SB9: Exchange and Transport in Animals

Question 1

SB9a
1) State what is meant by the ecological terms community, interdependence, population and habitat.
2) Give examples of an ecosystem, a community, a population and a habitat.
3) Describe the organisation of the components of an ecosystem (including populations, communities, habitats and abiotic factors).

Answer 1

1) Community: all the organisms that live and interact in an ecosystem.
Habitat: where an organism lives.
Interdependence: all species depend on other species in some way.
Population: all the members of a single species that live in a habitat.
2) Examples of populations include the human population, the population of apple trees, or total population of deer in a forest. Examples of ecosystems include: a swamp, ocean or rainforest. Examples of habitats include: forest, grassland, and desert. An example of a community is a forest of trees and undergrowth plants, inhabited by animals and rooted in soil containing bacteria and fungi.
3) There are 4 levels of ecological organisation. It starts at the lowest level: individual organisms, then populations, then communities, then finally to the whole ecosystem. Individual species of living organisms include every single plant and animal species that can be found on our planet. A habitat is where the organism lives, and the abiotic factors are non-living parts of the environment that can affect organisms.

Question 2

SB9a
1) Describe how the interdependence of organisms in an ecosystem allows their survival.
2) Explain how to estimate population size, including the use of quadrats.

Answer 2

1) Interdependence: all species depend on other species in some way. All organisms that live in an ecosystem depend upon each other, for food, protection, shelter, etc, in order to survive.
2) Population size can be estimated by taking samples using a quadrat. Quadrants are placed randomly in the area, and the number of individuals in each quadrat is counted. Then, the following formula is used:
Population size: number of organisms in all quadrats x (total size of area where organism lives / total area of quadrats)

Question 3

SB9c
1) What is an abiotic factor?
2) Give examples of abiotic factors.
3) Explain how communities are affected by abiotic factors (temperature, light, water, pollutants).

Answer 3

1) Abiotic factors are non-living parts of the environment that can affect organisms.
2) Examples of abiotic factors include: light intensity; carbon dioxide concentration; temperature; moisture levels; intensity and direction of the wind; and the pH and mineral content of the soil.
3) Water: few organisms can survive a drought for long. Most land plants cannot survive if their roots are underwater for long. If the climate changes resulting in more flooding or more drought, then many species in different communities may die out.
Temperature also affects the distribution of organisms. E.g. polar bears are adapted to living in cold regions, well cacti are adapted to living in hot deserts. However, all organisms have adaptations that make them suited to life at particular temperatures. A long-term rise or fall in temperature in an ecosystem will change the distribution of some organisms and so affect the whole community.
Light is essential for plants and algae to grow. In the oceans, most algae can only get enough light within 30m of the surface. On land, light is limited within forests. In dense forests, few plants can grow on the forest
Substances that cause harm in the environment are pollutants and cause pollution. Many human activities release pollutants. These can poison organisms or cause harm to the organisms in other ways such as plastics being eaten by fish and other organisms.

Question 4

SB9c
Explain how to investigate the effect of abiotic factors on the distribution of organisms using belt transects.

Answer 4

Quadrats are placed along a line in a habitat, and the abundance of organisms is measured as well as the abiotic factors in each quadrat position. Changes in abundance can show which abiotic factor has the greatest affect on the organism.

Question 5

SB9d
1) What is a biotic factor?
2) Give examples of biotic factors.
3) Describe how competition can affect communities.

Answer 5

1) Biotic factors are the organisms in the ecosystem that affect other living organisms.
2) Examples of biotic factors include: competition for resources or habitat; the amount of disease; the availability of food; predation (ie. predators).
3) If two species compete for the same resource(s) and one is better adapted to take advantage of these resources, then that species will outcompete the other. This may continue until there are too few members of the lesser adapted species to breed successfully.

Question 6

SB9d
1) Describe how predation can affect communities.
2) Explain how predator–prey cycles affect communities.
3) Explain how the structure of a community can affect biodiversity.

Answer 6

1) In balanced ecosystems, predators catch enough prey to survive but not so many that they wipe our the prey population. If a new predator is introduced to the ecosystem, it may become unbalanced.
2) - The number of predators increases when there is more prey because there is more food
- The number of prey reduces since there are more predators, meaning that more prey get eaten
- The number of predators reduces because there is less prey as there is less food
- The number of prey increases since there are less predators, so less prey get eaten
3) Larger numbers of species a higher abundances of species leads to higher species diversity and biodiversity.

Question 7

SB9i
1) Define the term ‘food security’.
2) Describe the effect of increasing human population on food security.
3) Describe the effect of new pests and pathogens on food security.

Answer 7

1) Food security means having access to enough safe and healthy foods at all times.
2) Food security is reduced by the increasing human population. A higher birth rate means that there is less food for each person.
3) The use of pesticides on crops may lead to the evolution of new pests that are resistant to the pesticide. The resistant pests will not be killed by the pesticides and will damage crops, leading to lower yields and less food produced.

Question 8

SB9i
1) Describe the effect of animal farming and consumption on food security.
2) Describe the effect of human-induced environmental change on food security.
3) Describe the effect of sustainability issues [production of biofuels, cost of agriculture] on food security.
4) Explain what ‘sustainability’ means

Answer 8

1) Overfishing wild fish may mean that there aren’t enough fish available to catch in the future.
An increased amount of animal farming would reduce food security. This is because, for a given area of land, less food is produced by rearing livestock than growing crops and because livestock must be for crops that could be given directly to humans.
2) The earth’s temperature is increasing as a result of human activities. The increasing temperature may reduce crop growth or lead to other forms of climate change (eg. changing rainfall patterns) that reduce crop growth. This may reduce crop yields, which may mean we are unable to grow enough (safe, nutritious) food to feed the growing human population.
3) Biofuels are more sustainable than fossil fuels, but can have a negative impact on food security. This is because growing biofuels takes up land that could be used for food crops. As land becomes more and more expensive and agriculture is requiring more inputs e.g. fuel for transport and crops are becoming cheaper, farmers are moving professions in search of greener pastures. This threatens food security.
4) Sustainability is meeting the needs of today’s population without affecting the ability of future generations to meet their needs.

Question 9

SB9h
1) Define the term conservation.
2) Explain what is meant by reforestation.
3) Give examples of animal conservation.

Answer 9

1) Conservation is when an effort is made to protect a rare or endangered species of habitat.
2) The replanting trees in the of areas of a forest which have previously been damaged or destroyed.
3) Animals are conserved through breeding programmes. For example, pandas are an endangered species, and there are breeding programmes to protect them. There is also a development of endangered habitats that are suitable for the endangered species to thrive in.

Question 10

SB9h
1) Explain how animal conservation can benefit biodiversity.
2) Explain how reforestation can benefit biodiversity.
3) Explain how reforestation can benefit a country’s society

Answer 10

1) If one species goes extinct then the food chain that it is a part of will be disrupted. Protecting one species will help to protect the other species that feed on it. Efforts to protect one species may involve the protection of the habitat of that species, in which case other species within the habitat will also be protected.
2) Increased forest cover is likely to increase the biodiversity of the area, as many more species will be able to survive in the forested areas.
3) - Increased biodiversity may bring more money to a country through ecotourism.
- Ecotourism and the reforestation programmes themselves will create new jobs, so more people will have an income.
- Reforestation may also help to protect species that are important to the county’s cultural heritage, or plants that could be beneficial as medicines.
- By reforesting the land, the soil will be less exposed to the rain and Sun, so there will be less soil erosion and drought. This will help to increase soil quality and make it easier for farmers to grow crops on the land. This in turn will mean that there will be more food available for the population.

Question 11

SB9g
1) Define the term eutrophication.
2) Describe examples of the introduction of non-indigenous species.
3) Describe the advantages of fish farming.

Answer 11

1) Eutrophication is the addition of more nutrients to an ecosystem than it normally has.
2) One example is the introduction of cane toads to Australia.
Cane toads are native to South and Middle America but were introduced into Australia in the 1930s to control pests that ate sugar cane, an important crop.
Since their release, the toad population has grown to over 200 million and spread across the country. They have several impacts on biodiversity:
- The cane toads are poisonous to animals that eat it, reducing the number of predators
- The toad eat insects, reducing their population
- It competes with native species for food
3) - The ability to selectively breed fish to ensure high quality, fast-growing fish
- The ability to protect against predators
- The ability to control water quality (many wild-caught fish have significant levels of pollutants such as mercury in their flesh)
- The ability to control feeding to ensure rapid growth

Question 12

SB9g
1) Explain how fish farming can affect ecosystems and biodiversity (state 4).
2) Explain how the introduction of species can affect ecosystems and biodiversity (state 3).
3) Explain how eutrophication can affect ecosystems and biodiversity.

Answer 12

1) - Other species may swim into the nets and become trapped and die, reducing the number of species and therefore biodiversity in the water.
- Farmed fish may escape into the wild and cause the death of indigneous species, leading to a reduce in biodiversity.
- The fish farms may act as a breeding ground for parasites which could get out and infect and kill wild populations of fish, reducing biodiversity.
- The food given to the fish or the waste produced by the fish may leak out into the water and increase the nutrient content of the water. This leads to eutrophication in the same way fertilisers in the water do.
2) - The new species may outcompete native species for resources or food or shelter
- They may bring new diseases to the country, which could infect or kill large numbers of native species
- The may feed or prey on native species
3) - Many fertilisers contain nitrates. If too much fertiliser is applied to the fields, it will run off the fields when it rains into nearby water sources, leading to eutrophication.
- Eutrophication is where excess nitrates in the water cause algae to grow fast and block out light.
- This means that less light reaches plants, which then can’t photosynthesise and so die.
- The microorganisms that feed on dead plants increase in number and use up the oxygen in the water. This means that there is not enough oxygen available for other organisms, e.g. fish, which then also die.
- The death of all of these organisms reduces biodiversity.

Question 13

SB9k
1) Give examples of decomposers.
2) Define the term decomposer.
3) Describe the carbon cycle.

Answer 13

1) Some examples of decomposers are fungi and bacteria.
2) Decomposers are bacteria and fungi, which break down dead organisms in a process called decomposition or rotting.
3) Carbon is taken out of the atmosphere by photosynthesis. It is passed on to animals and decomposers by feeding. It is returned by respiration; in plants, in animals and in decomposing microorganisms. In addition, it is returned (in increasing amounts) by the combustion of fossil fuels.

Question 14

SB9k
1) Identify the key processes in the carbon cycle.
2) Explain how carbon is cycled through the biotic and abiotic components of an ecosystem.
3) Explain the importance of the carbon cycle

Answer 14

1) Photosynthesis is a process where the carbon starts as carbon dioxide and ends as glucose. It is important because photosynthesis convert carbon dioxide from the air into carbon compounds in plants, making a carbon available for use in the ecosystem.
Respiration is a process where the carbon starts as glucose and ends as carbon dioxide.
The process of combustion (burning) is where the carbon starts as fuel (eg. methane or wood) and ends as carbon dioxide.
The process of decomposition (decay) is where the carbon dioxide is returned back to the atmosphere when the microorganisms involved in decay respire.
2) Carbon moves through ecosystems in two cycles that overlap. In the biotic cycle, it moves between living things and the air. In the abiotic cycle, it moves between the air, ground, and oceans.
Carbon is taken out of the atmosphere by producers via photosynthesis. It is passed on to animals and decomposers by feeding. It is returned to the atmosphere by respiration; in plants, in animals and in decomposing microorganisms.
3) A balanced carbon cycle is essential. Carbon is a major component in carbohydrates, fats and proteins. The carbon cycle involves the exchange of carbon between living organisms (biotic) and their atmosphere (abiotic). In the carbon cycle, carbon is constantly removed from, and returned to, the environment. It balancing photosynthesis and respiration, and removes of wastes by decomposition.

Question 15

SB9f
1) Define the term ‘parasitism’.
2) Define the term ‘mutualism’.
3) Describe how parasites are dependent on their hosts.

Answer 15

1) Parasitism is where parasites live in or on a host organism taking what it needs to survive without any benefit to the host.
2) Mutualism is where there is a relationship between two organisms from which both organisms benefit.
3) Parasitism is the relationship between a parasite and its host.
The parasite benefits by gaining nutrients and/or energy from the host.
Parasites often have a very limited metabolism and cannot survive out of contact with a host.
The most effective parasite is one that does not kill its host completely. This helps ensure a continues supply of nutrients or energy.

Question 16

SB9f
1) Describe how hosts are harmed by parasites.
2) Identify parasites in examples.
3) Explain how mutualists benefit from their relationship.

Answer 16

1) The host is harmed by losing energy and/or nutrients.
2) An example of a parasitic relationship is fleas being a parasite to mammals (e.g. dogs). The fleas feed on the host’s blood but don’t provide anything to the host in return.
3) In mutualism, an example is bees and flowering plants have a mutualistic relationship. Bees obtain nectar for food and spread the flower pollen from one flower to another, which helps reproduction in plants.

Question 17

SB9c - Core Practical
1) What is the aim of the quadrats and transects core practical?
2) What is the method of the quadrats and transects core practical?

Answer 17

1) Investigate the relationship between organisms and their environment using field work techniques, including quadrats and belt transects.
2) A. Peg out a long tape measure (at least 20m) on the ground, starting where there is no shade and ending in heavy shade. This is the transect line.
B. You will need to make measurements at regular intervals along the transect line. Decide on your measurement intervals, which may depend on how long the line is and how much time you have to record information.
C. Place the top left-hand corner of the quadrat at a measurement point on the transect line.
D. Measure the abiotic factors at that point and record them.
E. Record the abundance of your selected plants in the quadrat.
F. Repeat steps C to E at each measurement point along the transect.

Question 18

SB9c - Core Practical
1) Describe a disadvantage of measuring at short intervals along a long transect
2) Describe a disadvantage of measuring at long intervals.
3) Give a reason why the quadrats are placed at regular intervals along a transect and not randomly

Answer 18

1) Measuring at short intervals along a long transect will take too long.
2) Measuring at long intervals could mean that you will miss gradual changes in distribution of organisms or abiotic factors, so the relationship between them will not be as clear.
3) This avoids unconscious bias; if you sample randomly, you cannot be sure that you’ll get a gradual change in abiotic factors or organisms.

Question 19

SB9c - Core Practical
1) Describe how you would identify the plants in the investigation
2) How can you improve the accuracy of the core practical?
3) What is the equation used to calculate an estimate of the total population of a species?

Answer 19

1) To identify the plants, use an identification or field guide to grassland plants.
2) Sample a greater number of 1m squared areas.
3) population = mean number of individuals per quadrat x (area of habitat / area of quadrat)

Question 20

SB9j
1) Give examples of materials that cycle through ecosystems.
2) Describe the processes by which water cycles through abiotic parts of an ecosystem.
3) Describe the processes by which water cycles through living organisms [humans, plants].

Answer 20

1) Examples include substances such as water, carbon and nitrogen compounds.
2) Liquid water from the surface of the Earth (in oceans, lakes, etc.) evaporates as water vapour into the air. The water vapour condenses as water droplets, forming clouds, and may freeze
to form hail or snow. Rain, hail or snow fall to the ground, with hail or snow melting to water. The water forms rivers, lakes, and oceans.
3) Humans take in water through food and drink. Water leaves the body through urine, faeces (poo), evaporation of sweat, water vapour and breathing.
Plants soak up large amounts of water through their roots. The water then moves up the plant and evaporates from the leaves in a process called transpiration.

Question 21

SB9j
1) Describe how drinking water is produced where water is plentiful.
2) Explain how drinking water can be produced by desalination in areas of drought.
3) Explain why water is important to living organisms.

Answer 21

1) To make potable water in areas with plenty of water, the water must be treated with chemicals and filtered, to remove dirt, pathogens and any toxic substances (such as metal ions). The water may also be treated to improve the taste, by removing other non-toxic substances.
2) By boiling sea water in a vessel so that the water evaporates to form steam and leaves the salt behind. The steam then enters a pipe connected to the vessel with a partially permeable membrane at a high pressure. The high pressure will cause the water molecules to move in reverse direction to osmosis from a higher salt concentration to a lower salt concentration. The water is forced through the membrane, leaving the salt behind and allowing pure water to be collected for drinking.
3) Water makes up the majority of most organisms’ body mass. Much of the cell cytoplasm is water, and reactions of substances often take place there. Organisms are continually losing water to the environment, so they need to take in more water to replace it.

Question 22

SB9l
1) Describe how plants use nitrates.
2) Describe the different roles of bacteria in the nitrogen cycle.
3) Explain how fertilisers increase the nitrate content of the soil.

Answer 22

1) Plants contain nitrogen compounds in proteins and DNA. To grow well, plants need nitrogen to make more of these compounds.
2) Bacteria in the soil or in plant roots convert nitrogen gas from the environment into solid nitrogen molecules that plants can utilize in the soil. The bacteria within the nodules convert free nitrogen to nitrates, which the host plant uses for growth.
3) Artificial fertilisers contain nitrogen compounds which are soluble and dissolve in soil water. This helps to increase the soil fertility.

Question 23

SB9l
1) Explain why bacteria is important for soil fertility.
2) Why do farmers use plants that have a mutualistic relationship with nitrogen fixing bacteria in their crop rotation cycle?
2) Explain how crop rotation can increase the nitrogen content of the soil.

Answer 23

1) Soil fertility is maintained by decomposers such as bacteria in the soil. These organisms release nitrogen compounds when they decompose dead plants and animals and their wastes.
2) Farmers use plants that have a mutualistic relationship with nitrogen fixing bacteria to increase nitrate and ammonia levels in the soil because nitrogen fixing bacteria live in colonies on the roots of certain plants (such as pea and bean plants). Nitrogen fixing bacteria produce nitrates from nitrogen in the soil atmosphere.
2) Farmers often grow crops such as peas or beans as these crops can form nitrates, as they have nitrogen-fixing bacteria in their roots. This will increase the nitrate content and fertility of the soil.
Leguminous crops are planted, that have nitrogen-fixing bacteria in root nodules, which fix nitrogen gas. This will increase the nitrate content and fertility of the soil.
Crop plants will take in the nitrates and use it to make proteins for growth. One year the farmer will grow one of these crops and then the following years, the farmer will plant another crop in the nitrate rich soil. Growing different crops each year in a cycle is called crop rotation.

Question 24

SB9c - Core Practical
1) What is the independent, dependent and control variables for the quadrats and transects core practical?
2) What are the safety hazards for the quadrats and transects core practical?

Answer 24

1) The independent variable is the location that the quadrat is placed. The dependent variable is the number of plants counted.
The control variables include: the size of quadrats, the number of repetitions in each site, the method of counting and the coordinate system at each site.
2) - Follow local rules on working in an outside environment, and wash hands after the lesson.
- When any fieldwork is undertaken, work in groups and be aware of any hazards in that specific environment.
- Sensible footwear and clothing should be worn. If the weather is hot and sunny, sunscreen and hats are required.

Question 25

SB9m
1) Describe ways that food is preserved.
2) Explain why food is preserved in different ways [reducing temperature, water content and oxygen availability].
3) Describe how compost is made.

Answer 25

1) - Reducing temperature, for example in fridges and freezers.
- Reducing water content, for example by salting and then drying meat to make ham or salami.
- Irradiation of packaged food to kill decomposers
- Reducing oxygen, for example storing foods in oil. Foods that easily decay (eg. salad leaves) are often packaged in an unreactive gas, such as nitrogen.
2) - Colder temperatures will affect decomposing organisms so that they are less active. Therefore, food is kept in a fridge or freezer.
- Low levels of water will mean that the decomposers cannot survive. Therefore, water content is reduced by salting the food and drying it,
- Oxygen is needed for many decomposers to respire, to enable them to grow and multiply. Therefore, reducing oxygen slows down decay.
3) Compost is formed by collecting garden waste into a heap, and keeping it until it is well-decayed.

Question 26

SB9m
1) Explain how the rate of decomposition in composting can be increased.
2) Calculate the rate of decay in food and compost.

Answer 26

1) Colder temperatures will affect decomposing organisms so that they are less active. At extremely high temperatures, decomposers will be killed, therefore decomposition will stop. Therefore, the temperature must be optimal for the organisms to survive. High levels of water will increase the rate of decomposition, as decomposers tend to secrete enzymes onto decaying matters, then it absorbs any dissolved molecules.
High levels of oxygen will encourage decomposers to survive as they require oxygen to respire and survive.
2) rate of decomposition = mass lost / number of days

Question 27

SB9m
Explain why reducing the water content of food will preserve it

Answer 27

By reducing the water content, it reduces the number of organisms that can reproduce. As there is a reduction of organisms, this slows down the decay process, and preserves the food.

Question 28

SB9e
1) Name two indicator species and what they indicate (beginning with ‘L’ and ‘B’)
2) Explain why indicator species are evidence for a particular level of air or water pollution.

Answer 28

1) Lichen (that grow on trees and buildings) can be used as an indicator species for air pollution. For example, a high abundance of lichen indicates clean air. The abundance (number) and type of lichen species growing at a particular location can be monitored to determine how clean the air is.
Another indicator species for air pollution is blackspot fungus, which grows on rose leaves.
2) For air pollution:
Lichen can be used as an indicator species because lichens are highly sensitive to sulfur dioxide concentrations in their environment. Sulfur dioxide is one of the air pollutants released from car exhausts and power stations (i.e. during the combustion of fossil fuels).
Black spot fungus is also sensitive to sulphur dioxide concentrations and its presence indicates clean air. A high abundance of black spot fungus indicates clean air. Black spot fungus forms on leaves, and looks like black spots.
For water pollution:
Stonefly (stonefly nymph), larvae (mayfly larva) and water shrimps, caddis fly larva can only survive when the level of water pollution is low as very sensitive to the oxygen levels. If these animals are found in a river, it shows that the river is clean.
However, some animals are adapted for surviving in polluted conditions and can survive in low oxygen concentrations. Examples are blood worms and sludge worms. The presence of these species indicates there is a high level of water pollution.

Question 29

SB9e
1) Describe the advantages of using indicator species as evidence for the level of pollution.
2) Evaluate the use of indicator species for assessing the level of pollution.

Answer 29

1) - Using indicator species is a fairly simple and cost-effective method of determining whether a habitat is polluted or not
- By looking at the number and type of indicator species present in various locations, scientists can determine how clean or how polluted the air is.
Describe the disadvantages of using indicator species as evidence for the level of pollution.
- It can’t give accurate numerical (quantitative) figures for exactly how much pollution is present.
- The presence or absence of indicator species can also be affected by factors other than pollution, for example the presence of predators or disease
2) If more detailed information on pollution levels is required, non-living indicators can be used instead. For example:
- Dissolved oxygen meters and chemical tests can be used to very accurately determine the concentration of dissolved oxygen in the water and can be used to show changes in levels of water pollution over time
- Electronic meters and laboratory tests can be used to very accurately determine the concentration of sulfur dioxide in the air and can be used to show changes in levels of air pollution over time

Question 30

1) Explain why increased nitrate levels in the soil improve crop yield
What type of microorganisms are involved in the following stages of the nitrogen cycle:
2) Nitrogen being transferred from dead animals and plants to ammonia
3) Nitrogen being converted from ammonia into nitrates

Answer 30

1) Nitrates are needed to make proteins which are needed for growth.
2) Decomposers
3) Nitrifying bacteria

Question 31

SB9b
1) Describe the energy transfers that occur between trophic levels.
2) Explain how energy is transferred at each trophic level, including making some energy less useful.
3) Explain how energy transfers limit the length of a food chain.

Answer 31

1) Producers are eaten by primary consumers, which in turn may be eaten by secondary consumers and then tertiary consumers. Consumers that kill and eat other animals are predators, and those eaten are prey. In a stable community the numbers of predators and prey rise and fall in cycles.
2) Only some of the energy in the biomass of the prey is transferred to the predator. This is due to the following reasons: not all of the organism is eaten; not all of the organism can be digested; movement; respiration; transferred to the surroundings as heat.
3) Some energy is transferred to less useful forms at each trophic level. This affects the number of organisms at each trophic level, limits the length of a food chain and determines the shape of a pyramid of biomass in an ecosystem

Question 32

SB9b
1) Explain how energy transfers determine the shape of pyramids of biomass.
2) Calculate the efficiency of energy transfer between trophic levels.
3) Calculate the percentage of biomass transferred between trophic levels.

Answer 32

1) If the biomass of all the organisms at each trophic level is measured, we can display them in a pyramid of biomass. This has the producers at the bottom, and the tertiary consumer at the top.
2) Energy transferred to biomass / total energy supplied to organism
3) (predator biomass / prey biomass) x 100

Question 33

Explain what belt transects are and how they can be used

Answer 33

Throughout some areas, there can be changes in the physical conditions
For example, there may be changes in altitude, soil pH or light intensity
When investigating the species distribution in these kinds of areas sampling is appropriate
Methods using transects can help show how species distribution changes with the different physical conditions in the area
A transect is a line (usually formed by a measuring tape), along which samples are taken
One form of transect is a belt transect. For a belt transect:
Lay out a measuring tape in a straight line across the sample area
Place quadrats at regular intervals along the tape and record the abundance of each species within each quadrat
Another simpler form of transect is a line transect. For a line transect:
Lay out a measuring tape in a straight line across the sample area
At equal distances along the tape record the identity of the organisms that touch the line
This method only measures which species are present in the area and should not be used to measure the abundance (number of individuals) of a particular species

Question 34

Explain why the gardener believed that the gardening society website is a good source of information

Answer 34

The content is likely written by experts and checked using peer review, making it a reliable source.

Question 35

1) Explain a possible cause of eutrophication
2) What factors should be controlled when sampling a habitat

Answer 35

1) The run off of fertilisers causes a build up of nitrates in the water.
2) Sample at the same time of day; sample for the same length of time; use the same equipment and techniques; same time period between first and second sample; same marking process; do not harm organisms when sampling.