genetics, populations, evolution and ecosystems Flashcards
1
Q
What is the definition of genotype?
A
Genetic constitution of an organism, the alleles it has.
2
Q
What is the definition of phenotype?
A
The expression of the genetic constitution (genotype) and its interaction with the environment, observable characteristics.
3
Q
What is a gene?
A
the section of DNA that codes for the amino acid sequence of a polypeptide of RNA molecule
4
Q
What is an allele?
A
Different forms of a gene
usually 2 alleles for each gene one from each parent
5
Q
What does dominant mean in genetics?
A
Allele whose characteristic is expressed in phenotype when only one copy present, capital letter.
6
Q
What does recessive mean in genetics?
A
Allele whose characteristic is expressed in the phenotype if 2 copies are present, lowercase letter.
7
Q
What is a locus?
A
Fixed position a gene occupies on a chromosome, all alleles are found at the same locus on homologous chromosomes.
8
Q
What is codominance?
A
Alleles are both expressed in the phenotype, neither is recessive.
9
Q
What is homozygous?
A
2 copies of the same allele (AA/aa).
10
Q
What is heterozygous?
A
2 different copies of alleles (Aa).
11
Q
What is a carrier in genetics?
A
A person carrying an allele which is not expressed in the phenotype but can be expressed in offspring.
12
Q
What is monohybrid inheritance?
A
The inheritance of characteristics controlled by a single gene.
13
Q
What is the example organism used by Gregor Mendel for studying inheritance?
A
Pea plants.
14
Q
In Mendel’s pea plant study, what color pods are dominant?
A
Green pods.
15
Q
What is the phenotypic ratio in the F2 generation of a monohybrid cross?
A
3:1 (dominant to recessive).
16
Q
What is dihybrid inheritance?
A
The inheritance of 2 characters from 2 different genes located on different chromosomes at the same time.
17
Q
What is the phenotypic ratio in the F2 generation of a dihybrid cross?
A
9:3:3:1.
18
Q
What does the Law of Segregation state?
A
In diploid organisms, characteristics are determined by alleles that occur in pairs. Only one of each pair can be present in a single gamete.
19
Q
What does the Law of Independent Assortment state?
A
Each member of a pair of alleles may combine randomly with either of another pair.
20
Q
What is codominance exemplified by in snapdragons?
A
Red and white alleles producing pink flowers when both are present.
21
Q
What is a multiple allele system?
A
Where there are more than two alleles, of which only two may be present at the loci of an individual’s homologous chromosomes.
22
Q
What are the three alleles associated with blood groups?
A
- I^A (produces antigen A) * I^B (produces antigen B) * I^O (produces no antigen).
23
Q
What is the universal donor blood type?
A
Blood group O.
24
Q
What is the universal recipient blood type?
A
Blood group AB.
25
What is sex-linkage?
Characteristics controlled by genes located on the sex chromosomes.
26
What chromosome configuration do females have?
XX.
27
What chromosome configuration do males have?
XY.
28
What is an example of an X-linked genetic disorder?
Hemophilia.
29
True or False: Haemophilia primarily affects females.
False.
30
Fill in the blank: An X-linked genetic disorder is caused by a defective gene on the _______.
[X chromosome].
31
What is haemophilia primarily caused by?
A recessive allele with an altered sequence of DNA nucleotide bases on the X chromosome that codes for a faulty protein.
## Footnote
Haemophilia is a sex-linked condition primarily affecting males.
32
How do males inherit haemophilia?
Males always inherit it from their mothers, as the Y chromosome from their father does not contain the allele.
## Footnote
This means that males cannot pass the condition to their sons.
33
What is autosomal linkage?
The situation where two or more genes are carried on the same autosome.
## Footnote
Autosomes are the 22 chromosomes in humans that are not sex chromosomes.
34
What happens to linked genes during meiosis if there is no crossing over?
All linked genes remain together and pass into gametes together.
## Footnote
This is contrary to Mendel's Law of Independent Assortment.
35
What is the difference in the number of possible gametes between linked and unlinked genes?
Linked genes produce 2 possible gametes, while unlinked genes produce 4 possible gametes.
## Footnote
This is due to the arrangement of alleles on separate chromosomes.
36
What is epistasis?
When the allele of one gene affects or masks the expression of another gene in the phenotype.
## Footnote
For example, a recessive allele may prevent the expression of a dominant allele.
37
Why are genetic crosses rarely the same as predicted results?
Due to chance, statistical error, small population sizes, and selection advantages or disadvantages.
## Footnote
Larger sample sizes tend to yield results closer to expected outcomes.
38
What do pedigree charts use to represent males and females?
Males are represented by squares and females by circles.
## Footnote
Shading indicates the presence of a trait, such as haemophilia.
39
What is the chi-squared test used for?
To determine whether the difference between observed and expected data is due to chance.
## Footnote
It tests the null hypothesis.
40
What are the assumptions of the Hardy-Weinberg principle?
* No change in allele frequency between generations
* No migration
* No mutations
* No selection
* Mating is random
* Large population
## Footnote
These assumptions allow for predictions of allele frequencies in a population.
41
What does the formula p + q = 1.0 represent in Hardy-Weinberg?
The frequencies of the dominant (p) and recessive (q) alleles in a population.
## Footnote
p^2 + 2pq + q^2 = 1.0 provides frequencies for genotypes.
42
What factors contribute to genetic variation in a population?
* Mutations
* Meiosis (crossing over and independent segregation)
* Random fertilization of gametes
## Footnote
These processes create new allele combinations.
43
What are polygenic characteristics?
Traits controlled by many genes, leading to a continuum of variation.
## Footnote
Examples include human height and mass.
44
What is natural selection?
The process where organisms better adapted to their environment tend to survive and produce more offspring.
## Footnote
Selection pressures include predation, disease, and competition.
45
What is stabilizing selection?
Selection that favors the mean phenotype and eliminates extreme phenotypes.
## Footnote
This occurs in stable environmental conditions.
46
What is directional selection?
Selection that favors phenotypes that vary in one direction and eliminates one extreme phenotype.
## Footnote
This occurs when environmental conditions change.
47
What is disruptive selection?
Selection that favors extreme phenotypes and eliminates intermediate phenotypes.
## Footnote
This can lead to speciation over time.
48
What is the significance of the peppered moth in evolutionary biology?
It is an example of selective predation and directional selection.
## Footnote
The shift in its coloration due to environmental changes illustrates natural selection.
49
What is disruptive selection?
A type of selection that can lead to evolutionary change by increasing genetic variation.
## Footnote
Continued disruptive selection can ultimately lead to speciation.
50
What is polymorphism?
A condition where a species has two or more distinct forms that are genetically different but can interbreed.
51
What is the significance of the peppered moth (Biston betularia) in evolutionary studies?
It is an example of selective predation and directional selection, illustrating natural selection's role in evolution.
52
How did the Industrial Revolution affect the peppered moth's coloration?
Soot covered buildings made black moths less conspicuous, leading to a shift in predation pressures.
53
What role does variation play in natural selection?
Variation provides the potential for a population to evolve and adapt to new circumstances.
54
What is the relationship between population size and genetic variation?
Larger populations with more genetic variation have a greater chance of survival.
55
What is speciation?
The evolution of new species from existing ones, resulting from reproductive isolation.
56
What are the two ways populations can become reproductively isolated?
* Geographically (allopatric)
* Changes in reproductive mechanisms (sympatric)
57
Define allopatric speciation.
Speciation that occurs when populations become separated geographically, leading to reproductive isolation.
58
What is sympatric speciation?
Speciation that occurs without geographical separation, often due to behavioral differences.
59
Provide an example of allopatric speciation.
Galapagos finches, which evolved different adaptations on separate islands.
60
Provide an example of sympatric speciation.
Apple maggot fly, which began laying eggs in apples instead of hawthorns, leading to reproductive isolation.
61
What is genetic drift?
The change in allele frequency within a population between generations, with a greater impact in smaller populations.
62
How does population size affect the impact of genetic drift?
Smaller populations experience greater effects from genetic drift due to lower genetic diversity.
63
What is the carrying capacity of an ecosystem?
The maximum stable population size of a species that an ecosystem can support.
64
List the main abiotic factors affecting population size.
* Temperature
* pH
* Light
* Water and humidity
65
How does temperature affect population size?
Each species has an optimum temperature for survival; deviations can reduce population size.
66
What is the competitive exclusion principle?
If two species try to occupy the same niche, one species outcompetes the other.
67
What are biotic adaptations?
Features that help organisms survive and reproduce, such as foraging, mating, or reducing competition.
68
What are abiotic adaptations?
Features that help organisms survive environmental conditions, such as hibernation or body insulation.
69
What is intraspecific competition?
Competition between individuals of the same species for limited resources.
70
What is interspecific competition?
Competition between individuals of different species for limited resources.
71
What is carrying capacity?
The maximum population size that an environment can sustain.
72
What is competition in ecological terms?
When two or more individuals share a resource that is insufficient to satisfy all their requirements.
73
What are the two types of competition?
* Intraspecific (same species)
* Interspecific (different species)
74
How does intraspecific competition affect population size?
Population increases with plentiful resources, declines when resources become limiting.
75
What is the competitive exclusion principle?
When two species compete for limited resources, one will outcompete the other, leading to the elimination of one species.
76
What is predation?
An interspecific relationship where one organism (predator) consumes another (prey).
77
How does predation affect prey population size?
Prey population drops, but is usually never extinct; predator populations fluctuate with prey availability.
78
What factors can allow one species to outcompete another?
* Better at obtaining food
* Faster metabolism
* Growing faster
* Reproducing faster
79
What are the basic factors affecting human population growth?
* Birth rate
* Death rate
80
What is the equation for calculating population growth?
Population Growth = (births + immigration) - (deaths + emigration)
81
What is a stable population pyramid?
A pyramid where birth and death rates are balanced, showing no increase or decrease in population size.
82
What characterizes an increasing population pyramid?
A high birth rate with a wider base and fewer older people.
83
What characterizes a decreasing population pyramid?
A lower birth rate with a narrower base and a higher proportion of elderly.
84
What occurs in Stage 1 of the Demographic Transition Model?
High birth and death rates, leading to a stable population size.
85
What happens in Stage 2 of the Demographic Transition Model?
Death rates decrease due to modern medicine while birth rates remain high, resulting in rapid population growth.
86
What factors are used in sampling to investigate population size?
* Random sampling
* Systematic transect
* Opportunistic sampling
* Stratified sampling
* Systematic grid
87
What is the purpose of using quadrats in sampling?
To measure the abundance of non-motile or slow-moving organisms.
88
What is the Mark-Release-Recapture method?
A technique to estimate population size of motile species by capturing, marking, and recapturing individuals.
89
What assumptions are made in the Mark-Release-Recapture method?
* Marked individuals mix back into the population
* No births, deaths, or migration
* Mark does not affect survival
* Mark is not lost
90
What abiotic factors can affect population size and distribution?
* Temperature
* Oxygen concentration
* pH
* Conductivity
* Nitrates
* Turbidity
91
What ethical considerations should be taken in ecological studies?
Minimize environmental impact and avoid trampling on plants.
92
What is succession in ecology?
The change in an ecological community over time through a series of seral stages.
93
What is a climax community?
The final, stable community in the process of ecological succession.
94
What does it mean for ecosystems to be dynamic?
Ecosystems are constantly changing with populations fluctuating at different rates.
95
What is succession in ecology?
A series of seral stages leading to a climax community.
96
How do new species influence an ecosystem during succession?
New species colonise the area, making it less suitable for existing species and outcompeting them.
97
What is a climax community?
The final stable community in an ecological succession.
98
What is primary succession?
An ecological process occurring in areas with no previous ecosystem or soil.
99
Give an example of where primary succession might occur.
Bare rock or sand, such as new land from volcanoes or sediment deposition.
100
What is the role of pioneer species in primary succession?
They break down rocks into smaller particles and contribute organic matter.
101
List three adaptations of pioneer species.
* Ability to photosynthesise
* Rapid germination of seeds
* Ability to produce large quantities of wind-dispersed seeds/spores
102
What is soil formation in the context of primary succession?
Accumulation of organic matter and rock fragments that leads to the creation of humus.
103
What occurs during intermediate succession?
Mosses and smaller plants establish as soil depth and nutrient content increase.
104
How does biodiversity change during succession?
Increases during early succession, peaks in mid-succession, then decreases slightly in climax communities.
105
What characterizes a climax community?
Stable environment in equilibrium with the climate, dominated by trees.
106
What is secondary succession?
An ecological process occurring in previously inhabited ecosystems after a disturbance.
107
List examples of events that can trigger secondary succession.
* Fire
* Flood
* Deforestation
* Hurricane
* Overgrazing
108
Why does secondary succession occur more rapidly than primary succession?
Soil already exists, holding spores and seeds.
109
What is a hydrosere?
A plant succession occurring in an aquatic environment.
110
Define xerosere.
A plant succession in an area with limited water availability.
111
What is a lithosere?
A plant succession that starts on a bare rock surface.
112
What is a psammosere?
An ecological succession that begins on newly exposed coastal sand.
113
What is a halosere?
An ecological succession in saline water environments.
114
Describe the migration stage in sand dune succession.
Sand grains move inland by wind and accumulate around obstructions.
115
What happens during the colonisation stage of sand dune succession?
Pioneer species germinate and develop on the embryo dune.
116
What is the establishment stage in sand dune succession?
Marram grass stabilizes the sand, turning it into a yellow dune.
117
What occurs at the competition stage in sand dune succession?
Marram grasses die and decay, adding nutrients and moisture to the sand.
118
What is the climax stage in sand dune succession?
Woody trees dominate, reducing species diversity due to shading.
119
What is conservation?
The management of Earth's natural resources for sustainable use.
120
List the main reasons for conservation.
* Personal
* Ethical
* Economic
* Cultural and aesthetic
121
What is plagioclimax?
An artificially prevented climax community due to human activities.
122
How can conservation prevent succession?
By maintaining habitats that would otherwise evolve into climax communities.
123
What are some methods to manage succession?
* Allowing grazing
* Managed fires
124
What does sustainable conservation mean?
Meeting current resource needs without compromising future generations.
125
What are seedbanks used for in conservation?
To grow new plants if they become extinct in the wild.
126
What are fishing quotas?
Limits on the amount of certain fish that can be caught to reduce overfishing.
127
What is the importance of negative controls in experiments?
They provide a baseline for comparison to evaluate the effects of experimental treatments.
128
What is required to draw valid conclusions from studies?
Similar studies showing consistent results to establish a link between variables.
