What is a genotype?	An individual's unique genome / collection of alleles.
What is a phenotype?	The visible characteristics of an individual as a result of their genotype interacting with the environment.
What is an allele?	A version of a gene (as a result of mutation).
What are the 3 causes of genetic variation in a population?	Mutation, meiosis, random fertilisation
What are the 3 causes of genetic variation that occur during meiosis?	Crossing over / chiasmata / allele shuffling, independent assortment in meiosis I, independent assortment in meiosis II
When does allele shuffling due to crossing over occur during meiosis?	Prophase I
When does independent assortment of chromosomes occur during meiosis?	Metaphase I
When does independent assortment of chromatids occur during meiosis?	Metaphase II
What are the 4 chromosomal mutations that can occur during meiosis?	Deletion, inversion, translocation, duplication
What are the 3 features of discontinuous genetic variation?	Qualitative differences in phenotype, no intermediate phenotypes, usually monogenic
What are the 3 features of continuous genetic variation?	Quantitative difference in phenotypes, a range of phenotypes, polygenic
Name 2 examples of environmental variation.	Dialect / accent, scar
What is a gene locus?	The position of a gene on a chromosome.
How many alleles are inherited for a single gene?	2
How many dominant alleles are needed for its phenotype to be expressed?	1
How many recessive alleles are needed for its phenotype to be expressed?	2
What is meant if an individual is homozygous at a gene locus?	Alleles are identical.
What is meant if an individual is heterozygous at a gene locus?	Alleles are different
What is meant by a true-breeding individual?	An individual homozygous for a particular trait.
What does it mean if a characteristic is monogenic?	It is controlled by one gene.
What is the expected phenotypic ratio for monogenic inheritance in offspring from heterozygous parents?	3:1
What is a test cross?	A cross between an individual from the F2 generation and a true-breeding recessive individual in order to determine the F2 individual's genotype.
What is the expected outcome for a test cross if the F2 individual is homozygous?	100% dominant phenotype.
What is the expected outcome for a test cross if the F2 individual is heterozygous?	50% dominant, 50% recessive phenotype.
What is meant by codominance?	Both alleles contribute to the phenotype in a heterozygous individual.
What is meant if a gene has multiple alleles?	There are 3 or more possible alleles within the gene pool.
What is the human male combination for the sex chromosomes?	XY
What is the human female combination for the sex chromosomes?	XX
What is meant by the homogametic sex?	Sex chromosomes that are fully homologous and so result in only one type of gamete e.g. XX
What is meant by the heterogametic sex?	Sex chromosomes that are not fully homologous and so result in 2 types of gamete e.g. XY
What is a sex-linked characteristic?	Characteristic with a gene locus on a sex chromosome.
What is an X-linked characteristic?	Characteristic with a gene locus on the X chromosome.
How many alleles do males have for an X-linked characteristic?	1
How many alleles do females have for an X-linked characteristic?	2
Haemophilia is an example of which type of inheritance?	Sex Linkage
Calculate the probability of the offspring being a female carrier if the father was a haemophiliac male and the mother carried no alleles for haemophilia.	50%
Fur colour in cats is partly controlled by a gene on the X chromosome. The gene has two alleles, one coding for balck fur and one coding for ginger fur. The two alleles are codominant, so a heterozygous cat has pathces of black and patches of ginger fur, a pattern called tortoiseshell. When a black cat was mated with a ginger male, the F1 generation consisted of black males and tortoiseshell females. What phenotypic ratio would be expected in the F2 generation?	1 black female: 1 tortoiseshell female: 1 black male: 1 ginger male
What is dihybrid inheritance?	Inheritance involving 2 genes with loci on different chromosomes.
What is the expected phenotypic ratio for dihybrid inheritance in offspring from heterozygous parents?	9:3:3:1
What are autosomes?	Chromosome (pairs) that are non-sex chromosomes
What is autosomal linkage?	Multiple gene loci located on the same non-sex chromosome and inherited together.
What is the expected phenotypic ratio for the inheritance of 2 autosomally linked genes in offspring from heterozygous parents?	3:1
What is a recombinant genotype?	A genotype only possible due to meiotic crossing over.
What is epistasis?	Where one gene masks or suppresses the expression of another gene.
What is antagonistic epistasis?	Where one gene suppresses the expression of another gene.
What is an epistatic gene?	Gene that prevents the expression of another gene.
What is a hypostatic gene?	A gene whose expression is prevented by another gene.
What is recessive epistasis?	Where the epistatic gene locus must be homozygous recessive in order to prevent the expression of the hypostatic gene.
What phenotypic ratio in offspring from heterozygous parents may suggest recessive epistasis?	9:03:04
What is dominant epistasis?	Where the epistatic gene locus must have at least 1 dominant allele in order to prevent the expression of the hypostatic gene.
What 2 phenotypic ratios in offspring from heterozygous parents may suggest dominant epistasis?	13:3, 12:3:1
Epistasis is shown in the inheritance of corn colour, with gene P that codes for a purple (P) or red (p) pigment and gene C (dominant) allows the expression of gene P. If gene P is not expressed, then the corn remains yellow. If two sweetcorn plants were crossed which were heterozygous for both genes P and C, what would the probability be of the offspring being yellow?	25%
What is complementary gene action?	Where 2 genes contribute to a final phenotype.
What 3 phenotypic ratios in offspring from heterozygous parents may suggest complementary gene action?	9:7, 9:3:4, 9:3:3:1
What statistical test can be used to determine whether the observed phenotypic ratio is significantly different from the expected ratio?	Chi-squared
What form should the null hypothesis for a chi-squared test take?	There is no significant difference between the observed and expected data. Any difference is due to chance.
What is the Hardy-Weinberg principle?	In a stable population with no disturbing factors, the allel frequencies will remain constant from one generation to the next, and there will be no evolution
What are the 2 Hardy-Weinberg equations?	p + q = 1, p2 + 2pq + q2 = 1
What are the 5 assumptions made if the Hardy-Weinberg principle applies to a population?	No mutation, random mating, no migration, large population size, no selection (natural of genetic drift)
The deer in a captive population vary in colour. 53 deer are brown and 14 are white. The coat colour of is determined by the gene R/r, where the dominant allele R codes for brown and recessive allele r codes for white. Calculate the frequency of the allele R in the population using the Hardy-Weinberg principle.	0.54
What is genetic drift?	Changes in allele frequencies caused by chance events.
What are the 2 causes of genetic drift?	Genetic bottleneck, founder effect
What is a genetic bottleneck?	When a population dramatically shrinks in size and then increases again.
What is the effect of a genetic bottleneck on genetic diversity?	Decrease
What is the founder effect?	Establishment of a new, small population of a species derived from a larger, parent population.
What is the effect of the founder effect on genetic diversity?	Decrease
Selection pressure can affect homozygous individuals. The effect can be investigated using a model gene pool. Why is a large gene pool neccessary?	So the effect of chance variation in gene frequencies are minimised.
What is natural selection?	Changes in allele frequencies caused by environmental selection pressures favouring the survival of some individuals over others.
What is stabilising selection?	Natural selection that favours normal phenotypes due to unchanged environmental selection pressure
What is directional selection?	Natural selection that favours one extreme phenotype due to a change in environmental selection pressure
What is disruptive selection?	Natural selection that favours both extremes of a given phenotype due to a change in environmental selection pressures
What is speciation?	Splitting of a population into 2 or more reproductively isolated populations.
What is meant by geographical isolation?	A population that is separated and reproductively isolated by geographical barriers such as rivers, lakes, mountains.
What type of speciation is a result of geographical isolation?	Allopatric
What is reproductive isolation?	A population that is separated due to biological and behavioural changes.
What type of speciation results in reproductive isolation?	Sympatric
What is sympatric speciation?	Speciation that occurs within populations in the same habitat
What can lead to sympatric speciation?	Members of two different species interbreed and form fertile offspring (more common in plants), forming a hybrid that usually is infertile/reproductively isolated

Define the term 'abiotic factor'	any non-living factor e.g. sunlight
Define the term 'biotic factor'	any living factor e.g. predators
Give 3 examples of abiotic factors	temperature, light, pH, water, humidity, oxygen availability, edaphic(soil) factors
Give 3 examples of biotic factors	Competition, food, territory, breeding partners, predators
Describe the importance of soil for plants	Soil provides minerals for growth, water for photosynthesis, anchorage for roots
Explain how particle size affects the air content and permeability of soils	small particles - few air spaces, retains water and floods easily eg. clay. large particles - lots of air spaces, does not retain water eg. sand
Define the term ecosystem	Made up of all the living organims that interact with one another in a defined area and also the physical factors presetn in that region eg. rock pool
Define the term producer	Producer - makes its' own food, usually by photosynthesis to produce biomass ( inlcudes algae and plankton)
Define the term carnivore	eats only other animals
Define the term herbivore	Eats only plants
Define the term Omnivore	Eats both plants and animals
Define the term primary consumer	Eats producers, usually a herbivore
Define the term secondary consumer	Eats primary consumers, usually an omnivore
Define the term tertiary consumer	Eats a secondary consumer
Define the term trophic level	Trophic level - position or stage that something occupies in a food chain
Define the term biomass	The mass of living material present in a particular place or in particular organisms
How do you find the dry mass of an organism?	Organism has to be killed and put in an oven to evaporate the water
How do you calculate the net production of biomass made by a primary producer?	Net production = gross production – respiratory losses
A group of scientists measured the gross production of a grassland area as 60gm-2yr-1. if respiration loss was 20gm-2yr-1, calculate the net production of this area of grassland	60-20 =40gm-2yr-1
Why can't plants use all of the sunlight that hits them?	some parts of a plant do not photosynthesis, some light passes through, some is the wrong wavelength
Why isn't all energy transferred to the next trophic level?	some parts of an organism are not digested, some parts are not eaten eg. bones, some is used up for energy for movement/ respiration (respiratory losses)
approximately what % of energy is passed to the next trophic level	10%
How do you calculate % efficiency of energy transfer?	net productivity of energy transfer of trophic level/ next productivity of previous trophic level x 100
What is the role of a herbicide?	kills weeds that compete with crops - reduces competition
What is the role of a fungicide?	kills fungal infections that damage crops
What is the role of an insecticide?	kills insect pests that damage and eat crops
What is the role of fertiliser?	a chemical that provides crops with the minerals required for growth
Why is intensive farming beneficial?	controls living conditions for organisms so that more energy is put in to growing e.g. animals are kept warm and move around less
Define the term ecosystem	Self contained unit in ecology made up of biotic and abiotic factors
Define the term Community	All the populations of different species living and interacting with eachother in a particular area
What is meant by 'nitrogen fixation'?	When nitrogen gas is converted to nitrogen containing compounds
Give examples of two types of bacteria that are involved in nitrogen fixation	Azotobacter and Rhizobium
Explain why Rhizobium bacteria can be described as mutualistic	Rhizobium live in root nodules in peas and beans and they get carbohydrates from the plant, the plant gets amino acids from the bacteria
What is meant by ammonification?	production of ammonia from organic compounds e.g. urea, proteins and nucleic acids
Describe the process of nitrification	Ammonium ions --> nitrite ions --> nitrate ions
Give the role of nitrosomonas bacteria in the nitrogne cycle	ammonium ions --> nitrite ions
Give the role of nitrobacter bacteria in the nitrogen cycle	nitrite ions --> nitrate ions
What is denitrification and how does it occur?	when soil nitrates are converted to nitrogen gas. Occurs when sol becomes waterlogged, short of oxygen and carried out by anaerobic bacteria - means that less nitrogen compounds are available to plants.
List 3 processes that return carbon dioxide to the atmosphere	respiration, decomposition and combustion
name a process that removes carbon dioxide from the atmosphere	photosynthesis
Give reasons for the levels of carbon dioxide increasing over the past 100 years	combustion of fossil fuels, deforestation
Define the term global warming	the increase in average temperature over the last century
Give 3 consequences of global warming	changes in temperature, precipitation, failure of crops, timings of the seasons may change, melting ice caps, flooding of low lying land, increasing extreme weather, alter niches available - loss of species we don't know
Give reasons for the levels of methane increasing	increased extraction of fossil fuels, increased decaying waste in landfill, more cattle producing methane, frozen stores are thawing
Define the term succession	The process of ecosystem change over time
State features of a pioneer species	produce large quantities of easy to disperse seeds/spores, rapid germination of seeds, ability to photosynthesise, ability to fix nitrogen, withstand extreme conditions
Define the term deflected succession	A community that remains stable only because human activity prevents succession from running its course
Where does primary succession occur?	on land that has been newly formed
What is meant by the term 'climax community'?	when the soil is rich enough to support large trees the climax community is formed (may not be large trees if in the Arctic for example)
When does secondary succession occur?	on land that has been cleared but where soil remains
Give the calculation for estimating population size using 'capture, mark, release and recapture'	population size = (number in first sample x number in second sample) / number in second sample previously marked
Define the term abundance	the number of individuals of one species in a particular area
Define the term distribution	where a particular species is within the area you are investigating
How could you ensure that your sampling method is random?	use a random number generator for coordinates
What is a transect?	A transect is a line across an area of land
Name 2 types of quadrat	frame quadrat and point quadrat
How could you capture fish?	use a net
How could you capture insects?	use a sweepnet
How could you capture butterflies?	make a pitfall trap
Name 2 pieces of apparatus needed for calculating percentage cover of plant species	frame quadrat and measuring tape(transect) (could have species index)
How can distribution of organisms be measured?	Using line or belt transect - non-random, systematic sampling
Should measuring distribution be random or non-random?	Non-random
Give the equation to calculate the estimated plant abundance within an area of 1m2.	(number of individual in sample) ÷ (area of sample in m2)
What method is used to find the animal abundance in an area?	Capture-mark-release-recapture technique
Name an assumption you make when you use the mark-release-recapture method	marking the organism does not impact its survival / no migration / organisms randomly distribute after first release
What is the term to describe the maximum population size that an ecosystem can maintain?	Carrying capacity
Why can't populations cannot reach an infinite size?	Limiting factors - Resources are limited.
True or false: exponential growth always takes place in real ecosystems.	FALSE
State the term for non living factors.	Abiotic factors
What will happen to the population size when abiotic conditions are favourable?	Increase
What is a limiting factor?	A factor in a habitat limits the further growth of a population.
Are limiting factors abiotic or biotic?	Both abiotic and biotic.
What is happening at the lag phase of a populations growth?	Indivuduals are aclimitising to a habitat, low reproduction rate.
What is happening at the log phase of a populations growth?	Plenty of resources available in good conditions, population increasing rapidly.
What ia happening at the stationary phase of popuation growth?	Rate of reproduction equals mortality, stable population size.
What are the names given to the different stages of a population growth curve?	lag, log (or exponential), stationary
What does it mean by 'density independent factors'?	They act irrespective of the size of the population.
Suggest an example of a denstiy independent factor.	Weather or climate
Give 3 examples of limiting factors that are density dependent to birds?	List 2 from: Availablity of food, water, light, oxygen, nesting sites
Name the type of competition between individuals of different species.	Interspecific
Name the type of competition between individuals of the same species.	Intraspecific
In interspecifc competition, what biotic factors could be involved?	Food source, habitat
Fill in the gaps: There is a limited supply of resources in ecosystems. Species have .....?.... that allow them to gain resources faster than other species are more likely to survive and therefore ....?....	adaptations / reproduce
What is a predator?	Animals that hunt other animals for food
What are prey?	Animals that are hunted by other animal (predators) for food
What is the relationship between the numbers of a predator and a prey?	When the predator population increases more prey are eaten and the numbers of prey fall. When the prey population decreases there is less food for predator and so their numbers fall.
What mechanism controls the predator and prey populations?	Negative feedback
Define Preservation.	Keeping a species or habitat as they are now, minimising any human impact.
Define Conservation.	A active management process of a species, habitat or ecosystem involving human intervention.
Which strategy focuses on improving biodiversity, preservation or conservation?	Conservation strategies.
What is biodiversity?	The range and number of different living species in an ecosystem.
How is the human population threatening biodiversity?	Over-exploitation of wild populations for food/ disruption and fragmentation of habitats/ introduction of new species to an ecosystem outcompeting native species.
What is an important factor of a successful conservation strategy?	Effective education and liason with the local community.
Give 2 examples of the strategies that could be used for conservation?	Any 2 from: providing extra food raising the carrying capacity/ restricting dispersal of individuals using fencing/ vaccination of animals against disease/ controling predators or poachers/ preserving habitats by preventing pollution/ moving individuals to enlarge populations.
What ethics are involved in a conservation strategy?	All species have value and humans have an ethical reponsibility to look after them.
What economic or social reasons might influence the conservation of a species or habitat?	A valuable food source or potential food source/ potential drug sources or potential biological control agent for pests.
Cutting down trees in a way in which lets them grow back is known as	Coppicing
Without management, grassland would quickly turn into shrubs and then woodland by...	Succession
What is sustainable management mean?	Management of an ecosystem to provide resources in a sustainable way avoiding depletion of natual resources.
Why have humans had to use more intensive methods of agriculture?	Increasing population
What problems has the increasing world population caused to ecosystems?	More intensive land use/ disruption or destruction of ecosystems, reducing biodiversity.
How does coppicing provide sustainable timber production?	Woodland is divided in sections, with only one section harvested each year in rotation.
What is pollarding of trees?	Branches of a tree are cut back to a point higher up the mainstem from the ground.
What is the difference between coppicing and pollarding?	Coppicing cut branches at ground level while in pollarding they are cut above ground level.
Why is rotational coppicing good for biodiversity?	Different areas of the woodland will be at different stages of development providing a variety of habitats.
Why is large scale clear felling of woodland not good for biodiversity?	Habitats are destroyed on a large scale and the soil is left susceptible to erosion.
What land management problems could result from clear felling a large forest?	Erosion of the soil and reduction of soil mineral content.
Why is there an optimal distance for planting trees in woodland?	Too close - too much competition for light, producing tall and thin trees, poor quality timber.
What are the principles of modern sustainable forestry?	Replace any tree that's harvested/ maintain the ecological function of a forest/ local people should be able to benefit from the forest.
What is selective cutting or harvesting in forests?	Removing the largest or most valuable trees.
How is selective cutting good for biodiversity?	Only a few trees are removed which leaves the habitat broadly unaffected.
How do foresters manage the trees in sustainable woodland to maximise yields?	Control pest and diseases/ only plant tree species that will grow well/ position trees the optimum distance apart.
Name two ways of managing fish stocks.	Fishing quotas/ mesh sizes
List the prinicples of fish sustainability proposed by the Marine Stewardship Council.	Fish at a level that ensures continuing fish stocks/ fish to maintain diversity of ecosystem/ follow local and national regulations.
To allow sustainablity of fish populations, what must happen if there is over fishing?	The fish population must be allow to build back up.
What would be the optimum strategy for managing fish populations?	Maintain the fish population at the carrying capacity for that environment, while fishing continues to harvest fish in excess of that capacity.
How can human activities affect populations of plant and animals?	Habitat destruction/ competition for natural resources/ hunting/ pollution.
What protection areas have humans set up to protect plant and animal species around the world?	Setting up mational parks and reserves/ green belt land/ world heritage sites/ marine protected areas/ areas of outstanding natural beauty.
Why has the human population on the Galapagos islands increased?	Increased demand for marine products and increased tourism.
How has more building development and increased use of land for agriculture affected the Galapagos islands?	Destruction and fragmentation of habitats.
Why has it been difficult to foster a culture of conservation and education on the Galapagos Islands?	Because most residents were not born on the islands.
Large areas of the coastal zones have been designated 'No Take' zones. What are they?	No extraction of any resources are allowed, leaving communities undisturbed.
What are financial incentives given to farmers for in national parks?	To reduce chemical use/ safeguard hedges/ care for natural habitats.
How do they manage cliffs, rock and scree habitats in the Lake District?	Seasonal restrictions on walkers during nesting/ education of visitors/ good maintenance of paths.

6 - Ecology and genetics