Biodiversity Flashcards
1
Q
Why have so few bacteria and viruses been named?
A
-new species are evolving
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.
3
Q
In species they generally have DNA which is…
A
> 99% similarity
4
Q
What reason makes offspring not viable?
A
-meiosis requires homologous chromosomes
5
Q
What is fertility?
A
The ability to produce viable gametes
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
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.
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)
9
Q
If there is overlap between standard deviations of measurements of different species…
A
The species may be the same
10
Q
Why are only female bats analysed?
A
-limits variation due to sex
11
Q
What is the definition of ecology?
A
-study of interactions between organisms and their environment
12
Q
What is the biosphere?
A
-the biosphere is the part of the earth and atmosphere that is inhabited by living organisms
13
Q
What are biotic factors?
A
Living factors
14
Q
What are abiotic factors?
A
Non living factors
15
Q
What is an ecosystem?
A
An area in which organisms interact with each other and with their environment
16
Q
What is a community?
A
An entire set of organisms which coexist in a particular ecosystem at a particular time
17
Q
What is the environment?
A
The physical and biotic surroundings
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
19
Q
What is the habitat?
A
An area within an ecosystem in which a particular organisms lives
20
Q
What is a niche?
A
The way an organism uses its environment + its role in the community
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
22
Q
What is the fundamental niche?
A
The largest niche an organism could occupy if there was no competition
23
Q
What is the realised niche?
A
The niche that is actually occupied
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)
25
Describe a leaf cutters bees niche:
-herbivore
-competes with other insects for leaves
-use the leaves to make nests where they lay eggs
26
What are adaptations?
-behavioural physiological and anatomical features that help an organism to survive in its habitat
27
Behavioural adaptations are…
Actions which help an organism to survive in its habitat
28
What are physiological adaptations?
-features of the cell tissues and systems of an organisms which help it survive in its habitat
29
What are anatomical adaptations?
Anatomical adaptations are visible physical features of an organism which help it survive in its habitat
30
What is coadaption?
Mutual adaption of two (or more) organisms as a result of mutual survival benefits
31
How does genetic variation come about?
Random mutation
32
Directional selection is when…
A selection pressure favours one extreme of a phenotype and the other extreme is selected against
33
What is stabilising selection?
-when the selection pressure favours the mean and both extremes are selected against
34
What is disruptive selection?
-when the selection pressure FAVOURS both extremes and they mean is selected against
(Salmon)
35
What is micro evolution?
A change in allele frequency in a population overtime (which results in a change in behaviour physiology or anatomy)
36
What is a gene pool
All of the alleles of all the genes in a population
37
If the gene pool is constant: population…
Is not evolving
38
What does it mean if the gene pool is changing?
There are selection pressures and the population is evolving
39
What are the two hardy Weinberg equations?
P2 + 2pq + q2 = 1
P+q = 1
40
What does the hardy-Weinberg principle state?
That original proportions of genotypes in a population will remain constant from generation to generation as long as the following assumptions are met:
41
What are the assumptions that are required for the hardy Weinberg principle?
-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
42
What does it mean if the hardy Weinberg assumptions are met?
-the dominant alleles will not replace recessive ones because their proportions will not change. The genotypes are said to be in hardy Weinberg equilibrium.
43
Why are the assumptions needed for H-W rarely met?
-allele frequencies are changing all of the time
44
The hardy Weinberg principle sets a…
Baseline against which to measure changes
45
What is the study of heterozygosity?
-hardy-Weinberg
-its used by conservation geneticists to assess the genetic diversity of a population
46
The more heterozygous a population…
The better chance it has of surviving an environmental change (selection pressure)
47
Why is heterozygosity lost in small populations?
-inbreeding
-increases homozygosity and is bad for survival
48
By studying changes in heterozygosity…
Biologists can figure out what is causing changes in allele frequency (micro-evolution)
49
What causes allele frequencies to change?
-mutations
-genetics drift
-natural selection
-non random mating
-migration/gene flow
50
What is genetic drift?
A change in allele frequency caused by chance
51
What is a bottleneck event?
= population rapidly decreases e.g due to disease/natural disaster
52
What is as founder effect?
=new population is established with different allele frequency
53
Give an example of evolution without natural selection:
-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)
54
What determines a populations ability to adapt to environmental change?
-strength of selection pressure
-size of gene pool
-reproductive rate of organism
55
Why is it unlikely that populations become perfectly adapted to their environment?
-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
56
Why might it be a problem to be too perfectly adapted to the environment?
-dependant on other species
-vulnerable if other species die out
-less likely to survive environmental change
57
What is speciation?
The formation of new species
58
Describe how speciation occurs:
-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
59
What is biodiversity?
-biological diversity
-the number of different species and the genetic variation within species
60
What is species richness?
The number of species present in a habitat
61
What is species evenness?
-when there are similar numbers of Indivudals in most species (no dominant species)
62
What is the diversity index?
-a measure of biodiversity that takes into account other species richness and species evenness
-a diversity index is used to compare habitats
63
What are biodiversity hotspots?
Areas with high levels of biodiversity
64
What are sources of genetic variation?
-crossing over
-independent assortment
-random fertilisation
-mutation
-chromosome mutation
65
How can the alleles present in DNA be identified?
-dna can be sequences to determine the order of bases and therefore alleles present
66
How else can DNA profiles be obtained?
-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
How can dna profiles be used?
-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
If the proportion of heterozygotes and homozygotes in a population changes then one of these must be happening:
-mutation
-migration
-non random mating
-genetic drift
-selection
69
What makes plants so good at building tall structures?
- strong cell walls made of cellulose
- columns and tubes of specialised cells
- lignin stiffens some specialised cells
70
What is the function of chloroplasts?
- double membrane
- site of photosynthesis
71
What are amyloplasts?
- membrane bound tonoplast
- starch storage
72
What are vacuoles?
- surrounded by membrane (=cytoplasm)
- storage of waste,food and water
- provides turgor pressure
73
What are plasmodesmata?
- channels of plasdtid through cell walls
- formed when ER is trapped between newly divided cells
- allow for transport of materials between cells
74
What are pits?
- thin areas of cell wall that allow fluid transport between cells
E.g bordered pits between xylem vessels
75
What is the middle lamella?
- layer of pectin between cell walls
- gives stability to plant tissues
76
What is the epidermis?
- single layer of cells on outside of plant
77
What is vascular tissue?
- for transport and support
78
What is ground tissue?
- cells for photosynthesis, storage or support
79
What are three types of ground tissue?
- parenchyma
- collenchyma
- sclerenchyma
80
What is parenchyma?
- ‘packing tissue’
- thin cellulose walls
- provides mechanical support
E.g chlorenchyma + aerenchyma
81
What is collenchyma?
- below epidermis
- tightly packed
- thick cellulose walls
- provides flexible support
82
What is sclerenchyma?
- cells die when mature and remain in position
- rigid, thick, lignified cell walls
- support plant as they are very strong
83
What are stone cells?
/sclereids
- mechanical support
84
What are fibres?
- long cells with characteristics tapering tips: mechanical support
85
1 - epidermis
2 - phloem
3 - xylem
4 - cortex
5 - procambium
6 - interfascicular parenchyma
7 - vascular bundle
86
1 - epidermis
2 - cortex
3 - endodermis
4 - pericycle
5 - primary phloem
6 - primary xylem
87
What are sieve tube elements?
- living cells
- few organelles, no nucleus
- perforated ends = sieve plates
- bidirectional flow up or down
88
What are companion cells?
- cytoplasm contains many solutes
- provides substances for sieve tube elements (phloem cells)
- pores for transport between companion cell and phloem
89
What is sucrose and amino acids transported in the phloem?
- translocation
- this is an example of a mass flow system
90
What is translocation?
- 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
What are vessel elements?
- 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
What are the bonds in between microfibrils
- hydrogen bonds
93
Why is cellulose straight?
- 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
Why does amylose have a helical structure?
- 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
How long is a microfibril?
- 60-70 cellulose chains
96
What polysaccharides glue microfibrils in place?
- hemicellulose and pectin
97
What contains a few pectins?
- middle lamella
98
What makes cell walls strong and flexible?
- microfibrils which are laid down in different directions
99
What allows the cell to stretch a bit when turgid
- crosslinking between microfibrils
100
What type of transport transports minerals and solutes into routes?
- ATP
101
What moves water up the xylem?
- adhesion between H2O and walls of xylem
102
What holds the water column together?
- cohesion between H2O molecules
103
What causes a hydrostatic pressure gradient?
- evaporation from leaves
104
How does water move in a xylem vessel in terms of pressure?
- high to low
105
How does water exit the leaf?
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
What is the transpiration stream?
- the water passing upwards through the plant and out of the leaves
107
What drives the transpiration stream?
- energy from the sun
108
Why does tree trunk circumference change over the course of the day?
- no transpiration during night so water pools in the xylem
- more outward pressure so trunk has a larger circumference
109
Why is active transport required for minerals to move into root hair cells?
- against concentration gradient
110
Why do minerals then move through the root to the xylem by diffusion?
- following the concentration gradient
111
Why are nitrates needed in plants?
- in amino acids
- in chlorophyll, DNA, ATP
112
What are the deficiency symptoms of nitrate?
- stunted growth
- yellow leaves
113
Why is magnesium needed in plants?
- its in chlorophyll
114
What are defiency symptoms of magnesium?
- yellow leaves
115
Why is phosphorus needed in plants?
- its in DNA and ATP
116
What are defiency symptoms of phosphorus?
- purple leaves
- stunted growth
117
Why is calcium needed in plants?
- needed for cell wall and membrane permeability
118
What are calcium deficiency symptoms?
- stunted growth (especially at leaf margins)
119
What is lignin?
- a carbohydrate polymer made of CHO
120
What does lignin do?
- 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
What role does lignin play in xylem vessels?
- lignin waterproofs the xylem and gives it support
- its arranged in spirals or rings
122
What role does lignin play in sclerenchyma?
- lignified sclerenchyma fibres die leaving narrow hollow tubes
123
What does the strength of fibres (xylem + sclerenchyma) depend on?
- their length
- the amount of lignification
124
Describe the structure of tall plants:
- majority of the trunk is lignified and dead
- new (living) layers are towards the outside (under the bark)
125
Describe the structure of non-woody plants:
- only vascular bundles lignified
- tightly packed, fully turgid parenchyma cells provide support
126
Why do people use plant fibres?
- they are strong, flexible, long and thin
- they can be sustainably produced
- they are biodegradable
127
What are plant fibres used for?
- clothing, ropes, paper, etc
- hydrocarbon absorption (oil pollution control)
- biocomposites (fibre + plastic)
128
What are two ways to extract plant fibres?
- mechanically
- by digesting surrounding tissue
129
How do you extract plant fibres by digesting surrounding tissue?
- 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
What are monocotyledons (monocots)
- endospermic seeds
E.g corn kernels
131
What are dicotyledons (dicots)
- no endosperm
- embryo absorbs food (stored in cotyledon)
E.g beans
132
1 - testa (seed coat)
2 - endosperm (food storage)
3 - cotyledon (seed leaves)
4 - plumule (young shoots)
5 - radicle (young root)
133
Describe seed germination
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
What are the 3 requirements for popcorn to pop?
- water inside seed
- tight seed coat (testa)
- starch inside (endosperm)
135
How does water cause popcorn to pop?
- water evaporates upon heating
- steam causes pressure to build up
- kernel explodes
136
How does the seed coat allow popcorn to pop?
- air-tight structure allows pressure to build up
- hard seed coat: resists pressure when heated up to about 250C
137
What happens to starch when popcorn pops?
- 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
What is gelatinisation?
- when starch is heated in water it absorbs the water and thickens liquids (corn starch in cooking)
139
- how can popcorn be useful?
- packing materials
140
What is starch used for?
- adhesives, paints, plaster, toiletries, and foods (custard,) paper and some cloth is stiffened with starch
141
What are the problems with oil based plastic
- not biodegradable
- crude oil
- requires high temp + pressure
142
Why is biofuel not perfect?
- energy needed for all steps in processes
- deforestation
- change of land use
143
Why are plant products not necessarily the answer
- lots of water
- energy
- pesticides
- transport
144
What is the problem with biodegradable products in deep landfill
- anaerobic
- bacteria produced methane
145
How do you improve reliability of drug testing?
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
How do you improve validity?
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
