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A- Level Biology > C10- Classification and Evolution > Flashcards

C10- Classification and Evolution Flashcards

1
Q

Species definition

A

A group of organisms that are capable of interbreeding and producing fertile offspring.

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2
Q

Why classify organisms

A

To establish evolutionary links

Identify (new) species

Sharing research across the world (using the same ‘language’)

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3
Q

Linnaen system- descirbe

A

Carl Linnaeus grouped organisms together, based on their observable structure and characteristics.

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4
Q

Linnean system- names of categories

7

A

Kingdom
Phylum
Class
Order
Family
Genus
Species

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5
Q

What happens as you descend the levels of classification

A

The organisms at that level have more in common so the groups get smaller.

They are more closely related.

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6
Q

Binomial nomenclature

(Binomial naming)

A

Genus species

By convention the Genus (first part of the name) has a capital letter.

The name is written either in italics or underlined.

e.g. Homo sapien

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7
Q

Autotrophic

define

A

organisms get their nutrition from photosynthesis

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8
Q

Heterotrophic

define

A

Organisms get their nutrition from ingesting other organisms

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9
Q

Saprotrophic / saprophytic

define

A

Organisms that get their nutrition by extracellular digestion and absorption of soluble molecules (usually from decaying organic matter)

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10
Q

5 kingdoms

name

A

Prokaryotae (bacteria)
Protoctista (unicellular eukaryotes)
Fungi (yeasts, moulds, mushrooms)
Plantae (plants)
Animalia (animals)

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11
Q

Who proposed the 5 kingdom system

A

Proposed by Robert Whittaker in 1969

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12
Q

How to classify organisms into the 5 kingdom system

A

observable characteristics

Unicellular or multicellular (or both?)
The nature of their genetic material
Ability to move
How they obtain nutrients

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13
Q

Motility

Define

A

the ability to contract muscles to enable movement

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14
Q

Prokaryotes

Characteristics

A

unicellular

no membrane-bound nucleus
–>loop of naked circular DNA (no histones)

no chromosomes

no membrane bound organelles

the cell wall of bacteria contains peptidoglycan, composed of sugars and amino acids. Archaea cell walls do not contain this.

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15
Q

3 most common shapes of prokaryotes

A

Helix

Sphere

Rod

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16
Q

Protoctista

7

kingdom

A

eukaryotic and unicellular

organisms show characteristics of both plants and animals.

Include the algae, seaweeds, amoeba, plasmodium (malaria parasite).

Some are autotrophic and some have heterotrophic nutrition.

They are mobile due to either flagella, cilia, or pseudopods (“false feet”).

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17
Q

Plantae

7

kingdom

A

Eukaryotic

Multicellular

Cells surrounded by a cellulose cell wall.

Store energy as starch

Have chlorophyll and chloroplasts.

Mostly autotrophic by photosynthesis.

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18
Q

Fungi

12

kingdom

A

Eukaryotic (nucleus and membrane-bound organelles)

No chlorophyll – do not photosynthesise

Single celled (yeasts) and multicellular (filamentous - macroscopic)

Body is a mycelium that consists of hyphae.

Cell walls made of chitin

Extra-cellular digestion - secreting enzymes onto organic matter and absorbing soluble products.

Reproduce asexually by release of spores- can reproduce sexually

Store glycogen as an energy source

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19
Q

Animalia

6

kingdom

A

Eukaryotic

Multicellular

Heterotrophic nutrition

Have muscles and nervous systems – in order to search for, locate and digest food.

Glycogen is stored energy source

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20
Q

Evidence for evolution

A

Palaeontology- study of the fossil record

Comparative anatomy- the study of similarities and differences between organisms anatomy

Comparative biochemistry- similarities and differences between the chemical makeup of organisms

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21
Q

Who developed the theory of evolution

A

Charles Darwin and Robert Whittaker

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22
Q

Theory of evolution

A

The way in which organisms evolve over many years a sa result of natural selection

23
Q

Darwin’s conclusions on evolution

Survival of the fittest

A

Organisms best suited to their environment are more likely to survive and reproduce, passing on their characteristics to their offspring

Gradually a species changes over time to have the advantageous phenotype for the environment in which it lives

24
Q

Evidence for evolution

Paleontology and what it tells us

A

Fossil analysis

Layers of rock separate geological eras

Fossils of simplest organisms are found furthest back, supporting the theory life gradually evolved towards complexity

Sequencing organisms: plant fossils appear before animal fossils
therefore animals most likely eat plants

25
Problems with using the fossil record as evidence for evolution
Incomplete Soft bodied organisms decay quickly The conditions needed to form fossils are not always present Fossils have been destroyed by earths movements and volcanos
26
Evidence for evolution Comparative anatomy
Study of similarities and differences between the anatomy of different living species
27
What are homologous structures
A structure that appears superficially different (and may perform different functions), but have the same underlying structure
28
What does the presence of homologous structures give evidence for
Divergent evolution
29
What is divergent evolution
All species have evolved form a common ancestor From this different species have evolved with a different set of adaptive features Occurs when closely related species diversify and adapt to new habitats
30
The hypothesis of neutral evolution
Most of the variability in the structure of a molecule does not affect its function Due to most of the variability occurring outside of the molecule's functional regions Since they have no function their accumulation is not a result of natural selection As a result natural substitutions happen at a fairly high rate
31
How to biochemically discover how closely related two organisms are
Compare the molecular sequence of a particular molecule Such as DNA or the order of amino acids in proteins plot a graph of the n of differences against rate of substitutions Estimate point of last common ancestor
32
Convergent evolution
Previously unrelated species become more and more similar over time because they live in similar environments e.g. birds, bats and insects have all evolved the ability to fly. Organisms evolve similarities as they adapt to similar environments or similar selection pressures. Could be because similar phenotypes are produced by different genes or different changes (mutations) in the same gene.
33
Interspecific vs intraspecific variation
Interspecific variation: the differences in characteristics between organisms of different species e.g. cats and dogs Intraspecific variation: The differences between organisms of the same species e.g. between dogs
34
Two causes of variation
Genetic variation: due to difference in the genes you inherit from your parents. Environmental variation due to the environment in which an organism lives.
35
3 genetic causes of variation
Mutations Meiosis: Crossing over and independent assortment Random fertilisation of gametes
36
Germ cells
Diploid cells in reproductive organs that divide by meiosis to form gametes
37
What is an allele
Different version of a gene
38
What is a homologous pair of chromosomes
Pair of chromosomes with the same genes and at the same locus but different alleles
39
What is a mutation Potential effects
change in the DNA base sequence (which causes a change in the gene) – this may produce a new allele. this MAY change the sequence of amino acids which MAY alter the structure of the protein produced which MAY result in a new phenotype
40
Nature of mutations
Mutations occur randomly and frequently They can be sudden and spontaneous
41
Somatic vs germ cell mutations
Somatic cell mutations: a mutation in a somatic (body) cell Only the individual is affected Mutation not passed onto offspring Germ cell mutation: mutation in the DNA in a gamete Mutation will be passed onto the offspring
42
Somatic cells
any cell of a living organism other than the reproductive cells. a body cell
43
What is a silent mutation
There is no change in the phenotype of the gene a neutral mutation
44
Where does genetic variation come from during meiosis
Crossing over (during prophase I) Independent assortment (in metaphase I and metaphase II)
45
Crossing over process
Non-sister chromatids break and re-join at points called chiasmata DNA / blocks of genes is/are exchanged between chromatid This creates chromatids with new combinations of alleles (called recombinants)
46
Independent assortment process
During metaphase 1 homologous pairs of chromosomes assemble along the metaphase plate. The orientation of each pair is random and independent of the other homologous pairs. Independent assortment occurs again during metaphase II
47
Random fertilisation how does it cause genetic variation
Sexual reproduction involves fusion of two gametes, one from male parent and one from female parent. Offspring inherit a mix of genes from both parents. Fertilisation is a random process.
48
Examples of environmental factors that cause gene variation in humans and plants
Humans: diet, exercise, alcohol, smoking, mutagens (see next slide) Plants: Light intensity Availability of minerals ions Soil pH competition
49
What is a mutagen
an agent that causes a mutation in DNA (genetic mutations) Mutagens are agents that can disrupt the cell cycle and lead to tumour formation.
50
Examples of mutagens
Chemicals e.g in cigarette smoke Radiation e.g. ionising radiation (nuclear), UV, X-rays Viruses e.g. HPV Nitrites in processed meats
51
Advantages of having a genetically varied population
Some organisms will have the combination of alleles needed to survive if conditions change adversely (there is a new selection pressure) These organisms will be more likely to survive and breed and pass on their favourable alleles to their offspring. Variation provides the potential for a population to evolve and adapt if conditions change
52
Continuous variation
A range of values wit no distinct categories Can be measured- quantitative- e.g. height Influenced by environment Usually polygenic Plotted on a histogram
53
Define polygenic
Controlled by more than one gene
54
Discontinuous variation
Data grouped into categories with no intermediate values e.g. blood group data is qualitative Not affected by environment Controlled by a limited number of genes

A- Level Biology (11 decks)

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