Topic 7 - Genetics, population, evolution and ecsystems Flashcards

Question 1

Q

Define ecology

Answer

A

the study of inter-relationships between organisms and their environment

Question 2

Q

What sort of factors does the environment include?

Answer

A

Biotic factors: Living factors

2. Abiotic factors: Non-living or physical factors

Question 3

Q

Examples of biotic factors

Answer

A

Predation, competition, number of mates, disease, prey and predator numbers

Question 4

Q

Examples of abiotic factors

Answer

A

Soil pH, water availability, space, rainfall, nutrients, light intensity

Question 5

Q

Define the biosphere

Answer

A

The biosphere is the regions of the surface (land) and atmosphere (air) and earth occupied by living organisms

Question 6

Q

Describe the biosphere (3 points)

Answer

A

Shaped by interactions within organisms and environment
An interconnected network
Involved in the study of ecology

Question 7

Q

Define ecosystem

Answer

A

An ecosystem is all the interacting biotic and abiotic factors in an area

Question 8

Q

What are the two main components of an ecosystem

Answer

A

The flow of energy

- The cycling of elements

Question 9

Q

Different ecosytem cycles and what they are

Answer

A

Water cycle – cycling of water (H and O) through the water cycle
Respiration – transfer of energy and elements
Nutrient cycles – nutrients contain elements (nitrates and phosphates) are recycled in pond
Photosynthesis – plants utilising the suns energy and converting some to ATP/chemical energy
Decay – decay of material releases CO2

Question 10

Q

What is a habitat

Answer

A

A habitat is where the community (different organisms in the same place) is found

Question 11

Q

Within each habitat there are smaller microhabitats, what are these?

Answer

A

A habitat which is of small or limited extent

- Differs in character from surrounding habitat (own microclimate)

Question 12

Q

What are the different microhabitats present in a mature fruit tree?

Answer

A

Leaves, flowers and fruits (different microhabitats throughout year (seasons) and fruit and flowers in specific times of year)
Bark (Lichens and mosses grown on the bark (habitat for them) and different depending on position, shelter age and light intensities = different conditions
Lichens and mosses (provide microhabitat for small insects)
Canopy deadwood (micro-organisms involved in decay found)
Plants colonising the tree base/surface (millipedes, woodlice and caterpillars)

Question 13

Q

What is a population?

Answer

A

A population is a group of interbreeding organisms of one species in a habitat

Question 14

Q

.A number of ______ can be found within each ecosystem

Question 15

Q

.Members of the same species group together forming a ________

Answer

A

population

Question 16

Q

.Different _____ group together to form different populations

Question 17

Q

Population boundaries are difficult to define because organisms move, explain this in more detail

Answer

A

All herons can breed with one another so form a population
Woodlice on a rotting log on one side of the pond could breed with woodlice on the other side of the bond
If interbreeding is unlikely = two populations

Question 18

Q

A community is …

Answer

A

… all the populations of different species living and interacting in a particular space at the same time

Question 19

Q

In the pond ecosystems, the community would consist of:

Answer

A

Frogs
Herons
Bacteria
Bull rushes
Trees
Grass
Fish
Worms
Insects
Fungi
Snails

Question 20

Q

What is an ecological niche?

Answer

A

An ecological niche is how an organisms fits into its role within the environment

Question 21

Q

What does an ecological niche include?

Answer

A

Where it lives and what it does

- The biotic and abiotic factors required for an organisms survival

Question 22

Q

Why do no two organisms occupy the same niche?

Answer

A

Different tolerance levels to environmental factors
Best adapted species survives and reproduces
At the expense of the weaker species (if conditions remain stable)
Competitive exclusion principle (two species competing for the same limited resource cannot coexist at constant population values as one will always outcompete the other)

Question 23

Q

What is population size?

Answer

A

Population size is the number of individuals within a population

Question 24

Q

What is exponential growth?

Answer

A

Growth rate is proportional to time
As time increases, the variable being recorded increases
At an exponential rate
But most population growth in the wold does not follow this trend

Question 25

Q

What is most population growth like?

Answer

A

Slow growth – initially a small number of individuals to reproduce
Rapid growth – increased number each reproducing
Population doubles, increasingly steep curve
Stable state, no growth – rate of growth declines until roughly stable, the population reaches its carrying capacity

Question 26

Q

What is carrying capacity?

Answer

A

the number of organisms which an ecosystem can support without environmental degradation

Question 27

Q

A limiting factor is …

Answer

A

… an environmental condition that limits the growth, abundance, or distribution of an organism or a population of organisms in an ecosystem

Question 28

Q

Why do limiting factors matter?

Answer

A

Limiting factors prevent the population growing exponentially

Question 29

Q

What are the main limiting factors?

Answer

A

Disease
Predators
Water/Humidity
Oxygen
Competition
Food
Light
Shelter
Waste accumulation
Temperature
pH

Question 30

Q

How are all of the population limiting factors limiting population?

Answer

A

Disease Mutation = no antigens, no memory cells
Predators New adaptations, introduction of species, competition
Water/humidity Transpiration, photosynthesis, osmotic lysis, drought tolerance (GM)
Oxygen Respiratory rate, haemoglobin, tertiary structures, affinity
Competition Intra and inter specific, food webs
Food New sources, global warming, monocultures, deforestation
Light Light intensity – photosynthesis, transpiration, food production
Shelter Shade tolerance, competition
Waste accumulation Mutations for tolerance, pH changes = enzymes
Temperature Enzymes, transpiration, all metabolic processes
pH Enzymes, tissue fluid, mutations, O2 affinity, metabolic processes

Question 31

Q

Describe the growth rate in bacteria

Answer

A

.Quick/rapid growth
.Asexual reproduction
.Less complex
.Binary fission

Question 32

Q

Describe the growth rate in humans

Answer

A

.Slow growth/stabilises
.Sexual reproduction
.Long development
.Few offspring

Question 33

Q

Describe the growth rate in cats

Answer

A

.Middle term
.Long gestation
.Multiple births

Question 34

Q

Is the rate of population change between species the same?

Question 35

Q

When should you use logarithmic scales?

Answer

A

.Rapid growth

.Long period of time

Question 36

Q

Why should you use logarithmic scales?

Answer

A

.Reduces wide-ranging quantities to tiny scopes

.Clearer pattern shown

Question 37

Q

If log x (y) = z then …

Answer

A

… x^z = y

Question 38

Q

A new pond has formed and some algae cells have been found.
Predict what will happen and explain why you think this.
Hint, it is summer, there are no nutrients in water, there are no limiting factors, they reproduce asexually

Answer

A

• They reproduce asexually
- Reproduction is quick so number rapidly increases
• It is summer
- High rate of photosynthesis = growth occurs quickly
• There are nutrients in the water
- Mineral ions used up by increasing population.
• There are no limiting factors BUT this changes
- Algae on surface block light reaching deep into the pond.
- Fewer ions or sunlight available for algae
- Other species arrive better adapted to different abiotic factors
- Increase competition and/or predation.
- Changing seasons = temperature drop and lower light intensity
- Algae population decrease

Question 39

Q

Describe the human population growth with figures

Answer

A

The human population has doubled in the last 50 years. Now over 7 billion. If this rate continues we will double our population in the next 40 years!

Question 40

Q

What factors are increasing human population growth?

Answer

A

Health Care – Fewer people are dying/aging population
Infrastructure and resources – More houses/workplaces/stability
Economy – More money for medical care, houses, food
Food availability (Agricultural Revolution) – Better nutrition/growth
Better quality of life – Better hygiene, fewer diseases
Industrial Revolution

Question 41

Q

.Human population growth does not follow the usual _______ shape

Answer

A

sigmoidal

Question 42

Q

For human population growth, the exponential phase is still continuing rather than plateauing, why?

Answer

A

Birth rate outweighs death rate

- Immigration outweighs emigration

Question 43

Q

Population growth =

Answer

A

(births + immigration) - (deaths + emigration)

Question 44

Q

Percentage population growth rate =

Answer

A

(Population change during time period / population at start of period) x 100

Question 45

Q

Birth rate is affected by:

Answer

A

Contraception
Money
Culture and Religion
Social Pressures
Politics (Education and Taxes)

Question 46

Q

Death rate is affected by:

Answer

A

Age of population
Life expectancy at birth
Food supply and range
Natural Disasters and War
Water and Sanitation

Question 47

Q

What is a population pyramid?

Answer

A

.Age and gender profiles are displayed graphically by stacked bars which represent the % age of males and females in each age group

Question 48

Q

What do population pyramids give information on?

Answer

A

.They give information on future trends of populations, for example how many females of child bearing age

Question 49

Q

In a population pyramid with a narrow base and wide apex what can you deduce

Answer

A

Lower birth rate = narrower base.
Lower mortality rate = more elderly people so apex is wider.
Applies to certain economically more developed countries (Japan)

Question 50

Q

In a population pyramid with a wide base and narrow apex what can you deduce?

Answer

A

High birth rate = wider base.
Fewer old people = narrow apex.
Typical of economically less developed countries.

Question 51

Q

In a population pyramid with an in balance birth and death rate what can you deduce?

Answer

A

Birth rate and death rate are in balance
No change in population size.
Typical of economically developed countries.

Question 52

Q

As countries develop economically, their human populations display a pattern of growth known as what?

Answer

A

demographic transition.

Question 53

Q

Demographic transitions can be divided into 4 stages depending on what?

Answer

A

Death Rate - Birth Rate - Total population

Question 54

Q

What are the four stages in demographic transition and describe them

Answer

A

Small and stable – high birth rate, high death rate
Early expansion – high birth rate, decreasing death rate
Late expansion – decreasing birth rate, low death rate
Large and stable – low birth rate, low death rate

Question 55

Q

Draw a demographic transition

Answer

A

check notes

Question 56

Q

What is a predator?

Answer

A

A predator is an organism that feeds on another organism (prey)

Question 57

Q

Predators have evolved to become better adapted for capturing their prey, give some examples of adaptations

Answer

A

Faster
Better camouflage
Sense of smell/eyesight
Claws/teeth
Agile

Question 58

Q

What is a prey?

Answer

A

A prey is an organism that is attacked/eaten by another organism

Question 59

Q

Prey have evolved to become better adapted for escaping predators, give some examples

Answer

A

Camouflage
Concealing behaviour
Speed
Protective features

Question 60

Q

Explain how prey become adapted for escaping their predators.

Answer

A

New mutations occur within the prey population, those with mutations that are advantageous to escaping the predators survive and reproduce and their alleles are passed on at the expense of the less advantageous alleles.

Question 61

Q

What is a stable community?

Answer

A

A stable community is where all the species and environmental factors are in balance so that population sizes remain fairly constant

Question 62

Q

Draw and label a graph that shows the effect of change in temperature on a stable community

Answer

A

Check notes

Question 63

Q

Describe predator prey cycles

Answer

A

Predator and prey populations determine one another’s growth
The size of one population has a direct impact on the others
This is a cyclic relationship (recurring in cycles)

Question 64

Q

Describe the predator prey cycle graph

Answer

A

The pattern shown is that whenever the prey rises to a peak in population size, the population size of the predator grows soon after (but not to the size of the prey), then then as soon as the population size of the prey starts to drop again, soon the population of the predator will as well, this pattern continues multiple times.

Answer 62

A

This pattern exists as, since the population of the prey rises, then the predators have more food to eat, so they have more chance of survival, so they can reproduce more, so their populations increase, which means they need more food to maintain their population, so they eat more prey, so the population size of the prey falls, so the predators have less food, so they have less chance of survival, so they reproduce less, so their population falls as well, and now since theirs less predators to eat the prey the prey have a higher chance of survival and so their population rises again and the cycle starts again.

Answer 63

A

a. Evolving or recurring in cycles – changes in population size
b. Recurrence in cycles – as one population changes it directly affects another

Answer 64

A

a. Climatic changes

b. Disease

Answer 65

A

The number of food sources relied upon (If only one food source is relied upon, and it is destroyed, the population will crash/die. If it has other options its likelihood of survival is higher)
Genetic diversity (Increased probability that there is an advantageous allele in the population)
Availability of mates (Those with advantageous allele or those who survive can breed easily and increase the population size rapidly. Lack of mates means the population cannot increase)
Gestation time (asexual or sexual) (Can lots of offspring be produced very quickly after a crash or decline to re-build the population quickly?)
Intensity of change (Has the environment significantly changed i.e. a drought or is it a period of prolonged dryness that can be survived?)

Answer 66

A

Check notes

Answer 67

A

Advantages –
• Control group for comparison
• Investigate multiple factors i.e. is it food availability, poaching or both
• Difficult to count all organisms in the wild so data is unreliable

Disadvantages –
• Results in extermination of the prey which would not happen in nature. Why?
• Habitats are varied in the wild (could have an effect)
• Area the organisms can travel is much larger
• Prey can escape predation

Answer 68

A

… 2 or more individuals share any resource that are insufficient to satisfy their requirements

Answer 69

A

space, mates, food and minerals, light, territory and water

Answer 70

A

Intraspecific (same species) i.e. mates

2. Interspecific (different species) i.e. space/food

Answer 71

A

• The availability of resources determines the population size as the greater the availability, the larger the population size as there are more resources to grow and breed

Answer 72

A

Mutation occurs
Mutation is advantageous (causes leaf to have larger leaves or extended roots)
Organisms is better adapted to access the requirements for photosynthesis
Organisms grows and survives to reproduce
Frequency of allele increases in subsequent generations
At the expense of the smaller leaved plants

Answer 73

A

Limpets, competing for algae (food)
Oak trees, many small trees, some grow and block light, smaller ones dies, left with few large, dominant oaks
Robins, breeding territory, females only mate with males with territory, each territory only supports one family, scarce food, territories become larger

Answer 74

A

Populations of 2 different species initially occupy the same/very similar niche BUT…..
One will normally have a competitive advantage over the other so….
Best adapted survives and breed
Population increases at the expense of the weaker, less adapted species, resulting in…..
Complete removal of the weaker species

Answer 75

A

No two species competing for limited resources can co-exist (or occupy the same niche) as one will always eliminate the other

Answer 76

A

Red : Native to UK
Grey : Introduced from America
2.5 million grey squirrels and only 160,000 red.

Answer 77

A

More grey squirrels, less red squirrels as competing for food, habitats and space
Number of predators increase, grey squirrels do not increase in number as predators eat grey squirrels but the ones alive still outcompete red
As predation decreases, population of red squirrels decrease and grey squirrels growth slows, grey squirrels are not eaten but more competition within grey

Answer 78

A

Many other factors involved (abiotic)
A causal link has to be established
Often a time lag (population change may be due to competition that took place many years earlier)
Data on population sizes are hard to obtain and not always reliable

Answer 79

A

the number of individuals of a species in a given space

Answer 80

A

.Study small sections of the habitats in detail

Answer 81

A

Random sampling in the form of frame quadrats and point quadrats
Systematic sampling along transects

Answer 82

A

investigate the difference between two or more sites

Answer 83

A

The size of the quadrat to be used
The number of sample quadrats to record within the study area
The position of each quadrat within the study area

Answer 84

A

.Size of the species being studied
.Size of the area being studied
.Are species evenly distributed or clustered in small groups? If not, a large number of small quadrats is representative

Answer 85

A

.Larger sample = more reliable the results
.Number of species present in the sample area
.Larger number of different species in the sample, the greater the number of quadrats required to produce valid results

Answer 86

A

.Sampling must be random

Answer 87

A

Two long tape measures at right angles along 2 sides of the study area.
Use coordinates by using random numbers from a table/computer
Place a quadrat at the point of intersection
Repeat multiple times

Answer 88

A

Avoid sampling bias
Ensure data obtained is valid
Produce statistically significant results

Answer 89

A

Choose a quadrat of appropriate to the size - plants are quite small but area is quite large so 1m2 would be most suitable
Choose 2 fields close together as this minimises soil, climatic and other abiotic differences
One site is regularly grazed, the other is not
Take random samples at many sites in each field either by dice, random number generator, co-ordinates out a hat
Place the quadrat on the ground and record the names and numbers of the different species present
Repeat to increase reliability and calculate a mean

Answer 90

A

Horizontal bar supported by 2 legs.
Pins are dropped through holes in the top
Each species the pin touches is recorded.

Answer 91

A

.Difficult to identify and count every organism
.Time consuming
.May damage the habitat.
.Difficult to avoid introducing an element of personal bias
.No indication of pattern

Answer 92

A

\+ Smaller organisms
\+ Small areas or specific detail 
-Tedious 
-Hard to use
-Time consuming

Answer 93

A

.Construction sites, less environmental costs
.Finding the optimum conditions for horticulture
.Finding the optimum conditions for agriculture

Answer 94

A

The distribution of a species

Answer 95

A

.Gradual changes occur across a habitat
.Transitions within communities occur
.Zonation is present

Answer 96

A

.Belt transect

.Line transect

Answer 97

A

.String or tape
.Organisms over which the line passes are recorded
.Usually using a quadrate

Answer 98

A

.Strip or meter wide tape
.Second placed parrall to the first
.Species between the two belts are recorded

Answer 99

A

.Limited Time (Quick)
.Easily shows species range along the transect
.Clear visual of how species change
.Harder to see the range across a large area
.Less data collected

Answer 100

A

.More data
.Tells you more about the abundance AND range of individual species at different points along the line
.Shows changes/distribution more clearly as more data
.Dominance of one species can be determined
.Larger area covered
.Time Consuming

Answer 101

A

change in the number of species over a given area
.It is not a comparison between two area
.It is used to show a trend

Answer 102

A

Place a transect (tape measure) down across a given area
Place a quadrat down at equal or random intervals along the transect
Carry out a second transect in a different part of the sample are but still close by your first sample, so that there is not too much variance in the environment as to change the results massively
Calculate a mean across the 3 transects studied and display your results in a table
Plot a graph and describe the pattern shown

Answer 103

A

… the number of individuals in a given space

Answer 104

A

.The likelihood of a particular species occurring in a quadrat

Answer 105

A

.Estimate of the area within the quadrat that a particular plant species covers

Answer 106

A

Per quadrat = (number of squares species occurs / number of squares in total) x 100

Answer 107

A

Often expressed as a %
Useful where a species is easier to count
A quick idea of the species present
Lacks information on the density
No detailed information distribution of a species
Can be quite time consuming

Answer 108

A

Useful when a species is abundant or difficult to count
Data can be collected quickly
Gives a representation of distribution/density
Less useful where organisms occur in overlapping layers
Can be less precise
Often subjective

Answer 109

A

A specific number of animals are caught, marked and then released
After some time, a given number of animals are collected randomly
The number of marked animals counted

Answer 110

A

(total number in 1st sample x total number in 2nd sample) / number of marked individuals recaptured

Answer 111

A

… they might have different adaptations to make them more camouflaged/escape

Answer 112

A

Live organisms
Large areas to sample
Focus of one species

Answer 113

A

Proportion of marked to unmarked in the second sample is the same as the proportion of marked to unmarked in the whole population – results not due to different sizes of sample
Marked individuals distribute evenly – results are valid and not in clusters
The population has a definite boundary – you are studying the whole population
Markings are nontoxic and makes it no more conspicuous – do not injure of reduce the survival chances
Population is constant e.g. not breeding season – ‘new’ individuals would not be marked
Markings cannot be rubbed off during the investigation – population size in second sample is not reduced = valid

Answer 114

A

When organisms can move, hide, and are difficult to find and identify

Answer 115

A

Time consuming (need to leave time)
Risk of predation changing sample size
Disturbance of habitat
Trauma or injury to the organism (ethics)

Answer 116

A

The binding of the first oxygen to haemoglobin makes the binding of the second and then third easier

Answer 117

A

Organisms will compete for the same resources, the better adapted will survive at the expense of the weaker

Answer 118

A

the change in species in an area over time

Answer 119

A

It can be either

Answer 120

A

Seen in a range of environments:
.Silt/mud deposits at estuaries
.Lakes/ponds created by land subsiding
.Sand forming dunes

Answer 121

A

it becomes more suitable for other species with different adaptations

Answer 122

A

Pioneer species (a species colonises an inhospitable area, the first one)

Climax community (stable community, very little/no change, the last one)

Answer 123

A

Reproduce asexually
Produce large quantities of wind dispersed seeds or spores
Can tolerated/are adapted to survive in harsh conditions i.e. low light intensities, low/high pH
Short dormancy or fast germination
Photosynthesise
Are nitrogen fixing

Answer 124

A

.They reproduce asexually so that they do not rely on another species to increase its population size
.They produce large quantities of wind dispersed seeds or spores so that they can spread to remote areas and without the need for other organisms
.The can tolerate harsh conditions so that they can survive and reproduce when no other organism can
.They have short dormancy/fast germination so that they can reproduce/increase in number quickly
.They can photosynthesise so that they do not rely on food sources
.They are nitrogen fixing so they improves soil quality in when few nutrients

Answer 125

A

Pioneer species colonises inhospitable area
Reproduces = increases
Changes the conditions/a species makes the conditions less hostile;
New/primary coloniser is better competitor/pioneer species outcompeted; Example = Lichens
Pioneer species grows, dies and nutrients are recycled via decay
Increase in secondary coloniser, changing abiotic factors further
Better adapted/tertiary species increases and secondary decreases
Process continues until a climax community is formed
Few if any new species are replaced

Answer 126

A

Pioneer Species
Colonises harsh environment
Reproduce and increase population size
Changes the environment – nitrogen fixing
Improve soil quality
Primary Coloniser – for example Lichens who colonise bare rock and can survive desiccation (extreme dryness)
New species better adapted
Outcompete pioneers
New community forms
Continue to change the environment (abiotic factors) to make it less hostile
Secondary Coloniser
Weathering of the rock creates sand and soil
Lichens die and decompose
Nutrients are recycled
Nutrients support small plant species
• The quality and quantity of the soil improves
• Rock erosion continues and plant species die and decompose.
• The smaller plants again change and improve the abiotic factors
• The area can support larger species: grasses, shrubs then trees.
• Continues until the climax community is reached.

Answer 127

A

Cessionary

Answer 128

A

Animals are still reliant on the pioneer plant species
Lichen dies and provides food for detritus feeders  Mosses and grasses provide food and habitat for insects  Secondary consumers feed on the insects  Flowering plants and trees support reptiles, mammals and birds
They are still reliant on lichens to provide primary colonisers with food

Answer 129

A

plant

animal

Answer 130

A

It does it much faster as the seeds and spores are already present therefore it does not begin at a pioneers species
- The climax community will be different as there are different abiotic factors

Answer 131

A

Maintaining individuals, populations and ecosystems in their current state without the exploitation of their natural resources

Answer 132

A

Allowing ecosystems to evolve (change) naturally, without resources being overused, there is active human management and two forms:
-	Ex-situ:
Individual endangered species in zoos
Outside natural habitat
-	In-situ:
Whole ecosystems and landscapes
Within habitat
Monitoring succession

Answer 133

A

Allows ecosystems to evolve naturally
No detrimental effects on any stage of succession
Enables maximum diversity and ecosystems

Answer 134

A

Mid Succession
Not dominated by one species (low diversity)
Not a very hostile environment
Can support multiple species, more habitats/food sources = higher biodiversity

Answer 135

A

Dominated by one species
High competitive element
Competitive exclusion principle
Low Biodiversity

Answer 136

A

SOME areas are burnt = Prevent succession
Prevents dominance/climax community
Older forms are less palatable and less nutritious
New heather and other new species can grow
Biodiversity is increased

Answer 137

A

Habitats
Food sources
Species

Answer 138

A

Grazing by sheep and/or periodic burning
Maintains low growing plant populations
Provide plentiful food sources for grouse
Increases number of grouse
Happy hunters!

Answer 139

A

Moorland would undergo secondary succession
Moorland would reach its climax community
Community would be dominated by deciduous oak woodland (one species)
Reduction in biodiversity

Answer 140

A

Hunters pay to shoot/only allowed at given times

Payments control and coordinate conservationist burning the land

Answer 141

A

Money - Medicines
Tourism - Wood
Food - Horticulture
Removal of CO2

Answer 142

A

all the alleles of all the genes of all the individuals in a population at a given time at a given time

Answer 143

A

the process by which organisms that are better adapted to their environment tend to survive and breed at the expense of those less well adapted.

Answer 144

A

Genetic factors

2. Environmental factors

Answer 145

A

Meiosis
Sexual reproduction
Main factor – Mutations
All can result in selection occuring

Answer 146

A

.The most common result (mode) is near the average (mean) and the middle value (mode)

Answer 147

A

Change shape

Answer 148

A

Change in environment
Changes the mean
Extreme is selected for
Antibiotic Resistance

Answer 149

A

Selection against both extremes
Phenotypic variation decreases
Environment has remained stable
Birth Weight

Answer 150

A

Random mutation of alleles within the gene pool
The new allele has an advantage in a SPECIFIC environment
The individuals are better adapted/obtain resources
These individuals grow rapidly and live longer compared to other alleles
Reproduce passing on this allele.
Offspring survive better and reproduce
The advantageous allele increases at the expense of the individuals with the less advantageous allele.
Change in the allele frequencies in a population occurs = Evolution

Answer 151

A

environmental factors that limit the population of a species

Answer 152

A

Determine the frequency of all the alleles within the gene pool
Vary from time to time and place to place

Answer 153

A

… certain factors may increase the chances of selection occurring

Answer 154

A

dation, competition, disease, natural disasters

Answer 155

A

A spontaneous mutation results in a different protein structure, a new enzyme breaks down the antibiotic. Bacteria with the mutation survived. Antibiotic resistance bacteria multiply, this creates an increased frequency of antibiotic resistant alleles at the expense of the non-resistant population.

Answer 156

A

exponentially

Answer 157

A

… the growing total number or size’

Answer 158

A

organisms reproduce and have sufficient resources and genetic variation is present within the population and phenotypic variation is present within the population (greater diversity = adapt to change)

Answer 159

A

have a high reproductive success and a suitable population size to minimise intraspecific competition

Answer 160

A

high death rates from predators, low parental investment and lack of resources

Answer 161

A

Turtle – some food sources, some camouflage
Arctic Fox – Not camouflaged, too warm in summer, some possible food
Hedgehog – lots of food sources, camouflage, hibernation, adapted to predators
Eagle – plenty of food sources, adapted to hunt, suitable habitats
Human – not camouflaged, ability to hint but possible limited food sources

Answer 162

A

Be better adapted to the environment i.e. Camoflagued
- Suited to prevailing conditions i.e. Catch food
- Resit disease

Answer 163

A

Changing environments - New diseases

- New predators - New competitors

Answer 164

A

When high number of eggs, each individual young will receive less food; reference to mortality rates to disease / predators for
low numbers of eggs; so in both cases low number of offspring will reach maturity / survive;
so less likely to pass on genes / alleles;

Answer 165

A

environmental factors that limit the population of a species

Answer 166

A

Stabilizing Selection –
.Selection pressure against both extremes
.(Mean remains the same)
Directional Selection –
.Selection pressure for an extreme
.(Mean changes)

Answer 167

A

evolution

Answer 168

A

.Least common form of selection
.Opposite to stabilizing selection
.Favors the extremes at the expense of the intermediate phenotypes

Answer 169

A

When an environmental factor i.e. temperature takes two or more distinct forms. Summer – warm, Winter = cold

Answer 170

A

5 degrees in winter (long fur). 15 degrees in summer (Short fur)
Result: Two different species, each activie in each season
One active in summer so only breed with others active in summer, producing short haired cubs.
One active in winter only breed with those active in winter

Answer 171

A

Most important for causing evolutionary

* Could result in two distinct species

Answer 172

A

Large males and small males have a selective advantages
Small males sneak up to females so reproduce and pass on their alleles
Large males’ fierce competitors so attract the females and reproduce passing on their alleles
Intermediate sized is selected against as has no selective advantage

Answer 173

A

A mathematical equation used to calculate the frequencies of the alleles of a gene in a population

Answer 174

A

statitical

Answer 175

A

Establishes the frequency of the dominant and recessive alleles
Establishes the frequency of carriers (heterozygotes) in a population

Answer 176

A

Dominant allele = p

Recessive allele = q

Answer 177

A

p x p = p2

Answer 178

A

q x q = q2

Answer 179

A

p x q = pq

Answer 180

A

q x p = qp

Answer 181

A

the frequency/ number of individuals in that population that are homozygous dominant (AA)

Answer 182

A

the frequency/number of individuals that are heterozygous (Aa or aA)

Answer 183

A

the frequency / number of individuals in that population that are homozygous recessive (aa)

Answer 184

A

The proportion of dominant and recessive alleles of any gene in a population remains from one generation to the next

Answer 185

A

No new mutations arise
The population is isolated (no gene flow / flow of alleles into or out of the population)
There is no selection bias
Population studied is large
Mating is random

Answer 186

A

No new mutations arise – no introduction of new alleles
The population is isolated (no gene flow / flow of alleles into or out of the population) – movement encourages interbreeding which reduces genetic differences between populations
There is no selection bias – natural selection = advantageous alleles favoured
Population studied is large – prevents the effects of random events affecting allele frequencies or changes due to chance
Mating is random – prevents the selection of particular alleles, selective breeding would alter allele frequencies

Answer 187

A

The formations of two populations from one

Answer 188

A

Allopatric speciation and sympatric speciation

Answer 189

A

.Haemoglobin carries oxygen / has a high affinity for oxygen / oxyhaemoglobin;
. Loading / uptake / association in lungs;
.at high p.O2;
.Unloads / dissociates / releases to respiring cells / tissues
.at low p.O2;
.Unloading linked to higher carbon dioxide (concentration);

Answer 190

A

… environmental factors that limit the population of a species

Answer 191

A

… selection pressure against both extremes, and so the mean remains the same

Answer 192

A

… selection pressure for an extreme, and so the mean changes

Answer 193

A

Selects against the average phenotype
Favours the extreme phenotypes
Can lead to speciation

Answer 194

A

the evolution of new species from existing species

Answer 195

A

.It enables evolutionary change and diversity

Answer 196

A

Reproductive isolation
Genetic differences (mutations)
Geographical isolation
o Differences in two populations gene pools

Answer 197

A

Allopatric Speciation:

Sympatric Speciation:

Answer 198

A

.More common
.Different locations
.Geographic separation

Answer 199

A

.Less common than allopatric
.Same location
.Reproductive isolation

Answer 200

A

.Each species will have its own range, within which there will be a number of other populations of that species
.Populations can still interact and interbreed
.Unless a barrier occurs, preventing migration between populations of the same species
.The environments of each new range may be different
.Different mutations occur in each range
.Due to different selection pressures, different mutations are favoured
.No gene flow can occur and so changes in allele frequency occur
.Eventually they will be unable to interbreed even if the barrier is removed

Answer 201

A

The diversification of a species into forms adapted to different ecological niches

Answer 202

A

.More common than sympatric
Different locations
.Geographic seperation 
.Physical barrier i.e. Lake, desert, mountain area
.Takes millions of years

Answer 203

A

.Less common than allopatric
.Same locations
.Reproductive isolation
.Breeding seasons or food preference

Answer 204

A

Only lay eggs inside Hawthorns Fruits (native to North America)
Apple trees introduced
Some flies lay eggs in apples
Mates are found by searching site where they were raised
Raised in apples, mate with flies raised in apples
Mutations may result in two new species

Answer 205

A

apple maggot fly, seasonal breeding

Answer 206

A

In a small populations there will be:

A small variety of alleles (lower genetic diversity)
Not equal chance of each allele being passed on OR if a muation occurs….
One allele/mutation is passed on very quickly
Increase in allele frequency
Speciation is more likely

Answer 207

A

Genetic drift is genetic change due to chance, eg. By chance fewer decesendents of one phenotype are left behind after some organisms of a species get stamped on

Answer 208

A

Geographic(al) isolation;
Separate gene pools /no interbreeding/gene flow
Variation due to mutation;
Different selection pressures / different abiotic / biotic conditions / environments / habitats
Different(ial) reproductive success / selected organisms (survive and) reproduce
Leads to change / increase in allele frequency

Answer 209

A

Observation
Hypothesis (Null hypothesis, Alternative hypothesis)
Experimentation
Results Analysis
Further Research

Answer 210

A

.There will be no significant difference between two sets of data

Answer 211

A

.There will be a significant difference between two sets of data

Answer 212

A

a mechanism for making quantitative decisions about a process or processes

Answer 213

A

comparing observed and expected values

Answer 214

A

looking for significant differences between two sets of data

Answer 215

A

is there a significant correlation between 2 variables?

Answer 216

A

The level of probability that you can accept or reject your null hypothesis (significant or due to chance)

Answer 217

A

Calculate a chi squared value
Compare your calculated value with a critical value
At a 0.05 level of probability
95% confidence the difference is significant
5% probability it is due to chance

Answer 218

A

.The number of variables that are free to change
.Calculated by number of categories (n) – 1
.Example: 3 categories – 1 = degrees of freedom is 2

Answer 219

A

.Conduct your statistical test = calculated chi squared value
.Compare calculated chi squared and critical values
.If your Chi squared value is higher than the critical value at 0.05 probability, reject the null hypothesis and the results are not due to chance.
If your value is LESS, ACCEPT null hypothesis.
If your value is GREATER, REJECT null hypothesis.

Answer 220

A

Harry Robinson - HR - Higher Reject, for the chi test

Answer 221

A

Formulate a Null Hypothesis
Select the appropriate statistical test
Carry out the calculation
Determine the degrees of freedom
Compare your calculated value to the critical value calculated at 0.05
Compare the calculated value with the critical value:
a) Higher than the critical value = difference is not due to chance = reject the null hypothesis
b) Lower than the critical value = difference is likely due to chance = accept the null hypothesis

Answer 222

A

.Identify significant differences between observed and expected results
.Measure the degree of deviation between them
.Determine if differences present between data sets (2+) are significant or due to chance

Answer 223

A

.Data is categorical Phenotypes i.e. eye colour, gender, location
.The portion of numbers expected in each category is known
.The number in each category is greater than 5

Answer 224

A

Chi-squared = Sum ( (observed result – expected result)^2 / expected result)

Answer 225

A

observed result

Answer 226

A

Excepted result

Answer 227

A

Selective pressures against the intermediate trait

Answer 228

A

fur length (medium against)

Colour or rabbit (white against)

Answer 229

A

Speciation is the formation of two species from one

Answer 230

A

Sympatric Speciation = Same place

Answer 231

A

Examples are mayflies or seasonal breeding

Answer 232

A

away from species

Answer 233

A

Geographic(al) isolation
Separate gene pools / No gene flow
Variation caused by a mutation
Different selection pressures
Different(ial) reproductive success
Change in allele frequency.

Answer 234

A

Genetic Change due to CHANCE dissapearance of certain alleles
In small populations
Increases liklihood of speciation

Answer 235

A

Smaller population, fewer alleles, less diversity
By chance, one allele is not passed on
By chance fewer decedents of one phenotype are left

Answer 236

A

Way in which a population becomes separated

* Required for speciation to occur

Answer 237

A

Inhabit different areas (within the same area), individuals rarely meet or cross paths/mating grounds

Answer 238

A

Breeding seasons do not coincide, may not be fertile at the same time, no interbreeding

Answer 239

A

Different chromosome number, fusion of gametes cannot produce viable gametes, horse (2n = 64), donkey (2n = 62) = mule 63 – no pairing

Answer 240

A

Courtship behaviors are different, no attracted to one another scent, different mating rituals

Answer 241

A

• Allowing ecosystems to evolve naturally
• Without resources being overused or exploited
• Active human management
Ex situ vs in situ

Answer 242

A

Gradual change
Each species changes the conditions for the next
Conservation of middle stages
Maintains more habitats, food sources, diversity

Answer 243

A

Pioneer species (inhospitable area)  Intermediate stages (highest diversity)  Climax community (domination of one species)

Answer 244

A

Example, burning heathlands –
1. SOME areas are burnt = Prevent succession
2. Prevents dominance/climax community
3. Older forms are less palatable and less nutritious
4. New heather and other new species can grow
5. Biodiversity is increased
Problems? This can be costly as hunters pay a charge to hunt

Answer 245

A

Slow growth  rapid growth  carrying capacity

Answer 246

A

Best to use with rapid growth or when studying a long period of time
• Reduces wide-ranging quantities to tiny scopes
• Clearer Pattern shown

Answer 247

A

• Bacterial Growth

Answer 248

A

.Looking for significant differences between 2 sets of data

Answer 249

A

The sample size is less than 25

- The data is normally distributed

Answer 250

A

T = (x1 – x2) / (root( (s1^2 / n1) + (s2^2 / n2) ))

Answer 251

A

mean of first sample

Answer 252

A

mean of second sample

Answer 253

A

standard deviation of first sample

Answer 254

A

standard deviation of second sample

Answer 255

A

number of measurement sin fist sample

Answer 256

A

number of measurements in second sample

Answer 257

A

.How much the data deviates from the mean

.Average distance between each of the data points and the mean

Answer 258

A

68% of the data lies within 1 s.d

95% of the data lies within 2 s.d

Answer 259

A

S = root( ( sum( x-mean(x) )^2 ) ) / (n-1) )
X = each score
N = the number of values

Answer 260

A

.Identify significant differences between observed and expected results
.Measure the degree of deviation between them
.Determine if differences present between data sets (2+) are significant or due to chance.

Answer 261

A

.Data is categorical (e.g. Phenotypes i.e. eye colour, gender or location)
.The portion of numbers expected in each category is known
.The number in each category is greater than 5

Answer 262

A

χ^2=∑((O-E)^2/E)

Σ Sum of
O Observed result
E Expected result

Answer 263

A

Formulate a Null Hypothesis
Select the appropriate statistical test
Carry out the calculation
Determine the degrees of freedom (n-1)
Compare your calculated value to the critical value calculated at 0.05
Compare the calculated value with the critical value:
Higher than the critical value = difference is not due to chance = reject the null hypothesis
Lower than the critical value = difference is likely due to chance = accept the null hypothesis

Answer 264

A

Formulate a Null Hypothesis
Select the appropriate statistical test
Carry out the calculation
Determine the degrees of freedom (n-1)
Compare your calculated value to the critical value calculated at 0.05
Compare the calculated value with the critical value:
a) Higher than the critical value = difference is not due to chance = reject the null hypothesis
b) Lower than the critical value = difference is likely due to chance = accept the null hypothesis

Answer 265

A

.If there is a statistically significant difference between two means when…..
.The sample size is less than 25
.The data is normally distributed

Answer 266

A

root( (sum (x - mean(x))^2 ) / (n-1) )
x = each score
n = the number of values

Answer 267

A

t = (x1 - x2) / root( (s1^2 / n1) + (s2^2 / n2) )

x1 = mean of 1st sample 
x2 = mean of 2nd sample
s1 = S.D of 1st sample
s2 = S.D of 2nd sample
n1 = no. measurements in 1st sample
n2 = no, measurements in 2nd  sample

Answer 268

A

.If t is HIGHER than the critical value = REJECT the null hypothesis = there is a significant difference between both samples, differences are not due to chance
.If t is LOWER than the critical value = ACCEPT the null hypothesis = differences between the samples are not significant and are likely due to chance

Answer 269

A

to find if there is a significant correlation between 2 variables

Answer 270

A

.If there is a significant correlation
.If the correlation is positive or negative
.Compares data which from two values
.May be visible on a graph

Answer 271

A

( sum(XY) – ( ( (sum(x)) x (sum(y)) )/n ) ) / root( ( sum(x^2) – ( (sum(x) )^2 /n ) ) x ( sum(y^2) – ( (sum(y) )^2 /n ) ) )

Answer 272

A

the number of values of x and y

Answer 273

A

r will always be between -1 and 1

Answer 274

A

stronger the positive correlation

Answer 275

A

the weaker the correlation

Answer 276

A

stronger the negative correlation

Answer 277

A

Weak positive correlation

Answer 278

A

.Strong negative correlation

Answer 279

A

Formulate a Null Hypothesis
Select the appropriate statistical test
Carry out the calculation
Determine the degrees of freedom
Compare your calculated value to the critical value calculated at 0.05
Compare the calculated value with the critical value:
a) Higher than the critical value = difference is not due to chance = reject the null hypothesis
b) Lower than the critical value = difference is likely due to chance = accept the null hypothesis

Answer 280

A

Access to medical care
How much money people in the country have
How developed the country is, e.g. water quality
Benefits systems
Religious beliefs, contraception
Education, contraception
Social pressures
Availability of contraception
Culture
Age of population
Life expectancy low at birth
Natural disasters and war
Sanitation

Answer 281

A

Reproduce asexually
Reproduce quickly (short gestation period)
Produces lots of offspring
Movement of offspring
Doesn’t rely on other organisms
Adapted to harsh environments
Photosynthesise
Are nitrogen fixing

Answer 282

A

maintaining individuals, populations and ecosystems in their current state without the exploitation of their natural resources

Answer 283

A

allowing ecosystems to evolve (change) naturally, without resources being overused

Answer 284

A

Line Transect
.String or tape
.Organisms over which the line passes are recorded
.Usually using a quadrat

Belt Transect
.Strip or metre wide tape
.Second placed parallel to the first
.Species between the two belts are recorded

Answer 285

A

Line - .Limited time (quick)
.Easily shows species range along the transect
.Clear visual of how species change
.Harder to see the range across a large area
.Less data collected

Belt -
.Mora data
.Tells you about the abundance and the range of individual species at different points along the line
.Shows changes/distribution more clearly as more data
.Dominance of one species can be determined

Answer 286

A

Proportion of marked to unmarked in the second sample is the same as the proportion of marked to unmarked in the whole population – so results not due to different sizes of sample
Marked individuals distribute evenly – so results are valid, representative and not a result of clusters
The population has a definite boundary – so you are studying the whole population/habitat
Markings are nontoxic and makes it no more conspicuous – so it does not injure them or reduce their survival chances
Population is constants (not breeding season) – ‘new’ individuals would not be marked/representative
Markings cannot be rubbed off during the investigation – so that the population in second sample is not reduced

Answer 287

A

The Hardy-Weinberg principle is a mathematical equation used to calculate the frequencies of the alleles of a gene in a population.
Classed as a statistical analysis
- Established the frequency of the dominant and recessive alleles
- Established the frequency of carriers (heterozygotes) in a population

Answer 288

A

The proportion of dominant and recessive alleles of any gene in a population remains the same from one generation to the next

Answer 289

A

No new mutations arise, so no introduction of new alleles
The population is isolated, so no movement which encourages interbreeding which would reduce genetic differences between populations
There is no selection bias, natural selection = advantageous alleles favoured
Population studied is large, prevents the effects of random events affecting allele frequencies or changes due to chance
Mating is random, prevents the selection of particular alleles – selection breeding would alter allele frequencies

Answer 290

A

p = dominant allele
q = recessive allele
p2 + 2pq + q2 = 1
p2 is frequency of individuals that are homozygous dominant (AA)
2pq is frequency of individuals that are heterozygous (Aa or aA)
q2 is the frequency of individuals that are homozygous recessive (aa)
1 = all the alleles present must add up to 1 or 100%

Answer 291

A

A segment of a nucleic acid that carries the code for a particular polypeptide or fRNA

Answer 292

A

The location of a specific gene on a chromosome

Answer 293

A

Monomers which make up proteins, coded for by 3 nucleotides

Answer 294

A

3 bases code for 1 amino acid

Answer 295

A

The sequence of bases on mRNA which codes for amino acids

Answer 296

A

Base combinations that lead to the same amino acid

Answer 297

A

Each of the amino acids that are coded for are distinct from the bases of adjacent amino acid codes

Answer 298

A

The same in all living organisms and cells

Answer 299

A

A part of DNA which codes

Answer 300

A

A part of DNA which doesn’t code

Answer 301

A

Structures found inside the nucleus which hold genetic information

Answer 302

A

One of the two strands of a chromosome, held together by the centromere, after DNA replication, before division

Answer 303

A

Proteins found in the nucleus of eukaryotes which DNA coils around

Answer 304

A

A version of a gene

Answer 305

A

Choose a letter to represent the trait you are investigating (B for blue eyes)
Choose letters that are different lower case and capitals (Gg not Ww)
Capital = dominant, lower case = recessive
Label parents and their phenotypes (parent 1 = brown eyes)
Label gametes the parents produce and circle them
Draw a Punnett square
Label the gender of each parent
Always write the dominant allele first
Work out the cross
State the phenotypes
Calculate the ration

Answer 306

A

a cross in which the alleles of only one gene are involved

Inheritance of a single gene
Used to determine the dominance relationship between two alleles
The cross begins with the parental (P1 or P) generation

Answer 307

A

Consider the inheritance of two characteristics at the same time
Shows how two characteristics, determined by 2 different genes, located on different chromosomes, are inherited

Answer 308

A

Pea plants varied in two ways:
1.	Seed colour
2.	Seed shape
Yellow and round = dominant
Green and wrinkled = recessive
So there were 4 possible combinations:
1.	R and Y
2.	R and G
3.	W and Y
4.	W and G
Or by genotype
1.	RY
2.	Ry
3.	rY
4.	ry
1 and 4 are homozygous, dominant and recessive respectively

He bread these two to produce a plant with 100% chance of RrYy (heterozygous for both characteristics, so all round and yellow), Mendel then crossed these two over

That means there was a ratio of RY:Ry:rY:ry of 9:3:3:1

Answer 309

A

Each member of a pair of allels may combaine randomlu with either of another pair

Answer 310

A

different

Answer 311

A

When both alleles are expressed in the phenotype

- Neither allele is dominant nor recessive, they are both equally dominant

Answer 312

A

One allele codes for an enzyme that catalyzes the synthesis of a red pigment in flowers
The other allele code for an altered version of the enzyme that doesn’t produce the red pigment – flowers remain white

Homozygous for allele 1 – pigment produced – red flowers
Homozygous for allele 2 – no enzyme activity so no pigment – white flowers
Heterozygous – single functioning allele so only produces enough pigment to make the flowers pink

Answer 313

A

We can’t use upper and lower case letters as this implies dominant/recessive
- We use different letters instead
o R = red
o W = white
- Letters should be superscript to the letter that represents the gene in question:
o C = colour

Answer 314

A

Multiple alleles have more than two alternate forms of a single gene, located at the same loci of homologous chromosomes
Polygenetic traits (eye colour) are determined by several genes at different gene loci
Multiple alleles are involved in the determination of a single train by codominance
E.g.
o Human blood groups
o 3 alleles associated with he immunoglobulin gene (gene I)
o Gene I dictates the presence of a certain antigen on the cell surface of red blood cells

Answer 315

A

A
IAIA and IAIO
A

check notes

Answer 316

A

B
IBIB, IBIO
B
Check notes

Answer 317

A

Neither
IOIO
O
Check notes

Answer 318

A

A and B
IAIB
AB
Check notes

Answer 319

A

This is because there are only two homologous chromosomes, so only 2 gene loci

Answer 320

A

A, B, AB, O

O is the most common – 48%

Answer 321

A

Rhesus (Rh) D antigen

Answer 322

A

The antibodies will attack the cells
BUT
As group O red blood cells have no antigens, it can safely be given to any other group

Answer 323

A

A antigens on the red blood cells with anti-B antibodies in the plasma
B antigens with anti-A bodies in the plasma
O antigens but both anti-A and anti-B antibodies in the plasma
Both A and B antigens so no antibodies

Answer 324

A

Transferring DNA fragments from one organism to another
Produces transgenic organisms
Produces genetically modified organism
Produces large quantalities of a required protein

Answer 325

A

Isolation of the DNA fragment that carries the desirable gene
Insertion of the DNA fragment into a vector
Transformation (moving DNA into a host cell)
Identification of the host cells that have successfully taken up the gene by using gene markers
Growth/cloning of the population of host cells

Answer 326

A

genetic code is universal

- Mechanisms involved in transcription/translation are universal

Answer 327

A

Before replication, one chromosome is composed of one DNA molecule
Following replication, each chromosome is composed of two identical DNA molecules (i.e. DNA replication increases the amount of DNA but does not increase the number of chromosomes)
The two identical copies – each forming one half of the replicated chromosome – are called chromatids
During the later stages of cell division, these chromatids separate longitudinally to become individual chromosomes

Answer 328

A

46 chromosomes
23 pairs
22 of the 23pairs have homoglous partners which are identical
23rd pair are sex chromosomes (X and Y)

Answer 329

A

XY – male

XX – female

Answer 330

A

Offspring – 2x XX, 2x XY
Phenotype – 2x male, 2x female
Ratio – 1:1

Answer 331

A

sex-linked

Answer 332

A

Homologous equivalent

Answer 333

A

This is because they have no homologous series on Y that could carry the dominant allele

Answer 334

A

X-linked genetic disorder (defective gene on X)
Blood does not clot correctly
Leads to excess bleeding following a cut or persistent internal bleeding
Fatal if not treated
Fatalities have selectively reduced the gene in the population to approximately 1 in 20,000

Answer 335

A

Have two x chromosomes

- Hemophiliac females used to die at the onset of puberty

Answer 336

A

Recessive

Answer 337

A

codes for an alternative sequence which results in a faulty protein

Answer 338

A

Allow us to trace inheritance of sex-linked characteristics

Answer 339

A

mRNA  cDNA using reverse transcription
Using restriction endonucleases to cut out desired gene
Making the gene in a gene machine

Answer 340

A

CHECK NOTES

Answer 341

A

HIV binds to helper T cells
Protein capsid fuses
Reverse transcriptase converts HIV RNA to DNA
The new DNA moves into the nucleus to create mRNA
New viral proteins and HIV made
HIV bud away from the helper T cell

Answer 342

A

Protein producing cell with large amounts of relevant mRNA is selected
Desired genes mRNA is extracted
Reverse transcriptase forms a single-stranded complementary copy of DNA (cDNA) from mRNA = template strand
Hydrolysis of the mRNA isolates cDNA
DNA polymerase forms DNA on the template cDNA
Desire gene is formed
Could be inserted into plasmids

Answer 343

A

A restriction enzyme
Cutes DNA at a specific sequence of bases – recognition sequence
Has two results
o Producing ‘blunt ends’
o Producing ‘sticky ends’

Answer 344

A

Are a palindrome
o Same forward and backward
4 unpaired bases are opposite
Recognition sequence is 6 bp palindromic sequence
o 6 because restriction endonuclease recognizes a 6 base pair sequence
o Complementary to plasmid

Answer 345

A

Used to create the gene required
Synthesizes DNA fragments from scratch
No need for a pre existing DNA template

Answer 346

A

Desired protein identified
Base sequence determined
Amino acid order determine
Amino acid sequence helps work out complementary mRNA codons
mRNA used to produce complementary DNA

Answer 347

A

The DNA sequence is designed (if not known) and fed into the computer
First nucleotide is fixed to a support
Nucleotides are added in correct order
Protecting groups are added to ensure bases are added at the right place
Compurers design oligonucleotides
a. Short sections of single stranded DNA
Protecting groups are removed and oligonucleotides joined
Double strands are formed to replicate a gene
Gene is inserted into a plasmid
Vector (bacteria) stores, replicates, and transfers the gene
New gene is checked for mistakes
Bacteria carrying suitable gene are cloned

Answer 348

A

Once a DNA fragment containing the desired gene you need is isolated you need to:

Clone it
Produce enough of it for medical or commercial use

Answer 349

A

Two main methods:

In vivo – transferring into a host cell using a vector
In vitro – polymerase chain reaction

Answer 350

A

In vivo amplification involves the same 5 steps:

Isolation
Insertion
Transformation
Identification
Growth

Answer 351

A

Restriction endonuclease
Complementary sticky ends
A vector
A plasmid

Answer 352

A

Desired gene (from a human) is cut at the recognition site with a restriction enzyme
The section of DNA from E.coli (bacteria) is cut using the same restriction enzyme at the same recognition site
Complementary sticky end is produced
Complementary base pairing occurs
Weak hydrogen bonds form
DNA ligase reforms the sugar-phosphate backbone

Answer 353

A

Cuts at the same base sequence
Ensures sticky ends are complementary
Only cuts at specific recognition site
Ensures DNA fragment can insert into the plasmid

Answer 354

A

RNA Polymerase
Transcription factors to bind near gene
Promoter region: initiates transcription
o Tells RNA polymerase where to bind
Terminator: releases RNA polymerase

Answer 355

A

Introducing recombinant plasmids into a host
Mixing bacterial cell and plasmid in a medium containing
o Calcium ions
o Ice cold

Answer 356

A

Ice cold calcium chloride solution
Increases permeability
Heat shock
Encourages uptake

Answer 357

A

Less than 1% take up the plasmids
Some plasmid close before the new DNA is added
Some DNA joins to form its own plasmid

Answer 358

A

Using a second, separate gene on the plasmid that is easily identifiable –

Resistant to an antibiotic
Make a fluorescent protein
Produce an enzyme whose action can be identified

Answer 359

A

When 2 or more genes are carried on the same autosome = autosomal linked
• All linked genes stay together during meiosis
• This means they will pass into the gamete together
• Meaning they will pass into the offspring together
• They do not follow Mendel’s Law of Independent Assortment as each allele is not free to mix with either allele from another pair

Answer 360

A

GGNN
GgNn
GgNn
ggnn

Answer 361

A

Bacterial cells are grown in a medium containing antibiotic
Plasmids taken up, have resistance so survive
Any that do not will die
Problems –
Plasmids may be taken up but close before gene is inserted

OR

Second antibiotic resistance gene is cut when new gene is incorporated
Bacteria with required gene are not resistant
Grown in medium containing antibiotic 2
Those with required gene die

Answer 362

A

One or more secondary petri plates are inoculated with the same colonies of microorganisms from a primary plate, reproducing the original spatial pattern of colonies

Answer 363

A

The bacteria is gown on agar treated with ampicillin (antibiotic)
Colonies grow if resistant to ampicillin (the bacteria that took up the plasmid)
A replica plate is now made by pressing the agar of one petri-dish, onto the agar of a new petri-dish, transferring bacterial cells from each colony onto the new agar
Second agar plate is treated with antibiotic 2
Colonies are allowed to develop
Missing colony did not have resistance, must be a colony containing cells with the plasmid

Answer 364

A

monohybrid two heterozygous

Answer 365

A

dihybrid two heterozygous

Answer 366

A

blood group (heterozygous A and B) or sex linkage (carrier female and normal male)

Answer 367

A

Codominant heterozygous

Answer 368

A

upon/over

Answer 369

A

Epistasis describes a condition whereby one gene controls the expression of another gene
Or
When an allele of one gene affects or masks the expression of another in the phenotype

Answer 370

A

The expression of gene B affects the expression of gene A
bb = no melanin/white
If there is no melanin then gene A cannot be expressed
This means AA, Aa, and aa, will all produce white fur if bb is present
If B is present in the genotype, melanin is produced
If A and B are produced then melanin and banded are produced, so agouti
If B is found with aa, then melanin I produced but bands are not, black

Answer 371

A

Some genes act in sequence by coding for specific enzymes in a pathway
Dominant alleles code for the functional form of the enzyme
Recessive homozygotes would disrupt the pathway
The presence of one non-functional gene will affect the other as failure to express one gene will result in no pigment being made

Answer 372

A

Select a plasmid with two antibiotic resistant genes
Insert the DNA fragment in an antibiotic gene
Grow bacteria on an agar plate containing antibiotic 2
replica plating
Missing colony did not have resistance, and so must be a colony containing cells with he plasmid, you compare this with the first plate, and identify the desired cells to clone

Answer 373

A

Something which carries foreign DNA molecules into another cell.

Answer 374

A

Acts as a marker gene, which allows the detection of cells containing the plasmid.

Answer 375

A

How?
- Organisms such as jellyfish can produce green fluorescent protein (GFP)
- GFP is introduced into bacterial plasmids
- Required gene is inserted in the middle
What?
- Hybrid plasmid is inserted into host (bacterial cell)
- Any cells that successfully took up plasmids will not fluoresce
- These are collected and cloned

Answer 376

A

Desired gene inserted into a gene coding for an enzyme i.e. lactase
Colorless substrate Xgal  lactase  blue
Bacteria are grown in a medium containing Xgal
Bacteria with plasmid cannot produce lactase
Cannot convert colour to blue
Colorless spots identified and cloned

Answer 377

A

Copying DNA fragments outside of living organisms
Fully autonamted
Fast and efficient
Highly used in forensic science

Answer 378

A

PCR (polymerase chain reaction)
DNA sequence is exponentially amplified
Thousands/millions of copies of DNA segment

Answer 379

A

DNA fragment – specimen of interest that needs to be copied
DNA Polymerase – enzyme that joins nucleotides together
Primers – short nucleotide sequence that has bases complementary to one end of the DNA fragments
Nucleotides – contain the 4 DNA bases and are used to join to the DNA fragments
Thermocycler – automated machine that controls the temperature during the PCR cycle

Answer 380

A

DNA Fragments, DNA polymerase, and primers are mixed and put in the thermocycler
Temperature increased to 95’C which causes the hydrogen bonds to break which separates the DNA strands
Cooled to 55’C which causes the primers to anneal to the complementary bases at the ends of the DNA fragments
Primers stop DNA strands from re-joining
Primers provide the starting sequence for DNA polymerase, which can only join nucleotide onto an existing chain
DNA polymerase beings DNA copying
It begins at the primer until it reaches the end of the fragment
Temperature increases to 72’C, which is the optimum temperature for DNA polymerase

Answer 381

A

Produces 2 copies of the original double stranded fragment
One cycle takes about 2 minutes
More than 100 billion copies can be made in a few hours
Process is repeated

Answer 382

A

o It is taken from bacteria in hot springs
o Its an extremophile
o It is thermostable (works functionally in high temperatures)

Answer 383

A

Identify genes responsible for diseases
Infer treatments
Allow early diagnosis
Recombinant gene technology

Answer 384

A

Labelled DNA probes

- DNA hybridization

Answer 385

A

Double stranded DNA is heated
The single stranded DNA is mixed with a labelled DNA probe (marker)
The solution is cooled so the complementary bases can anneal DNA hybridisation
The marker on the probe identifies the gene present

Answer 386

A

Short, single-stranded sections of DNA fragments
Bind to complementary sections on other DNA strands
Labelled so easily identifiable

Answer 387

A

Fluorescently labelled
Radioactively labelled
Isotope 32P
IDd using X-ray film

Answer 388

A

Screen for mutated genes
Create a probe complementary to mutated gene
Sequence the mutant gene
o DNA sequencing is used to determine the nucleotide order of the mutant allele

Answer 389

A

DNA sequencing determines the nucleotide order
DNA fragments complementary to the mutant gene are made
The DNA fragment is radioactively/fluorescently labelled (DNA probe)
PCR used to copy the DNA probe
PCR used to copy the DNA prove
DNA from the patient is heated to make it a single strand
The probe is added
DNA prove will bind if complementary mutant DNA is present
Sample is washed to remove any unattached proves
Labeled DNA fragments labelled are identified

Answer 390

A

A service that help individuals to:

Understand a screenings emotional, psychological, medical and economic consequences
Get more accurate testing and understand results of this
Help make more appropriate and informed decisions

Answer 391

A

Family history
High probability of having children with the disorder
Increased risk/risk factors

Answer 392

A

A collection of microscopic DNA spots
Attached to a solid tile
In a known position

Answer 393

A

It is a lab tool used to:

Detect the expression of different gees
At the same time (simultaneously)
Identify multiple genetic disorders

Answer 394

A

Identify different disease causing genes
Amplify the DNA probes using PCR
Attach them to a glass slide
Extract the DNA/RNA you want to test (from different areas of the genome)
Add a label to this so that it can be identified
Add this to your slide
Complementary DNA in the donor will bind to probes
Wash the array to remove any unbound sample fragments
Expose to UV light
Any DNA bound to the probe will fluorescence

Answer 395

A

If the fluorescent spot contains the probe for the mutated gene, the sample donor has that genetic disorder.

Answer 396

A

A microarray can be very useful for identifying:

Cancer causing mutations
People at risk of genetic diseases
The most effective medicines

Answer 397

A

One alleles of the tumour suppressing gene = can survive

- Both alleles of the tumour supressing gene = tumour may develop

Answer 398

A

Identify people at risk
Ensure they cut down on mutagens
Regular check ups

Answer 399

A

Genotypes affect the effectiveness of some drugs
Dosages can be controlled, making it
o Cheaper
o More effective
o Reduces harm
Cancer screening could show:
Oncogene mutations
o Determine the type of cancer = the best drug or chemo to use
Gene changes
o Predict likely benefit from different treatments
Single cancer cells
o Could cause a relapse
Other Examples:
Painkillers
o Effectiveness linked to activating enzyme levels
Vitamin E
o Reduces risk of cardiovascular disease in some diabetic patients, increases it in others

Answer 400

A

A change to the structure or quantity of DNA

Answer 401

A

There are 2 categories of mutation
o Gene mutation
o Chromosome mutation

Answer 402

A

A change to one or more of the bases
A change to the order of the bases
Can happen during DNA replication

Answer 403

A

Change to the structure or number of chromosomes
o Polyploidy
 Change in whole set, usual when organism has 3 or more sets (plants
o Non-Disjnction
 When homologous pairs don’t separate during meiosis, gametes end up with more or fewer chromosomes

Answer 404

A

One base is replaced with another
3 possible outcomes
o A stop codon is formed
 Polypeptide chain formation is stopped prematurely
o Different amino acid formed
 Polypeptide different by one amino acid
 Protein may have different shape (active site)
o Different codon produce by codes for the same amino acid

Answer 405

A

Deletion of base
Can have a huge impact
Frameshift left
Reading frame shifts so all triplets are changed
All amino acids are different
Worse if deleted base is at the start of a sequence

Answer 406

A

Addition of a base –
- Similar to deletion if its one base – frameshift tight
- If 3 bases (or a multiple of 3 bases) area added there will be no frameshift and so the change less dramatic
Duplication of a base –
- One or more bases repeated
- Frameshift right

Answer 407

A

A group of bases separate from the sequence and re-join in the same place but in inverted order
The base sequence is reversed

Answer 408

A

A group of bases separate from one chromosome and join another
Usually have a marked effect
Translocation between chromosomes 9 and 22 causes leukaemia

Answer 409

A

Translocation is a mutation, crossing over is not
Translocation result in a change in the genetic information between non-homologous chromosomes
Crossing over simple swaps genetic material between homologous chromosomes unchanged

Answer 410

A

Spontaneous
o No outside factors involved, usually during DNA replication
Natural mutation rate = 1 or 2 mutations per 100,000 genes per generation
Mutagenic agents/mutagens increase this
o Chemicals
 Nirogen dioxide affects transcription
 Benzopyrene (tobacco) inactivates tumour suppressor genes
o High energy ionising radiation
 Alpha and beta particles
 Xrays
 UV
 All disrupt DNA Structure

Answer 411

A

Genetic fingerprinting is a forensic diagnostic tool which uses analysis of DNA to identify individuals

Answer 412

A

It is useful for:
-	Forensic science
-	Genetic relationships
o	Paternity testing
-	Genetic variation/diversity
-	Medical diagnosis
-	Plant and animal breeding
o	Identify organism the desired genes
o	Identify paternity (pedigrees)
o	Prevent interbreeding

Answer 413

A

Genomes contain repetitive, non-coding bases (introns)
Contain repeated sequences called variable number tandem repeats (VNTRs)
VNTRs number and length gives a unique pattern
Close related = more similar the VNTRs

Answer 414

A

Extraction
Digestion
Separation (gel electrophoresis)
Hybridization
Development

Answer 415

A

DNA is extracted from a sample (blood, hair, semen, skin)

- Amplified using PCR or cells broken down to release DNA

Answer 416

A

Restriction endonucleases

- Cut close but not within the target DNA (VNTR)

Answer 417

A

What is Gel Electrophoresis?
-	Separates DNA fragments by size
How does it work?
-	Agar gel with electrical current running through it
-	Fragments are labelled
-	Small fragments travel further
-	Final position can be viewed

Answer 418

A

Short sequences of non-coding DNA
Repeat in tandem (end to end)
Number of repeats varies
Length varies

Answer 419

A

Extraction – cell lysis and/or PCR
Digestion – restriction endonuclease
Separation – gel electrophoresis
Hybridization – labelled probe
Development – UV or radioactive analysis

Answer 420

A

DNA sample added to well
Power source turned on and DNA migrates through the gel
The fragments are separated by size
Smallest move further

Answer 421

A

Control = DNA ladder
Sample from scene
Suspects DNA
Comparisons made
Criminal identified

Answer 422

A

A lab technique
Transfer’s electrophoresis-separated DNA fragments
To a filter membrane (nylon sheath)
Prepares fragments for hybridization
Enables identification

Answer 423

A

Nylon membrane
Absorbent paper
Exact position of fragments
DNA probes
Hybridization
Analysis and identification

Answer 424

A

DNA fragments produced on gel
Placed in alkali to separate double strands
Thin nylon membrane laid over gel and covered with absorbent paper sheets
Paper draws up the liquid containing the DNA by capillary action, DNA fragmens fix to the nylon in the same position as the gel
DNA fragments are fixed to the nylon using UV light, nylon is peeled off

Answer 425

A

Radioactive/fluorescent DNA probes are added to label the VNTRs (hybridization)
Specific probes bind to complementary sequences
Washed to remove excess probes
Membrane is dried

Answer 426

A

Nylon sheet is placed under X-ray film
Radioactive probes on the DNA fragments expose the film
Produces visible pattern of light and dark bands
Pattern is unique
Distribution analyzed

Answer 427

A

Extraction
Digestion
Separation
o Including Southern Blotting
Hybridization
Development
o Including Analysis

Answer 428

A

o The DNA may have been left on some other, innocent occasion
o The DNA may belong to a very close relative
o The DNA sample may have been contaminated after the crime, either by the suspects DNA or by chemicals which affect the action of the restriction endonuclease used in preparing the fingerprint
o The calculation used to suggest the probability of a DNA match is based on the assumption that the binding pattern DNA is randomly distributed within the community, but in the case where small religious or ethnic groups tend to have partners within their own community

Answer 429

A

Undifferentiated cells that can mature into any type of cell
All specialised cells originally came from stem cells.
Stem cells divide to become new cells, which then become speciailised.

Answer 430

A

Self-renewal – the ability to go through numerous cycles of cell division while maintaining the undifferentiated state.

Answer 431

A

early stages of development, very flexible

Answer 432

A

found in fetus  adult, specific to a particular tissue/organ, allow self-regeneration only

Answer 433

A

Blood vessels
Skin
Heart
Liver
Gut
Bone marrow
Peripheral blood
Skeletal muscle

Answer 434

A

o Can produce all cell types (embryo and placenta)

o Only present during the first few cell divisions

Answer 435

A

o Can become body cells found in an embryo but not the placenta
o Can divide in unlimited numbers so used in medicine

Answer 436

A

o Found in adults
o Give rise to several different types of specialised cells, but are restricted to a certain organ or tissue types e.g. blood cells

Answer 437

A

o Found in adults

o Can only make one type of cell e.g. epidermal skin cells

Answer 438

A

Totipotent cells have the ability to develop into any cell found in the human body and during its development
Useful during embryo development, as we start off as a single cell, but are eventually a collection of millions of different cell types

Answer 439

A

Embryonic stem cells are important because they can differentiate into any type of cell
For the first few weeks, the developing embryo contains unspecialised cells, these are embryonic stem cells

Answer 440

A

Specialised cells all contain the same genetic information.

A cell becomes specialised as different genes are expressed, and so only some DNA is translated into proteins
All cells in the body do not make all of the products they are genetically capable of, as it would be a waste of resources

Answer 441

A

Some genes are permanently expressed
Some genes are never expressed
Some switch on and off
Differentiated cells produce different proteins as a result
Essentially:
Gene expressed  mRNA transcribed and translated into proteins  proteins modify the cell  cell becomes specialised for a particular function
Genes switched off  mRNA not transcribed  protein not produced

Answer 442

A

The prevention of transcription (therefore no mRNA)

2. Break down of mRNA before translation

Answer 443

A

unipotent

Heart muscle cells
Originally thought they were unable to divide to replicate themselves in mature mammals
Now thought that we have unipotent stem cells in the heart that can replace the old/damaged cardiomyocytes

Answer 444

A

A heart attack occurs when the coronary arteries are blocked
With no blood flow, the cells die, causing cardiac tissue to die
Once these tissues are lost, they cannot be replaced, thus causing permanent damage
Current research has shown that it may be possible to repair damaged cardiac tissue with stem cells
Human embryonic stem cells can differentiate into cardiomyocytes under appropriate conditions

Answer 445

A

Cells can be taken from the early stages of an embryo, grown in vitro, and induced to develop into tissues

Answer 446

A

Degenerative neurological disorder that affects the body’s motor system
It is caused by a lack of dopamine made by brain cells
10 million sufferers

Answer 447

A

iPS cells are induced pluripotent stem cells that are produced from unipotent cells

Answer 448

A

They are genetically altered so that they have the characteristics of embryonic stem cells (pluripotent), this is done by inducing genes and transcriptional factors to be expressed (switches on ‘off’ genes)
Since the genes can be ‘switched on’ it shows that adult stem cells retain the genetic information that was present in the embryonic stage

Answer 449

A

iPS cells are similar to embryonic stem cells, capable of self-renewal, and have the potential to divide indefinitely

Answer 450

A

They could be useful as they replace embryonic stem cells in research and treatment, as well as removing ethical complications

Answer 451

A

Mature plants have many totipotent cells, this allows them to form clones from a single cell

Answer 452

A

Huge potential to cure debilitating disease
Wrong to allow suffering when it can be relieved
Embryos are created for other purposes (IVF) so why not stem cells
Embryos of less than 14 days are not recognisably human and so do not command the same respect as adults or fetuses
There is no risk of research escalating or including fetuses because of current legislation
Adult stem cells are not as suitable as embryonic stem cells and it may be many years before they are, in the meantime many people will suffer unnecessarily

Answer 453

A

It is wrong to use humans, including potential humans, as a means to an end
Embryos are human, they have human genes, and deserve the same respect and treatment as adult humans
It is a ‘slippery slope’ to the use of older embryos and fetuses for research
It could lead to research and development of human cloning and, although banned in the UK, the information gained could be used elsewhere
It undermines respect for life
Adult stem cells are an available alternative and energies should be directed towards developing these

Answer 454

A

Can add a gene to a different organism via a vector
Little risk of contamination as restriction endonuclease is specific
Isolates specific genes
Very accurate/mutation rate is low
Contaminated in In Vivo will not be taken up by the plasmid due to specific sticky ends

Answer 455

A

Very fast (in vitro takes weeks)
Forensic analysis – produce samples quickly from a tiny specimen
Does not require living cells
No time consuming culture needed
Only need a DNA sequence

Answer 456

A

When RNA polymerase reaches a stop triplet, it detaches – the production of pre-mRNA is complete

Answer 457

A

RNA-protein complex made up of small nuclear ribonucleoproteins (snRNPs)

Answer 458

A

check notes

Answer 459

A

The open-end of a tRNA molecule is the amino acid attachment site
The opposite end is the anticodon loop
The anticodon loop consists of 3 unpaired bases
These bases vary, giving tRNA specificity to amino acids

Answer 460

A

Peptide bonds are formed with the enzyme peptidyl transferase and ATP in translation

Answer 461

A

The ribosome loves along the mRNA until it reaches a stop codon, there it detaches due to the presence of a release factor.

Answer 462

A

check notes

Answer 463

A

check notes

Brainscape's Knowledge GenomeTM

Topic 7 - Genetics, population, evolution and ecsystems Flashcards

Brainscape's Knowledge Genome^TM