Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

A-level Biology > GENETICS, POPULATIONS, EVOLUTIONS + ECOSYSTEM > Flashcards

GENETICS, POPULATIONS, EVOLUTIONS + ECOSYSTEM Flashcards

TOPIC 7 (65 cards)

Start Studying
1
Q

SPECIES

A

organisms can interbreed to produce fertile offspring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

POPULATION

A

All individuals of one species in same area at same time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

COMMUNITY

A

all species in particular area at particular time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

ECOSYSTEM

A

community and non-living components of an area
they can range from very small to very large in size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

HABITAT

A

range of physical, biological and environmental factors in which species can live

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

BIOTIC FACTORS

A

.other species compete for resources
.other species that cause disease
.other species used for food
.other species that are predators

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

NICHE

A

role of species in its ecosystem or community – what it eats, where it eats and when it eats
can be abiotic or biotic and niches can be separated by time, location, or behaviour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

CARRING CAPACITY

A

maximum population size an ecosystem can support

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

INTERSPECIFIC COMPETITION

A

Competition between members of different species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

INTRASPECIFIC COMPETITION

A

Competition between members of same species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

RANDOM SAMPLING

A

.if environment is stable
.removes bias
.computer/dice used randomly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

SAMPLING ALONG TRANSECT

A

.environment is changing-succession
.need to sample regularly along transect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

BELT TRANSECT

A

one tape measure is placed through an ecosystem that is not uniform
quadrat is placed at every position along tape measure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

INTERRUPTED BELT TRANSECT

A

one tape measure is placed through an ecosystem that is not uniform
quadrat is placed at set intervals along tape measure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

3 MEASUREMENTS WHEN COUNTING PLANTS IN QUADRAT

A

density-when you count individuals present

percentage cover-investigator estimates the percentage of entire quadrat covered w/species that is being investigated standardise by counting 1% for every small square that is at least half covered by plant

frequency-count how many squares out of 100 contain species you are investigating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

DESCRIBE HOW YOU COULD ESTIMATE SIZE OF POPULATION OF SUNDEWS IN SMALL MARSH IN USING QUADRAT

A
  1. use grid
  2. use random computer generator
  3. count number in quadrat
  4. large sample + calculate mean
  5. calculate total number of sundrews: mean number of plant per quadrat x number of quadrat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

MARK RELEASE RECAPTURE EQUATION

A

N=(number marked in first catch) x (total number in second catch) / number of recaptures in second catch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

MARK RELEASE RECAPTURE RULES

A

.Random collection
.Large sample size
.Ethical treatment
.No net deaths
.Mark –not acting as selection pressure: paint
.Must give time to mix with population before recatching
.Modern – tagging, DNA sample

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

DESCRIBE HOW YOU COULD ESTIMATE SIZE OF POPULATION OF SUNDEWS IN SMALL MARSH IN CAPTURE RECAPTURE

A
  1. collect, mark and release
  2. leave time for species to disperse before second collection
  3. population= (number marked in first catch) x (total number in second catch) / number of recaptures in second catch
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

PRIMARY SUCESSION

A

starting point is bare ground e.g rock, sand or water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

SECONDARY SUCCESSION

A

community is damaged and soil is left Plants then colonise e.g woodland has been felled or fire occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

DESCRIBE + EXPLAIN HOW SUCCESSION OCCURS

A
  1. colonisation by pioneer species
  2. pioneer changes environment
  3. environment become less hostile for new species
  4. increases biodiversity
  5. climax community
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

PRIMARY SUCESSION VS SECONDARY SUCCESSION

A

.starts on bare rock vs soil is already present
.has pioneer species vs no prisoner species
.soil must be formed before plants grow vs would occur after forest fire
.would occur after lava cools + harden to rocks vs grasses are first plants to grow
.no previous life vs occurs where organism lived previously
.both=result in climax community
.both=cause increase in climax community
.both=grows over long period of time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

CONSERVATION

A

maintenance of biodiversity, including diversity between species, genetic diversity within species and maintenance of variety of habitats and ecosystems

involves active human involvement and is often orientated around managing community by halting succession to preserve species that would be extinct by climax community being established

balance between conversation and human needs is necessary in order to maintain sustainability of natural resources

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
GENETIC DIVERSITY
number of different alleles of genes in population
26
WHAT CAUSES DIVERSITY
.new combinations of allele: crossing over independant segregation random fertilatistion
27
SELECTION PRESSURE
factor enabling natural selection to occur-can act on certain alleles + can change allele frequency and gene pool
28
PRINCIPLE OF NATURAL SELECTION
.random mutation result in new alleles of gene .selection pressures exist in environment .increase/decrease in chance of survival and reproduction .advantageous alleles pass on to offspring .many generations-increasing allele frequency in population and change in gene pool
29
DIRECTIONAL SELECTION
for: one extreme trait against: other extreme
30
DISRUPTIVE SELECTION
Individuals w/either extreme trait are more likely to survive and pass on their alleles middling trait allele becomes less frequent leads to speciation
31
STABILISING SELECTION
for: moderate traits against: both extremes
32
GENE POOL
population is collection of all alleles for all of organism’s genes -Species w/more genetically diverse gene pool is more stable and more likely to adapt survive if selection pressures change
33
GENETIC DRIFT
change in allele frequency in population between generations occurs from one generation to next substantial genetic drift results in evolution
34
BOTTLENECK EFFECT
previously large population suffers dramatic fall in numbers major environmental event can massively reduce number of individuals in population which in turn reduces genetic diversity in population as alleles are lost surviving individuals end up breeding and reproducing w/close relatives
35
SPECIATION
when disruptive selection occurs to split population so that both extremes are selected for and median characteristics are selected against splits one population to two diverse and isolated populations each w/different gene pool Over time they will become two different species because they eventually become too diverse to reproduce to produce fertile offspring – one species becomes two
36
FOUNDER EFFECT
only small number of individuals from large parent population start new population new population is made up of only few individuals from original population only some of total alleles from parent population will be present not all of gene pool is present in smaller population gene pool is complete range of DNA sequences that exist in all individuals of population or species
37
ALLOPATRIC SPECIATION
1.Geographical isolation splits population into two eg. emigration/physical barrier 2. prevents interbreeding between populations & separate gene pools form 3. Different random mutations occur in each population and different selection pressures act on each population 4. causes the allele frequency to change differently in each population they become more genetically diverse over time 5. Over time two populations become two species = disruptive selection
38
SYMPATRIC SPECIATION
1. Random mutation in population causes reproductive isolation for few individuals-occurs in same environment 2. prevents interbreeding between populations & separate gene pools form-reproductive isolation 3. new population will pass their alleles on to their offspring and population will rise-change in allele frequency 4. two populations are two species cannot interbreed if reintroduced = disruptive selection
39
ALLELE
one of number of alternative forms of gene
40
LOCUS
location of gene on chromosome
41
DIPLOID
cells which nucleus contains two set of chromosomes
42
HAPLOID
cells that contain only single copy of each chromosome
43
GENOTYPE
genetic constitution of an organism
44
PHENOTYPE
expression of genetic constitution and its interaction w/environment
45
HETEROZYGOUS
two different alleles for same gene
46
HOMOZYGOUS
two copies of same allele for gene
47
CARRIER
Individual who is heterozygous- have mutated allele that can be passed to offspring but it is not expressed in their phenotype
48
RECCESIVE ALLELE
allele that is only expressed if there are no dominant alleles present
49
DOMINANT ALLELE
allele that is always expressed in phenotype
50
MONOHYBRID
Inheritance of one gene-two heterozygous organisms will produce offspring in ratio of 3:1
51
CODOMINANCE
both alleles are expressed in phenotype
52
MULTIPLE ALLELES
More than two alleles for gene eg. Blood groups are both multiple alleles and co-dominance -There are three alleles: IA, IB, IO IA and IB are dominant over IO- IA and IA are co-dominant
53
DIHYBRID
inheritance of two genes-two organisms that are heterozygous for both genes will produce offspring in ratio of 9:3:3:1
54
SEX LINKAGE
gene is on either X or Y chromosome
55
AUTOSOMAL LINKAGE
two genes are on same chromosome
56
PEDIGREE ANALYSIS
Doctors use pedigree analysis chart to show how genetic disorders are inherited in family-They can use this to work out probability that someone in family will inherit condition
57
EPISTASIS
When one gene modifies w/expression of another gene
58
CHI SQUARED TEST
determine whether difference between an observed and expected frequency distribution is statistically significant or due to chance-For inheritance expected frequency can be found using phenotype ratio from Punnett square
59
SUGGEST REASONS WHY OBSERVED PHENOTYPIC RATIO IS NOT OFTEN SAME AS EXPECTED RATIO
1. small sample size 2. fertilisation of gametes is random 3. linked genes 4. epistasis 5. lethal genotypes
60
HOW TO TEST FOR SIGNIFICANCE STEPS
1. Null hypothesis- There is no significant difference between observed and expected frequencies 2. Work out expected frequencies divide number of organisms by phenotype ratio 3. Determine Chi squared value 4. Determine degrees of freedom 5. Find p value and make your conclusion final step is to apply value generated to a chi-squared distribution table to determine if difference is statistically significant- value is significant if there is less than 5% probability results are due to chance
61
HARDY-WEINBERG PRINCIPLE
equation can be used to estimate allele frequency of gene in population or number of carriers/heterozygous organisms p=frequency of dominant allele q=frequency of recessive allele p + q=1 p2=frequency of dominant homozygous allele 2pq=frequency of homozygous genotype q2=frequency of homozygous recessive allele p2 + 2pq + q2=1
62
WHAT HARDY-WEINBERG PRINCIPLE STATES
NO change to allele frequencies as long as: random mating no natural for/against alleles large population size no immigration no mutations
63
ALLELE FREQUENCY
proportion of certain allele in gene pool
64
STUDENT T-TEST
comparing mean values of two data sets
65
CORRELATION COEFFICIENT
when examining an association between two sets of data

A-level Biology (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions