B10 - Classification and Evolution Flashcards
1
Q
What is the classification system?
A
2
Q
Why do scientists classify organisms?
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3
Q
How are organisms classified?
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4
Q
How are organisms named?
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5
Q
What are the five kingdoms?
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6
Q
What are the features of prokaryotae?
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7
Q
What are the features of protoctista?
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8
Q
What are the features of fungi?
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9
Q
What are the features of plantae?
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10
Q
What are the features of animalia?
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11
Q
What are the six kingdoms?
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12
Q
What are the features of archae/eubacteria?
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13
Q
What is phylogeny?
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14
Q
What are phylogenetic trees?
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15
Q
What are the advantages of phylogenetic classification?
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16
Q
Who developed the theory of evolution?
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17
Q
What evidence is used for the process of evolution?
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18
Q
What is palaeontology?
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19
Q
What is comparative anatomy?
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20
Q
What is comparative biochemistry?
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21
Q
What is variation?
A
- the differences in characteristics between organisms
22
Q
What are the different types of variations?
A
- interspecific = variation between members of different species
- e.g. mouse has four legs, fur, and teeth whereas bird has two legs, two wings and feathers
- intraspecific = variation between organisms within a species
- e.g. people vary in height, build, hair colour
23
Q
What causes variation?
A
- organism’s genetic material:
- differences in genetic material and organism inherits from its parents leads to genetic variation
- environment:
- causes environmental variation
24
Q
What are the genetic causes of variation?
A
- alleles:
- gene for a particular characteristic can have different alleles that produce different affects
- e.g. human blood groups have three different alleles (A, B, O)
- depending on the parental combination, four different blood groups can be formed (A, B, AB, O)
- individuals in a species population may inherit different alleles of the same gene
- mutation:
- changes in the DNA sequence (genes) can change proteins they code for
- can affect physical/metabolic characteristics
- if it occurs in just the body (somatic) cells it only affects that one organism
- but if it occurs in the gametes it can be passed on to the offspring (both result in variation)
- meiosis:
- gametes (ovum/sperm) are produced which receive half the genetic material of a parent cell
- independent assortment and crossing over occurs before the nucleus divides and chromatids separate (mixes genetic material)
- leads to the gametes showing variation
- sexual reproduction:
- offspring inherits genes (alleles) from both parents
- so each individual produced differs from the parents
- chance:
- many different gametes are produced from parental genome
- so during sexual reproduction, it is a result of chance as to which two gametes combine (random fertilisation)
- so individuals produced are different to their siblings
- ** there is much more variation in organisms that reproduce sexually than asexually **
- ** asexual reproduction produces clones and can only increase variation as a result of mutation **
25
What are the environmental causes of variation?
- plants may be more affected than animals as they lack mobility
- e.g. a bush planted with a greater access to the sun will more likely grow larger than the one in the shade
- as it cannot move into the sunlight, it is more affected by the environment than an animal
- pure environment variation
- presences/absence of a scar
- this may have occurred due to an accident or a disease (cannot be inherited from a parent)
26
What are environmental and genetic causes of variation?
- height:
- tall parents = inherit genes to grow tall
- poor diet = you may only grow below average height
- skin colour:
- determined by how much melanin your skin contains
- at birth = purely determined by genetics
- when exposed to sunlight, more melanin is produced to protect skin from UV rays (causing your skin to turn darker/tan)
- ** it can be diffuse to draw conclusions about the causes of variation in any particular case **
- ** this is referred to as the ‘nurture vs nature’ argument **
27
What is discontinuous variation?
- characteristic that can only result in certain values (no in-between values)
- variation determined purely by genetics fall into this category
- e.g. animal’s sex (male/female)
- human blood group
- in microorganisms:
- shape of bacteria
- spherical
- rods
- spiral
- comma
- corkscrew shaped
28
How is discontinuous variation represented?
- bar chart (or pie chart)
29
What is continuous variation?
- characteristic that can take any value within a range
- there is a graduation in values from one extreme to the other of a characteristic (continuum)
- e.g. height/mass of plants
- these characteristics are not controlled by a single gene but a number of them (polygenes)
- they are also often influenced by environmental factors
30
How is continuous data represented?
- collected in frequency table
- plotted on histogram
- curve is then drawn to show a trend
31
What is a normal distribution curve?
- bell-shaped curve produced when continuous variation data is plotted
- data is *normally distributed*
- characteristics:
- mean, mode, median are the same
- bell-shape is symmetrical about the *mean*
- 50% greater than mean, 50% less than mean
- most values lie *close* to the mean value (no. of individuals at extremes are low)
32
What is standard deviation?
- how spread out the data is
- greater the standard deviation, the greater the spread of data (larger amount of variation)
- normal distribution:
- most of the data lies close to the mean (99.7%)
33
What are other statistical tests used to calculate significance of data?
- student’s t test = compare means of data values of two populations
- data must be normally distributed (*enough data should be collected*)
- different sample sizes may be used
- (Spearman’s rank) correlation coefficient = considers relationships between two sets of data
- no correlation
- +ve correlation
- -ve correlation
34
What are adaptations?
- characteristics that increase an organism’s chance of *survival* and *reproduction* in its environment
- three groups:
- anatomical adaptations (physical features)
- behavioural adaptations (can be inherited/learned from parents)
- physiological adaptations (internal processes)
- many adaptations fall into *more than one* category
35
What are examples of anatomical adaptations?
- body covering:
- hair, scales, spines, feathers, shells
- can help to stay warm, fly, provide protection
- thick waxy layers on plants prevent *water loss*
- spikes can deter herbivores and protect tissues from sun damage
- camouflage:
- outer colour allows it to blend into its environment
- snowshoe hare is white in winter and turns brown in summer
- this makes it harder for predators to spot it
- teeth:
- shape and type are related to its *diet*
- herbivores have growing molars to chew tough grass/plants
- carnivores have sharp large canine to kill prey/tear meat
- mimicry:
- copying another animal’s appearance/sounds to fool predators
- harmless organisms do this to appear poisonous/dangerous
- e.g. harmless milk snake mimics appears of deadly coral snake
36
How is marram grass adapted?
- it is a *xerophyte* and lives in an environment with very little water
- to reduce rate of transpiration:
- curled leaves to minimise SA of moist tissue exposed to the air
- hairs on inside surface of leaves to trap moist air (reduces *diffusion* gradient)
- stomata sunk into pits (less likely to open)
- thick waxy cuticle on leaves and stems
37
What are examples of behavioural adaptations?
- survival:
- e.g. opossum plays dead and a rabbit freezes when they think they have been seen
- courtship:
- many exhibit *elaborate courtship* behaviours to attract a mate
- increases their chance of reproduction
- seasonal behaviours:
- adaptations allow for them to cope with changes in environment
- migration (move from one region to another and then back again)
- hibernation (period of inactivity which helps to conserve energy, reducing requirement for food)
38
What are the types of behavioural adaptations?
- innate:
- ability to do this is inherited through genes
- e.g.spiders building webs
- allows for organism to survive in its habitat
- learned:
- learnt from experience or observing other animals
- e.g. use of tools (sea otters use stones to hammer shells off rocks)
39
What are examples of physiological adaptations?
- poison production:
- many reptiles produce venom to kill their prey
- plants also produce poisons in their leaves to protect themselves from being eaten
- antibiotic production:
- some bacteria produce antibiotics to kill other species of bacteria
- water holding:
- e.g. water-holding frog stores water in its body
- allows it to survive in the desert for more than a year without access to water
- many desert plants/cacti can also hold large amounts of water
- other:
- reflexes
- blinking
- temp. regulation
40
What are analogous structures?
- different species have a structure with the same function but originate from a different genetic origin
- they are adapted to perform the same structure
41
What is convergent evolution?
- where unrelated species begin to share similar traits
- they evolve as organisms adapt to similar environments/other selection pressures
- these organisms live in a similar way to each other
- e.g. whales and fish share similar characteristics as they have evolved over time to move efficiently through water
42
What are examples of convergent evolution?
- marsupials in Australia and placental mammals
- placental = placenta connects the embryo to its mother
- nourished the embryo and allows it to mature before birth
- marsupials = start life in uterus (complete development by suckling milk)
- these two subclasses were separated from a common ancestor more than 100 million years ago
- each lineage evolved independently
- North America has produced similar bear species
- this is because they have adapted to similar climates/food supplies
- their different methods of reproduction accurately reflects their distinct *evolutionary relationships*
43
What are other specific examples of convergent evolution?
- marsupial and placenta mice:
- both small and agile climbers
- live in dense ground cover
- flying phalangers and flying squirrels:
- both are gliders that eat insects and plants
- skin is stretched between forelimbs
- marsupial and placental moles
- both burrow through soft soil to find worms and grubs
- streamlined body shape
- plants:
- aloe and agave have both adapted to survive in the desert
- however, they have developed entirely separately
- aloe = old world
- agave = new world
44
What is natural selection?
- *selection pressures* = factors that affect the organism’s chances of survival/reproductive success
- organisms that are best adapted to their environment are more likely to survive and reproduce
- these characteristics will become more common in the population
- the characteristics of those who die out will be less common
45
What are the steps of natural selection?
- organisms within a species show variation in their characteristics that are caused by differences in their genes
- e.g. they may have different alleles of a gene (can arise by mutation)
- organisms with characteristics best adapted to selection pressure (predation, competition, disease) have an *increased* chance of survival
- they will go on to reproduce and pass on their genes
- this is survival of the fittest
- the successful organisms pass the allele with the *advantageous characteristic* onto their offspring
- those who die out cannot do this
- this process is repeated for *every generation*
- as the proportion of individuals with the advantageous allele increases, the frequency of it in the gene pool also increases
- over long period of time (many generations), this process can lead to the evolution of a new species
46
What are modern examples of evolution?
- antibiotic resistant bacteria
- peppered moths
- sheep blowflies
- flavobacterium
47
How have antibiotic resistant bacteria evolved?
- methicillin resistant (bacteria) = MRSA
- bacteria are able to reproduce very rapidly and so they evolve in a short amount of time
- when they replicate their DNA can be altered and results in the bacteria dying
- when the bacteria are exposed to the antibiotic, the resistant individuals survive and reproduce
- they pass on their allele for resistance on to their offspring
- over time he resistant individuals in the population increased
48
How have peppered moths evolved?
- before the industrial revolution, most peppered moths were pale coloured
- this allowed for camouflage against the light-coloured tree bark (increased chance of survival)
- the darker ones were easily spotted and eaten
- during the industrial revolution, trees became darker (covered in soot, loss of lichen covers due to pollution)
- this meant that the darker coloured moths were now better adapted to survive
- they went on to reproduce and pass on their dark allele
- since Clean Air Act of 1956, levels of pollution have decreased
- the bark on trees have become lighter which has increased the frequency of the light allele in the moth gene pool
49
How have sheep blowflies evolved?
- they lay their eggs in faecal matter around sheep’s tail
- larvae hatch and cause sores (flystrike)
- in Australia, the pesticide diazinon was used to kill the blow flies
- within six years, they had developed a high level of resistance
- individual insects survived this exposure and passed on this characteristic through their allele, allowing a resistant population to survive
- scientists extracted DNA from an old blowfly, two Australian sheep blowflies were studied
- they compared the resistance genes before and after the introduction of the pesticide
- 70-year-old = resistance genes were not found
- but when investigating *mathalion* (organophosphate pesticide), they found that both blowflies had resistance genes for it
- this shows *pre-adaptation* which helped to contribute to the development of the diazinon resistance
- pre-adaptation = when the organism’s existing trait is advantageous for a new situation and allows for the rapid development of another one
- the existence of pre-adaptation in an organism may help researchers predict potential insecticide resistance
50
How has Flavobacterium evolved?
- an example of evolution due to new opportunities in environment
- new strain of F. bacterium living in waste water from factories
- digests the nylon which this produced in waste water
- this is beneficial to humans as they help to clear up factory waste
- bacteria uses enzymes to digest the nylon (nylonases)
- unlike other enzymes in F. bacterium, they do not help the bacteria digest anything else
- they believe this has occurred due to a gene mutation
- duplication, frame shift mutation
