Biology Option C

What affects the distribution of plant species? (Abiotic)

Water, pH, Nitrogen, Light, Humidity, Wind, Latitude, Altitude, Carbon Dioxide, Salinity, Temperature, Day length

What affects the distribution of plant species? (Biotic)

Predators, Disease, Competition, Humans

What affects the distribution of animal species? (Abiotic)

Water, Nitrogen (DNA), pH, Light, Humidity, Wind, Breeding sites, Altitude, Oxygen, Carbon Dioxide, Salinity, Temperature, Tide, Territory, Latitude

What affects the distribution of animal species? (Biotic)

Predators, Diseases, Competition, Food Supply, Humans

What is a living factor?

A living factor is a resource or environmental condition that limits the distribution of an organism or population of organism in an ecosystem.

What does it mean by ‘optimal range’?

This is the best living condition for an organism considering abiotic and biotic tolerance.

How have Oak and Maple trees adapted to live in temperatures as low as -40°C?

They synthesise ‘antifreeze proteins’ which prevent the formation of ice crystals inside cells, ensuring that the sharp crystals can not burst their cells. If they were in warmer climates they would transpire readily and therefore dehydrate too easily.

What is a keystone specie?

A keystone specie is a specie that has a disproportionately large effect on its natural environment.

What are examples of keystone species?

Prairie dog: their foraging caused soil to retain water better and forces fresh new grasses to continuously grow.

Pisaster starfish: as it is a key predator, if removed it will cause remaining organisms to compete and reduce the biodiversity (study showed that it has reduced a biodiversity from 15 → 8 when removed.

Sea Otter: regulate sea urchin population, since sea urchins destroy/feed upon kelp forests. Thus kelp forest can remain a habitat for many of species, keeping ecosystem in balance.

Northern American Beaver: Their dams allow for blockages that help weed growth and frog breeding.

Saguaro cactus (Carnegieu gigantea): keystone host species, providing habitat for other species.

What is the purpose of a line transact?

This can be used to correlate the distribution of a plant or animal species with a abiotic variable. (e.g. elevation, light level, temperature or pH of soil)

What is a niche?

A niche is the fundamental role an organism plays in their ecosystem (where it lives, what it eats or how it interacts with other species).

What is a fundamental niche?

A fundamental niche is the complete range of biological and physical conditions under which an organism can live.

What is a realised niche?

A realised niche is the actual area a species live in, often being much smaller than the fundamental niche due to competition and predation.

What is a competitive exclusion principle?

When organisms can grow in number when grown separately but when grown together they compete and one dominates (i.e. P. caudatum and P. aurelia, having the P. aurelia out compete the P. caudatum (both being paramecium, a unicellular organism)).

Provide another example of competitors.

The red and grey squirrels:

The grey squirrel was introduced from the USA to Britain, becoming a competitor with the red native squirrel. The grey squirrel is larger, stronger and can store more fat making it better at survival , causing the red squirrel to now be endangered.

Define ‘predation’.

A predator is a consumer feeding on another consumer (prey)

Define ‘competition’.

Two organisms striving for the same resources in the same place due to overlapping niches.

Define ‘herbivory’.

A primary consumer (herbivore) feeding on a producer (plant).

Define ‘allelopathy’.

A plant produces chemicals that can be harmful or give benefit to another plant.

Define ‘parasitism’.

The close relationship between two organisms where one is benefited and the other is disadvantaged.

Define ‘symbiosis’.

The relationship between two organisms where both organisms benefit from the relationship.

Give an example of a symbiotic relationship.

Coral and algae zooxanthellae have a symbiotic relationship. This is because the algae gives oxygen and other nutrients that coral polyp needs to live and in return the polyp gives the algae carbon dioxide and other substances it needs to survive.

What are trophic levels?

The position of an organism in the food chain.

1st Trophic Level: Producer	Makes its own food
2nd Trophic Level: Primary Consumer	Consumes producers
3rd Trophic Level: Secondary Consumer	Consumes primary consumers
4th Trophic Level: Tertiary Consumer	Consumes secondary consumers

What trophic level is Euglena?

Since Euglena ingests other organisms and has chloroplasts for photosynthesis, it is both a producer and a consumer.

How efficient is energy transfer?

The energy transfer for level to level has an efficiency of only 10% as organisms require this energy for metabolic processes such as heat or respiration.

What is the Gershmel diagram used for?

The Gershmel diagram and pyramids of energy model the differences in nutrient flow and the storage between different eco systems.

What are the three sinks in the Gershmel diagram?

Litter, Biomass and Soil

What flows between the sinks in the Gershmel diagram?

Litter, decomposition and nutrient uptake by plants.

What are the nutrient outputs (losses) from the ecosystem in the Gershmel diagram?

Surface runoff and Leaching.

What are the nutrient inputs into the ecosystem in the Gershmel diagram?

Nutrients dissolved in rainfall and the nutrients from weathered rocks.

How can you differentiate the biomes (tagia, desert and tropical rainforest) in a Gershmel diagram?

Tagia (temperate forest) = larger litter,

Desert = larger soil

Tropical rainforest = larger biomass

What is biomass?

Biomass is the total fry mass of organic matter in organisms or ecosystems.

How is biomass measured?

Net production = gross production - respiration rate.

Why is measuring biomass useful?

• differentiate ecosystems and their productivity can be compared

• see the changes in ecosystems over time

• farmers can assess changes over time

• looks for disturbances caused by humans

What is the unit for net production?

km^-2y^-1

What is the food conversion ration?

The food conversion ratio (FCR) is a measure of an animals efficiency to convert food mass into increased body mass (biomass). This is calculated by dividing the mass of food eaten by the gain in body mass over a period of time. (A low number means they are efficient)

Why are energy conversion along aquatic animals more efficient than in terrestrial food chains?

• difference in diet

• aquatic animals dont regulate body temperature

• aquatic animals do not need as much energy for movement as the water is supporting the body (buoyancy causes less energy use)

• respiration rate is lower for aquatic animals.

Define ‘succession’.

Succession is a series of changes in an ecosystem over a period of time so that the appearance of the whole are evolves and changes. This consists of abiotic and biotic components until a stable situation is reached.

What is primary succession?

Primary succession starts in an environment where living organisms have not previously existed. (Surtsey Island near Iceland)

What is secondary succession?

Secondary succession occurs in areas where is ecosystem is present, but is replaced by another ecosystem following environmental change. (succession after a forest fire)

How do primary succession develop?

• first colonisers are lichens

• soil builds up

• larger plants can grow as soil deepens

• burrowers, worms and detritivores move in

• nutrient recycling as plants and animals die

What is a climograph used for?

To predict the type of stable ecosystem that will emerge in an area, for information about the mean annual temperature and mean annual precipitation in the region.

What is an open system?

An open system exchanges both matter and energy with its surroundings.

What is a closed system?

A closed system is when energy but not matter is exchanged. These are rare in nature and usually set up for experiments and are artificial.

What do disturbances do?

Disturbances affect the structure and the rate of change of an ecosystem.

How can humans influence nutrient cycling?

• harvesting of crops

• crops removed from where they are grown

• new nutrients must be added to the soil

• phosphate and nitrogen are mostly added

What is biomagnification?

A process by which chemicals become more concentrated as they move along the food chain.

What is fat soluble?

The chemicals which are biomagnified are stored in the fat of the consumer, and are fat soluble.

Example of biomagnification.

DDT (dichlorodiphenyltrichloroethane) is an insecticide that was used to kill mosquitoes that carry malaria. It was successful as it remained effective for a long time without breaking down and was sprayed everywhere.

In Europe in the 1960s it became apparent that it was an issue when peregrine falcons showed a decline. Their bodies has high concentrations of DDT, causing the shell of their eggs to be thinner than normals, thus when being sat on for incubation by females, they broke. This was even reported in the Antarctic with penguins.

The spray started at about 3× 10-6ppm but as it entered waterways an was taken up by microscopic plant, this was eaten by microscopic animals and found in small fish at around 0.5 ppm, later being found in the fat of flesh-eating water bird at around 25ppm.

How are humans exposed to DDT and what impacts does it have?

By eating contaminated fish and shellfish it can expose us and infants through drinking breast milk. Or by eating crops exposed to DDT.

It can cause:

• Human carcinogen (liver cancer)

• Damages the liver

• Temporarily damages the nervous system

• Reduces reproductive success

• Damages reproductive system

Compare micro and macro plastic debris.

Microplastic debris <5mm across (PVC, polyester, acrylic)

Macroplastic debris >5mm across (platic bottles, bags, food wrapping)

What is are alien species?

An alien species is a species that has been transferred from their natural habitat to a new environment, becoming successful in the new habitat and invasive.

What are the two forms of alien species?

• Deliberate: for biological control or another reason such as hunting recreation.

• Accidental release.

Provide an example of a deliberate alien species.

The cane toad that was introduced to Australia from central and south America. It was brought to eat the sugar cane beetles but was ineffective as it did not eat them and became competitive with native frogs, ate native insects and produced a poison that was dangerous to other animals. Now they kill them (freezer, golf), encourage native ants to eat the baby toads, genetically engineer worms to infest their lungs or try kill the eggs before hatching.

Rabbits were brought from England for hunting in 1859 (only 24) but spread rapidly and competed with native species (bilby) and ate native crops/plants. So they rabbit proofed fences, hunted more, release the myxoma virus in 1950 but survivors passed on genetic resilience, calici virus was genetically engineered and released in 1991 and was successful, pet rabbits can be vaccinated.

Provide an example of a accidental alien species.

The zebra muscle attached to boats and accidentally arrived in North America.

Name a species used for biological control.

The Cactoblastic moth was introduced to control the prickly pear cactus in 1925. The caterpillar larvae feed on the cactus to cause damage.

What are indicator species?

Species that are sensitive to environmental changes as they have a limited range of tolerance.

What are some air pollution indicator species?

Lichen and Bryophytes (mosses)

• Lichen have no waxy cuticle and can absorb and accumulate various pollutants, including metal ions in airborne dust.

• Large branching lichens growing show good air while small flat lichens are in pulluted air.

What indicator species is there for polluted water?

Invertebrates such as stonefly nymphs, mayfly larvae and flatworms are very sensitive to water pollution because they require a lot of oxygen. (polluted water lacks oxygen from the bacteria that feeds on the organic matter and respire aerobically, using up the oxygen).

Bloodworms, sludge worms and leeches are more tolerant to low oxygen levels thus many of them may indicate polluted water.

What is the Biotic Index?

This is an indication of the health if freshwater lakes or rivers.

A high biotic index shows good quality water.

How is the ASPT water quality, biotic index calculated?

When looking into a stream, the number of organisms that are in the species family in that stream is divided by the overall number of families/species present.

(e.g. 4 leeches, 2 midget larvae and 6 pond skaters = number of organisms that are in the species family in that stream (12) / overall number of families/species present (3) = 4 ASTP)

How is the BMWP water quality, biotic index calculated?

This is calculated by adding up the number of organisms that are in the species family in that stream.

(e.g. 4 leeches, 2 midget larvae and 6 pond skaters = number of organisms that are in the species family in that stream (12))

Defines ‘richness’.

It is either a count of the number of, or the list of, species inhabiting a given area or habitat.

Define ‘evenness’.

It is a description of the distribution of abundance across the species in a community.

What is the Simpson’s Reciprocal Index of Diversity used for and how is it calculated?

It gives a measure of both richness and evenness.

The formula is D=N(N-1)/∑n(n-1)

D - diversity index

N - total number of organisms in the habitat

n - the number of individuals of each species

What are the 3 main influences on biodiversity?

• island size

• edge effect

• wildlife corridors

Define ‘edge effect’.

The comparison between the centre and edge of a nature reserve.

• a woodland reserve has more light, more wind and less moisture at the edge

• organisms that live in the centre are more protected from the influence of other organisms, such as farm animals or human activity.

• small reserves have more edge per hectare, thus having a greater edge effect impact.

Define ‘Wildlife corridor’.

The connection between two or more smaller nature reserves, these are often built under busy roads or railway lines, so organisms have a larger area to move around in.

Negative:

• exposed to dangers outside the reserve while crossing

• can act as conduits for the spread of diseases

• make certain species easier for poachers to target

Postive:

• gene flow between two otherwise isolates areas can take place, promoting biodiversity.

Define ‘in situ conservation’

Protects species in their normal habitats as each species has adapted to a particular environment.

• often in nature reserve or national park

• can involve removal or invasive species or protecting certain species from predators.

Define ‘ex situ conservation’

Preserving a species whose numbers are very low in a captive breeding program in a zoo or botanic garden.

Benefit:

• gives rise to the opportunity for captive breeding using scientific knowledge and modern technology.

• Use artificial insemination or embryo transfer

(Arabian Oryx became extinct due to poaching in 1972 but 9 animals were successfully bred in Phoenix zoo).

How can you conserve plants?

Through seed banks, many stable crop seeds (rice or maize) can be preserved for future use.

• The Svalbard Global Seed Vault on the Norwegian island of Spitsbergen holds duplicate seed samples that are held in gene banks worldwide in a underground cavern.

List some sampling techniques.

• quadrant sampling

• transect sampling

• capture-mark-release-recapture

What is the Lincoln Index?

Helps estimate the population size in that area through the capture-mark-release-recapture sampling technique.

total population p = number of animals in forest sample x number of animals in second sample / number of marked animals in second sample

p = (n1 x n2) / n3

• at least 20 animals in a sample

• markings must not harm them or cause them to be conspicuous to predators

• should be minimal immigration or emigration

• must be conducted within a singe life cycle

What is commercial fishing?

Commercial fishing has become an industrial process (using technology and sound waves to track shoals of fish and large scale machinery like trawling nets to catch them).

Many species are in danger of being over fished, some species lack the number of adults needed to breed at a faster rate than what is being removed.

How do you monitor fish populations?

The ICES organisation monitors harvests in the North Atlantic.

• Fish move long distances so the count needs to be an estimate

• This is estimates by:

  • Fish for sale in fish markets

  • the number of fish discarded from fishing boats

  • targeted surveys with research vessels

  • satellite images

  • echolocation

Why and how can you estimate a fishes age?

• too few young fish indicate the fish are not spawning sufficiently to replace caught fish

• too few old, larger fish indicated over-fishing is occurring

• fish age is estimated though length and weight

• more accurately, through the fish ear bone, based on the number of rings

Define ‘maximum sustainable yield’

The largest proportion of fish that can be caught without endangering the population.

What are some solutions for this fishy problem?

• quotas

• monitoring fish population

• closed fishing seasons

• net sizes being monitored so small fish can be left to mature and breed

• banning or regulating fishing

• international cooperation being needed

How does stabilisation naturally occur?

Rabbit example:

few rabbits arrive → eat grass → reproduce → population increases rapidly → food used faster that it can grow → population stabilises

What does the Sigmoid population growth chart show?

growth and time impacting the carrying capacity or K of a species.

What are the phases in a Sigmoid population growth chart?

• Exponential phase

  • Natality high

  • Immigration high

  • Mortality low

  • Emigration low

• Transitional phase

  • Natality slows

  • Immigration increases

  • Mortality slows

  • Emigration increases

• Plateau phase

  • Natality = Mortality low

  • Immigration = Emigration

What can be observed in the exponential phase?

• population increases

• abundant food

• little competition

• effect of disease limited

What can be observed in the transitional phase?

• competition for food and space

• increase in predators

• increase diseases

What can be observed in the plateau phase?

• reaching carrying capacity

• birth + immigration = deaths + emigration

What is the calculation for population size?

population size = (natality + immigration) - (mortality + emigration)

Define ‘top-down’ limiting factors.

An organisms higher up on the food chain limiting the numbers of species at a lower level, usually through predation.

Sea otters to Sea urchins

Define ‘bottom-up’ limiting factors.

The nutrient supply and productivity of primary producers control the structure of the ecosystem.

Control through nutrient supply, light, temperature.

Define ‘algal bloom’.

fast growth of algae that blocks sunlight from other plants causing bacteria to thrive and use dissolved oxygen in water.

Define ‘nitrogen’

• has a triple bond, causing it to be stable and not react

• approximately 80% of earths atmospheric gas

• requires to build proteins from amino acids, also vital for DNA and RNA

• must be recycled in the ecosystem

Define ‘nitrogen fixation’

Bacteria transfer of nitrogen compounds from the abiotic to the biotic environment.

This breaks apart the N2 and adds hydrogen to form NH3 (ammonia) or NH4+ (ammonium).

Define ‘Azobacter’

Free living bacteria in soil.

Define ‘Rhizobium’

not free living in the soil, invades the roots of legumes to form nodules that have a mutualistic relationship between bacteria and plant.

State two other ways for nitrogen to fixate.

Lightening combines nitrogen gas in the air with oxygen forming nitrates that enter the soil.

Humans fix nitrogen in the Haber Process, through manufactured fertilisers.

Explain assimilation.

When ammonia is taken up by plants to form molecules such as DNA.

Explain nitrification

• ammonia uses a nitrifying bacteria that oxidises to form nitrites (NO2-) and the nitrobacter oxidises that to form nitrates (NO3-). The nitrate can also be assimilated for biological molecules.

Explain decomposition

One the nitrate is in living organisms these are consumes and passed on through the food web/chain. Later the consumer dies and decomposes returning nitrogen back to the soil as ammonia through ammonification.

Explain denitrification

Denitrifying bacteria converts the nitrates into nitrogen gas, reducing the fertility of soil, this occurs in anaerobic conditions such as in compacted or waterlogged soil.

How have plants adapted to low nitrogen?

• when there is water-logging, there is an encouragement of growth in denitrifying bacteria

• insectivorous plants supplement their nutrition by trapping or digesting insects and other small arthropods, providing with nitrogen needed to form proteins

• (Venus fly trap or sundews)

Define ‘phosphorus’.

• essential to form DNA + RNA and the production of ATP

• Found in rock or soil as inorganic phosphate

• rate of turn over is very slow

State the phosphorus cycle

• weathering causes the inorganic phosphate (PO4-3) in the rocks and soil to travel through the soil, being absorbed by plants or entering water sources.

• the absorption of phosphate helps plant growth, having some enter oceans or freshwater and then be drank from animals or the animals will eat the plants and pass it on through the food chain/web.

• through animal waste and decomposers, the waste and dead animals can be converted from organic phosphate to inorganic phosphate through mineralisation.

• some phosphorus is buried in sediments which overtime become rocks allowing for geological upheaval and a repeat of the cycle.

• some phosphorus from soil enters the ocean where aquatic plants and animals repeat the cycle (marine sediments).