2.1 Classification and Biodiversity Flashcards
1
Q
What is classification based on?
A
Classification is based on evolutionary relationships. The term for this is phylogenetic.
2
Q
How are organisms classified?
A
Closely related organisms are grouped together.
Organisms in the same group have a more recent common ancestor with each other than with organisms not in their group.
If they are closely related, they may show physical similarities.
3
Q
Classification is _____
A
hierarchical.
4
Q
What does hierarchical classification mean?
A
This means that there is a system of ranking where large groups are divided up into smaller subgroups.
A hierarchical system has been devised for all living organisms.
5
Q
Define taxon.
A
Each group within a system of classification is called a taxon (pl. taxa)
Within each taxn, organisms are more similar to each other and more closely related than to organisms outside the taxon.
6
Q
The hierarchy of biological classification is:
A
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
7
Q
Taxa are _____.
A
discrete.
8
Q
What does discrete mean?
A
This means at any level of classification, an organism belongs to one taxon and no other
9
Q
Why is classification tentative?
A
Tentative means subject to change/likely to change over time.
This is because, more information becomes available to us through research in genetics, so classification is tentative.
10
Q
Why classify organisms?
A
- Humans always seek to put things into groups.
- A phylogenetic classification allows us to infer evolutionary relationships.
- It allows us to predict characteristics when we find new members of a taxon.
- Allows us to name creatures rather than list all of their features.
- Counting families rather than species is helpful in ecosystem conservation.
11
Q
Define taxonomy.
A
The identification and naming of organisms.
12
Q
Define classification.
A
Putting items into groups.
13
Q
Define hierarchy.
A
A system of ranking in which small groups are contained within larger groups.
14
Q
Define taxon.
A
A group within a system of classification.
15
Q
Define phylogenetic.
A
Reflecting evolutionary relationships.
16
Q
Define artificial.
A
A classification system that is based on arbitrary criteria, e.g. colour.
17
Q
Define discretion.
A
Belonging to one taxon only.
18
Q
Define tentative.
A
Altered with future knowledge.
19
Q
What is the domain.
A
A domain is the largest taxon.
20
Q
How many domains are there?
A
3
21
Q
How can organisms be classified into the 3 domains?
A
Using rRNA base sequences and more recently DNA base sequences.
22
Q
What are the 3 domains?
A
- Eubacteria: True bacteria or familiar bacteria, e.g. prokaryotes.
- Archaea: Bacteria, often with unusual metabolism, e.g. extremophiles and prokaryotes.
- Eukaryota: Plants, animals, fungi and protoctista. e.g. eukaryotes.
23
Q
What is the 5 kingdom classification?
A
This system classifies organisms on the basis of their physical/morphological appearance rather than DNA analysis.
24
Q
How many kingdoms are there?
A
5
25
What are the 5 kingdoms?
1. Prokaryota: all the bacteria, eubacteria and archaea are placed here.
2. Protoctista
3. Fungi
4. Plantae
5. Animalia
26
What is a phylum?
A subgroup of a kingdom.
27
What is a class?
A subgroup of a phylum.
28
What is an order?
A subgroup of a class
29
What is a family?
A subgroup of an order.
30
What is a genus?
A subgroup of a family.
31
Define species.
A group of organisms, sharing a large number of physical features, and able to interbreed to produce fertile offspring.
32
List the features of prokaryotes.
1. Unicellular.
2. Microscopic
3. No membrane-bound organelles
4. No nuclear membrane
5. Cell wall of murein/peptidoglycan
e.g. bacteria, blue-green algae.
33
List the features of Protoctista.
Mainly single-celled eukaryotes, no tissue differentiation.
34
List the features of plants.
Multicellular eukaryotes, photosynthetic, cell wall of cellulose
35
List the features of animals.
Nervous co-ordination, multicellular eukaryotes, no cell wall, heterotrophic.
36
List the features of fungi.
Heterotrophic eukaryotes, cell wall of chitin, most have filaments called hyphae, reproduce by spores.
37
What does the theory of evolution suggest?
The theory of evolution suggests widely separated groups of organisms share a common ancestor.
The more similar two organisms are, the more recently they are assumed to have diverged.
Organisms with little in common will have diverged from a common ancestor much earlier in time.
38
How can relatedness be assessed by?
Physical features
Genetic evidence
39
How can relatedness be assessed by physical features?
Biologists look for homologous structures, brought about by diverged evolution.
40
What are homologous structures?
structures with a similar structure and developmental origin, but different functions.
41
Give an example of a homologous structure.
pentadactyl limb.
This is a limb with 5 digits found in all 4 classes of land vertebrates.
In all 4 classes the limb has different functions.
42
What does the pentadactyl limb demonstrate?
This demonstrates divergent evolution where a common ancestral structure has evolved and performs different functions.
43
What is convergent evolution?
When structures evolve from different structures, with different developmental origins, but have the same function. Such structures are called analogous and are not used to classify organisms.
44
How can relatedness be assessed through DNA base sequences?
During evolution, species undergo changes in their DNA base sequences.
More closely related species show more similarity in their DNA base sequences than more distinctly related species.
DNA analysis has helped to confirm evolutionary relationships and correct mistakes made by using physical features only.
45
What is DNA hybridisation?
A technique used to compare the DNA sequences of 2 species.
DNA from two species is extracted, separated and cut into fragments.
The fragments of the two species are mixed and where they have complementary base sequences, they hybridise together.
Chimps and humans have 95% of their DNA in common.
46
How can we determine if species are closely related based on DNA base sequences?
The DNA base sequences determine the sequence of amino acids in proteins.
The similarity of the amino acid sequence in the same protein species will reflect their relatedness.
Fibrinogen and haemoglobin have been used.
47
How can we compare proteins of different species using immunological techniques?
If you mix the antigens of one species, such as blood protein albumen, with specific antibodies of another, the antigens and antibodies form a precipitate.
The closer the evolutionary relationship, the more the antigen and antibody react and make more precipitate.
48
Morphological definition of species.
When organisms have similar physical features. Watch out for sexual dimorphism.
49
Define sexual dimorphism.
Where the male and female of the same species look different.
50
Reproduction definition of species.
When organisms can interbreed to produce fertile offspring.
Dissimilar organisms may have a different chromosome number, incompatible physiology or biochemistry and so the hybrid would not be viable or fertile. e.g. mule
51
Describe the binomial system of naming organisms.
Each organism is given two names:
1. the name of the genus
2. the name of the species.
52
Define biodiversity.
The number of species and the number of individuals of each species in a given environment.
53
What is species richness?
The number of different species
54
What is species evenness?
The number of organisms of each species.
55
How can biodiversity vary?
spatially and over time
56
Tell me about the spatial variation of biodiversity.
Biodiversity is the greatest at the equator and in the tropics.
Biodiversity reduces towards the poles and away from the equator and the tropics.
57
What is biodiversity the greatest at the tropics?
Near and on the tropics, there is high light intensity.
More light means more photosynthesis carried out, more produces, so more consumers, which increases biodiversity.
58
Why might biodiversity increase/decrease?
1. Succession : the change in the structure and species composition of a community over time.
Over time, a community changes its habitat making it more suitable for species.
2. Natural Selection
This can generate and change biodiversity
3. Human influence.
This usually decreases biodiversity and may even lead to extinction of a species.
1. deforestation
2. overfishing
3. misuse of marginal land causing desertification
4. water pollution
Human activity can also enhance biodiversity
59
What is sustainable fishing?
fishing a reasonable amount, allowing enough to be left behind to replenish the population.
60
Why do we rely on a range of plant and animal species for?
1. food
2. medicines
3. raw materials
4. useful genes to make GM crops
61
What is the Simpson's Biodiversity Index?
Used to describe the biodiversity of organisms such as invertebrates in a stream.
The value will be between 0 and 1.
The higher the value, the greater the biodiversity.
62
How do you assess biodiversity at the genetic level?
Assessing biodiversity at the genetic level involves looking at alleles in the gene pool, both:
1. The number of different alleles
A gene's position on a chromosome is its locus. A locus showing polymorphism leads to several different forms or types of individuals in a population.
If a gene has more alleles, its locus is more polymorphic than if there were fewer, so greater diversity is seen.
2. The proportion of alleles in the gene pool
If 99% of the alleles in a gene pool are the same recessive allele, then there is low biodiversity for that gene.
If 50% of the alleles are this recessive allele, 50% would be other alleles and so the biodiversity would be higher.
63
Define polymorphism.
Two or more alleles for the same locus, at frequencies greater than would occur by mutation alone.
64
Give an example of polymorphism.
Banded land snails.
65
How do you assess biodiversity at the molecular level?
By examining DNA.
The more closely related organisms are, the more similar the base sequences of their DNA.
The technique of genetic profiling produces a unique pattern of bands for an individual. Comparing the number and the position of these bands indicates how similar or how different the DNA of individuals are.
66
What are SNPs (single nucleotide polymorphisms)?
When only a single base differs
67
What are HVRs (hypervariable regions) or STRs (short tandem repeats)?
Region of DNA 20-40 base sequences long that become repeated many times.
68
Define evolution.
The process by which new species are formed from pre-existing ones over geological time.
69
What is the mechanism of evolution?
Natural selection.
70
Describe the process of natural selection.
1. Populations show genetic variation due to sexual reproduction and mutation.
2. Organisms reproduce in very large numbers, far more than can survive.
3. So, there is competition for survival. The best adapted individuals to the environment out compete the others, gain resources and survive. The less well-adapted die.
4. The survivors reproduce and pass on their favourable alleles to the next generation. In time, a group of individuals may change to the extend that they become a separate species.
71
Define natural selection.
The gradual process in which inherited characteristics become more or less common in a population, in response to the environment determining the breeding success of individuals possessing those characteristics.
72
What is selective pressure?
An environmental pressure that affects an individual's reproductive success.
73
Why does natural selection generate biodiversity?
As a habitat undergoes change, over many generation, individuals with suitable adaptations will flourish.
If the environment then changes, different adaptations may be advantageous. Over many generations the make up of the population changes and biodiversity is generated
74
What follows after mass extinctions?
radiations of new species.
75
What is adaptive radiation?
Formation of new species form a single common ancestor by natural selection.
75
Define adaptation.
the change in a species as a useful characteristic becomes more common.
75
How are nectar guides adaptive traits?
draws insects to feed on nectar, pollination occurs.
75
What is the useful characteristic referred to as?
An adaptive trait.
76
What are the different types of adaptive traits?
anatomical
physiological
behavioural
76
How is the aye-aye's tapping finger an adaptive trait?
long, thin digit for tapping bark, finding hollows and retrieving larvae.
77
How are the kangaroo rat's kidneys an adaptive trait?
They have a very long loop of Henle, relative to their size, allowing them to conserve water in a desert environment by producing very concentrated urine.
78
How is the autumn leaf fall in deciduous trees an adaptive trait?
Los of leaves, reduces transpiration as the replacement water in the soil may be frozen.
79
How is the Great Crested Grebe's complex mating dance an adaptive trait?
Complex behaviours in courtship ensure that the female selects a male of the same species who is healthy and strong, who will be a good provider as a parent.
