Topic 7 Flashcards
1
Q
What is a genotype?
A
Describes alleles organism has
Determines what limitations there are of individual characteristics
2
Q
What is the phenotype?
A
Observable / biochemical characteristics of an organism , as a result of the expression between the genotype and environment
3
Q
What is the gene?
A
Length of DNA, sequence of nucleotide bases that code for polypeptide (particular one)
Exist in forms of allele and has locus position In particular DNA
4
Q
What is an allele?
A
Different forms of genes
5
Q
What’s a homozygous pair?
A
If both alleles are same
6
Q
What’s a heterozygous pair?
A
If both alleles are different
7
Q
What is a dominant allele?
A
Alleles that’s always expressed
8
Q
What is a recessive allele?
A
An allele that’s not expressed unless there is no dominant allele
9
Q
What a pure breeding allele?
A
Have two same alleles
10
Q
What is the first filial?
A
F(small1) generation
First offspring from parent generation
11
Q
What are the laws of genetics ?
A
-laws of segregation
-law of independent assortment
12
Q
What is the law of segregation?
A
In diploid organism , characteristics are determined by alleles that occur in pairs.
Each allele Can be expressed as a single gamete that one of each is randomly allocated to the other gamete from other parent randomly
13
Q
What is the law of independent assortment?
A
Each member of a pair of alleles may combine randomly with either of another pair
14
Q
What is codominance?
A
Where both alleles are expressed in phenotype as they are both dominant alleles
15
Q
What are multiple alleles on a gene?
A
When a gene has more than 2 alleles
(Alleles might associate with same gene to have more than 2 alleles foem) [exp blood]
But only 2 can be present in individual homologous chromosomes. As each chromosome has 1 gene loci for 1 allele.
16
Q
How are chromosomes distributed in humans?
A
• 22 homologous partners identical in appearance
• 1 sex chromosomes (X or Y chromosome)
17
Q
What are female sex chromosomes ?
A
XX (all gametes same) (can be carriers of disease)
18
Q
What are make sex chromosomes ?
A
XY chromosomes
(two different gametes )
(More frequently have recessive alleles appear on chromosomes as there is no portion on Y chromosome that’ll have dominant allele present )
19
Q
What is consisted on a pedigree chart?
A
-males represent a square
-females represent a circle
-shading of shape represent a character in phenotype
20
Q
What is linked genes
A
Genes that occur on same chromosomes
21
Q
What are linkage groups?
A
Genes on single chromosome
22
Q
What are sex linked genes?
A
Genes carried on sex chromosome
23
Q
What are autosomes?
A
Remaining 22 homologous chromosomes pairs that are not the sex chromosomes
24
Q
What is autosomal linkage?
A
Two or more genes carried by same autosome
If not crossed over . They do not segregate according to law of independent assortment
25
What is epistasis?
Allele of one gene affects/ masks expression of another in the phenotype.
Changes Mendelian ratio 9:4:3
26
What is the other method epistasis can become present?
Genes act in sequence determining enzymes in biochemical pathway to produce phenotype
Enzyme A might be coded by gene A, likewise with enzymes B
So recessive alleles don’t code for enzymes. So if bith alleles are recessive , the pathway can’t be completed. Even if alleles on other gene can produce an enzyme, it won’t be expressed as phenotype can’t be manufactured with one enzyme
27
What does the chi squared test test?
Tests the null hypothesis ( result of scientific based assumption no statistically significant difference in observations sets, so difference due to chance)
To find if there is a significant deviation in observed and expected numbers in investigation
28
What is the criteria required to operate the chi-squared test?
• large sample size
• Data into discrete categories
• only raw counts and not percentages can be used
• compare results with theoretical ones
29
What is the formula used for chi-squared test?
Sum of[ (observed number (0) -expected number(E))squared/ expected number]
30
How do you use the chi squared table to calculate results?
Use value from chi-squared test. Compare it to degrees of freedom to percentage likelihood. The lower the value, the higher percentage % it’s due to chance, but if the value is less 5 percent % for chance. Then reject null hypothesis. And accept alternative hypothesis that it’s due to other conditions
31
What is the critical value used for the chi-squared distribution table?
0.05%
32
What is the degrees of freedom?
Number of class (n) - 1
33
What is the expected results for genetic tests with di-hybrid heterozygous cross?
9:3:3:1
34
What is the expected results for genetic test for monohybrid heterozygous cross?
3:1
35
What is a population?
A group of organisms of same species occupying a particular space at a particular time and can interbreed
Can vary as a result of:
-abiotic factors
-intersections between organisms (intraspecific/ interspecific competition/ predation )
36
What is a gene pool?
All alleles of all genes of all individuals in a population at a given time
37
What is allele frequency?
Number of times allele occurs in gene pool
38
When counting allele frequency in gene pool, what needs to be considered ?
If One gene has two alleles, then as alleles are same in every person . Only count one pair of alleles (both , 2 alleles) in gene per individual when considering gene pool
(Exp: 10,000 people, they’ll have 20,000 allele)
39
What is the hardy Weinberg principle?
Mathematical equation that calculates allele frequency of particular gene in population
assuming proportion of dominant and recessive alleles of any gene in population remains same from one generation to the next
Equations:
P + q=1.0
pp +2pq +qq =1
p=probability of allele (A) (dominant)
q=probability of allele (a) (recessive)
40
What condition are required for the hardy Weinberg principle to be used?
-no mutations
-population is isolated
-no selection
-large population
-random mating in population
41
What factors influence phenotype variation?
Genetic factors and environmental influences
42
What genetic factors affect phenotype variation ?
• mutation: change gene and chromosome that can be inherited
• meiosis: produce new combinations of alleles before passed onto gametes
• random fertilisation of gametes: sexual reproduction produces new combinations of alleles. So offspring are different from parents and fertilisation process is random
43
What are genetic factors affecting phenotype variation controlled by? And its affects on variation?
A single gene , it fits organisms into few distinct forms with no intermediates
(process called discontinuous variation)
(it creates this variation)
44
How do environmental influences affect phenotype variation?
Determine where organisms (in genes limitation created by genetic factors ) obtain there genetics
Includes climate conditions influences
It distorts where organisms on continium lies
Causes the bell shaped curve to occur when measuring individuals phenotypes, called a normal distribution curve
45
What is the continium in an organism?
Is formed from characteristics of organisms grading into one another
That is controlled by many genes (polygenes) and environment influences where organism lies on continium.
46
What is important to consider when making conclusions on phenotype variation?
They are tentative. So they must be treated with caution.
47
What are selection pressures?
Environmental factors limiting population species (predation, disease & competition)
48
What are factors natural selection depends on?
-Organisms produces more offspring than supported by avalible food supply
-genetic variety in population of all species
-variety of phenotype that selection operate against
49
What is the role of over production of offspring in natural selection?
- so when there are too many offspring, overproduction. there is intraspecfic competition for limited resources.
Causing best suited individual to prevail , so they pass on more favourable allele conditions to survive
50
What are the ways species control and increase their population?
• high reproductive rates ensures large population to breed and produce to compensate for high death rate.
• low reproductive rates means higher parental care, causing lower death rates
51
What is the role of variation in natural selection?
There is a wide range of genetically different (phenotype) in population. Which means some have better gene combinations to survive in almost any situation
So organisms with little genetic variation are more vulnerable to disease, climate change, predation (selection pressures)
Causes more reproduction , which given a species is capable of adapting to changes resulting from evolution of other species, causes more genetics varied individuals , more likely survive
52
What is stabilising selection?
-preserves average phenotype of a population (at mean) by favouring average individuals
-eliminates extreme phenotypes
-occurs when environmental conditions are constant over a long period of time
(Selection against extreme phenotypes)
53
What is Directional selection?
Changes the phenotype of a population by favouring phenotypes that vary in one direction from the mean of population
-when an selection pressure favours individuals to either left or right of mean that posses new allele combinations for new optimum of phenotype. Causing the mean to move left or right of its original position
(Selection for one extreme phenotype)
54
What is disruptive selection?
Favours individuals with extreme phenotypes than those with phenotypes around the mean of a population
-occurs when environmental factors takes two or more distinct forms (hot & cold temperatures in an environment, hot temp= thick fur, cold temperatures= thin fur,)
-can eventually lead to two distinct sub-populations forming
55
What is polymorphism?
Species had two or more distinct forms. They are generally distinct but exist within the same interbreeding population
56
What is selective predation?
-predators which favour individuals that lie at one extreme or the other of a range of different colour types
57
What is speciation?
Evolution of a new species from existing ones
58
What is a species?
Group of individuals that have common ancestors and so share same genes but different alleles and are capable of breeding with one another to produce fertile offspring
(Members of same species are reproductively separated from other species)
59
What is adaptive radiation?
Involves the Population becoming separated. Which causes each population to evolve and change there phenotypes and allelic frequencies caused by natural selection from facing different selection pressures.
Causing populations to be unable to interbreed successfully. So each become a different species with their own gene pool
60
What is a genetic drift?
-When one allele in the small gene pool is favoured to be selected in a population. So the allele frequency in population increases
-occurs in small populations
-increases chances an population will develop into a seperate species
61
What is allopatric speciation?
Two populations become geographically separated.
Potentially a result of a barrier between the two population preventing them interbreeding
62
What is sympatric speciation?
Speciation that results within a population in the same area. Leading to them becoming reproductively separated
63
What are the isolation mechanisms which causes organisms to become isolated?
-Geographical: physical barriers
-Ecological: inhabit different habitats in same area
Temporal: breeding seasons don’t coincide
Behavioural: variation in courtship
Mechanical: anatomical differences prevent mating occurring
Gametic: gametes prevented from meeting from genetic/biochemical incompatibility
Hybrid serility: hybrids formed from fusion of gametes from different species are sterile as they can’t produce viable gametes (mule = 63 chromosomes, can’t pair up during meiosis)
64
What are abiotic and biotic factors?
Abiotic are non-living factors
Biotic are living factors
65
What are ecosystems?
Dynamic systems made up of community and all non living factors of it’s environment
Contain to major processes:
-flow of energy through the system
-cycling of elements in a system
66
What is the carrying capacity?
The size of a population of a species an ecosystem can support
67
How can the size of a population vary?
From the effects of abiotic factors
-Interactions between organisms (intraspecific and interspecific competition)
68
What is a community?
All the populations of living species living and interacting in particular place at the same time
69
What is a habitat?
The place where an organism normally lives and is characterised by physical conditions and other types of organisms present
70
What are microhabitats?
Smaller units within each habitat , each with their own microclimate
71
What is an ecological niche?
How an organisms fit into an environment
-where an organisms lives and what it does there. Includes all biotic and abiotic conditions to which an organisms is adapted in order to survive, reproduce and maintain a viable population
-section of ecosystem one species inhabits
72
When is it required to use a logarithmic scale?
When the population grows rapidly over a short time. Causing the curve to run off
73
What Abiotic factors affect the growth of a population?
-temperature: each species has different optimum temperature they are best able to survive ( organisms might expend more energy to maintain their body temperature)= less energy for growth= mature slowly= reproduction slows= carrying capacity reduced
Light: increase or decrease photosynthesis which plant are dependant on for growing
Ph: affects enzyme activity
Water and humidity: humidity affects transpiration rates in plants and evaporation of water from bodies of animals
74
What is intraspecific competition?
Individuals in the same species compete with one another for resources (food,water,mates)
75
What is interspecific competition?
-occurs when individuals of different species compete for resources (food, light)
Causes the competitive exclusion principle to take place
One type: predator-prey relationship
76
What is the competitive exclusion principle?
-occurs from interspecific competition
Where when two species compete for limited resources. The one using resources most effectively will eliminate the other
(Not two species occupy same niche indefinitely when resources are limited
77
What is the predator-prey relationship?
-where an organisms (predator) that feeds on another organism (prey)
The predators have adapted to capture the prey by being faster, more effective camouflaged and have better prey direction skills
The prey have adapted to avoid their predator, through better camouflage, more protective features and concealement behaviour
78
What would happen if either the prey or predator did not match the adaptation of the other ?
Then they would became extinct
79
What is predation?
When an organism is consumed by another
80
What are the limitations for collecting evidence of predation in a laboratory?
-range and variety of habitat provided is normally limited to the confines of the laboratory
= less refuges
=not reflect what happens in real world
=not possible to count all individuals in natural population (uses certain amount)
=only as good as the techniques used (sampling & surveys)
81
Why does a prey not became extinct?
They travel in a large and very diverse environment. So there are many potential refuges
Allowing prey to escape predation
(Meaning population most likely will only drop to a low level)
82
What are the effects of a predator prey relationship on a population size?
-predators eat prey = reduce population of prey
-fewer prey avalible, the predators are in greater competition with eachother for prey left= predator population reducing as some cannot obtain enough prey for their survival/ reproduction
-less prey are eaten as fewer predators are left, so more prey survive/ reproduce
-more prey available as food, predator population increases
83
Why are predator prey relationships not as severe in natural ecosystems?
Organism each a range of food. So fluctuations in population sizes aren’t as severe
84
What are the other reason for Cyril fluctuations in populations?
Disease
Climate factors
85
Why are periodic population crashes important in evolution?
-it provides an selection pressure to allow individuals who escape predators, withstand disease or climate changes to escape predators, so more likely to survive/repoduce.
So population evolves to be better adapted for the conditions
86
What is abundance?
Count the number of individuals of a species in a given space
87
Why are small samples of habitat studied?
-is impossible to identify and count every organism as its:
• too time consuming and it would cause damage to habitat studied
88
What sampling techniques are used in the study of habitats?
-random sampling : using qaudrats
-systematic sampling: along belt transect
89
What are the two types of quadrats used?
Point qaudrat: consist of horizontal bar supported by two legs. At set intervals along horizontal bar are ten holes. Where a long pin can be dropped in. Each species pin touches are reported
Frame qaudrat: square frame divided by string/ wire into equally sized subdivisions. Is designed to make it more compact for storage and transport. Qaudrat Is place in different location with area being studied. Abundance of each species in qaudrat is studied
90
What factors need to be considered when using qaudrats?
-size of qaudrat: depends on size of plants/animals being counted and how they are distributed in the area. Larger species need larger quadrats. Where population of species is not evenly distributed in area. Using large number small qaudrats is better than small number large qaudrats
-number of sample qaudrats used to record in area: large qaudrat sample, more reliable results are. Although this is time consuming. Greater number of different species present=more qaudrats required to produce reliable results for valid conclusion
-the position of each qaudrat in study area: use technique random sampling to produce statistically significant results
91
What is the procces of random sampling?
Choosing two areas as close together as possible
1) May two long tape measures at right angles, along two sides of study area
2) obtains series of coordinates using random numbers generated by computer/ from table
3)place qaudrat at intersection of each pair of coordinates and record species in it
92
What is systematic sampling along belt transects?
-shows stages of succession using transects (important when gradual changes occurs in communities)
-belt transect made by stretching string/tape alongside line and qaudrat is laid along line and species within it are recorded. Then it moves along the line and process is repeated to give record is species in continuous belt
93
How is abundance measured?
(Species that don’t move around) and move around?
-frequency: likelihood particular species occurs in qaudrats. Useful for species (grass) is hard to count. Gives quick idea on species present and general distribution in area. Doesn’t provide density and detailed distribution of species
-percentage cover: estimate of area within qaudrat a particular plant species covers. Usefal where species is particularly abundant or difficult to count . Data is collected rapidly and individual plants don’t need to be counted. Less usefal where organisms occur in several overlapping layers
94
What is the mark-release-recapture technique?
Used for motile animals that move away when approached
-1) known number of animals are caught
-2) animals are marked
-3) they are released back into community
-4) after some time given number of marked individuals Is recorded.
Size of population recorded using equation
Population size=
Total number of indv in 1st sample * total number of indv in /2nd sample/
Number of marked indv recaptured
95
What assumptions does the mark-release - recapture technique rely on?
- proportion of marked to unmarked individuals in second sample is same proportion of marked to unmarked individuals in population as whole
- marked individuals released from first sample distribute themselves evenly amongst in sufficient time amongst remainder of population
-population has definite boundary so there is no immigration into or emigration out of population
-few deaths and births in population
-method of marking is not toxic to individual nor does it make individual more conspicuous and liable to predation
-mark/ label is not lost/ rubbed off during investigation
96
What is succession?
Describes population changes over time in species that occupy area (changes in ecosystem)
97
Why might barren (inhospitable) land arise?
-glacier retreating and depositing rock
-sand being piled into dunes by wind or sea
-volcanoes erupting and depositing lava
-silt and mud being deposited at river estuaries
98
How might a species alter the environment during the stages of succession?
-less suitable for the existing species. Which might Cause the new species to out compete existing one and take over area
-more suitable species with different adaptations. Might Cause species to be outcompeted by better adapted new species
99
What is the first stage of succession?
Colonisation of inhospitable environment by pioneer species. Which have features to make them suitable to colonisation
100
What features do pioneer species have which makes them better adapted to colonisation?
-asexual reproduction so a single organism can rapidly multiply to build up population
-production of vast quantities of wind-dispersed seeds/spores. To easily reach isolated situations (volcanic island)
-rapid germination of seeds on arrival as they don’t need dormancy
-able to photosynthesis (not animal dependent)
-able to fix nitrogen from atmosphere as soil has low to no nutrients
-tolerant to extreme conditions
101
What is the second stage of succession?
Where Secondary coloniser occurs
-from pioneer settler death and decomposition releasing sufficient nutrients to support community of small plants (creating soil and nutrients for other organisms to use)
(Exp: mosses)
102
What is the third stage of succession?
-more erosion of rock and increasing amount of organic matter available from death of plants . Causes thicker layer of soil to be built
-organic material can hold water to make it easier for other plants to grow
= less hostile abiotic environment
(Grasses)-(shrubs) (tree)
Causing more sources of food to develop and for more food chains that develop into complex food webs= stable communities
103
What is the fourth stage of speciation?
Climax community: Stable state compromises balanced equilibrium of species with few new species replacing those that are established
104
What are the feature that emerge during a succession?
• non-living (abiotic) environment is less hostile=
• greater number and variety of habitats and niches=
• increased biodiversity (increase earlier but decreases when climax community is reached)=
• more complex food webs=
•increased biomass
105
What determines the dominant species in climax community
-abiotic factors
106
What is secondary succession?
Land that sustains life is altered. (From land clearance for agricultural/ forest fire)
So repeats through succession stages.
_
But more faster as soil already exists there. So spores and seeds remain alive in soil= influx of animals and plant from dispersal and migration from the surrounding area
-
changes climax community
107
What is conservation?
Management of earths natural resources by humans in a way so maximum use of them is possible in the future
[to maintain ecosystems and biodiversity]
108
What are the main reasons for conservation?
• Personal: maintain our planet and hence our life support systems
• ethical: other species have lived longer on earth than humans, so should be allowed to coexist with us. [Showing respect to living things]
• economic: organisms contain large gene pool that are able to make substances that might have future value.
• cultural & aesthetic: organisms enrich our lives , brings it east to our life, they inspire people who entertain us
109
How can you conserve habitats by managing succession?
By adding a factor that prevents further succession and development of an climatic climax in the ecosystem
