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Biology > Biodiversity > Flashcards

Biodiversity Flashcards

1
Q

Why have so few bacteria and viruses been named?

A

-new species are evolving

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2
Q

What is a species?

A

-a species is a group of closely related organisms with similar morphology, physiology and behaviour, that have the ability to interbreed and produce viable and fertile offspring.

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3
Q

In species they generally have DNA which is…

A

> 99% similarity

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4
Q

What reason makes offspring not viable?

A

-meiosis requires homologous chromosomes

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5
Q

What is fertility?

A

The ability to produce viable gametes

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6
Q

How do we know if organisms are the same species (rank 5 most to least important)

A

-observation of reproductive behaviour
-comparison of DNA composition
-comparison of karytotypes
-comparison of primary structure of cytochromes (proteins involved in respiration)
-comparison of leg structure

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7
Q

Why are strucural similarities least useful?

A

-There is large variation between and within different species.
-Taxonomists may disagree about descriptions of structural similarities.

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8
Q

What are problems associated with studying reproductive behaviour?

A

-not possible if species is extinct

-not possible with asexually reproducing species (bacteria)

-difficult when potential members of the same species dont live in the same areas

-may not be able to do breeding tests on rare specimens (too risky to transport them to a research facility, may not survive)

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9
Q

If there is overlap between standard deviations of measurements of different species…

A

The species may be the same

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10
Q

Why are only female bats analysed?

A

-limits variation due to sex

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11
Q

What is the definition of ecology?

A

-study of interactions between organisms and their environment

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12
Q

What is the biosphere?

A

-the biosphere is the part of the earth and atmosphere that is inhabited by living organisms

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13
Q

What are biotic factors?

A

Living factors

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14
Q

What are abiotic factors?

A

Non living factors

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15
Q

What is an ecosystem?

A

An area in which organisms interact with each other and with their environment

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16
Q

What is a community?

A

An entire set of organisms which coexist in a particular ecosystem at a particular time

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17
Q

What is the environment?

A

The physical and biotic surroundings

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18
Q

What is the population?

A

The total number of individuals of a species within a community in a particular ecosystem at a particular time

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19
Q

What is the habitat?

A

An area within an ecosystem in which a particular organisms lives

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20
Q

What is a niche?

A

The way an organism uses its environment + its role in the community

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21
Q

What do niches include?

A

-habitat
-food sources
-uses of abiotic resources (CO2, oxygen, light)
-the influence of abiotic factors (e.g temperature)
-the way it interacts with other individuals of the same or different species

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22
Q

What is the fundamental niche?

A

The largest niche an organism could occupy if there was no competition

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23
Q

What is the realised niche?

A

The niche that is actually occupied

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24
Q

What are two outcomes of two different species occupying the same niche?

A

Outcome 1:
-species compete with each other but both survive
(Splitting the niche + division of resource)

Outcome 2:
-due to competition species 2 is completely wiped out and only species 1 survives
(Extinction)

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25
Q

Describe a leaf cutters bees niche:

A

-herbivore
-competes with other insects for leaves
-use the leaves to make nests where they lay eggs

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26
Q

What are adaptations?

A

-behavioural physiological and anatomical features that help an organism to survive in its habitat

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27
Q

Behavioural adaptations are…

A

Actions which help an organism to survive in its habitat

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28
Q

What are physiological adaptations?

A

-features of the cell tissues and systems of an organisms which help it survive in its habitat

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29
Q

What are anatomical adaptations?

A

Anatomical adaptations are visible physical features of an organism which help it survive in its habitat

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30
Q

What is coadaption?

A

Mutual adaption of two (or more) organisms as a result of mutual survival benefits

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31
Q

How does genetic variation come about?

A

Random mutation

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32
Q

Directional selection is when…

A

A selection pressure favours one extreme of a phenotype and the other extreme is selected against

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33
Q

What is stabilising selection?

A

-when the selection pressure favours the mean and both extremes are selected against

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34
Q

What is disruptive selection?

A

-when the selection pressure FAVOURS both extremes and they mean is selected against
(Salmon)

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35
Q

What is micro evolution?

A

A change in allele frequency in a population overtime (which results in a change in behaviour physiology or anatomy)

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36
Q

What is a gene pool

A

All of the alleles of all the genes in a population

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37
Q

If the gene pool is constant: population…

A

Is not evolving

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38
Q

What does it mean if the gene pool is changing?

A

There are selection pressures and the population is evolving

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39
Q

What are the two hardy Weinberg equations?

A

P2 + 2pq + q2 = 1
P+q = 1

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40
Q

What does the hardy-Weinberg principle state?

A

That original proportions of genotypes in a population will remain constant from generation to generation as long as the following assumptions are met:

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41
Q

What are the assumptions that are required for the hardy Weinberg principle?

A

-population is very large
-random mating occurs
-no mutations take place so alleles do not change
-no migration or emigration because population is isolated (no alleles are introduced/lost)
-no natural selection

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42
Q

What does it mean if the hardy Weinberg assumptions are met?

A

-the dominant alleles will not replace recessive ones because their proportions will not change. The genotypes are said to be in hardy Weinberg equilibrium.

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43
Q

Why are the assumptions needed for H-W rarely met?

A

-allele frequencies are changing all of the time

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44
Q

The hardy Weinberg principle sets a…

A

Baseline against which to measure changes

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45
Q

What is the study of heterozygosity?

A

-hardy-Weinberg
-its used by conservation geneticists to assess the genetic diversity of a population

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46
Q

The more heterozygous a population…

A

The better chance it has of surviving an environmental change (selection pressure)

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47
Q

Why is heterozygosity lost in small populations?

A

-inbreeding
-increases homozygosity and is bad for survival

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48
Q

By studying changes in heterozygosity…

A

Biologists can figure out what is causing changes in allele frequency (micro-evolution)

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49
Q

What causes allele frequencies to change?

A

-mutations
-genetics drift
-natural selection
-non random mating
-migration/gene flow

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50
Q

What is genetic drift?

A

A change in allele frequency caused by chance

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51
Q

What is a bottleneck event?

A

= population rapidly decreases e.g due to disease/natural disaster

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52
Q

What is as founder effect?

A

=new population is established with different allele frequency

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53
Q

Give an example of evolution without natural selection:

A

-genetic drift often happens following a bottleneck event (disease/natural disaster)
-the event leaves a small population of chance survivors
-these contribute alleles to future generations
-population has reduced considerably and allele frequencies are likely to have changed
(Small founder populations also experience chance genetic drift in allele frequencies)

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54
Q

What determines a populations ability to adapt to environmental change?

A

-strength of selection pressure
-size of gene pool
-reproductive rate of organism

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55
Q

Why is it unlikely that populations become perfectly adapted to their environment?

A

-environments change continually
-always selection pressure
-time lag for populations to adapt (i.e for allele frequencies to change)
-mutations occur - new alleles make population less well adapted

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56
Q

Why might it be a problem to be too perfectly adapted to the environment?

A

-dependant on other species
-vulnerable if other species die out
-less likely to survive environmental change

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57
Q

What is speciation?

A

The formation of new species

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58
Q

Describe how speciation occurs:

A

-some individuals migrate to nearby islands
-geographic isolation of island communities
-random mutations occur, some are advantageous
-each island population experiences different selection pressures
Many generations ->
-some mutations (new alleles) are selected for
-the island species are no longer able to produce viable offspring w/ mainland population

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59
Q

What is biodiversity?

A

-biological diversity
-the number of different species and the genetic variation within species

60
Q

What is species richness?

A

The number of species present in a habitat

61
Q

What is species evenness?

A

-when there are similar numbers of Indivudals in most species (no dominant species)

62
Q

What is the diversity index?

A

-a measure of biodiversity that takes into account other species richness and species evenness
-a diversity index is used to compare habitats

63
Q

What are biodiversity hotspots?

A

Areas with high levels of biodiversity

64
Q

What are sources of genetic variation?

A

-crossing over
-independent assortment
-random fertilisation
-mutation
-chromosome mutation

65
Q

How can the alleles present in DNA be identified?

A

-dna can be sequences to determine the order of bases and therefore alleles present

66
Q

How else can DNA profiles be obtained?

A

-amplifying DNA by copying it many times using PCR
-then cutting it with restriction enzymes
-the resulting fragments are separated by gel electrophoresis to give a banding pattern

67
Q

How can dna profiles be used?

A

-to calculate a heterozygosity index
-quantitifies the genetic diversity in a population
-conservations often use a heterozygosity index to help them make decisions about which populations to conserve

68
Q

If the proportion of heterozygotes and homozygotes in a population changes then one of these must be happening:

A

-mutation
-migration
-non random mating
-genetic drift
-selection

69
Q

What makes plants so good at building tall structures?

A
  • strong cell walls made of cellulose
  • columns and tubes of specialised cells
  • lignin stiffens some specialised cells
70
Q

What is the function of chloroplasts?

A
  • double membrane
  • site of photosynthesis
71
Q

What are amyloplasts?

A
  • membrane bound tonoplast
  • starch storage
72
Q

What are vacuoles?

A
  • surrounded by membrane (=cytoplasm)
  • storage of waste,food and water
  • provides turgor pressure
73
Q

What are plasmodesmata?

A
  • channels of plasdtid through cell walls
  • formed when ER is trapped between newly divided cells
  • allow for transport of materials between cells
74
Q

What are pits?

A
  • thin areas of cell wall that allow fluid transport between cells
    E.g bordered pits between xylem vessels
75
Q

What is the middle lamella?

A
  • layer of pectin between cell walls
  • gives stability to plant tissues
76
Q

What is the epidermis?

A
  • single layer of cells on outside of plant
77
Q

What is vascular tissue?

A
  • for transport and support
78
Q

What is ground tissue?

A
  • cells for photosynthesis, storage or support
79
Q

What are three types of ground tissue?

A
  • parenchyma
  • collenchyma
  • sclerenchyma
80
Q

What is parenchyma?

A
  • ‘packing tissue’
  • thin cellulose walls
  • provides mechanical support

E.g chlorenchyma + aerenchyma

81
Q

What is collenchyma?

A
  • below epidermis
  • tightly packed
  • thick cellulose walls
  • provides flexible support
82
Q

What is sclerenchyma?

A
  • cells die when mature and remain in position
  • rigid, thick, lignified cell walls
  • support plant as they are very strong
83
Q

What are stone cells?

A

/sclereids

  • mechanical support
84
Q

What are fibres?

A
  • long cells with characteristics tapering tips: mechanical support
85
Q
A

1 - epidermis
2 - phloem
3 - xylem
4 - cortex
5 - procambium
6 - interfascicular parenchyma
7 - vascular bundle

86
Q
A

1 - epidermis
2 - cortex
3 - endodermis
4 - pericycle
5 - primary phloem
6 - primary xylem

87
Q

What are sieve tube elements?

A
  • living cells
  • few organelles, no nucleus
  • perforated ends = sieve plates
  • bidirectional flow up or down
88
Q

What are companion cells?

A
  • cytoplasm contains many solutes
  • provides substances for sieve tube elements (phloem cells)
  • pores for transport between companion cell and phloem
89
Q

What is sucrose and amino acids transported in the phloem?

A
  • translocation
  • this is an example of a mass flow system
90
Q

What is translocation?

A
  • organic molecules are actively transported into the phloem tubes and them move from a high pressure to lower pressure (e.g leaves to roots)
  • pressure is high due to the osmotic effect of water moving with the solutes
91
Q

What are vessel elements?

A
  • vessel elements are dead hollow cells
  • autolysis of cell contents leaves empty xylem cells
  • perforated ends allow transport of water
  • lignin forms a secondary cell wall inside the primary cell wall
  • lignified cell walls withstand pressure + provide water proofing
  • pits allow lateral water movement
  • transport of minerals and water in the xylem is another example of mass flow system
92
Q

What are the bonds in between microfibrils

A
  • hydrogen bonds
93
Q

Why is cellulose straight?

A
  • cellulose is made up of beta glucose
  • glucose units are arranged in alternately inverted orientations
  • hydrogen bonds form between cellulose molecules forming crossings to other cellulose molecules rather than forming hydrogen bonds with the same molecule
94
Q

Why does amylose have a helical structure?

A
  • amylose is made up of alpha glucose
  • glucose units arranged in same orientation
  • hydrogen bonds form in specific positions between parts of the same polysaccharide chain, causing a helix to form
95
Q

How long is a microfibril?

A
  • 60-70 cellulose chains
96
Q

What polysaccharides glue microfibrils in place?

A
  • hemicellulose and pectin
97
Q

What contains a few pectins?

A
  • middle lamella
98
Q

What makes cell walls strong and flexible?

A
  • microfibrils which are laid down in different directions
99
Q

What allows the cell to stretch a bit when turgid

A
  • crosslinking between microfibrils
100
Q

What type of transport transports minerals and solutes into routes?

A
  • ATP
101
Q

What moves water up the xylem?

A
  • adhesion between H2O and walls of xylem
102
Q

What holds the water column together?

A
  • cohesion between H2O molecules
103
Q

What causes a hydrostatic pressure gradient?

A
  • evaporation from leaves
104
Q

How does water move in a xylem vessel in terms of pressure?

A
  • high to low
105
Q

How does water exit the leaf?

A
  1. Continuous column of water drawn up inside xylem vessels
  2. Water drawn out of stomata
  3. Water replaced via capillary action (water travels within permeable cell walls)
  4. Water evaporates from spongy mesophyll cells into air spaces
  5. Water diffuses out of stoma = transpiration (evaporation via stoma)
106
Q

What is the transpiration stream?

A
  • the water passing upwards through the plant and out of the leaves
107
Q

What drives the transpiration stream?

A
  • energy from the sun
108
Q

Why does tree trunk circumference change over the course of the day?

A
  • no transpiration during night so water pools in the xylem
  • more outward pressure so trunk has a larger circumference
109
Q

Why is active transport required for minerals to move into root hair cells?

A
  • against concentration gradient
110
Q

Why do minerals then move through the root to the xylem by diffusion?

A
  • following the concentration gradient
111
Q

Why are nitrates needed in plants?

A
  • in amino acids
  • in chlorophyll, DNA, ATP
112
Q

What are the deficiency symptoms of nitrate?

A
  • stunted growth
  • yellow leaves
113
Q

Why is magnesium needed in plants?

A
  • its in chlorophyll
114
Q

What are defiency symptoms of magnesium?

A
  • yellow leaves
115
Q

Why is phosphorus needed in plants?

A
  • its in DNA and ATP
116
Q

What are defiency symptoms of phosphorus?

A
  • purple leaves
  • stunted growth
117
Q

Why is calcium needed in plants?

A
  • needed for cell wall and membrane permeability
118
Q

What are calcium deficiency symptoms?

A
  • stunted growth (especially at leaf margins)
119
Q

What is lignin?

A
  • a carbohydrate polymer made of CHO
120
Q

What does lignin do?

A
  • stops vessel forms collapsing when pressure in the vessel is low (when transpiration is happening)
  • it gives vessels high tensile strength (resists tension) as the plant bends in the wind
121
Q

What role does lignin play in xylem vessels?

A
  • lignin waterproofs the xylem and gives it support
  • its arranged in spirals or rings
122
Q

What role does lignin play in sclerenchyma?

A
  • lignified sclerenchyma fibres die leaving narrow hollow tubes
123
Q

What does the strength of fibres (xylem + sclerenchyma) depend on?

A
  • their length
  • the amount of lignification
124
Q

Describe the structure of tall plants:

A
  • majority of the trunk is lignified and dead
  • new (living) layers are towards the outside (under the bark)
125
Q

Describe the structure of non-woody plants:

A
  • only vascular bundles lignified
  • tightly packed, fully turgid parenchyma cells provide support
126
Q

Why do people use plant fibres?

A
  • they are strong, flexible, long and thin
  • they can be sustainably produced
  • they are biodegradable
127
Q

What are plant fibres used for?

A
  • clothing, ropes, paper, etc
  • hydrocarbon absorption (oil pollution control)
  • biocomposites (fibre + plastic)
128
Q

What are two ways to extract plant fibres?

A
  • mechanically
  • by digesting surrounding tissue
129
Q

How do you extract plant fibres by digesting surrounding tissue?

A
  • cellulose and lignin are very resistant to degradation
  • polysaccharides (e.g hemicellulose) that holds fibres together can be digested by enzymes
  • bacteria and fungi can provide these enzymes in piles of plant tissue (retting)
  • modern equivalents of retting where enzymes are added in a biochemical process
130
Q

What are monocotyledons (monocots)

A
  • endospermic seeds
    E.g corn kernels
131
Q

What are dicotyledons (dicots)

A
  • no endosperm
  • embryo absorbs food (stored in cotyledon)
    E.g beans
132
Q
A

1 - testa (seed coat)
2 - endosperm (food storage)
3 - cotyledon (seed leaves)
4 - plumule (young shoots)
5 - radicle (young root)

133
Q

Describe seed germination

A

Water is taken in through the seed coat
- metabolic changes are triggered
- plant growth substances produced

Amylase and Malta’s produced
- starch converted to glucose and sucrose for transport

134
Q

What are the 3 requirements for popcorn to pop?

A
  • water inside seed
  • tight seed coat (testa)
  • starch inside (endosperm)
135
Q

How does water cause popcorn to pop?

A
  • water evaporates upon heating
  • steam causes pressure to build up
  • kernel explodes
136
Q

How does the seed coat allow popcorn to pop?

A
  • air-tight structure allows pressure to build up
  • hard seed coat: resists pressure when heated up to about 250C
137
Q

What happens to starch when popcorn pops?

A
  • gelatinises
  • hydrogen bond breaks
  • starch absorbs water and swells increasing pressure
  • as kernel explodes, water steam creates bubbles in starch jelly which creates 3D foam that solidifies in air
138
Q

What is gelatinisation?

A
  • when starch is heated in water it absorbs the water and thickens liquids (corn starch in cooking)
139
Q
  • how can popcorn be useful?
A
  • packing materials
140
Q

What is starch used for?

A
  • adhesives, paints, plaster, toiletries, and foods (custard,) paper and some cloth is stiffened with starch
141
Q

What are the problems with oil based plastic

A
  • not biodegradable
  • crude oil
  • requires high temp + pressure
142
Q

Why is biofuel not perfect?

A
  • energy needed for all steps in processes
  • deforestation
  • change of land use
143
Q

Why are plant products not necessarily the answer

A
  • lots of water
  • energy
  • pesticides
  • transport
144
Q

What is the problem with biodegradable products in deep landfill

A
  • anaerobic
  • bacteria produced methane
145
Q

How do you improve reliability of drug testing?

A

Large sample size
- if results are similar they are considered to be reliable
Statistical analysis
- tests significance of results (probability results are not due to chance)
Removing anomalies

146
Q

How do you improve validity?

A

Double blind testing
- avoid research subconsciously influencing outcome

Random assignment
- removes potential bias in assigning to a particular group

Placebo controlled
- control experiment - shows if effect is due to active ingredient

Biology (4 decks)

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