herbicide formulations and application methods. The degradation of herbicides renders them inactive while transfer processes may remove herbicides from the application site.
This document contains an answer scheme and summary for an IB ESS grade 11 summative assessment from September 2012. It provides the marking criteria for questions about estimating population size, food chains, and biomagnification up the trophic levels. The key points assessed include appropriate sampling methods, representing trophic interactions in diagrams, explaining energy losses between levels, and defining producers and top carnivores.
This mark scheme provides guidance to examiners on how to award marks for the Biology exam. It shows the requirements for each question and lists acceptable answers. The mark scheme should be used along with the question paper and examiner report to ensure marks are awarded consistently. Cambridge will not discuss the mark scheme further, but has published it to aid teachers and students.
The document contains mark schemes for International GCSE Biology exam papers from June 2003. It provides the answers and number of marks awarded for multiple choice, short answer, and extended response questions on topics including the kidney, eye structure, plant transport, and ecology. The mark schemes also show the level of detail or reasoning required to earn each mark.
This document contains an answer scheme for an end of semester test in Grade 11. It provides the questions asked in the test and the marking scheme for student responses. The test covered topics related to population ecology, including predator-prey interactions, food webs, methods for estimating population sizes, biodiversity indices, and energy flow through ecosystems. The summary provides the essential information while being concise.
MULTIFACETED POTENTIAL OF EICHHORNIA CRASSIPES (WATER HYACINTH) LADENED WITH ...Dr Varruchi Sharma
Water hyacinth is an invasive aquatic plant that has spread widely and poses ecological issues. However, it also has potential value-added and therapeutic uses that could help address the invasion. It can be used for bioremediation to remove pollutants from wastewater. Its biomass can also be converted to biofuels like biodiesel and bioethanol, providing renewable energy. Additionally, extracts from water hyacinth have shown therapeutic effects, though more research is still needed to fully understand its medical applications. Utilizing water hyacinth for these beneficial purposes could help curb its invasion while providing useful products.
A trusted hat and two new shoes: Forages for Eco-efficiencyCIAT
This document provides information on CIAT's tropical forage research program including germplasm development, high value products, and integrating forages into smallholder crop-livestock systems. It summarizes outputs across various regions and describes benefits like improved livelihoods and environmental outcomes. Expertise within the program spans various disciplines including plant genetics, animal nutrition, and molecular biology.
This document contains a summary of a 40-mark exam on environmental management. It includes the following key points in 3 sentences:
The exam covered topics such as calculating percentages from data, interpreting graphs, sustainable charcoal production, shrimp farming impacts, and fish population management techniques. Questions addressed environmental monitoring of an oil pipeline project, impacts of oil extraction, and alternative energy sources for Ecuador. The summary provides an overview of the various sections and question topics assessed on the exam.
This document contains answers to questions about photosynthesis, reproduction in flowering plants, adaptations to habitats, ecosystems, human influences on the environment, and classification and variation from the Cambridge Checkpoint Science Workbook 3. The questions cover topics such as the process of photosynthesis, parts of flowers, dispersal of seeds, food webs, water and air pollution, intensive farming, and indicators of pollution. Diagrams, tables, and graphs are included as part of some answers.
The document discusses alternative pest management (APM) strategies that are ecologically sound and economically viable. It outlines APM principles and defines pests. It then discusses factors that affect pest populations and different pest management approaches like integrated pest management, ecological pest management, and alternative pest management which uses cultural, physical, mechanical, biological and botanical controls and avoids synthetic pesticides.
1. The document describes a system designed to meet the basic needs of a family of four living in the tropics. The system generates fuel gas from bacterial fermentation of urine and feces. It uses solid waste from the fermenter as fertilizer for crops and stocks the pond with fish that feed on algae rather than carnivorous fish.
2. The document discusses student responses to questions about the nitrogen cycle and leguminous plants. It notes confusion between nitrogen fixing and denitrifying bacteria. It also notes that students have difficulty with the sequence of changes in the nitrogen cycle and defining nitrogen compounds.
3. The document evaluates student essays on relationships between animals and plants. It finds the scientific
This document describes a system designed to meet the basic needs of a family of four living in the tropics. The system includes crop plants, solid and liquid waste, cattle, chickens, algae in a shallow pond, and fish. Urine, feces, and crop waste are recycled through various processes involving bacteria, plants, and animals to provide nutrients to crops and meet other needs in a sustainable cycle.
The document describes a system designed to meet the basic needs of a family of four living in the tropics. The system uses natural processes to cycle nutrients between different components. Urine and feces from humans and livestock are used to fertilize crop plants through the nitrogen cycle. A fermenter containing bacteria breaks down liquid waste, while solid waste is used directly as fertilizer. Algae in a shallow pond produce carbon dioxide and oxygen, and are eaten by fish which provide a source of protein. This sustainable system recycles resources to grow crops and raise animals.
Deforestation, especially in tropical rainforests over the past 60 years, has contributed to both local decreases in biodiversity and global climate effects. Deforestation and the burning of fossil fuels have increased carbon dioxide levels in the atmosphere and global temperatures. New ideas to address global warming include planting trees on farms to offset industry emissions by acting as carbon sinks, and reducing plowing which allows soil to store more carbon.
This document discusses exam responses on topics related to carbon and nitrogen cycling. It provides feedback on common mistakes and omissions in student answers. For example, many students stated carbon is converted to oxygen during photosynthesis rather than being used to produce organic molecules. The document also notes better responses incorporated appropriate scientific terminology and integrated knowledge from the passage with their own biological understanding.
1. Most candidates understood how species conservation could result from selective logging but had difficulty clearly expressing these ideas. Some incorrectly imagined minerals redistributing over long distances from unlogged to logged areas. Most recognized the importance of sufficient time for tree regrowth.
2. Many candidates confused fertilizers and pesticides. Most explained ladybird consumption of greenflies accumulating insecticide but some incorrectly suggested insecticide increasing from greenfly reproduction. Patterns of population changes were often described poorly.
3. Candidates correctly identified interspecific competition but had difficulty calculating growth rate differences between spruce and heather in a control experiment.
Large-scale deforestation leads to environmental problems like soil erosion and decreased biodiversity. Sustainable logging of tropical rainforest helps conserve the ecosystem by only removing mature trees from sectors in sequence, allowing regeneration. Integrated pest management uses both chemical and biological controls, along with other practices, to manage pests in a balanced way while reducing chemical use. Enhancing environmental conditions in greenhouses, like carbon dioxide levels and temperature, can increase crop yields. However, overuse of fertilizers can pollute water sources with nitrates.
This document contains summaries of exam responses on topics related to ecology and succession:
1) Many candidates incorrectly described industrial effluent or slurry spillage instead of the provided explanation of weathered rock for shoreline deposits. Few could apply knowledge of succession to explain climax communities.
2) Most calculated diversity indices correctly but responses varied in interpreting the results. Better responses recognized adaptations allowing Fucus spiralis to outcompete others in its habitat.
3) Some wrote too much about succession where not required, failing to distinguish key points about changes in species numbers and individuals. Most described pioneer species roles but some unnecessary detailed climax communities.
4) Many misinterpreted the provided graph and did
1. Energy transfer
1. (a) Soil erosion / mud slides / flooding / leaching
of minerals – trees no longer protect soil from rain / from
wind / roots no longer hold soil;
Increased CO2 (in air) OR “greenhouse effect” – trees remove
CO2 / trees photosynthesise / burning releases CO2;
Less diversity / loss of (forest) species / fewer individuals – loss
of food / loss of habitat / niches / ecosystem;
Changed rainfall patterns / drought – less transpiration from trees; 2 max
(b) 1. Suitable habitat / food nearby for displaced animals;
2. Later recolonisation possible from adjacent areas;
3. Reference to sufficient time for recovery (e.g. not felled again
for 280 years); 3 max
[5]
2. (a) greenflies take in (small mass of) insecticide from roses/leaves;
ladybirds eat large numbers of/more/many greenflies;
bioaccumulation idea / insecticide cannot be excreted/remains in
body/stored in fat/not broken down; 3
(b) (i) chemical: numbers fluctuate throughout year;
biological: numbers fairly constant throughout year /
accurate description; 2
(ii) number of plants drops because of spraying/reapplication, then
rises because insecticide washed away/new plants grow; 1
(c) (i) chemical: some plants/parts of plants are not sprayed / spray washes
off before it has effect;
plant may be resistant to spray; (Reject ‘ immune’) 2
(ii) biological: because biological control never eats all plants;
as weeds diminish so do control agents and/or vice versa / is balance
between food and consumer; 2
[10]
3. (a) interspecific; 1
(b) one mark for two resources e.g. light; named nutrient, water; 1
Hyde Clarendon Sixth Form College 1
2. (c) (i) one mark for working showing spruce and heather as control;
0.16/0.17 metres per year; 2
(ii) produces substance/ nutrient which stimulates
growth of spruce / inhibits growth of spruce /
provides nitrogen-fixing bacteria; 1
[5]
4. (a) similar characteristics / physically similar / DNA similar;
breed among themselves;
to produce fertile offspring;
do not share same ecological niche with any other species; max 2
(b) (i) isolation;
no gene flow between populations;
variation;
different environmental factors;
natural selection / selection for specific alleles / characteristics;
change in allele / phenotype frequency;
changes over a long period of time; max 4
(b) (ii) more habitats / niches;
more / greater range of food for herbivores;
more / greater range of food for carnivores / predators;
more detritus; max 2
(c) colonisation / description e.g. seeds blown in / pioneer species;~
succession;
alteration of habitat / more humus / deeper soil;
development of herbaceous / field layer;
followed by shrub layer; max 4
[12]
5. (a) Shells;
Spray/flooding by seawater;
Weathering of underlying rock;
Nitrogen fixation;
Excretory products; max 2
Hyde Clarendon Sixth Form College 2
3. (b) One mark for correct numbers = 4, 1, 1/2;
(i) The last stage in succession, therefore furthest from sea
has greatest diversity/number of species of plants;
greatest amount of organic matter;
(ii) Little humus/organic matter to hold/retain moisture/
More sand promoting drainage;
(iii) Pioneer species/colonisers are often wind-dispersed/need large
numbers of small seeds in order for some to land on bare sand; 4
[6]
6. (a) dry ice;
combustion;
manure / compost; max 2
(b) not cost effective;
since some other factor limiting rate of photosynthesis; 2
(c) cost of provision covered by extra cash from sale;
as crops fetch higher price in winter; 2
[6]
7. (a) using a predator / parasite / pathogen to control (the numbers of) a
pest organism;
name of control organism and pest;
explanation of control method; 3
(b) advantages (max 3)
(if well-screened) a biological control agent only attacks the pest;
forms self-perpetuating population (only one application required);
cheaper (qualified) e.g. saves cost of repeatedly using chemicals;
safer because does not leave chemical residue;
organisms do not become resistant to biological control;
disadvantages (max 3)
doesn’t completely eradicate pest;
cost of researching / setting up a biological control system;
biological control agent may become a nuisance itself/must be well
screened;
slower to get rid of pest than chemicals;
more subject to environmental factors; any 4
Hyde Clarendon Sixth Form College 3
4. (c) use of restriction / endonuclease enzyme;
cuts DNA at specific base sequence / recognition site;
reference to vector / method of inserting DNA;
same endonuclease to cut vector/host DNA;
use of ligase enzyme (to join DNA strands);
(allow equivalent mark points for use of reverse transcript) max. 4
one mark for advantage of genetic engineering
e.g. much quicker / more efficient / several genes can be inserted at once;
[12]
8. (a) correct % reduction for A; (16.6 → 7.6 OR 9%)
correct % reduction for B; (15.04 → 10.07 OR 5%)
greater percentage reduction in A 3
(b) (i) destruction of affected trees;
use of insecticides;
release sterile males / females
selective breeding of beetle resistant palms max 2
(ii) if one method fails, other still partially effective;
reduced amounts of pesticides needed;
increased yield / less chance of resistant species developing /
less effect on food webs; max 2
(c) possible effects on non-target species;
possibility of population explosion due to lack of natural predators;
not all pests killed;
difficulty in maintaining population of control organism max 2
[9]
9. (a) (i) protein / amino acid production 1
(b) (i) increased yields;
replace ions taken in by crop; 2
(ii) increased application of fertiliser does not increase yields;
therefore uneconomic 2
Hyde Clarendon Sixth Form College 4
5. (c) (i) increased leaching as result of increased application 1
(ii) Either
increased rainfall (leading to increased volume of water flowing
into reservoirs);
increased volume leads to increased dilution of nitrate
Or
less rain;
therefore more uptake by crop / less leaching 2
(d) increased growth of plants / algae;
(leading to) eutrophication;
increase in microorganisms feeding on dead plants / algae;
leading to deoxygenation;
increased nitrate in drinking water;
causing human illness 4
[12]
10. (a) (i) lower light intensity limits rate of photosynthesis;
lower light duration limits total photosynthesis;
lower temperature limits rate of photosynthesis;
fewer products/use of stored products decreases growth rate;
for 2 factors not explained, allow 1 mark. max. 3
(ii) carbon dioxide, burning oil/ coal/ gas/compressed gas;
heat, use of heaters/undersoil heaters;
light, lights on for extra hours;
fertilisers, add regularly; max. 2
(b) 20-25°C;
greatest difference between the rate of photosynthesis and
the rate of respiration; 2
[7]
11. (a) name of pest and predator/parasite;
method of killing pest; 2
Hyde Clarendon Sixth Form College 5
6. (b) pest and its parasites are likely to occur in same place/more likely
to find suitable parasite;
if climate similar parasite more likely to survive;
laboratory conditions to study possible effect on native species;
as may compete with other species for habitat/food;
may parasitise other species/be preyed on by other species;
large numbers increases chance of successful introduction;
decline in pest indicates control is taking place/control is successful;
numbers of pest must be reduced so that amount of damage is economically
acceptable;
stable coexistence means no need for further introduction
of parasite/no additional measures are required;
pest needs to be kept at low levels to prevent damage to crop;
if pest dies out parasite may become a pest itself/if parasite dies out it
will have to be reintroduced; 8
(c) non-target species not killed/host specific;
no toxic residues/no accumulation up the food chain;
no resistance;
no resurgence;
continuous control;
only one application necessary/self perpetuating; 2
[12]
12. (a) Light / solar energy used for photosynthesis;
Synthesis of materials used in growth / storage;
Chemical energy stored / energy in biomass; 3
(b) (i) Fewer nutrients available;
Limited light penetration;
No organic matter from terrestrial sources;
Other limiting factor explained; max 2
(ii) Reason for difference, e.g. plants smaller / less vegetation / crops
harvested / grazing;
Explanation linked to difference, e.g. less area for photosynthesis / not
structured into layers / nutrients removed in harvesting; 2
(c) Desert, because lowest productivity;
few plant species so few animal species able to feed on them;
or, desert because abiotic conditions extreme / named factor;
few species adapted to extreme conditions / less stable food web; 2
[9]
Hyde Clarendon Sixth Form College 6
7. 13. (a) (i) glass allows light and heat through;
retains heat inside glasshouse;
limits wind/air movements; max 2
(ii) controls light entering glass house / shades plants from excess light;
controls heat entering glass house/prevents scorching; max 1
(iii) allows entry of carbon dioxide level;
prevents excess humidity;
limits spread of disease; max 1
(b) stomata close if water stressed;
(closed stomata) limits carbon dioxide absorption;
may wilt reducing surface area exposed to light; max 2
[6]
14. (a) (i) A = nitrogen is limiting so crop increases with nitrogen added;
B = nitrogen is no longer limiting crop growth restricted by
other factors/ shading / carbon dioxide;
C = nitrogen apparently inhibiting growth/high nitrate causes
plants to lose water; 3
(ii) fertiliser costs yield sales net profit
125 x 120 = £150 4.8 x 200 = £960 £810
150 x 120 = £180 5.0 x 200 = £1,000 £820 2
(b) Advantage:
ions in readily available form;
effects relatively rapid;
easy to apply;
quantities applied can be controlled/measured; max 1
Disadvantage:
quickly leached;
more likely to cause pollution;
relatively expensive; max 1
[7]
Hyde Clarendon Sixth Form College 7
8. 15. (a) method 2 apparently more effective as fewer aphids by day 49;
fewer aphids per leaf gives less damage and more/larger cucumbers;
Or
differences in aphids are not significant;
method 1 less economic as space occupied by maize could be used
for more cucumbers;
Or
differences in aphids are not significant;
method 1 more economic as aphid control system is self sustaining; max 2
(b) advantages:
specific to one pest/ chemicals may kill pollinators/useful insects
application linked to life cycle of pest;
number of applications depends on survival of control organism/
self sustaining;
no residues harmful to health left on crop;
does not result in resistant varieties of pest; max 3
disadvantages:.
can only be used for glasshouse crops;
may create an imbalance in natural ecosystem;
may be labour intensive/costly to maintain;
have to retain some of the pest to maintain the control organism; max 3
(section max 4)
[6]
16. (a) Energy required for producing things required in crop production; 1
Credit examples such as tractors / fertilisers etc
(b) (i) Greater mechanisation/more intensive in US;
Involves greater energy input/example; 2
(ii) Bred/selected for efficient energy conversion; 1
Hyde Clarendon Sixth Form College 8
9. (c) Different species have different root lengths;
Mineral ions/water can be obtained from different depths;
Shade plants grow as well as those needing full sunlight;
Pests tend to be specific;
Pests will not destroy total crop in mixed system;
Less fallow time; max 2
[6]
hÕ17. (a) Maximum of 4 marks, two for suggestions and two for
explanations:
e.g. the fungus will not destroy other (native) species/is
specific;
so not damaging/killing endangered species/damage
Everglades/environment;
fungus will replicate itself;
so no need for expense of repeated applications. 4
(b) Maximum of ‘two marks for two suggestions:
e.g. claim that fungus only attacks cannabis plant might
be wrong/fungus might mutate back;
so fungus attacks crops;
fungus attacks (endangered) wild species. 2
[6]
18. (a) increase growth of both weeds and cereal crop;
inorganic nutrients/minerals not a limiting factor /
more inorganic nutrients available; 2
(b) removal of competition by weeds; 1
(c) effective use of machinery;
timing of harvest for max yield; 2
(d) use plants with smallest amount of unwanted material;
detail of cross pollination / select and repeat cross; 2
[7]
19. (a) (i) low toxicity to mammals / humans; 1
(ii) excess would run off into water courses;
lethal to aquatic organisms;
at low concentrations; 3
Hyde Clarendon Sixth Form College 9
10. (b) (i) only affects an insect that eats plant;
insecticide not diluted / concentration inside plant is high /
reduce the amount needed;
not leached into environment / non polluting; 2
(ii) gene incorporated into genome of plant;
produces toxin which affects insects that eats plant; 2
[8]
20. (a) wrong wavelength;
reflected;
miss chloroplast / chlorophyll;
(carbon dioxide concentration) another factor may be limiting; 2
(b) oxygen produced / carbon dioxide used;
per unit time; 2
(c) description of how temperature is changed / range of temperatures used;
how other factors kept the same / named factors controlled;
measure mass of given product in given time; 3
[7]
21. (a) loss of hedgerows;
since small fields impracticable for large machines;
soil more exposed to wind;
resultant increase in soil erosion (once);
reduction in diversity;
since smaller variety of niches/habitats;
since smaller variety of producers/plants
deeper rooted plants removed;
resultant increased soil erosion (once);
increased risk of large-scale crop failure/increased disease/increased
number of pest;
since large numbers of same crop species grown close to each other;
increased use of fertilisers result in eutrophication/damage to soil structure;
reduction of gene pool
(references to pesticides neutral) 4 max
(b) (i) bioaccumulation in gull (via food chain);
explanation in terms of organisms at higher trophic level eating
large numbers of organisms at lower trophic level; 2
(ii) different shaped molecules;
do not fit active sites of enzymes produced by decomposers 2
Hyde Clarendon Sixth Form College 10
11. (iii) resistant forms more likely to survive/non resistant forms die;
to breed/reproduce;
their genes/alleles more likely to be passed to next generation
(natural selection unqualified neutral) 3
[11]
22. (a) (Light intensity)
When light intensity is increased, rate of photosynthesis increases; 1
(b) (Carbon dioxide)
An increase of CO2 from 0.03 to 0. 12% nearly doubles the rate of
photosynthesis/ temperature change from 20 to 30° C only small increase in
photosyntesis;
More CO2 to convert/combine with RuBp (to GP);
More GP available to use with the products of the light
dependent reaction; 2 max
(c) Light and CO2 will be limiting factors;
increase temp will increase rate of respiration as well as photosynthesis/
net gain / cost to increase temperature not matched by increase in
photosynthesis/yield/not cost effective; 2
(d) Any two from
Misses chloroplast/
Wrong wavelength/
reflected; 2
[7]
23. (a) does not need repeated treatment;
maintains low level of pest/ not allowing pest numbers to rise
(above economic threshold); 2
(b) only feeds on pest species/does not affect non-target population;
can live in environment of the host/ establish/maintain its population/
can reproduce under conditions of use/active during the season; 2
(ignore references to effect on crop)
[4]
24. (a) (i) (clover) gains ammonium compounds/ammonia/amino acids; 1
(reject nitrogen/nitrates) (accept nitrogen compounds)
(ii) (bacteria) get ATP/carbohydrate/organic compounds; 1
Hyde Clarendon Sixth Form College 11
12. (b) (max 2 marks for each advantage and explanation)
clover is a natural/green fertiliser; }
adds organic material/humus to the soil; }
clover adds nitrogen compounds/nitrates; }
needed by crop for protein production; }
clover releases minerals slowly; }
less run-off/less pollution; }
clover cheaper than fertiliser; }
therefore more profitable/fertilizer applied several times; } 4 max
[6]
25. (a) rate of photosynthesis increased;
normal atmospheric concentration a limiting factor;
more/faster production of biomass or sugars / more products of
photosynthesis transported to fruits; 2 max
(b) (increased temperature) increases rate of respiration;
rate of photosynthesis too low to replace respiratory loss 2
(c) lower water potential of nutrient solution;
less water absorbed into roots (by osmosis); 2
(not: water lost from roots)
[6]
26. (a) faster rate of growth;
reduced movement / lower respiratory losses;
more sustained/plentiful food supply;
high survival rate, e.g. due to protection from predators;
reduced fishing effort; 2 max
(b) activity of decomposers / microorganisms;
reduced oxygen content;
few species adapted to low oxygen conditions; 2 max
(c) not all fishmeal digestible / consumed;
used in respiration for movement / other valid use;
synthesis of biomass inefficient / involves energy or heat loss; 2 max
[6]
Hyde Clarendon Sixth Form College 12
13. 27. (a) 250 1
(b) grebes eat many fish;
accumulation of many doses;
insecticide not excreted / not biodegradable / remains in fat stores; 2 max
(c) (i) concentration which kills 50% / a certain percentage; 1
(ii) alter tertiary structure of proteins;
disrupt enzyme activity;
detail described, e.g. non-competitive inhibition / change to active site;
reference to nerve or brain damage, or kidney failure; 3 max
[7]
28. (a) (i) presence of -COOH group; 1
(ii) similar structure so fit same protein/receptors; 1
(b) 2,4-D adds to effect of IAA (already present) / affects all cells;
stimulates growth in parts other than growing points / stimulates
uncontrolled growth / makes walls of cells stretch too much /
makes growth outstrip nutrient availability; 2
[4]
29. (a) (i) presence of grass causes less nutrients/minerals/nitrates/
ammonium ions to be leached; 1
(do not allow references to less nitrogen)
(ii) clover contains nitrogen-fixing bacteria;
(do not allow references to nitrifying bacteria)
decomposition (of ploughed clover) introduces nitrates/
ammonium ions into soil; 2
(b) (i) minimal effect/no significant effect on yield/small
increase up to 25 kg ha–1;
increase in protein content of grain with all
fertiliser applications; 2
(ii) (37 ÷ 44 =) 0.84 : 1.0 (allow 0.8 : 1); 1
[6]
30. (a) limited genetic diversity in modern varieties / greater genetic
diversity in old varieties / older varieties contain other (useful)
alleles/genes;
old varieties useful for future breeding programmes; 2
Hyde Clarendon Sixth Form College 13