2.1 classification and biodiversity Flashcards
1
Q
what is classification?
A
the organisation of every living thing into groups
2
Q
what does classification aim to do?
A
- group organisms to reflect how closely they are related in terms of their evolutionary history and characteristics
3
Q
what does it mean that classification is hierarchical?
A
that large groups are split into groups of decreasing size.
4
Q
what does it mean that classification is phylogenetic?
A
that organisms in the same group are more closely related to each other
5
Q
what does it mean that the groups in classification are discrete?
A
an organism cannot belong to more than one group at the same taxonomic level
6
Q
what is each group in classification called?
A
a taxon
7
Q
what system do scientists use for classification?
A
the 5 - kingdom system
(since 1969, scientists have used the 5-kingdom system of classification)
every living organism belongs to one of 5 kingdoms
8
Q
which is the largest taxonomic group? which is the smallest taxonomic group?
A
domain = largest
species = smallest
9
Q
what does it mean that classification is described as having a tentative nature?
A
- classification is based on the information available at the time
- and is subject to change as new information comes to light
10
Q
what are the three domains?
A
- eukarya (eukaryotae)
- archaea
- bacteria
11
Q
• bacteria - prokaryotic
• archaea - also prokaryotic but are extremophiles
• eukaryotae - all eukaryotic organisms
A
12
Q
where do extremophiles live?
A
where environmental conditions are harsh
e.g in very high or low temperstures (thermophiles or psychrophiles), acids or very alkaline environments, and areas with high salinity (halophiles), or high pressures
13
Q
where did the evidence for the three lineages (domains) come from?
how was the three domain system of classification developed?
A
- a study of ribosomal RNA
- by analysing molecular differences between organisms to determine their evolutionary relationships
- evidence showed that the kingdom ‘prokaryotae’ could be divided into two groups. all other organisms are eukaryotes
14
Q
what are the five kingdoms?
A
- prokaryotae
- animalia
- plantae
- fungi
- protoctista
15
Q
what are prokaryotae? (features)
A
- have cells without a membrane-bound nucleus or membrane-bound organelles
- lack a true nucleus
- have 70S ribosomes
- have a cell wall of peptidoglycan (murein) (rigid)
- unicellular
- some are heterotrophic (feeding on organic molecules made by other organisms) while others are autotrophic
16
Q
what are Animalia? (features)
A
- multicellular eukaryotic organisms
- their cells dont have cell walls
- all heterotrophic and have holozoic nutrition, digesting food internally
- have nervous co-ordination
17
Q
what are plantae? (features)
A
- multicellular eukaryotic organisms
- have cell walls made of cellulose
- are autotrophs, using sunlight as a source of energy to make organic molecules by photosynthesis
- reproduce using spores or seeds
18
Q
what are Fungi? (features)
A
- can be multicellular or unicellular, bit they are all eukaryotes
- have cell walls made of chitin
- all heterotrophic and feed saprophytically by secreting enzymes extracellulary onto food
- multicellular fungi grow in long threads called hyphae (all the hyphae together are a mycelium) (grow by producing branching filaments, hyphae)
- all fungi reproduce by spores (asexual reproduction)
19
Q
what are Protoctista? (features)
A
- unicellular eukaryotic organisms
- no differentiation into tissues
- may be heterotrophic, autotrophic or both
- a very diverse grouping
- contain membrane-bound organelles and a nucleus
20
Q
what is a species?
A
a group of organisms with similar characteristics that can INTERBREED to produce fertile offspring
21
Q
what is an example of a sterile hybrid?
A
mules
sometimes it is because the gametes of the two species have different chromosome numbers, so the chromosomes cannot pair up at the start of meiosis, therefore the hybrid cannot make gametes
22
Q
can similar organisms (not same species) interbreed to produce offspring?
A
some similar organisms can interbreed to produce offspring - but if the offspring are sterile then the organisms are not the same species
23
Q
all species have a ___ name?
A
binomial name
(a name in two parts)
24
Q
what are the two components to a binomial name of an organism?
A
Genus species
Genus = generic name
species = specific name
25
remember that organisms in the same genus are more closely related to each other than to organisms in a different genus:
e.g chinstrap penguins (*Pygoscelis antartica*) and Adelie penguins (*Pygoscelis adeliae*)
these are two different species of penguins that cannot interbreed to produce fertile offspring but they are more closely related to each other than they are to Emperor penguins (*Aptenodytes forsteri*), who are in a different genus
26
what is the advantage of the binomial naming system?
- it is universal
- to avoid issues/confusion with language differences
27
what is a phylogenetic tree?
a diagram that represents the evolutionary pathways leading to different species
- shows how organisms are related by showing their common ancestors
- the axis is time, the tree branches as time moves forwards
- each junction represents the common ancestor of the organisms that branch from it
- a group of branches from one common ancestor is called a clade
- the more recent the common ancestor, the more closely related the organisms are
28
how can biological polymers that have different subunits, such as DNA, RNA, or protein be used to establish relatedness?
the sequences of subunits can be compared and the number of differences counted
- the more differences there are in sequence, the less closely related two organisms are
29
differences in sequences of DNA, RNA, proteins, etc. are owing to ____?
mutations
30
can can mutations in DNA lead to?
-differences in the amino acid sequence of proteins
- depending on the organism type and reproduction rate, it is possible to use these differences to construct a ‘molecular clock’ which shows how long ago that mutation occurred, and means that a timeline can be drawn as to when a species or group diverged
31
how can fragments of DNA and proteins be separated?
by gel electrophoresis
32
how are fragments of DNA and proteins separated by gel electrophoresis?
- the gel allows small fragments to move further and the electrical charge causes movements of the negatively charged DNA fragments to the positive electrode
- a banding pattern is produced, called a DNA fingerprint, which can be used for comparison
33
what does morphology mean?
looking at the shape and form of an organism
34
before biochemical analysis was possible, what was the main evidence that naturalists had to classify organisms and construct phylogenetic diagrams?
morphology
35
is it possible for some organisms to have similar morphology but be unrelated in evolutionary terms?
yes
e.g hedgehogs, echidnas, and porcupines are all similar looking and have spines for protection
THIS IS AN EXAMPLE OF CONVERGENT EVOLUTION
36
what is an advantage of using biochemical methods of classification?
- it can overcome issues caused by convergent evolution
- biochemical methods reduce mistakes made from observing physical features alone (due to morphological convergence)
37
what is convergent evolution?
where the selection pressures are similar and mutations give rise to similar features that provide an advantage
38
what are homologous structures?
similar structures in different species that have different functions
e.g pentdactyl (5 fingered) limb = in birds, for flight, in whales for swimming etc
- the structure is the same even though evolution has resulted in adaptations for particular function
- homologous structures indicate that organisms are related
- derived from a common ancestor
39
what do analogous structures arise through?
- convergent evolution
(the function is the same, however the origin of the structure is different)
e.g wings of birds and insects
40
convergent evolution leads to similarities in ____ organisms?
unreleated
41
homologous structures in two organisms means that they are ____ through evolutionary history
related
42
analogous structures have the same function in ____ organisms?
unrelated organisms
43
the more similar a nucleotide or amino acid sequence is, the more closely ____ two organisms are?
related
44
biodiversity definition
the number and variety of species in a given area
(it is affected by environmental, genetic and human factors)
the number of species and the number of individuals of each species in a specified geographic region
45
the more biodiverse an area is, the ___ types of species and individuals there are?
more
46
does biodiversity on the planet vary spatially?
yes
it increases going from the poles towards the equator
47
what are some reasons for an increase in biodiversity from the poles to the equator?
- more UV light causes a higher rate of mutation and therefore more rapid evolution
- more species types means there are more habitats (places to live) and niches (food types)
- a more stable temperature range and water availability means conditions are more favourable for survival
- with more species and individuals, competition is high, leading to more specialised and narrower exploitation of niches, making it more difficult to move out of the area
- warmer temperatures
- food availability
48
how do you investigate biodiversity in a habitat?
- by counting the number of different species (species richness) and the number of individuals of each species (species evenness) in the area
- the area is sampled , either by gridding or by sampling along a line (transect)
49
when is gridding for sampling?
- where two areas are to be compared, for example a mown and unmown area of grassland
50
when are transects used for sampling?
when there is a gradual change in the environment, for example from under a tree into the open
51
why is random sampling important when measuring biodiversity?
- as it avoids unconscious sampler bias
- which increases the reliability of the data
52
what is used to prevent bias while gridding?
- random number tables are used to generate random co-ordinates for a gridded area and the quadrats are placed at those co-ordinates only
53
what is used to prevent bias with transects?
sampling along a transect is often done at a fixed distance e.g every 2 meters
54
what type of sampling is used for measuring biodiversity in aquatic ecosystems?
- the method of collection in each area is standardised
- this could include time for collection or mesh size of net
- kick sampling is also used
many samples are take to improve reliability
55
in a stream, kick sampling can be used to collect organisms for counting.
the net is placed ____ of the area being disturbed by kicking
downstream
56
what are the main hazards in field work?
- biting and stinging insects and stinging or thorny plants - the risk is scratches or allergic reactions, and these are controlled by wearing insect repellent and protective clothing
- different ecosystems have different hazards e.g the tide is a hazard on a seashore
- slippery surfaces can be a hazard causing risk of strains and sprains - appropriate footwear with grip should be worn
57
what is Simpson’s Diversity Index?
a calculation that reduces the data about numbers of species and individuals of each species to a single number
- this number can be used to compare biodiversity in two different areas or ecosystems
(it is a measurement of diversity that considers both species richness and evenness)
58
simpson’s diversity index:
- the number is always between ___ and ___?
- a higher value indicates that the biodiversity is ___?
- between 0 and 1
- higher
59
how is simpson’s diversity index calculated?
D = 1-(Σn(n-1)/(N(N-1))
N = total number of organisms present
n = number in each species
D = 1 - (Σ(n/N)^2)
60
in order to draw conclusions about differences in simpson’s diversity index, it may be necessary to measure physical aspects of the areas or ecosystems.
what are these factors termed?
what do they include?
- termed abiotic factors
- may include temperature, pH, nitrate concentration, oxygen concentration (in aquatic systems) or light intensity
61
how can genetic biodiversity be assessed?
by determining the number of alleles at a locus within a given species and the proportion of the population that have a particular allele
- this provides a measure of the variation within a species
- the more genetic variation there is within a species, the more biodiverse the species is
62
what is polymorphism?
the presence of different phenotypes among members of a single species
(where a species has a number of different forms)
e.g banded snail Cepaea nemoralis
banded snails have shells of different colours and the shells have different number of bands. this is the result of having many different alleles for the same gene. many different alleles for the same gene, leading to different forms of the same organism is called genetic polymorphism
63
how can genetic polymorphism be assessed?
- by determining the number of alleles at any one gene locus
- and the proportion of the population that has a particular allele
64
what mechanism has generated biodiversity?
natural selection
65
what are the steps in natural selection?
- mutations cause variation in individuals that can be inherited
- all organisms overproduce offspring, so that there is a large variation of genotypes within the population, leading to some competition within a species (competition competition) for resources
- some variation confers a selective advantage to the individuals in a species
- this means they are better fitted to survive a selection pressure
- a selection pressure is something that causes the death of an organism, like predation, disease or climate (environmental change)
- the individuals that have a selective advantage survive and reproduce, passing the alleles to their offspring
- over many generations the allele frequencies of the favourable variation increase
• beneficial alleles
• selection pressures
• produces a useful phenotype
66
through natural selection, organisms with selective advantages become adapted to particular environments.
what are the 3 types of adaptations?
- anatomical - changes to physical features
- physiological - changes to bodily processes
- behavioural - changes to actions
67
e.g desert organisms face the same issues of extreme temperature fluctuations and low water availability. fennec foxes live in the sahara desert.
what do their anatomical adaptations include? their physiological adaptations? their behavioural adaptations?
anatomical:
- being small in size
- large ears to give a higher surface area to volume ratio to lose heat
- a long snout to being the temperature of inspired air closer to body temp before it enters the lungs
- a fur colour that provides camouflage
physiological:
- kidney’s with long hoops of Henle so that concentrated urine with a low volume is produced, thus losing less water
- breathing faster when temperatures are high to lose more heat
behavioural:
- being crepuscular (active at dawn and dusk) when temperatures are cooler
- digging dens to shelter in during the day
68
name the seven groups in the hierarchy of taxons:
kingdom
phylum
class
order
family
genus
species
69
what do organisms in the same domain have in common?
organisms in the same domain share a distinctive pattern of ribosomal RNA
70
what is Bacteria?
- one of the three domains
- consists of ‘true’ bacteria
- also known as Eubacteria
71
what is Archaea?
- one of the three domains
- made up of primitive bacteria existing in extreme environments e.g extremophile prokaryotes
- also known as Archaebacteria
72
what is Eukarya?
- one of the three domains
- consists of all eukaryotic organisms
73
how are the different types of evidence used in classification?
- observations (e.g fossils) - organisms are grouped based on similar physical characteristics
- biochemical methods (e.g DNA genetic fingerprinting)
74
what is DNA profiling?
- method of determining the characteristics of an individual’s DNA
- percentage of DNA or proteins shared between species is used to estimate relatedness
75
compare homologous and analogous features:
- homologous features have evolved from the same structure for different functions. they indicate a common ancestor
- analogous features are structures that have evolved independently for the same function (different shape/structure)
76
what is an example of a homologous feature?
pentadactyl limb (found in mammals, birds and reptiles)
77
what is an example of an analogous feature?
the wings of birds and insects
78
when measuring the biodiversity of a habitat, what must ecologists consider?
- species richness
- species evenness
79
species richness definition
the number of different species found within an area
80
species evenness definition
the number of individuals of each species living together in a community
81
how can biodiversity in a habitat be assessed?
using Simpson’s Diversity Index
82
how can we calculate genetic diversity within a species?
proportion of polymorphic gene loci = no. of polymorphic gene loci / total number of loci
83
how can biodiversity be assessed at the molecular level?
using DNA fingerprinting and sequencing
84
what is DNA sequencing?
determining the entire DNA nucleotide base sequence of an organism
85
how is DNA sequencing used to measure biodiversity?
comparisons between members of the same species can identify variation in base sequences and hence estimate genetic diversity
86
what is an adaptation?
a feature of an organism that increases its chance of survival in its environment
87
who introduced the binomial naming system? when?
Carl Linnaeus in 1735
88
autotrophic nutrition definition
is making complex organic molecules from simple inorganic ones using either light or chemical energy
e.g plantae - photosynthesis
use simple inorganic molecules to SYNTHESISE complex organic compounds
89
heterotrophic nutrition definition
involves consumption of already made complex organic molecules
e.g animalia
90
saprophytic nutrition definition
involves feeding on dead or decaying matter by the production of enzymes extracellularly and the subsequent absorption of the products
(feed by extracellular digestion and absorb the products)
91
parasitic nutrition definition
a nutrition by which organisms live on or in another host organism and obtain nutrients from it, causing harm to the host
92
the greater the variation in the base sequence, the ___ the genetic diversity of the species
greater
93
what are some factors affecting biodiversity?
- succession : the composition of a community changes over time as different species colonise
- natural selection
- human activity : pollution, overfishing, deforestation
94
why are reductions in biodiversity a concern?
- many plants provide staple foods e.g rice and wheat
- and provide raw materials e.g cotton
- many drugs are derived from plants e.g vincristine, which is used to treat cancer, and many have yet to be discovered
95
a gene’s position on the chromosome is referred to as its ___?
locus (loci)
96
a locus shows polymorphism if __?
it has two or more alleles that cannot be accounted for by mutation alone, resulting in two or more different phenotypes
e.g ABO blood grouping, the gene responsible for producing antigens on the surface of red blood cells has three different alleles : A, B and O
97
gene pool definition
total number of alleles within a population
98
what sampling technique could be used for terrestrial animals? what is the method?
- mark-release-recapture (Lincoln Index)
- animals are captured and marked (it is important they are not harmed or made more visible to predators) and then released
- once animals have had a chance to reintegrate with the population, the traps are reset e.g 24 hours
- the total population size can be estimated using the number of individuals captured in sample 2, and the number in that sample that are marked
- population size = (no. in sample 1 x no. in sample 2) / no. marked in sample
- have to assume that no births/deaths/immigration/emigration have occurred during the time between collecting both samples
99
what sampling technique could be used for freshwater invertebrates? what is the method?
- use kick sampling and use Simpson’s Index
- collect and identify invertebrates from a given area using a quadrat and a net
- kick or rake the area e.g 0.5m^2 for a set period, e.g 30 seconds, and collect invertebrates in a net downstream
- release invertebrates carefully
- use Simpson’s Index to calculate diversity
100
what sampling technique could be used for plants? what is the method?
- quadrats and transects
- estimate percentage area cover of different plants using a quadrat divided into 100 sections
- measure plant diversity by counting number of plants in quadrat e.g 1m^2
- a transect is a length of rope that can be used to measure intervals along an environmental gradient e.g distance from a woodland, along which quadrats can be placed
101
do you use the term allele or gene when describing natural selection?
allele
102
evolution definition
the process by which new species are formed from pre-existing ones over a period of time
(evolution repeats over many generations)
103
what does natural selection result in?
species that are better adapted to their environment
104
state why the head louse (Pediculus humanus) and flea (Pulex irritans) are classified in the same kingdom [1]
- have:
- nervous (coordination/system) / multicellular/heterotrophic / lacks cell wall
