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
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
This document discusses APIs and protocols. It defines that an API is a set of routines, data structures, classes and protocols to support application development, often across domains. A protocol is a standard or convention to control connections, communication and data transfer between computing endpoints, often within the same domain. The document provides examples of how APIs allow applications and systems to integrate and work together.
La pandemia de COVID-19 ha tenido un impacto significativo en la economía mundial. Muchos países experimentaron fuertes caídas en el PIB y aumentos en el desempleo debido a los cierres generalizados y las restricciones a los viajes. Aunque las vacunas ofrecen esperanza de una recuperación económica en 2021, el camino a seguir sigue siendo incierto dado el riesgo de nuevas variantes del virus.
The presentation discusses linked data and its potential impact on libraries. Linked data uses URIs and HTTP to identify things on the web and link related resources. It enables libraries to publish structured data on the web and connect their resources to other data sources. While challenging, linked data offers a way for libraries to share data on the web of data and transition from cataloging to "catalinking", connecting their resources on the semantic web.
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
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
This document discusses APIs and protocols. It defines that an API is a set of routines, data structures, classes and protocols to support application development, often across domains. A protocol is a standard or convention to control connections, communication and data transfer between computing endpoints, often within the same domain. The document provides examples of how APIs allow applications and systems to integrate and work together.
La pandemia de COVID-19 ha tenido un impacto significativo en la economía mundial. Muchos países experimentaron fuertes caídas en el PIB y aumentos en el desempleo debido a los cierres generalizados y las restricciones a los viajes. Aunque las vacunas ofrecen esperanza de una recuperación económica en 2021, el camino a seguir sigue siendo incierto dado el riesgo de nuevas variantes del virus.
The presentation discusses linked data and its potential impact on libraries. Linked data uses URIs and HTTP to identify things on the web and link related resources. It enables libraries to publish structured data on the web and connect their resources to other data sources. While challenging, linked data offers a way for libraries to share data on the web of data and transition from cataloging to "catalinking", connecting their resources on the semantic web.
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 document contains a chapter on biodiversity from a biology textbook. It includes formative and summative practice questions on topics like organisms, ecosystems, food webs, and human impacts on biodiversity. Sample questions are provided on classifying organisms as vertebrates or invertebrates, comparing monocots and dicots, and describing interrelationships between producers, consumers, and decomposers in an ecosystem.
This document is a mark scheme for a biology exam that provides guidance to teachers on how to award marks to student responses. It indicates the key points examiners were looking for in responses to each question, such as defining terms, describing processes, and stating relationships. The mark scheme also notes that examiners considered acceptable alternative answers beyond what is written. It is intended to be read along with the exam question paper and exam report to aid in marking consistency.
This document contains answers to objective, structured, and essay questions. For the objective questions, the answers provided are letters A through D. The structured questions address topics like population calculations, causes of water pollution, and reasons for declining fish populations. The essay questions discuss pioneer species adaptations and factors affecting dissolved oxygen levels in lakes.
The document provides information on the key concepts of ecology. It discusses ecology as the study of organisms in relation to their environment, including their relationships with each other and non-living components. Some key abiotic and biotic factors that influence organisms are described. The document also outlines different types of ecosystems and communities, and explains concepts such as niche, population, food webs, trophic levels, and energy flow through ecosystems.
This document contains a biology exam question with multiple parts about plant structure and function. It provides the questions, expected answers, and additional guidance for marking. The question covers topics like leaf structure, plant transport systems, photosynthesis, and factors affecting plant growth. Marking schemes allocate points for identifying specific plant structures or explaining their functions. Guidance notes indicate what level of detail is required to earn marks.
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.
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.
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 document contains a chapter on biodiversity from a biology textbook. It includes formative and summative practice questions on topics like organisms, ecosystems, food webs, and human impacts on biodiversity. Sample questions are provided on classifying organisms as vertebrates or invertebrates, comparing monocots and dicots, and describing interrelationships between producers, consumers, and decomposers in an ecosystem.
This document is a mark scheme for a biology exam that provides guidance to teachers on how to award marks to student responses. It indicates the key points examiners were looking for in responses to each question, such as defining terms, describing processes, and stating relationships. The mark scheme also notes that examiners considered acceptable alternative answers beyond what is written. It is intended to be read along with the exam question paper and exam report to aid in marking consistency.
This document contains answers to objective, structured, and essay questions. For the objective questions, the answers provided are letters A through D. The structured questions address topics like population calculations, causes of water pollution, and reasons for declining fish populations. The essay questions discuss pioneer species adaptations and factors affecting dissolved oxygen levels in lakes.
The document provides information on the key concepts of ecology. It discusses ecology as the study of organisms in relation to their environment, including their relationships with each other and non-living components. Some key abiotic and biotic factors that influence organisms are described. The document also outlines different types of ecosystems and communities, and explains concepts such as niche, population, food webs, trophic levels, and energy flow through ecosystems.
This document contains a biology exam question with multiple parts about plant structure and function. It provides the questions, expected answers, and additional guidance for marking. The question covers topics like leaf structure, plant transport systems, photosynthesis, and factors affecting plant growth. Marking schemes allocate points for identifying specific plant structures or explaining their functions. Guidance notes indicate what level of detail is required to earn marks.
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.
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.
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. 1. (a) Organic compounds of nitrogen / named example;
converted to ammonium compounds / ammonia;
by saprophytes / saprobionts / decomposers / equivalent;
to nitrites;
to nitrates;
by nitrifying bacteria / named bacteria;
uptake by roots; max 6
(b) (i) Nitrogen fixing bacteria / named e.g.;
in root nodules (of legumes);
convert nitrogen to ammonium / organic compounds (in legume);
released on decomposition;
and converted to nitrates; less need for fertiliser; max 4
(ii) Shorter food chain / less trophic levels;
will produce a greater yield of fish;
less energy lost between stages / more energy from producers;
(energy loss) in respiration / as heat;
fish prevent algal blooms / equivalent; max 3
[13]
2. (a) Mark for principle of placing quadrats at random;
marks for detail -
(method of) marking area out with grid/using tapes;
acceptable method of generating random numbers; e.g.
table/calculator; 3
(b) Any one correct change;
reason for diversity level;
explanation of how heather affects diversity; 3
(c) (i) Award two marks for 0.5 g m–2 yr–1;;
award one mark for answer without units
or 2.4 – 2.5 %; 2
(ii) Used for non photosynthesising/supporting organs;
eaten by grouse; 2
(iii) Younger plants have more shoots/provide more food;
Younger plants provide more cover;
Getting rid of old (unproductive) plants; max. 2
(d) (i) proteins/nucleic acids/amino acids/ATP/nucleotides;
(ii) ammonium/nitrate/nitrite;
+ – –
NH 4 NO 3 NO 2 [Formula must correspond if given] 1
Hyde Clarendon Sixth Form College 1
2. (e) Organic material/proteins to ammonia/ammonium compounds; 1
by saprobiotic/putrefying bacteria;
ammonia to nitrite;
nitrite to nitrate;
by nitrifying bacteria/named bacteria; max. 4
(f) In older stands, greater proportion of/more nitrogen in plants;
more lost when burnt: 2
[20]
3. (a) One mark for each correct column 2
Animalia/anim
al
Annelida/annel
id
Class
Order
Family;
Lumbricus
(L.) terrestris;
(b) (i) Enzymes are proteins;
large molecules so not reabsorbed;
are not used up in reactions (which they catalyse);
enzymes are not themselves digested; max. 2
(ii) Add starch to worm casts;
test for reducing sugars with Benedict’s / test for disappearance
of starch with iodine;
need for control with boiled worm casts / soil; 3
(c) Fungicide also killing earthworms;
earthworms break leaves down into smaller pieces;
making more surface for microbial action;
OR
soil fungi / fungal decomposers killed;
less decomposition of leaves; max 2
(d) (i) Nitrogen as inorganic ions/nitrate/ammonia / nitrite; 1
(ii) Nitrogen in waste products of metabolism/urea/uric acid /ammonia; 1
(ignore references to egestion)
Hyde Clarendon Sixth Form College 2
3. (e) (i) Any TWO from:
Protein/amino acid/nucleic acid/ATP / urea; 1
(ii) Decomposers/saprophytic/putrifying bacteria release ammonia;
ammonia → (nitrite) → nitrate;
(named) nitrifying bacteria / nitrification; 3
(f) (i) Reduces surface area minimising water loss; 1
(ii) Using food stores resulting in excretory nitrogen; 1
(g) Addition of nitrogen;
from excretion / decay / enzymes;
removal of carbon;
when lost as carbon dioxide / during respiration; max. 3
[20]
4. (a) ‘Slash’ / cutting down trees reduces photosynthesis;
Reduces removal of carbon dioxide from atmosphere;
‘Burn’ combustion releases carbon dioxide;
OR ‘Slash’ cutting down trees removes respiring organisms;
Reduces removal of carbon dioxide into atmosphere;
‘Burn’ / combustion releases carbon dioxide; max 2
(b) (Before clearing) soil exists / already produced;
(After clearing) recolonisation by new plants / seeds;
(Brings about) change in environment / soil;
(Allows) succession;
(Leading to) climax (community); max 3
(c) 1 Ammonium compounds from proteins / amino acids urea / N-containing;
2 Converted into nitrite;
3 Into nitrate; [Reject: Incorrect sequence once]
4 By nitrifying bacteria / correctly named;
5 Nitrogen-fixing bacteria;
6 Fix nitrogen from atmosphere / air;
7 Nitrate taken up by plants;
8 Nitrogen needed for protein synthesis / plant growth; max 6
Hyde Clarendon Sixth Form College 3
4. (d) Trees available as a sustainable resource;
Maintain habitats / niches / shelter;
Maintain diversity / avoid loss of species / protect endangered species.
Maintain stability (of ecosystem);
Maintain food chains / webs / supply of food;
Reduced loss of soil / erosion;
Reduced flooding;
Act as carbon sink / maintainO2and C02 balance reduce greenhouse effect
Reduce global warming;
Source of medicines;
[Ignore: eutrophication] max 4
[15]
5. (a) P – denitrification;
Q – Nitrogen fixation; 2
(b) Ammonia formed by decay/decomposition/putrefying/ammonifying/
by action of decomposers/saprobionts;
On nitrogenous waste/urea or nitrogenous compounds (e.g. proteins,
amino acids, DNA, ATP); 2
(c) Oxygen added / hydrogen removed; 1
Ignore references to electron loss
[5]
6. (a) collect a sample (of insects in each area) and mark unobtrusively/in
a way not harmful to insects;
release and allow time to re-integrate with rest of population/eq.;
collect second sample and count number marked;
number in population estimated by:
S1 × S2 /
nd
Number marked in 2 sample /
Total marked Population
=
Number marked in 2 nd sample second sample ;
4
Hyde Clarendon Sixth Form College 4
5. (b) (i) 1; 1
(ii) (p = ) 0.05/ 5%; 1
(ignore 95%)
(iii) value for χ2 exceeds critical value/ 125.8 > 10.8 ;
Results unlikely to be due to chance/ have a biological cause;
P <0.1% / < 5% ; 2 max
(c) (i) biomass respired/ GPP – respiration = NPP;
biomass lost as CO2; 2
(ii) more food for insects; 1
(iii) decomposers/ saprotrophs;
release enzymes and digest detritus/
substances found in detritus/ eq.;
absorb products of digestion/ suitable e.g. that relates to
candidates 2nd point;
respired and CO2 released;
used by plants in photosynthesis/ enters leaves; 4 max
[15]
7. (i) excessive use of fertilisers;
run-off /leaching; 2 max
(ii) 1. growth of algae/plants stimulated/increased;
2. death of algae/plants;
3. more bacteria/decomposers/decomposition;
4. respiration;
5. decomposers/bacteria remove oxygen;
6. animals die (because of lack of oxygen); 5 max
[7]
Hyde Clarendon Sixth Form College 5
6. (b) (i) 1; 1
(ii) (p = ) 0.05/ 5%; 1
(ignore 95%)
(iii) value for χ2 exceeds critical value/ 125.8 > 10.8 ;
Results unlikely to be due to chance/ have a biological cause;
P <0.1% / < 5% ; 2 max
(c) (i) biomass respired/ GPP – respiration = NPP;
biomass lost as CO2; 2
(ii) more food for insects; 1
(iii) decomposers/ saprotrophs;
release enzymes and digest detritus/
substances found in detritus/ eq.;
absorb products of digestion/ suitable e.g. that relates to
candidates 2nd point;
respired and CO2 released;
used by plants in photosynthesis/ enters leaves; 4 max
[15]
7. (i) excessive use of fertilisers;
run-off /leaching; 2 max
(ii) 1. growth of algae/plants stimulated/increased;
2. death of algae/plants;
3. more bacteria/decomposers/decomposition;
4. respiration;
5. decomposers/bacteria remove oxygen;
6. animals die (because of lack of oxygen); 5 max
[7]
Hyde Clarendon Sixth Form College 5