2.1 - Classification and biodiversity

Question 1

What is phylogenetic classification?

Answer 1

Evolutionary relatedness. Grouping organisms reflecting an organisms evolutionary history

Organisms in same group have a more recent common ancestor. If they’re closely related they may show physical similarities.

Question 2

What is a phylogenetic tree?

Answer 2

Branch points represent common ancestors of the organisms in the branches above. Living organisms are shown at the tips of the branches . Ancestral species (now extinct) would be shown in the trunk. The length of the branches indicate the time between branch points

Question 3

What is hierarchy?

Answer 3

A system of ranking in which small groups are components of bigger groups

Question 4

What is taxa? Why is it discrete?

Answer 4

Levels of classification. Large taxa (e.g. Domain, kingdom) contain smaller taxonomic groups (species) . Organisms become more closely related as you move down the taxonomic groups. Taxa is discrete because an organisms cannot belong to more than one taxon at each level (e.g. can’t be 2 different phylum’s)

Question 5

What is the hierarchy of biological classification?

Answer 5

Domain> Kingdom> Phylum> Class> Order> Family> Genus> Species

Domains contain Kingdoms. Kingdoms contain phyla. Phyla contain classes…

See NC 2

Question 6

Why do we need a phylogenetic classification system?

New animal…
Health of ecosystem…
Communicating
Evolutionary relationships…

Answer 6

Allows us to infer evolutionary relationships, 2 organisms in same taxon, we infer they’re closely related.
If a new animal is discovered with a beak and feathers, we predict some of its other characteristic, based on our general understanding of birds
When communicating its easier to say bird than ‘vertebrate, egg laying biped with beak and feathers)
When describing the health of an ecosystem/ rate of extinction, conservationists find it easier to count families than species

Question 7

Why is the nature of the classification system tentative?

Answer 7

Because it depends on our current knowledge, It may be altered as our knowledge advances.

Question 8

A Domain is the largest taxon and all living things belong in 1 of the 3 domains. A Domain is defined on the basis of rRNA base sequences and DNA base sequences.

Give the 3 domains and examples of kingdoms and phylum that are in them.

Answer 8

Eubacteria - Familiar bacteria such as E. coli and Salmonella. (Prokaryotes)
Archaea - Bacteria often with unusual metabolism. (Prokaryotes)
Eukaryota - includes Plantae, Fungi, Animalia and Protoctista (Eukaryotic)

Question 9

What are the 5 kingdoms and what are they based off?

Answer 9

Animalia, Plantae, Protoctista, Prokaryote, Fungi

Based off morphological similarities / physical appearance

See NC 3

Question 10

What is a phylum based on?

Answer 10

Subdivision of a kingdom, based on general body plan

See NC 3

Question 11

What is a species?

Answer 11

A group of organisms sharing a large number of physical features and able to interbreed to make fertile offspring

Question 12

What is the characteristic _____ of the 5 kingdoms?

Organisation? (prokaryote/ eukaryote) (single, multi cells)
Nucleus?
Mitochondria?
Chloroplast?
Size of ribosomes in cytoplasm?
ER?
Vacuole size and permeance?
Cell wall material?
Nutrition?
Nervous coordination?

Answer 12

See NC 4

Question 13

The theory of evolution suggests that widely separated groups of organisms share a _______ ancestor. Therefore it would be expected that they share basic ______, so their _______ should indicate how closely related they’re. The more similar 2 organisms are, the more recent they are assumed to have _______. Groups with little in common presumable diverged from a common ancestor much _____ in time.

Answer 13

common
features
similarities
diverged
earlier

Question 14

What does a biologist look for when deciding how closely related 2 organisms are? What does it mean?

Answer 14

Homologous structures - structures in different species with a similar anatomical position and development origin, derived from a common ancestor. But different functions.

See NC 5

Question 15

What does divergent evolution mean?

Answer 15

The development of different structures over long periods of time, from the equivalent structures in related organisms

Question 16

What does convergent evolution mean?

Answer 16

The development of similar features in unrelated organisms over long periods of time, related to natural selection of similar features in a common environment.

Example: butterfly and bat, both have wings but one is an insect and the other a mammal. They don’t have a common ancestor with wings, but because there ancestors adapted to a similar environment they all evolved wings, which preform the same function. Such structures are analogous.

Question 17

What is an analogous structure?

Answer 17

Have a corresponding function and similar shape, but have a different developmental origin

Question 18

Explain how DNA base sequences can be used to assess relatedness in organisms?

Answer 18

Over time species undergo changes in their DNA base sequences, which accumulates until organisms are so different they are considered to be different species. More closely related species show more similarity in DNA base sequence than those more distantly related. DNA analysis has confirmed evolutionary relationships, and corrected mistakes in classification based on physical characteristics.

Question 19

Explain how DNA hybridisation can be used to assess relatedness in organisms?

Answer 19

This involves comparing the DNA base sequence of 2 species. To work out how closely related they are DNA is extracted from e.g. human and a chimpanzee and then it’s separated and cut into fragments and then mixed together. Where they have complimentary base sequences they hybridise together. This shows that chimps and humans have at least 95% of their DNA in common

Question 20

Explain how Amino acid sequences
can be used to assess relatedness in organisms?

Answer 20

The sequence of amino acids in protein is determined by the DNA base sequence. The degree of similarity on the amino acid sequence of the same protein in 2 different species will reflect how closely related they are.

Question 21

Explain how Immunology
can be used to assess relatedness in organisms?

Answer 21

The proteins of different species can be compared using immunological techniques. If you mix the antigens of one species 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.

Question 22

There are 2 definitions of species, what are they and explain them?

Answer 22

Morphological definition - if 2 organisms look very similar they are likely to be in the same species, (sexual dysmorphism must be taken into account)

Reproductive definition - 2 organism are the same species if they can interbreed to produce fertile offspring

Question 23

What is taxonomy?

Answer 23

The identification and naming of organisms

Question 24

Many living organisms have common names that differ from country to country, this can cause confusion. Binomial system was introduced. What are the advantages of the Binomial system?

Answer 24

Based on Latin (international language)
Unambiguous naming (accepted and understood worldwide)
Implies that 2 species sharing part of there name are closely related e.g. Panthera leo and Panthera tigris

Question 25

How do you use the binomial system?

Answer 25

1. Each organism has 2 names genus and species
2. Genus comes 1st (capital letter)
3. Species comes 2nd (lowercase letter)
4. First time used in full (Panthera tigris), 2nd time used abbreviate (P. tigris)
5. Both names used are printed in italics or underlined when hand written

Question 26

What does the term biodiversity mean?

Answer 26

The number of species (species richness) and the number of organisms within each species (species evenness) in a specified region

Question 27

The number of species and the number of organisms depend, in part, on the environment. Why in places like tropical rainforests and coral reefs is there high biodiversity?

Answer 27

Because there are equatorial regions and so more energy is flowing through it producing more species and individuals.

More plants grow at high light intensity, so a bright environment can support more herbivores and therefore more carnivores than a dull one.

Question 28

What 3 process’ have effected biodiversity? How?

Answer 28

Succession
Natural selection
Human influence

Question 29

What is succession and how has it effected biodiversity?

Answer 29

Over time a community of organisms changes its habitat, making it more suitable for other species. The change in the composition of a community over time is called succession. It increases animal biodiversity, but ultimately decreases plant biodiversity

Question 30

Give examples of ways that plants and animals help support human civilisation

Answer 30

Source of food, e.g. wheat and rice (staple foods)
Medical drugs e.g. aspirin, antibiotics
Essential raw materials such as cotton, rubber and wood

Question 31

What is the formula for calculating the Simpsons diversity index, D? The higher the value of D…

Answer 31

D = 1 - Σn(n-1) / N(N-1)

N = total number of organisms
n = total number of organisms of each species

the higher the biodiversity

Question 32

What is polymorphism?

Answer 32

The occurrence of more than 1 phenotype in a population

Question 33

Gene T controls height. There’re 2 differnt alleles
Gene S controls whether or not pollen grains can germinate on the stigma of a flower of the same species. In one species of poppy, gene S has 31 different alleles

Which gene has more biodiversity

Answer 33

Gene S as more phenotypes are possible

Question 33

Gene T controls height. There’re 2 different alleles
Gene S controls whether or not pollen grains can germinate on the stigma of a flower of the same species. In one species of poppy, gene S has 31 different alleles

Which gene has more biodiversity?

Answer 33

Gene S as more phenotypes are possible

Question 34

Organisms that are more closely related to each other have DNA base sequences that are more similar. The DNA of organisms does not all code for protein. Like all DNA, non-coding sequences undergo mutation so individuals acquire different base sequences

What are the 2 types of base sequence differences?

Answer 34

SNPs (single nucleotide polymorphism) - one base differs
HVR (hyper-variable regions)
STR (short tandem repeats)
- regions of DNA that vary, generally 20-40 base sequences long, often repeated many times.

Question 35

Differences in SNP’s or HVR’s can be seen in DNA profiles or fingerprints. The more SNP’s and HVR’s a population has, the more differences there are in its DNA profiles. More differences means a ______ biodiversity.

Answer 35

Greater

Question 36

What is natural selection?

Answer 36

This is the gradual process in which inherited characteristics become more or less common in a population, in response to a change in the environment and new selection pressures.

Question 37

What is adaptative radiation?

Answer 37

This is the formation of new species from a single common ancestor

Question 38

Describe and explain the 6 events in the process of natural selection.

Answer 38

Mutation - changes in DNA form a new gene
Variation - Different physical appearance or behaviour
Competitive advantage - some organisms are more suited to the environment than others and out-compete them for resources
Survival of the fittest - Those more suited to the environment are more likely to survive
Reproduction - Those more suited to the environment have more offspring
Pass advantageous alleles to offspring - Offspring inherit the advantageous alleles, so they are also more suited to the environment

Question 39

As habitats change e.g. increasing temp, over many generations individuals with ______ more suited to higher temp will be selected for. These individuals will ______ more successfully as they have an advantage and are better suited to the environment. Environment may change again and same process will occur.

Answer 39

alleles
reproduce

Question 40

The change in a species, as a useful characteristic becomes more common, is called ‘adaptation’. The useful characteristic is referred to as an ‘adaptative trait’.

Give an anatomical trait of dolphins and penguins.

Give a physiological trait of plants in winter.

Give a behavioural trait of peacock?

Answer 40

Streamlined bodies, without this they would be less efficient at catching food or esacping predators

Leaves fall off plants when temp and light intensity decreases , this way, they don’t loose water by transpiration and risk dehydration throughout the winter when the water may be frozen, and so they survive the cold weather

Peacocks tail is displayed to help increase the animal’s chance of reproducing.