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AH Biology > Unit 2 - Organisms and Evolution > Flashcards

Unit 2 - Organisms and Evolution Flashcards

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1
Q

What is the difference between working in a lab and working outside?

A

The are many more potential hazards when working outside.

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2
Q

Which hazards must be considered when working in the field?

A

Weather
Isolation
Terrain

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3
Q

What must be considered when sampling wild organisms?

A

Keeping the impact on habitats and environment minimal.
Rare and vulnerable species should be treated with care.
Sampling methods must be appropriate.

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4
Q

How would you sample an elusive species?

A

With a direct method (e.g. Remote detection)

With an indirect method (e.g Scat sampling)

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5
Q

How can a sample be identified?

A

Using:
Keys
Classification guides
DNA and Protein analysis

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6
Q

What are the taxonomic groupings?

A 
Domain
Kingdom
Phylum/Division
Class
Order
Family
Genus
Species
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7
Q

Why is familiarity in taxonomic groupings important?

A

Familiarity in taxonomic groups allows predictions and interferences to be made between the biology of one organism and the better known model organisms.

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8
Q

Why is studying genetic evidence important?

A

Genetic evidence reveals true relatedness between organisms as it can sometimes be skewed by convergent and divergent evolution.

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9
Q

What are the three domains of life?

A

Archaea
Bacteria
Eukaryotes

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10
Q

What are the divisions in the plant kingdom?

A 
Mosses
Liverworts
Conifers
Ferns
Flowering Plants
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11
Q

What are the phyla of the animal kingdom?

A 
Chordata
Arthopoda
Nematoda
Platyhelminthes
Mollusca
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12
Q

What is a model organism?

A

An organism used to study other, more complex organisms that are difficult to study directly.

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13
Q

Name some important model organisms.

A

E.Coli
C.Elegans
Mice

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14
Q

What is an indicator species?

A

Indicator species are species whose presence, absence or abundance gives information about environmental qualities such as presence of pollutants.

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15
Q

How is the classification of vegetation types based?

A

Based upon the indicator species present in communities.

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16
Q

What does mark and recapture assume?

A

All individuals have the same chance of being captured
There is no immigration or emigration
There is no birth or death during sample
Sampling methods are identical each time

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17
Q

Name some different methods of marking populations.

A 
Rings or bands
Transmitters
Tagging
Colour marking
Hair clipping
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18
Q

What must be ensured when marking populations?

A

That the impact on species being studied is minimal.

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19
Q

What is an ethogram?

A

A table used by biologists to help monitor animal behaviour.

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20
Q

What should you measure when recording animal behaviour?

A

Start/Stop time of each behaviour
Overall length of time
Latency - time between stimulation and response
Frequency if behaviour
Time budget - length of time spent doing each thing

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21
Q

What is anthropomorphism?

A

Anthropomorphism is giving human attributes to animals, such as emotions, it is to be avoided as it can lead to misinterpretation.

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22
Q

What is evolution?

A

Evolution is the change over time in the proportion of individuals in a population, differing in one or more inherited traits.

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23
Q

What 3 processes can lead to evolution?

A

Genetic drift
Natural selection
Sexual selection

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24
Q

How does variation occur?

A

Variations results from rare and random mutations.

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25
Q

What are mutations?

A

Mutations are the original source of new DNA sequences in populations. General neutral or harmful, but occasionally can be beneficial.

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26
Q

What is absolute fitness?

A

Absolute fitness is the ratio of frequencies of a particular genotype from one generation to the next.

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27
Q

What does it mean when the absolute fitness is 1?

A

The genotype is stable.

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28
Q

What is relative fitness?

A

Relative is the ratio of surviving offspring, based off of absolute fitness.

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29
Q

How does selection pressure affect the rate of evolution?

A

Rate of evolution will be high when selection pressure is high.

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30
Q

Which 3 factors can effect rate of evolution?

A

Generation time - when generation times are short, rate of evolution will be high
Warmer environments increase the rates of evolution
Sharing Beneficial DNA sequences through horizontal transfer and sexual reproduction will increase rate

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31
Q

Why does evolution take so long?

A

Evolution takes millions of years due to long generation times.

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32
Q

What kind of generation time do bacteria have?

A

Bacteria have really short generation times, so have a high rate of evolution.

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33
Q

What is Co-evolution?

A

When the evolution of one species affects the evolution of another closely associated species.

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34
Q

Where is co-evolution usually found?

A

Usually seen in pairs of species that interact with each other frequently or closely, a change in the traits of one species acts as a selection pressure on the other.

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35
Q

Give some examples of where co-evolution occurs.

A

Herbivores and plants
Pollinators and plants
Predators and prey
Parasites and hosts

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36
Q

What is the ‘Red Queen Hypothesis’?

A

The co-evolutionary ‘arms race’ between a parasite and its host, as each organism must ‘keep running in order to stay still’.

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37
Q

How does having a greater fitness affect hosts and parasite?

A

Hosts better able to resist and tolerate parasitism have greater fitness.
Parasites better able to feed, reproduce and find new hosts have greater fitness.

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38
Q

What are the disadvantages of sexual reproduction compared to asexual reproduction?

A
  • Half the population are unable to produce offspring, this is known as the paradox of the existence of males.
  • By mixing the genetic info between 2 individuals, each parent disrupts a successful genome and only passes on half to each offspring.
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39
Q

What is the advantage of sexual reproduction?

A

Creates genetic diversity and variation, therefore allows evolution.

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40
Q

Why is genetic variation important to the Red Queen Hypothesis?

A

It is essential that genetic variation occurs to allow constant ‘running to stay in the same place’.

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41
Q

When is asexual reproduction a successful strategy?

A

When in very narrow, stable niches or when recolonising disturbed habitats.

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42
Q

Where is asexual reproduction common?

A

Asexual reproduction is common in plants and is called vegetative propagation, it is a useful strategy in perennial weeds.

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43
Q

What other mechanism do asexually reproducing organisms have?

A

The mechanism for horizontal gene transfer between individuals such as the plasmids of bacteria and yeast.

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44
Q

What is parthenogenesis?

A

Parthenogenesis is where animals are capable of reproduction without fertilisation of eggs.

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45
Q

How do Komodo dragons reproduce in the absence of males?

A

Female Komodo dragons reproduce alone, giving birth to males only.

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46
Q

How Stick insects reproduce in the absence of males?

A

Stick insects reproduce alone giving birth to females only.

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47
Q

Where is parthenogenesis common?

A

In Hymenoptera (social insects).

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48
Q

Where does parthenogenesis usually occur?

A

Usually occurs in cooler climates or where parasite diversity is low.

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49
Q

What is Meiosis?

A

Meiosis is the process of cell division that results in the formation of new haploid cells.
It produces four cells with (potentially) huge diversity.

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50
Q

What are Homologous Chromosomes?

A

Chromosomes that:

  • Are all the same size
  • Have their centromeres in the same place
  • Carry the same genes at the same loci
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51
Q

How does meiosis effect variation in organisms?

A

During the process of meiosis, homologous chromosomes line up randomly, this increases variation and is called Independent assortment.

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52
Q

Describe the whole process of meiosis.

A
  • Chromosomes undergo DNA replication
  • Homologous Chromosomes line up at the equator of the cell
  • Homologous Chromosomes touch at points called chiasmata
  • Crossing over occurs at points called chiasmata
  • Independent assortment occurs
  • Two haploid cells are formed
  • Chromatids are separated by spindle fibres
  • Four haploid gametes are produced
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53
Q

What happens during Meiosis I?

A
  • Starts with interphase, DNA replicates to form 2 sister chromatids
  • Homologous Chromosomes line up at the equator of the cell
  • Homologous Chromosomes touch at points called chiasmata
  • Crossing over occurs at points called chiasmata
  • Independent assortment occurs
  • Two haploid daughter cells are formed
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54
Q

What happens during meiosis II?

A
  • Chromatids are separated by spindle fibres

- Four haploid gametes are produced

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55
Q

What is the number of different combinations of gametes?

A

2^23

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56
Q

What can be said about distance between two genes and their chances of crossing over?

A

The further apart 2 genes are, the greater their chance of crossing over.

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57
Q

What is a Hermaphrodite?

A

Hermaphroditic species can contain both male and female reproductive systems or change sex.

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58
Q

What factors can determine sex in hermaphroditic species?

A

Size
Parasitic infection
Competition

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59
Q

What are simultaneous hermaphrodites?

A

Simultaneous hermaphrodites contain both male and female reproductive systems.

60
Q

What are sequential hermaphrodites?

A

Sequential hermaphrodites can change sex during their lifespan.

61
Q

What are the names of the sex bearing chromosomes in live-bearing mammals and some insects?

A

The X and Y Chromosomes.

62
Q

Which chromosome is responsible for male characteristics in live-bearing mammals?

A

The Y Chromosome.

63
Q

How may sex-linked patterns of inheritance occur?

A

The Y chromosome lacks homologous alleles for genes on the X chromosome.

64
Q

How are lethal doses of the products of gene expression avoided in females?

A

To compensate for an extra dose of genes, the portions of the X chromosome that are lacking on the Y chromosome are randomly inactivated on 1 of the homologous X chromosomes in each cell.

65
Q

Why are carriers less likely to be affected by deleterious mutations?

A

X chromosome inactivation is random, so only half of the cells in any sample will have a working copy of the gene.

66
Q

Compare sperm and eggs in terms of number, size and energy investment.

A

In animals, sperm is much smaller and more numerous than eggs.
Eggs contain a large food store and are a greater investment due to energy investment and their finite number. So require a greater deal of parental care

67
Q

What are sessile organisms?

A

Sessile organisms cannot move, they are fixed in place, which means it is harder for them to find a mate.

68
Q

How do plants find mates despite being unable to move?

A

Plants get help from pollinators and the wind to allow gametes to meet.

69
Q

Compare internal fertilisation and external fertilisation.

A

In internal fertilisation;

  • Few gametes produced
  • No external water available
  • Fertilisation occurs inside the female

In external Fertilisation

  • Many Gametes produced
  • External water available
  • Fertilisation outside female
70
Q

How does external fertilisation work?

A

The sperm and eggs are released into the water near each other and at the same time.

71
Q

What is parental investment?

A

Parental investment is a measure of the amount of time and effort a parent puts into raising its offspring.
It is costly but can improve the probability of production and survival of young.

72
Q

What does the level of parental care depend on?

A

Depends on the number of offspring produced and the environment.

73
Q

What are the features of r-selected parental care?

A
  • Rapid development
  • Small adult size
  • Many offspring
  • Short generation time
74
Q

What are the features of k-selected parental care?

A
  • Slow development
  • Large adult size
  • Few offspring
  • Long generation time
75
Q

What is optimal reproduction based upon?

A

The premise of a trade-off in terms of the number and quality of current offspring versus potential future offspring.

76
Q

What is Polygamy?

A

A polygamous organism is promiscuous with short-lived interactions.

77
Q

What is Monogamy?

A

A monogamous organism has generally one partner for a long time.
More parental care means more likely to be monogamous.

78
Q

What is sexual dimorphism?

A

When males and females look distinctly different, it is the result of sexual selection.

79
Q

How can males gain access to females?

A

Either through conflict with other males or by cleverly sneaking past other males.

80
Q

What features do males usually have compared to females?

A

Males of a species are often larger, more colourful and distinct.

81
Q

What is female choice?

A

While males can compete with eachother over a mate, or behave a certain way to attract females. Ultimately it is the females choice over who they mate with.

82
Q

How can fitness be assessed in males?

A

Females assess honest signals of the fitness in males, e.g low parasite abundance or good genes.

83
Q

What is lekking?

A

In animals where the only contribution is sperm, lekking is common, males display at a lek.

84
Q

What may happen in a lek?

A

The males that are not picked at a lek may try and sneak a chance at reproducing with a female rather than facing aggression.

85
Q

What is reversed sexual dimorphism?

A

Larger and more conspicuous females and smaller males.

86
Q

Where is reversed sexual dimorphism common?

A

In insects, spiders, birds of prey and some larger mammals.

87
Q

Why does reversed sexual dimorphism occur?

A

When males have to travel large distances it makes sense for them to be smaller for energy expenditure.

88
Q

What is species-specific signalling?

A

Many mating behaviours rely on signals and stimuli. This ensures mating occurs when organisms are most fertile.

89
Q

What is a fixed action pattern?

A

An innate response from males of a species to attract a female. E.g. male birds dance to attract females.

90
Q

What is imprinting?

A

Imprinting is an irreversible, rapid developmental process in young birds. When they are born they fixate on a larger object as they expect protection. This impacts their mate choice in later life.

91
Q

What is a parasite?

A

Parasites are symbiots that benefit in terms of nutrition at the expense of their host.

92
Q

What are hosts?

A

Hosts are harbourers of parasites and provide them with nourishment and safety, not always knowingly.

93
Q

How common are parasites and why?

A

Parasites are very common as at least half of all species are parasitic and all free-living species are thought to host parasites.

94
Q

How does reproductive potential compare in predator-prey relationships and host-parasite relationships?

A

The reproductive potential in host-parasite relationships is higher, and the reproductive potential of the parasite is far greater than that of the host.

95
Q

What is an ecological niche?

A

A complex outline of tolerances and requirements of a species.

96
Q

Why do parasites have a narrow niche?

A

Parasites have a very narrow niche due to high host specificity.

97
Q

Why do parasites have limited structures?

A

As the host provides so many of the parasites needs, many parasites are said to be degenerative, lacking in structures and organs found in other organisms.

98
Q

What are ectoparasites?

A

Ectoparasites (such as ticks) live on the surface of their hosts.

99
Q

What are endoparasites?

A

Endoparasites (such as tapeworms) live inside their hosts.

100
Q

What are definitive hosts?

A

The hosts in which parasites reach sexual maturity.

101
Q

What are intermediate hosts?

A

Hosts that are sometimes required for parasites to complete their life cycle, sometimes carrying out asexual reproduction to greatly increase its numbers, or as a means of transimission, which would make the host a vector.

102
Q

What is a fundamental niche?

A

The niche that organisms occupy when there are no other species present to compete with for space or resources.

103
Q

What is a realised niche?

A

The niche that an organism occupies when there is competition from other species.

104
Q

What is competitive exclusion?

A

When two species are in intense competition with one another, thus the niches occupied by each are very similar- the weaker of the two species will likely die out.

105
Q

What is resource partitioning?

A

Where two competing species occupy different realised niches, compromising over resources and thus managing to exist simultaneously.

106
Q

What is transmission?

A

Transmission is the spread of a parasite to a host.

107
Q

What is virulence?

A

Virulence is the deleterious effect that a parasite has on its host.

108
Q

What are the qualities of a successful parasite?

A

High transmission and high virulence.

109
Q

How can transmission rates be increased in parasites?

A

High host density - overcrowding of hosts

A means of transmission, such as the presence of vectors

110
Q

What is the extended phenotype theory?

A

Some parasites have developed a mans to exploit and change their host’s behaviour in order to increase transmission.

111
Q

Which host behaviours might a parasite alter?

A
  • Foraging
  • Movement
  • Sexual behaviour
  • Habitat choice
  • Anti-predator behaviour
112
Q

What may parasites suppress in hosts for their own benefit?

A

Parasites may suppress host immune responses and modify host size and reproduction for their own benefit.

113
Q

Describe the distribution of parasites.

A

The distribution of parasites is not uniform.

114
Q

How do parasites achieve rapid evolution?

A

By having both sexual and asexual phases.

115
Q

List the non-specific barriers mammals have to parasites.

A
  • Skin
  • Mucus, tears & stomach acid
  • Inflammatory response
  • Phagocytes
  • Natural killer cells (Lymphocytes)
116
Q

What are phagocytes?

A

Phagocytes are special white blood cells that engulf the parasite and digest it using enzymes held in lysosomes.

117
Q

Describe the process of phagocytosis.

A
  • Phagocytes move to the site of injury
  • Plasma membrane of the phagocyte engulfs the parasite
  • Parasite is brought into the phagocyte in a vacuole
  • Lysosomes move towards the vacuole
  • Lysosomes fuse with vacuole, releasing digestive enzymes
  • The parasite is digested
118
Q

What is specific defence?

A

Immune surveillance which is carried out by the white blood cells, kind of like a patrol.

119
Q

What are the two kinds of lymphocytes involved in specific defence?

A 
B lymphocytes (B cells)
T lymphocytes (T cells)
120
Q

What is the purpose of B lymphocytes in immune response?

A

In response to the foreign antigens presented by phagocytes, B cells produce proteins called antibodies that are specific in shape to the antigen.

121
Q

What is the purpose of T lymphocytes in immune response?

A

T cells work by destroying specific infected or damaged cells by brining about apoptosis.

122
Q

What is clonal selection?

A

Lymphocytes are amplified through mitosis. Some clones are used in combating the attack. Others be immunological memory cells.

123
Q

What are immunological memory cells?

A

Cloned lymphocytes that remain in the body to respond faster if the individual is exposed to the same antigen a second time.

124
Q

What is epidemiology?

A

Epidemiology is the study of outbreak and spread of infectious diseases.

125
Q

What is meant by ‘Herd immunity threshold’?

A

The density of resistant hosts in a population required to prevent an epidemic.

126
Q

How do endoparasites avoid destruction?

A

Endoparasites are able to mimic host antigens which allow them to avoid destruction.

127
Q

Why do parasites modify their hosts immune response?

A

Suppressing their immune system means they find it harder to fight off parasites and infections.

128
Q

What is antigenic variation?

A

Parasites can evade detection as they change quicker than the host immune system can keep up with. Being resistant to one strain does not make you resistant to all.

129
Q

List some common parasites.

A
  • Protists - single called organisms
  • Platyhelminthes - flatworms
  • Nematodes - roundworms
  • Arthropoda - e.g. ticks
  • Bacteria
  • Viruses
130
Q

Why do some parasites require more than one host?

A

Sometimes parasites require 2 hosts to complete their life cycles, e.g.
Plasmodium
Schistosomiasis

131
Q

How are endoparasites and ectoparasites of the main body cavities transmitted?

A

Ectoparasites of the main body cavities are transmitted via direct contact.
Endoparasites of the main body cavities are transmitted via contact or consumption of secondary hosts.

132
Q

How are endoparasites of the body tissues transmitted?

A

Endoparasites of the body tissues are transmitted via vectors.

133
Q

Give 3 examples of parasites that can complete their lifecycle in 1 host.

A

Ticks
Amoebas
Bacteria

134
Q

Give an example of a human bacterial disease.

A

Tuberculosis

135
Q

Give 2 example of viral human diseases.

A

Influenza

HIV

136
Q

What is a virus?

A

Viruses are parasites that can only replicate inside a host.

137
Q

What is the structure of a virus?

A

Viruses are composed of nuclei acid enclosed inside a protective protein coat. These contain genetic material in the form of DNA or RNA.

138
Q

What is a retrotransposon?

A

Pieces of DNA that carry out reverse transcription before being inserted into a new site on the genome.

139
Q

What is the origin of retrotransposons?

A

Retroviruses are the origin of retrotransposons.

140
Q

How have retrotransposons affected host immunity?

A

Our great variability of vertebrate antibodies is hypothesised to have evolved from retrotransposons.

141
Q

What are retroviruses?

A

Retroviruses are viruses that contain RNA as their genetic material rather than DNA.
HIV is a retrovirus.

142
Q

What is the enzyme involved in DNA formation in retroviruses?

A

Reverse transcriptase.

143
Q

State 3 challenges faced in the treatment and control of parasites.

A
  • Some parasites are difficult to culture in a lab
  • Rapid antigen change has to be reflected in the design of vaccinations
  • Similarities between host and parasite metabolism makes it difficult to find drug compounds that only target the parasite without negatively affecting the host.
144
Q

State 2 positive control strategies for parasites.

A
  • Civil engineering projects to improve sanitation

- Coordinated vector control

145
Q

What conditions do parasites thrive in?

A
  • Conditions of poor sanitation

- Overcrowded populations

146
Q

What are the advantages of increasing parasite control?

A
  • Reduce child mortality

- Have population-wide improvements in child development and intelligence.

AH Biology (3 decks)

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