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Biology A Level > Classification > Flashcards

Classification Flashcards

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1
Q

Animals

A
  • multicellular (cells 20-40μm)
  • no chloroplasts or cell wall
  • heterotrophic
  • store carbs as glycogen (broken down fast; high rate of metabolic reactions)
  • nervous co-ordination - able to move
  • e.g. mammals, insects
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2
Q

Plants

A
  • multicellular
  • contain chloroplasts and a cellulose cell wall
  • autotrophic
  • store carbs as starch or sucrose
  • e.g. cereals, legumes
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3
Q

Fungi

A
  • uni/multicellular
  • no chloroplasts, chiton cell wall
  • heterotrophic (saprotrophic)
  • store carbs as glycogen
  • mycelium made of thread-like hyphae contenting many nuclei
  • can be pathogenic
  • e.g. Mucor, yeast
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4
Q

Protoctista

A
  • unicellular
  • all have a cell membrane, cytoplasm and a nucleus
  • hetero/autotrophic
  • e.g. Plasmodium (malaria)
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5
Q

Bacteria

A
  • unicellular
  • murein cell wall, cell membrane and cytoplasm
  • no nucleus; circular chromosome of DNA and many plasmids
  • some have capsule or slime layer
  • some have flagella
  • most hetero, some autotrophic
  • much smaller
  • e.g. Lactobacillus, Pneumococcus
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6
Q

Murein

A

Polysaccharides and proteins

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7
Q

Plasmid

A

Circular loop of DNA

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8
Q

Viruses

A
  • genetic material surrounded by a protein coat
  • some have an envelope
  • parasitic
  • different types infect organisms across the kingdoms
  • wide variety of shapes and sizes
  • e.g. tobacco mosaic virus, influenza
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9
Q

Classification

A

The organisation of living organisms into groups

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10
Q

Artificial classification

A
  • groups organisms for convenience
  • based on observable characteristics
  • e.g. habitats, movement, colour, size
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11
Q

Natural classification

A
  • groups organisms according to their phylogeny

* based on information from molecular internal biology and external features

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12
Q

Phylogeny

A
  • φυλος γίγνομαι

* evolutionary relationships

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13
Q

Phylogenetic classification system

A
  • arrangés species into taxa based on evolutionary origins and relationships
  • arranged in taxa
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14
Q

Taxa

A
  • a series of groups arranged into a hierarchy
  • éach taxon contains diagnostic characteristics which indicate that they have common ancestry
  • there is no overlap between taxa
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15
Q

Taxonomy

A

The study of the classification of living things

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16
Q

The taxa hierarchy

A 
Domain 
Kingdom 
Phylum 
Class 
Order
Family 
Genus 
Species
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17
Q

Hierarchy

A

Each taxon is a subset of the one higher than itself; taxa become more exclusive as you go down, and there is no overlap

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18
Q

Domains

A
  • eukarya
  • archaea
  • bacteria
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19
Q

Kingdoms

A
  • animalia
  • plantae
  • fungi
  • protoctista
  • prokaryotae
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20
Q

Phylum

A
  • does the organism have a backbone?

* e.g. chordata

21
Q

Class

A 
• a group of organisms that all possess the same general traits 
• overall variation is still quite big 
• e.g. spiders (Arachnida) 
• e.g. fruit fly (insecta) 
-> different no of legs
22
Q

Genus

A

A group of similar species with a relatively recent common ancestor

23
Q

Species

A
  • organisms that can breed together to produce live, fertile offspring
  • when a species reproduces sexually, any of its genes can be combined with any other
  • all members of a species will show some variation (due to genetic and environmental factors), but are all essentially the same
24
Q

Phylogenetic group

A

A group of organisms with a common ancestor

25
Q

Phylogenetics is dependent on…

A

… the recent of common ancestors

Grouped by cladistics
Closer branches = more recent ÇA

26
Q

Clade

A

A group of organisms with a hypothetical ancestor that share a derived trait

27
Q

Derived trait

A

A new characteristic shared only by a group and its hypothetical common ancestor (evolved, causes genetic drift)

28
Q

Cladogram

A
  • an evolutionary tree that depicts hypothesised evolutionary relationships between organisms
  • constructed for competing hypotheses
  • depict parsimony
  • can show deevolution
  • can have outgroups
29
Q

Parsimony

A

the simplest possible hypothesis that can explain the observations

30
Q

Outgroup

A
  • does not have any of the observable traits
  • largest number of genetic differences
  • common ancestor is the most distant
31
Q

Binomial nomenclature

A
  • devised by Carl Linnaeus
  • ‘two names’: generic, specific
  • written: Generic specific
  • universal
  • based upon Latin and Ancient Greek
  • if the species name is unknown, written as sp.
32
Q

Morphology

A
  • previous classification technique
  • anatomy and bone structure
  • visual characteristics: size, height
  • massively flawed!
33
Q

Why is morphology flawed?

A
  • some visual characteristics are polygenic
  • some changes may be too discreet to notice
  • some changes may be environmental, not due to changes in alleles
  • there are also massive fluctuations in visual characteristics within a species
34
Q

Polygenic

A

Controlled by many genes

35
Q

Modern methods of classification

A

1) genetic comparisons
2) protein comparisons
3) immunological comparison
4) courtship behaviours

(Occasionally use biological molecules such as RNA polymerase)

36
Q

Genetic comparisons basics

A
  • can be done using DNA or mRNA (no introns)
  • DNA is extracted, base sequence read to determine similarity
  • less related species less similar- natural selection causes DNA base sequence to change (accumulation of mutations over time)
  • to be read, each nucleotide is tagged with a different fluorescent dye
  • only coding DNA is used in analysis, because introns vary massively within species’
37
Q

Fluorescent dyes used in genetic comparisons

A
  • A = green
  • T = red
  • C = blue
  • G = yellow
38
Q

Genetic comparisons in the lab

A

1) extract DNA from 2 species and remove introns
2) heat to break hydrogen bonds; separates strands
3) mix 2 species in 1 tube, keep 1 tube separate
4) cool
5) warm slowly
6) measure amount of single-stranded DNA every 2°C
7) determine temperature at which 50% of DNA has separated into single strands (T50H)
8) measures difference between 2 temperatures at T50H
9) 1°C difference = 1% difference in base sequence

39
Q

Why cool during genetic comparison in the lab

A
  • allows base pair formation between strands

* DNA with complementary sequences base pair; mismatched sequences do not

40
Q

DNA hybridisation

A
  • genome sequencing
  • v. Expensive
  • v. Slow
  • whole genome must be sequenced - only a few genes gives massively flawed evidence
41
Q

Protein comparisons

A
  • AA sequence; primary structure
  • usually uses cytochrome c/ Hb
  • species will likely have exactly the same amino acid sequence (could have 1 difference due to mutation of alleles)
  • not as accurate or reliable as DNA comparisons due to degenerate nature of DNA; multiple DNA triplets code for the same AA, so the difference in DNA sequence might not be reflected in the amino acid sequence
42
Q

Immunological comparisons - basics

A
  • antibodies

* often used because there are very few universal proteins, and protein sequences are different

43
Q

Immunological comparisons - theory

A
  • ‘agglutination’
  • bacteria and viruses (pathogens) have antigens, to which B cells have complementary antibodies
  • lymphocytes use antibodies to clump pathogens together, making cell invasion a lot harder
  • antibodies of one species will reine to specific antigens on proteins (e.g. albumin), in the blood serum of another
44
Q

Immunological comparisons in the lab

A
  • serum albumin from species A injected into species B
  • species B produces antibodies to all of the antigen sites on the albumin from species A
  • serum extracted from species B
  • serum B mixed with serum C from a third species
  • antibodies respond to their corresponding antigens on the albumin in serum C
  • a precipitate forms
  • precipitate formation increases with number of similar antigens, and therefore species relatedness
  • the more similar, the more anti-A antibodies will react
45
Q

Courting behaviour functions

A
  • essential; helps to achieve the maximum chance of survival
  • attract a mate
  • ensure a mage is of the right species and sex
  • ensures mate is capable of breeding
  • synchronises mating
  • heightens sexual responsiveness and suppresses other responses (e.g. flight and aggression) - allows close contact and copulation
  • brings a member of the opposite sex into a physiological state that allows breeding to occur
  • establishes a pair bond
46
Q

What determines capability of breeding?

A

Both partners must be sexually mature, fertile and receptive

47
Q

What is mating synchronising?

A

Brings partners together when they are more sexually responsive and fertile (during oestrus); maximum probability of sperm and egg meeting

48
Q

Process of courting behaviours

A

1) attracting a mate and signalling sexual status (responsiveness and readiness)
2) females use pheromones to attract males and to signal that they are in oestrus and can conceive

Biology A Level (45 decks)

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