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OCR Biology A Level Module 4 > 4.2.2 Classification and evolution > Flashcards

4.2.2 Classification and evolution Flashcards

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1
Q

What is classification?

A

naming and organising organisms into groups based on characteristics

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2
Q

What is the taxonomic hierarchy?

A

domain: archaea, eubacteria and eukaryotae
kingdom: plantae, animalia, fungi, protoctista, prokaryotae
phylum: same body plan
class: same general traits
order:
family
genus:
species

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3
Q

What is the trend in terms of ease and classification?

A
  • higher levels easier to classify e.g. two phyla in animals (chordata with backbone and arthropoda with exoskeleton)
  • as you descend it becomes harder due to fewer differences
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4
Q

What is the biological and phylogenetic definition of a species?

What are the issues with biological one?

A

biological: freely interbreed to produce fertile offspring ->
phylogenetic: organisms that are similar in anatomy, biochemistry, appearance, and physiology.

issues = asexual reproduction, fossils

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5
Q

What was early classification like?

A
  • appearance, anatomy and niche dependent
  • plant or animal -> water, land, air
  • similarities often led to incorrect groupings e.g. fins, wings.
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6
Q

What changed in the modern classification techniques?

A
  • electron microscopes caused adaptations
  • showed organisms with plant AND animal features e.g. Euglena
  • fungi were originally classified as plants but don’t photosynthesise and they digest organic matter
    -> led to 5 kingdoms. still based on observable features but at the microscopic level.
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7
Q

What is the binomial naming system?

A
  • genus + species. Genus as capital for first letter and the rest lowercase. e.g. Homo sapiens
  • Latin as universal language; can be understood better; avoids confusion often caused by common names;
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8
Q

What are the features of prokaryotae?

A
  • plasmids + non linear DNA
  • no membrane bound organelles
  • smaller ribosomes
  • free living or parasitic
  • uni cellular
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9
Q

What are the features of protoctista?

A
  • eukaryotic
  • MOSTLY unicellular
  • some feed using extracellular enzymes
  • autotrophic or heterotrophic
  • mostly free-living
  • wide variety of forms
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10
Q

What are the features of fungi?

A
  • eukaryotic
  • chitin
  • free living or saprophytic
  • multinucleate cytoplasm
  • unicellular or mycelium with hyphae
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10
Q

What are the features of plantae?

A
  • autotrophic
  • eukaryotic
  • multicellular
  • cellulose
    -chlorophyll
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10
Q

What are the features of animalia?

A
  • eukaryotic
  • multicellular
  • heterotrophic
  • able to move around
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11
Q

How did the 3 domain system come about?

A
  • ribosomal RNA gene research
  • divided Prokaryotae into 2 groups as Bacteria are fundamentally different from Archaea and Eukaryotae
  • bacteria have diff cell membrane structure, RNA synthesis enzymes, DNA replication mechanisms, flagella structure.
  • archaea and eukaryota have similar RNA synthesis enzymes, DNA replication
  • fits phylogeny better
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12
Q

What is phylogeny?

A
  • study of evolutionary relationships.
  • classification reflects phylogeny
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13
Q

What is artificial vs natural classification?

A

artificial: few characteristics, doesn’t reflect evolutionary relationships, limited info, stable
natural: many characteristics, reflects relationships, lots of useful info, may change -> can use to find out more about an endangered species.

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14
Q

What does monophyletic mean? What can we use to learn more about phylogeny

A
  • any two living species have a common ancestor
  • can use phylogenetic trees -> root is the very bottom. where two species meet is a node.
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15
Q

What is convergent evolution?

A
  • unrelated species evolve similar traits due to adapting to a similar niche
16
Q

What is homology?

A

grouping of organisms based on features that they share e.g. pentadactyl limb

17
Q

How can biological molecules be used as evidence of evolution?

A
  • help determine how closely related species are as we assume earliest organisms had identical versions

1) cytochrome C: similar/same amino acid sequence = CLOSELY RELATED. Differences = EVOLVED SEPARATELY LONG TIME AGO
2) DNA: changes due to mutations. more similar base sequence = evolved separately recently. More differences = less closely related.

18
Q

What is standard deviation? What does it indicate?

A
  • spread from the mean
  • LOW: greater reliability
    HIGH: lower reliability
  • anomalous data usually outside 2SD from mean.
19
Q

When do we use the correlation coefficient? What does it indicate?

A
  • tells us whether two sets of data are correlated or not
  • d.o.f = n-2
  • ranking must be done the same way for both variables
  • compare to table of critical values (ignore sign)
  • if GREATER than critical value for pairs of measurements at p = 0.05 = REJECT null hypothesis = strong correlation. Significant difference.
  • if LESS than critical value = no significant correlation, results due to chance.
20
Q

When do we use the students/unpaired t-test? What is degrees of freedom? How do we analyse the results?

A
  • two means to test for significance
  • degrees of freedom = (n1 + n2) -2 : n being number of data sets
  • can use a table of t values to assess whether our calculated one indicates a significant diff. use 5% probability level.
  • calc value GREATER = significant. 95% sure data is not due to chance
  • calc value LESS = insignificant
21
Q

How did Darwin and Wallace contribute to the theory of natural selection?

A
  • INDEPENDENTLY
  • Darwin: voyage and collected specimens and info, esp from Galapagos Islands
  • Wallace: collected specimens from South America and South East Asia.
22
Q

What was the deduction from this observation:
-offspring generally appear similar to their parents

A

characteristics are passed on

23
Q

What was the deduction from this observation:
no two individuals are identical

A
  • individuals with beneficial characteristics are among the few who survive
24
Q

What was the deduction from this observation:
- individuals have ability to produce large numbers of offspring

A
  • struggle to survive
  • individuals with beneficial characteristics among the few who survive
25
Q

What was the deduction from this observation:
- populations in nature tend to remain fairly stable

A
  • individuals with beneficial characteristics among the few who survive
  • struggle to survive
26
Q

What is the process of natural selection?

A

1) mutations occur = variation
2) selection pressure causes competition for resources
3) individuals with an advantageous characteristic will survive and reproduce
4) they pass on these advantageous characteristic
5) next generation will have a higher proportion of these alleles

27
Q

Explain the fossil evidence for natural selection

A
  • lots of changes in environments have caused changes in species overtime
  • fossils can be dated to put organisms into a sequence
  • show similarities and differences between extinct + present species, and ancestral and extinct species.
  • some incomplete though due to no discovery, rapid burial, lots washed away
28
Q

What are the types of variation? (Intra vs inter, genetic vs environment )

A

intraspecific: between members of SAME species
interspecific: between diff species
genetic: combo of alleles we inherit not same as others
environment: can affect characteristics and gene expression

29
Q

What is discontinuous vs continuous?

A
  • 2 + distinct categories, no or few intermediates
  • bar chart
  • single gene
  • gender, blood groups
  • two extremes and intermediates
  • more than 1 gene + environment
  • histogram (bell curve)
  • height, length
30
Q

What is an adaptation?

A
  • variation that helps an organism to survive
31
Q

A well-adapted organism will be able to….

A
  • find food
  • find water
  • defend
  • respond to changes
  • reproduce
32
Q

What does anatomical, physiological and behavioural mean?

A
  • anatomical: structural
  • behavioural: aspect of behaviour
  • physiological: ensures correct functioning of biochemical cell processes
33
Q

What are some examples of behavioural adaptations for marram grass? (xerophyte)

A
  • responds to shortage of water by rolling leaf more tightly and closing stomata.
  • when covered by sand it’ll grow quickly to reach sunlight
34
Q

What are some examples of anatomical adaptations of marram grass?

A

. long roots: reach water
. wide roots: stabilisation and to absorb more water
. curled leaves: reduces SA exposed to wind and traps air to avoid water loss
. lower epidermis covered in hairs: reduces air movement so water vapour retained close to epidermis.
. pits in lower epidermis: water vapour builds up -> reduces loss of water vapour
. low stomata density: less water vapour lost
. waxy cuticle: reduces evaporation of water

35
Q

What are some physiological adaptations of the marram grass?

A
  • maintains a water potential that is lower than other plants to enable it to survive in salty conditions
  • lignified cells to provide support when turgidity is lost
  • hinge cells lose water + turgidity = rolls leaf more tightly. when water available, they become more turgid and open up to allow easier gas access.
36
Q

What are some adaptations of the mole?

A
  • marsupial and placental moles share many characteristics despite being unrelated, due to similar environments
    1. small eyes
    2. short fur and tail
    3. large claws
    4. cylindrical body
    5. small front legs
37
Q

What is a problem with pesticides?

A
  • act as selection pressure and insects can become resistant to them -> spreads
  • e.g. DDT can accumulate in food chain which can be dangerous
  • mosquitoes have developed resistance to pyrethroids
38
Q

How has antibiotic resistance come about?

A
  • overuse and incorrect use of antibiotics have led to strains that are resistant
    1) before selection there is a variety of resistance levels due to variation
    2) directly after selection the least resistant ones have been killed
    3) the final population contains a much higher proportion of resistant individuals.
39
Q

Which option is commonly used to determine evolutionary relationships?

A) Amino acid sequence of collagen
B) amino acid sequence of messenger RNA
C) base sequence of cytochrome C
D) base sequence of ribosomal RNA

A

D

OCR Biology A Level Module 4 (3 decks)

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