P2: Module 6: Genetics, Evolution, Ecosystems Flashcards
Define Ecosystem (a)
A dynamic system were abiotic and biotic components interact
Define Population (a)
The number of individuals of the same species, living in the same place at the same time.
Define Community (a)
All the organisms, of all the different species living in a habitat
Define Habitat (a)
The place where an organism lives
Define Niche (a)
Role of an organism in the ecosystem
Define Biotic Factors and give examples (a)
The effect of other living organisms eg competition and predation, disease
Define Abiotic Factors and give examples(a)
Involve non-living components of the environment eg pH, temperature, light intensity
Name some abiotic and biotic factors of a rock pool(a)
Abiotic:
-Water availability
-Sunlight for seaweed
-pH of salt water
Biotic:
-Competition
-Parasitism (if there’s any parasites)
Name some abiotic and biotic factors in a large tree (a)
Abiotic:
-Temp
-Wind Speed
-Humidity
-pH of soil
Biotic:
-Competition (for space, food etc)
-Paraitism
What is a trophic level? (b)
Place in the food chain
What’s a primary consumer? (b)
Eats producer
What’s a secondary consumer? (b)
Eats primary consumer
What’s a producer? (b)
Fix carbon using sunlight to do photosynthesis
-It’s usually plants
Define biomass(b)
The mass of living matter in a particular food chain
How is biomass transferred and how can we measure this? (b)
Transferred up trophic levels through consumption . can be measured in terms of mass of carbon or dry mass of tissue
What’s an advantage and disadvantage of using dry mass in a pyramid of mass? (b)
If you use dry mass, you remove the water content this is an advantage
-As different organisms will have different water content which will in turn affect the biomass
-therefore by removing the effect of water we can compare more realistically and reliably
Disadvantage:
-Because we remove the water, organisms will have to die
-Some may argue that this is unethical
What is the formula for efficieny of biomass transfer, What units is biomass in?
Efficiceny= (biomass transferred/
biomass intake) * 100
Kg
How to calculate dry mass?(b)
-Use bomb calorimeter
-Burn sample in high pressure of O2
-The rise in temp of water is measured
-Can use that to calculate energy content of dry mass and compare w other organisms
How can human activities affect biomass transfer? (b)
Light, water, temperature maximised.
● Increased nutrients in soil.
● Pests and weeds removed.
● Growth rates boosted through
steroids, selective breeding, etc.
Outline the roles of microorganisms in the nitrogen cycle. (c)
Nitrogen-fixing bacteria e.g. Rhizobium in roots and Azotobacter in soil (leguminos plants), convert gaseous nitrogen into ammonia. also done by lightinig
● Nitrifying bacteria e.g. Nitrosomonas convert
ammonium compounds into nitrites.
Nitrobacter then convert nitrites to nitrates. the nirates is easily absorbed in the plant roots
Outline the role of organisms in the carbon cycle. (c)
- Respiration of plants and animals add carbon dioxide into the atmosphere.
- ● Photosynthesis of plants removes carbon dioxide from the atmosphere.
- ● Decomposers (microorganisms) decay plant and animal material into carbon dioxide.
Explain Ammonification (c)
list organisms involved
Saprobiotic Bacteria + Fungi turn Organic Nitriogen —> NH4+ by feeding on dead organic matter
the excess ammonium ions are excreted into the soil
The biomass in each trophic level is nearly always less than the trophic level below. Why does this occur? (b)
-Not all biomass is eaten (eg bones)
-Some is transferred to environment as heat
-Some is excreted eg urine
-Some is indigestable
Define succession(d)
A directional change in a community of organisms over time occurring in stages called seres
Summarise the process of primary succession.(d)
● Pioneer species, able to survive harsh conditions, colonise the area.
● They die, decompose, and add nutrients to the ground (humus).
● Over time, this allows more complex organisms to survive.
Define primary succession
Starts with a previously uncolonised area eg bare rock and has pioneer plants
Define Secondary succession(d)
Occurs on land with soil but no plant or animal species eg after a forest fire
Define pioneer plant(d)
First seral stage, colonisation of an inhospitable environment eg marram grass
Define climax community
Final seral stage when community is stable and there’s little change w few dominant animal and plant species
Define deflected succession(d)
Human activities that halt the flow of succession eg animal grazing
Define plagioclimax(d)
Final stage when deflected succession has happened
Define humus (d)
Decomposed organic material
State two examples of a plagioclimax (d)
-Garden
-Man made lakes
Describe two effects of the pioneer community on a habitat
-Can provide humus content after they die and decay
-Overtime humus content will increase so soil will become more fertile as it will have more mineral ions
Suggest 3 ways that farmers can maximise the efficiency of the transfer of energy up food chains from primary consumers to humans (3)
-Keep animals indoors
-Reduce animal movement
-Slaughter just before mature
Most of the minerals in a peat bog are held within the living plants at all times, not in the soil.
• Plants like bog cotton and bog asphodel recycle the minerals they contain.
• The leaves of these plants turn orange as the chlorophyll within them is broken down.
• Minerals such as magnesium ions are transported from the leaves to the plants’ roots for storage.
Describe one similarity and two differences in mineral recycling in a peat bog and in a deciduous forest (3)
Similarity:
-Chlorophyll breaks down
Differences:
-Decomposers aren’t active in big
-In bogs minerals stay in plant whilst in forest minerals are in soil
In Ireland in 2002, two well-preserved Iron Age human bodies were found in peat bogs. Despite having been dead for over two thousand years, the bodies had not decomposed. They still had skin, hair and muscle.
Suggest why these bodies had not decomposed. (2)
-Waterlogging reduces oxygen availability
-The pH is too low so it stops decay
Suggest two reasons why the large scale removal of peat from bogs for use in gardens is discouraged by conservation groups. (2)
-Bog takes a long time to form
-Loss of biodiversity
The sheep on this farm belong to a rare breed called Greyface Dartmoor. The Rare Breeds Survival Trust (RBST) gives advice on looking after these sheep and keep records to monitor the breeding of these sheep, in order to maintain a healthy population.
Why is the continued existence of rare breeds of farm animals desirable? (2)
-They have different alleles
-Which can be used for genetic engineering
North Ronaldsay sheep are listed as ‘endangered’ by the Rare Breeds Survival Trust. These sheep were raised on a small Scottish Island where they were kept along the seashore for most of the year. The sheep developed an unusual metabolism that allowed them to survive by eating seaweed. They are, however, susceptible to copper poisoning when fed on grass.
(i) State the two essential steps that must have occurred for a breed to develop a distinctive metabolism, such as the ability to eat mainly seaweed. (2)
(ii) Suggest what particular problems make the North Ronaldsay breed one of the most
endangered sheep breeds in the UK (2)
(i) A random mutation and selection pressure
(ii)
-You can’t feed them unless you live near the coast as they mainly eat seaweed
-Inbreeding so the allele frequency increases as small population so end up w/ high inbreeding
State the difference between a population and community(a)
Community is all organisms of DIFFERENT species but population is all organisms of ONE species
How temp affect an ecosystem?(a)
Temp has the biggest effect on enzymes in the organisms that live in the ecosystem
May trigger migration/ hibernation
Dormancy/ leaf fall/ flowering in plants
Why are ecosystems dynamic?(a)
Always changing due to many interlaced interactions that any small change causes several others–> alters flow of biomass
Why are sand dunes helpful in terms of succession?(d)
Shows us the stages of succession in order of occurrence whereas usually we only see the current stage
Summarise the process of primary succession.(d)
● Pioneer species, able to survive harsh conditions, colonise the area.
● They die, decompose, and add nutrients to the ground (humus).
● Over time, this allows more complex organisms to survive.
What is sampling?(e)
Selecting a group of individuals that will represent the whole target population. Allows us to measure the distribution and abundance of organisms.
Give methods of sampling and explain how they are used.(e)
● Quadrats= used in small areas. Randomly or regularly placed across habitat. Frequency or % cover calculated.
● Transects= used in larger areas. Sample taken along a line that crosses the habitat. Can be combined with quadrats in the form of a belt transect.
Explain what happens to the energy reaching the producers that is not converted to growth. (2)
-Reflected off the surface of the plant
-Passes through leaf and misses chlorophyll
Name one decomposer
Bacteria
Suggest two ways in which deflected succession could be caused (2)
-Farmers grazing animals
-Farmers mowing the land
Explain how biomass changes during a primary succession (2)
-Biomass increass
Explain how biomass changes during a primary succession (2)
-Biomass increases
-Plants at later stages are larger than plants in early stages.
Explain how the fungal decomposition of deadwood is of benefit to the living trees within a woodland (4)
-Release of CO2
-From fungal respiration
-Available for photosynthesis
-Also releases nitrates which taken up through roots of plants
Explain why organisms need to obtain energy and carbon (3)
Energy:
-For movement + to maintain body temperature
Carbon:
-C is a part of biochemicals used in organic matter e.g. proteins which is needed for organisms’ growth and repair
Nitrifying bacteria are chemoautotrophs. Some nitrifying bacteria gain energy from converting nitrite ions (NO2–) to nitrate ions (NO3–).
Explain how the activity of these bacteria affects the growth of plants in an ecosystem. (2)
-Nitrifying bacteria increases plant growth
-As bacteria makes nitrates available
-Plants need nitrates for mitosis
Before the widespread use of artificial fertilisers, farmers used a variety of methods to improve the fertility of the soil and so improve the yield of their crops. Two of the methods in common use were:
*Ploughing-in
In which legumes, such as beans, alfalfa or clover, were grown in a field and then harvested. The roots were then ploughed back into the soil rather than being dug up or burnt.
*Crop rotation
In which different crops were grown in a field in each year for three years. In the fourth year, the ‘fallow’ year, the field was not used for crops. In the following year the crop cycle was started again.
Explain how ploughing-in and crop rotation are able to improve the fertility of the soil (4)
Ploughing in:
-Legumes have root nodules
-Which contain rhizobium which provide the plant w/ nitrogen compounds
Crop Rotation:
-Diff crops have diff nitrate requirements
-Each year there’d be diff demands made on the soil
-So overtime nitrate levels are allowed to build up
Primary succession is the simplest type of succession, beginning with a bare surface such as rock or sand. The first organisms to colonise the area form the pioneer community.
Describe two effects of the pioneer community on the habitat. (3)
-Die + decay provide an increase in humus content in soil
-Overtime humus content will increase to the point where soil becomes fertile + favourable to new growth of plants
-As theres an increase of mineral ions and better water holding capacity
A footpath runs through the area of grassland and one student observed that very few bird’s foot trefoil plants were found on the trampled areas.
Explain how the students could use a transect to determine whether there is a link between trampling and the abundance of bird’s foot trefoil on this footpath. (5)
1) Lay tape measure across path
2) Include trampled + non trampled areas in same transect
3) Place Quadrats randomly
4) In each quadrat count number of plants
5) Plot a Graph
6) Repeat transect
7) Carry out a statistical test eg Spearman’s Rank
State a way nitrogen in air can be converted directly into nitrate ions (1)
Lightning
Explain the importance of rhizobium in the -nitrogen cycle (2)
-Provides NH4+ to legumes
-For nitrification
-So plant doesn’t have to rely on fertilisers in soil
There’s a profile of a sand dune system, together with kite diagrams of some plant species. This summarises The results of the transect were initially recorded using the ACFOR scale:
A – abundant
C – common
F – frequent
O – occasional
R – rare
(a)Outline the advantages and disadvantages of using a scale, such as the ACFOR scale.
the results of a belt transect carried out over the dunes. (3)
Advantages:
-Can be used with any species
-Quick to assess
Disadvantages:
-Subjective
-Dominant species may be overestimated
Explain how a transect could be carried out for for a belt transect over sand dunes (4)
-Lay a tape measure from shore to dune slack
-Use Quadrats which are 0.25m2
-Place them continuously along the tape measure
-Identify key species and record the abundance of each quadrat
The distribution of plant species in sand dunes will be influenced by a number of abiotic factors, such as temperature.
Explain how to measure, in different parts of the sand dune system, variations in temperature of the sand or soil (2)
-Use a temperature probe which is calibrated
-Push it into the sand at the same depth each time and take a reading when the temperature displayed is constant
-Repeat at each sampling point
What is meant by sere? (1)
A stage during succession
David Bellamy, the president of Plantlife, describes peat bogs as ‘the jewel of Britain’s habitats’.
‘You walk with a spring in your step – the peat underfoot is nine-tenths water – to the tireless song of a hovering skylark, on an undulating carpet of green, shot through with red, pink, burnished gold and orange, yellow and white flowers that thrive here. There are hundreds of insect species in the pools and on the plants and an abundance of round-leaved sundew, one of several carnivorous plants that get their nutrients (especially nitrogen compounds) from the insects they trap in their sticky leaves.’
Explain:
(i)why very wet soils are usually nitrogen-deficient and how the sundew is at a competitive advantage in such soils (4)
-Anaerobic conditions encourage denitrifying bacteria
-To convert nitrate ions into nitrogen
-This reduces the availability of nitrogen
-Sundew doesn’t rely on soil nitrate
Why, in addition to nitrogen-deficiency, many plants cannot grow successfully in very wet soils. (3)
-Reduces amount of air in soil
-So roots are starved of oxygen
-Respiration becomes anaerobic
-So it’s then not able to absorb enough ions
Explain the differences in the percentage of energy transferred between trophic levels (2)
-Plant material is difficult to digest because it has cellulose and lignin
-Less of producer is available eg caterpillar isn’t able to eat a whole tree by itself but a sparrow can eat a whole caterpillar
Suggest how allele B inhibits the expression of allele A.
-Protein for allele B produce repressive transcription factor
-Which binds to the promotor of A allele
What conclusions can you draw about the location and nature of the allele responsible
for causing agammaglobulinemia? Explain your conclusions.
Allele is located on X chromosome (sex linked) because all sufferers are male. The allele is recessive as male sufferers have parents neither of which have the disease
-Children w disease will have inherited the recessive alle from their heterozygous mother
When sequencing DNA, fragments of DNA are separated by electrophoresis.
Describe three differences between the process of thin layer chromatography and the form of
electrophoresis used to sequence DNA
-TLC seperates by adsorption, EP seperates by size
-TLC doesnt use electricity, EP uses electricity
-TLC seperates non charged particles, EP sepearates charged patricles
Bacteria and fungi can be used to make food for human consumption. The use of microorganisms
in food production creates fewer ethical issues than the use of animals.
(a) (i)* Using examples, describe and explain some other advantages of using microorganisms
to produce food for human consumption. (6)
Advantage: low cost
Explanation: many microorganisms require
only low temperatures / few energy
requirements / nutrients for growth are cheap
(e.g. waste materials)
Advantage: large numbers can be produced
quickly / high yield of product
Explanation: short generation time / reproduce
quickly
Advantage: better for the environment / less
pollution
Explanation: reduces use of land for food
production / lower energy requirements
Advantage: can be produced in many locations
Explanation: not affected by climate / easy to
control conditions
Advantage : suitable food for vegans / more
healthy food
Explanation: low in cholesterol and high in
protein or fibre / easy to genetically engineer to
improve food quality
Natural Selection; MARIA
M-Mutations create variation (new alleles)
A-Advantage, some have an advantageous allele
R-Reproductive success and increases chance of survival
I-Inheritance, pass on advantageous allele
A-Allele frequency changes over many generations=evolution
