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AS Biology > Chapter 10 Classification and Evolution > Flashcards

Chapter 10 Classification and Evolution Flashcards

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1
Q

Define ‘classification’.

A

The process by which living organisms are sorted into groups.

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2
Q

What are the 7 taxonomic groups?

A

(Domain)
Kingdom (biggest and broadest)
Phylum
Class
Order
Family
Genus
Species (smallest and most specific)

  • the organisms within each group share similar features.
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3
Q

Why do scientists classify organisms? (3)

A

(1) to IDENTIFY species
(2) to PREDICT characteristics
(3) to find EVOLUTIONARY LINKS

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4
Q

What are the 3 domains?

A

Archaea
Bacteria
Eukarya

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5
Q

What happens as you move down the hierarchy?

A

There are more groups at each level, with fewer organisms in each.

The organisms in each group become more similar and share more of the same characteristics.

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6
Q

What does the classification system end with?

A

Organisms being classified as individual species.
- (smallest units of classification)
- each group contains 1 type of organism

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7
Q

Define ‘species’?

(e.g.)??

A

A group of organisms that are able to reproduce to produce fertile offspring.

  • (e.g. horses and donkeys breed to produce mules/ hinnies - infertile)
  • (donkey’s) cells contain an odd number of chromosomes.
  • meiosis and gamete production cannot take place correctly all chromosomes must pair up.
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8
Q

How were organisms named before classification systems?
What were the problems associated with this? (2)

A

Many organisms were given names according to certain physical characteristics, behaviour, or habitat.
- ‘common names’

(1) not a useful system for scientist working internationally - organisms may have more than 1 common name

(2) doesn’t provide information regarding relationships between organisms

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9
Q

What system do scientists use now (naming)?

A

Binomial nomenclature.
- all species are given a scientific name (2 parts)

  • 1st part indicates the organisms GENUS (generic name)
  • 2nd part indicates the organism’s SPECIES (specific name)
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10
Q

What are the 5 kingdoms?

A

Prokaryotae (bacteria)

Protoctista (unicellular eukaryotes)
Fungi
Plantae
Animalia

  • organisms were originally classified into these kingdoms based on similarities in observable features
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11
Q

Prokaryotae??

A
  • unicellular
  • NO nucleus/ membrane-bound organelles
  • no visible feeding mechanism
    (nutrients absorbed through cell wall/ produced internally)
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12
Q

Protoctista??

A
  • (mainly) unicellular
  • contains nucleus + membrane-bound organelles
  • (some) contain chloroplasts
  • (some) are sessile
    (others move by cilia, flagella, amoeboid mechanisms)

nutrients are acquired by…
- photosynthesis (autotrophic feeders)
- ingestion of other organisms (heterotrophic feeders)
- OR both
- parasitic

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13
Q

Fungi??

A
  • unicellular OR multicellular
  • contains nucleus + membrane-bound organelles
  • (mainly) composed of chitin
  • NO chloroplasts (chlorophyll)
  • NO mechanism for locomotion
  • (most) have a body OR mycelium made up of threads/ hyphae
  • nutrients acquired through absorption (decaying material)
  • saprophytic feeders
  • (some) are parasitic
  • (most) store food as glycogen
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14
Q

Plantae??

A

(2nd largest after Animalia)

  • multicellular
  • nucleus + membrane bound organelles
    (chloroplasts + cell wall - cellulose)
    (chlorophyll)
  • (most) do NOT move
    (gametes of some plants have cilia/ flagella)
  • nutrients are acquired by photosynthesis (autotrophic feeders)
  • store food as starch
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15
Q

Animalia??

A
  • multicellular
  • nucleus + membrane bound organelles (no cell walls)
  • MOVE (with the aid of cilia/ flagella/ contractile proteins/ muscular organs)
  • nutrients acquired through ingestion (heterotrophic feeders)
  • food stored as glycogen
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16
Q

Explain the changes to classification systems?

A

Originally based on observable features.

Through the study of genetics and other biological molecules, scientists are able to study evolutionary links between organisms.
- links used for classification

As organisms evolve, internal and external features change.
DNA determines what proteins are formed, which in turn determines characteristics.

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17
Q

How does the 3 domain system group organisms?

A

Uses differences in the…
(1) sequence of nucleotides in the cells’ rRNA.
(2) membrane lipid structure
(3) antibiotic sensitivity

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18
Q

3 domain system??

A

3 domains - Archaea, Bacteria, and Eukarya
6 kingdoms

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19
Q

Eukarya??

A
  • have 80s ribosomes
  • RNA polymerase (responsible for most mRNA transcription)
  • contains 12 proteins
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20
Q

Archaea??

A
  • have 70s ribosomes
  • RNA polymerase of different organisms contains between 8-10 proteins

(very similar to eukaryotic ribosomes)

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21
Q

Bacteria??

A
  • have 70s ribosomes
  • RNA polymerase contains 5 proteins
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22
Q

3 domain system - prokaryotae kingdom??

A

Divided into 2 kingdoms…
(1) Archaebacteria
(2) Eubacteria

  • both are single celled prokaryotes
  • different chemical makeups
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23
Q

Archaebacteria??

A

Can live in extreme environments.
- hot thermal vents
- highly acidic environments
- anaerobic conditions

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24
Q

Eubacteria??

A

Are found in all environment.

(most bacteria)

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25
Q

Main (3) classification systems??

A

3 domain system
- bacteria - archae - eukarya

6 kingdom system
- eubacteria - archaebacteria - protoctista - fungi
- plantae - animalia

(traditional) 5 kingdom system
- prokaryotae - protoctists - fungi - plantae - animalia

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26
Q

Define ‘phylogeny’.

A

The name given to the evolutionary relationships between organisms.

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27
Q

Define ‘phylogenetics’.

A

The study of the evolutionary history of groups of organisms.

++ reveals which group a particular organism is related to, and how closely related these organisms are.

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28
Q

How are phylogenetic trees produced?

A

Looking at the similarities and differences in species’ physical characteristics and genetic makeup.

  • much evidence has been gained from fossils
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29
Q

What are the ADVantages of phylogenetic classification?

A

(1) Phylogeny produces a continuous tree, whereas classification requires discrete taxonomical groups.

(2) The hierarchal nature of the 5 kingdom system can be misleading.
(It implies that different groups within the same rank are equivalent and therefore comparable - not the case).

(3) Phylogenetic classification can be done w/o reference to the 5 kingdom system.

30
Q

What is (the theory of) evolution?

++ natural selection??

A

The theory that describes the way in which organisms evolve over many years, as a result of natural selection.

  • Darwin realised that organisms best suited to their environment are more likely to survive and reproduce, passing on their characteristics.
  • A species over time changes to have a more advantageous phenotype for the environment in which it lives.
31
Q

What evidence is there for ‘evolution’? (3)

A

(1) Palaeontology
- the study of fossils and the fossil record

(2) Comparative anatomy
- the study of the similarities and differences between organisms anatomy

(3) Comparative biochemistry
- the study of the similarities and differences between the chemical makeup of organisms

32
Q

How are fossils formed?

A

Fossils are formed when animal and plant remains are preserved in rocks.

Over time, SEDIMENT is deposited on the Earth to form layers (STRATA) of rock.

Different layers correspond to different geological eras.

33
Q

What is the fossil record?

A

Within the different rock strata (layers), the fossils found vary.

They form a sequence from oldest to youngest, which shows how organisms have gradually changed over time.

This is known as the fossil record.

34
Q

Evidence provided by the fossil record?? (4)

A

(1) Fossils of the simplest organisms are found in the oldest rocks, whilst fossils of more complex organisms are found in more recent rocks.
- supports the evolutionary theory that simple life forms gradually evolved into more complex life forms.

(2) The sequence in which the organisms are found matches their ecological links to each other.
- plant fossils appear before animal fossils
- consistent w/ how animals require plants for survival

(3) Similarities in the anatomy of fossil organisms - show how closely related organisms have evolved from a common ancestor.

(4) Fossils allow relationships between extinct and living (extant) organisms to be examined.

35
Q

Why isn’t the fossil record complete?

A

Many organisms are soft-bodied and decompose quickly - before they can fossilise.

The conditions needed for fossils to form are not often present.

36
Q

What is comparative anatomy and why is it relevant?

A

Scientists look for other sources of evidence to determine evolutionary links - as the fossil record is incomplete.

(++ comparative anatomy is the study of similarities and differences in the anatomy of different living species).

37
Q

What is a homologous structure?

A

A structure that appears superficially different (and may perform different functions) in different organisms, BUT has the same underlying structure.

38
Q

How do homologous structures provide evidence for evolutionary links?

A

The presence of homologous structures provides evidence for DIVERGENT evolution.

39
Q

What is ‘divergent’ evolution?

A

Describes how, from a common ancestor, different species have evolved.
(each with a different set of adaptive features).

40
Q

When does divergent evolution occur?

A

Occurs when closely related species diversify in order to…
- adapt to new habitats (due to migration)
- adapt to loss of habitat

41
Q

What is comparative biochemistry?

A

The study of the similarities and differences in the proteins and other molecules which control life processes.

Slight changes which occur in these (conserved) molecules can help identify evolutionary links.

42
Q

What are the 2 most common molecules studied in comparative biochemistry?

A

(1) cytochrome c (protein involved in respiration)

(2) ribosomal RNA (rRNA)

43
Q

What is the hypothesis of ‘neutral’ evolution?

A

States that most of the variability in the structure of a molecule does not affect its function.

Most of the variability occurs outside of the molecule’s functional regions.

Changes which do not affect a molecule’s function = NEUTRAL.
- their accumulation isn’t affected by natural selection

44
Q

How do scientists discover how closely 2 species are related?

A

(1) The molecular sequence of a particular molecule is compared.

  • this is done by looking at the order of DNA bases, amino acids.

(2) No. of differences PLOTTED against rate at which the molecule undergoes NEUTRAL BASE PAIR SUBSTITUTIONS.

  • can estimate the point at which the two species shared common ancestor.
45
Q

Why is rRNA commonly used to determine evolutionary relationships?

A

Ribosomal RNA has a very slow rate of neutral base pair substitution.

  • commonly used together w/ ++ fossil info
46
Q

Define ‘variations’.

A

The differences in characteristics between organisms.

47
Q

INTERspecific variation??

A

The WIDEST type of variation, between members of DIFF species.

48
Q

INTRAspecific variation??

A

Differences between organisms WITHIN the SAME species.

49
Q

What factors cause variation? (2)

A

Caused by a combination of both environmental and genetic variation.

(1) Genetic variation
- based on an organism’s genetic material

(2) Environmental variation
- based on the environment in which the organism lives

50
Q

What are the genetic causes of variation?? (5)

A

(1) Alleles (variants)
- genes have diff alleles (alternative forms)
- diff alleles produce diff effects
- individuals in a species population may inherit diff alleles (of a gene)

(2) Mutations
- changes to the DNA sequence… to genes
- … changes in the proteins that are coded for
- affects physical and metabolic characteristics

  • if mutation occurs in somatic (body) cells - individual is affected
  • if mutation occurs in gametes - may be passed on

(3) Meiosis
- gametes (sex cells - ovum/ sperm) are produced by meiosis
- INDEPENDENT ASSORTMENT
- CROSSING OVER

(4) Sexual reproduction
- offspring produced from 2 individuals
- inherits genes (alleles from each of the parents)
- offspring vary from parents

(5) Chance
- many diff gametes are produced from the parental genome
- combination of gametes is a result of chance
- random fertilisation

51
Q

Sexual vs. Asexual reproduction??
(in terms of genetic variation)

A

Much greater genetic variation in organisms which reproduce sexually, than asexually.

Asexual reproduction results in the production of clones (genetically identical to parents).
…
Genetic variation can only be increased as a result of mutation.

52
Q

What are the environmental causes of variation?

A

All organisms are affected by their environment.

  • plants affected to a greater degree, due to their lack of mobility.

(e.g. - scars)

53
Q

What is DIScontinuous variation?

(e.g.)??

A

(discrete variation)

  • A characteristic that can only result in certain values.
  • Controlled by a single gene.

(e.g.)
- sex
- shape of bacteria
- blood groups

54
Q

What is continuous variation?

(e.g.)??

A
  • A characteristic that can take any value within a range.
  • Controlled by a number of genes - polygenes.
  • Influenced by environmental factors.

(e.g.)
- height
- mass

55
Q

What is a normal distribution curve?

A

When continuous variation data is plotted onto a graph.
- produces a bell curve

  • data is normally distributed
  • mean, mode, median is the same
  • symmetrical about the mean
  • 50% values above and below the mean
  • most values lie close to the mean value
56
Q

What is standard deviation?

A

The standard deviation is a measure of how spread out the data is.

  • the greater the standard deviation, the greater the spread of the data
57
Q

When would you use a students’ T TEST?

A

When comparing the means of data values of 2 populations.

58
Q

When would you use the CORRELATION COEFFICIENT?

A

When considering the relationship between 2 sets of data.

59
Q

Types of correlation? (3)

A

NO correlation
- no relationship between the data

+ correlation

  • correlation
60
Q

What are adaptations?

A

Adaptations are characteristics which increase an organism’s chance of survival and reproduction in its environment.

61
Q

What are the types of adaptations? (3)

A

(1) Anatomical adaptations
- physical features
(internal and external)

(2) Behavioural adaptations
- the way an organism acts
- inherited OR learnt from parents

(3) Physiological adaptations
- processes which take place within the organism

62
Q

Examples of ANATOMICAL adaptations? (4)

A

(1) Body covering
- hair, scales, spines, feathers, and shells
- thick, waxy layers on plants
- spikes on plants

(2) Camouflage
- outer colour of an animal allows it to blend into its environment

(3) Teeth
- shape and type of teeth present in an animals jaw

(4) Mimicry
- copying another animals appearance

63
Q

What are adaptations of ‘marram grass’? (4)

A

XEROPHYTE
- plant adapted to an environment w/ little water
- adaptations reduce the rate of transpiration

(1) curled/ rolled leaves - minimises SA of moist tissue
- exposed to air
- protects leaves from wind

(2) hairs on the inside surface of the leaves trapping moist air
- reduces diffusion gradient

(3) stomata sunk into pits
- less likely to open

(4) thick waxy cuticle on leaves and stems
- reduces water loss

64
Q

Examples of BEHAVIOURAL adaptations? (3)

A

(1) Survival behaviours

(2) Courtship
- attracting a mate
- increases organism’s chance of reproducing

(3) Seasonal behaviours
- enable organisms to cope w/ changes in their environment

  • migration
  • hibernation
65
Q

What are the 2 main categories of behavioural adaptations?

A

Many behavioural adaptations are a combination of both innate and learned behaviours.

(1) INNATE (instinctive behaviour)
- ability to do so is inherited through genes

(2) LEARNED behaviour
- ability learnt from observation OR experience

66
Q

Examples of PHYSIOLOGICAL adaptations? (3)

A

(1) Poison production

(2) Antibiotic production
- some bacteria produce antibiotics killing other species of bacteria

(3) Water holding
- storing water

also includes: reflexes, blinking, and temperature regulation

67
Q

What is ‘convergent’ evolution?

A

Convergent evolution takes place when unrelated species begin to share similar traits.

These similarities evolve as the organisms adapt to similar environments OR selection pressures.

  • organisms live in a similar way to one another
68
Q

What is an ‘analogous’ structure?

A

Structures which have adapted to perform the same function BUT have diff genetic origin.

69
Q

What are selection pressures?

A

Factors which affects the organism’s chances of survival/ reproductive success.

70
Q

Outline the steps of natural selection?

A

(1) organisms within species show variation caused by differences in genes - INTRAspecific.
- may have diff alleles for a gene
- new alleles arise by mutation

(2) organism’s with certain characteristics are best adapted to a selection pressure.
- have increased chance of survival and reproductive success

  • less well-adapted organisms die or fail to reproduce

(3) successful organisms pass the allele encoding the advantageous characteristic onto their offspring

(4) process repeated for every generation
- proportion of individuals with advantageous adaptations increases
- frequency of the allele which codes for this characteristic increases in the gene pool

(5) process can lead to evolution of new species

71
Q

What are a modern examples of evolution? (4)

A

(1) Antibiotic resistant bacteria.
(MRSA) - methicillin resistant

(2) Peppered moths

(3) Sheep blowflies
- demonstrates pre-adaption

(4) Flavobacterium
- evolved due to opportunities which have arisen

72
Q

What is pre-adaptation?

A

Pre-adaptation is when an organism’s existing trait is advantageous for a new situation.

AS Biology (9 decks)

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