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A level biology > Topic 4 > Flashcards

Topic 4 Flashcards

1
Q

What is a species?

A

A basic unit of classification: organisms capable of breeding to produce living, fertile offspring

(Allows genes to combine together )

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2
Q

What is the binomial system and it’s features?

A

Common system of naming organisms

Consists of:
-printed in italics
-Latin/greek names
-Generic Names: (first name) denotes what genus organism belongs to
[first letter in capitals]
-Specific name: (second name) denotes what species organism belongs too
[first letter in lower case]
(Not shared by species unlike humans)

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3
Q

What should you write if the specific name is not known?

A

‘Sp’

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4
Q

How does courtship behavior support an individual?

A

-recognises members of same species (so mating takes place between members)
-identify mates capable of breeding
-form a pair bond= successful mating
-synchronise mating
-became able to breed

This determines if female is at receptive stage for a male

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5
Q

How do animals communicate with mate during courtship?

A

By using signals

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6
Q

What is classification and the two types of biological classification?

A

Grouping of organisms

•Artificial classification: divides organism according to differences useful at the time (analogous characteristics=same function but not same origins

•phylogenetic classification: based on evolutionary relationship between organism
-classify species into groups sharing features derived from ancestors
-arrange groups in hierarchy
(Based on homologous characteristics)

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7
Q

What is taxonomy?

A

Practice of phylogenetic/biological classification

Organise group of species

Groups are called taxa that are arranged in an hierarchical order based on evolution (is there taxonomic rank)

A Line of descent of group members

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8
Q

What is a domain (taxonomy terms)

A

Highest taxonomic rank
Either
-Bacteria
-archaea
-eukarya

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9
Q

What is an archaea?

A

-group of singles celled prokaryotes

Contains:
-more similar gene & protien synthesis to eukaryotes
-membrane contain fatty acids chains attached to glycerol by ether linkage
-has no murein in cell wall
-have more complex for of RNA polymerase

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10
Q

How are Eukarya classified? (Taxonomy)

A

-[kingdom] domain is divided into four kingdoms (protocista, fungi, plantae and animalia)
-[phylum] have body plan radically different from organism
-[classes] is diversity within phylum
-[order] organisms that have additional features in common
-[family]
-[genus]
-[species]

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11
Q

What is an phylogeny?

A

Evolutionary relationship between organisms

Reflects evolutionary branch leading up to organism

{ represented in an phylogenetic diagram (tree) with oldest species at base of tree and most recent one at end of branches }

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12
Q

What is the evidence for classification?

A

1) anatomical, it homologous structure
2) embryological, similarity in embryos
3)behavioural,
[longer periods of parental care, live in social groups, vocalisation and facial expressions]

4)biochemical, compare protien/ DNA (via DNA hybridisation: extract DNA)

5) immunological, immune system response

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13
Q

How can immunological evidence be used as evidence for classification?

A

Procces

Inject human serum into rabbit
-serum has protein acting as antigen

Rabbits produce antibodies specific to human serum protien

Sensitised rabbit serum removed & added to test tube with blood serum of another species. Antibodies respond to antigen in other species serum. producing precipitate from antibodies binding to antigen.

[higher precipitate =closer evolutionary relationship between human and other species]

{the serum has blood plasma without clotting protiens}

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14
Q

What is biodiversity?

A

Number & variety of living organisms in particular area

Consists of 3 components
Species/ Genetic/ Ecosystem diversity

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15
Q

What is species diversity?

A

Number of different species & individuals of each species within one community

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16
Q

What is genetic diversity?

A

Variety of genes passed by individuals that make up a Population of species
/
Total number of different alleles in population

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17
Q

What is ecosystem diversity?

A

Range of different habitats , from small local habitats to entire earth habitat

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18
Q

What is species richness?

A

Number of different species in particular area at given time / (community)

Is a measure for species diversity

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19
Q

What is included within the index of diversity? (Equation )

A

N-total number of organisms of all species

n- total number of organisms of each species

-the sum of

d-index of diversity

N(N-1)
———
Sum of n(n-1)
= index of diversity

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20
Q

What is DNA like in prokaryotic cells?

A

Shorter, forms circle , not associated with protien molecules

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21
Q

What is DNA like in eukaryotic cells?

A

Longer, forms line, then circle. Associated with protiens (histones) to form chromosomes in organelles

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22
Q

What is contained in the structure of an chromosome

A

Contains to threads (chromatids held together by histones)

-is highly cookies up
-a double helix
-contains single DNA molecule that has lots of genes

(Varys from species to species)

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23
Q

What is an homologous chromosome ?

A

Pairs which are similar to each other
(One from egg and one from sperm)

-two chromosomes that carry same gene but not same alleles of gene

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24
Q

What is the total number of homologous pairs?

A

Diploid number

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25
What is an allele?
One of a number of alternate forms of genes -inherited from parents -has different sequences. Has different amino acid sequences. So different polypeptide [a change in sequence means an mutation ]
26
What are the features consisted in the structure of ribonucleic acid?
Codon: sequence of bases on mRNA that code from single amino acids Genome: complete set of genes in cell Proteome: range of proteins produced by genome /complete proteome
27
What is mRNA ?
Messenger rna -single helix -associates with ribosomes - acts a as a template for protein synthesis -procces information In form of codons -codons sequence determines what polypeptide is made
28
What is tRNA?
Transfer rna -Small molecule made of 80 nucleotides -single chain folded into clover leaf shape where amino acids can easily attach -opposite end is an sequence of 3 organic bases (anti-codons) which is specific to amino acid
29
What is an gene??
Section of DNA contains coded information for making polypeptides & functional RNA Is in the from of specific sequences of bases along DNA molecule (Located in locus)
30
What is the genetic code? (Detailed explanation)
Has a minimum of 3 bases (from the 4 present in DNA) to code for a amino acid In order to produce the required number of amino acids (20) that regularly occur in protein each base codes for an different amino acid, so using a triplet of bases satisfies the demand - -proof; 4(power of 3) [3 bases] equal 64 which is more than 20
31
What are some features of the genetic code?
Genetic code :mRNA molecule that has sequence of nucleotides transcribed from DNA which is translated by tRNA, -some amino acids coded by 1 triplet -some amino acids coded for by more than one, between two and 6 (degenerate codes) -start DNA sequence codes for same triplet for all polypeptide is calle methionine (which is sometimes removed from final product) -3 triplets ‘stop codes’ don’t code for amino acids. That make end of polypeptide chain - universal code
32
What is a non overlapping code?
Each of the bases of the codon in sequence is read once
33
What are exons and introns?
Exons code for amino acids Introns do not code for amino acids
34
What is an coding strand?
Synthesised in direction 5’ to 3’ (not involved in transcription
35
What is template strand used in?
Transcription
36
What does upstream structural gene have?
Promotor region
37
What does down stream structural gene have?
-Terminator region used to end transcription -protien coding region that’s used during transcription -region towards 3’ end -nucleotides Are positively numbered (these re nucleotides that come after initiation [+1] site)
38
What is the process of transcription?
-two strands of structural gene uncoil , which is catalysed by DNA Helicase, breaking hydrogen bonds between complimentary nucleotide bases -this exposes nucleotides bases on template strand where complimentary RNA nucleotides move towards to form hydrogen bonds with exposed base -RNA polymerase binds to promotor region on rna nucleotides to form phosphodiester bonds . Moving in 5’ to 3’ direction until they reach the terminator region. Where RNA Polymerase detaches -producing messenger rna or pre-mRNA in prokaryotic cells
39
What is splicing?
Removing introns from the pre mRNA , only keeping extrinsic, joining them together Lead to mRNA leaving nucleas via nuclear pores & is attached to the ribosome
40
H
41
What is the process of translation involved in polyp peptide synthesis ?
1. Ribosomes attach codons on mRNA molecule end 2. tRNA molecule with complimentary anticodon sequences moves onto ribosomes & pairs up with codons in mRNA, carrying starting codons. tRNA carries specific amino acid 3. A Complimentary anti codon on tRNA pairs with next mRNA codon. tRNA molecule carries specific amino acid [Ribisomes move along mRNA to bring together 2 tRNA molecules at one time, pairing with corresponding 2 codons in mRNA ] [Two amino acids on tRNA joined by peptide bind using enzyme & ATP hydrolysed to provide energy] 4. Ribisomes move to third codon on sequence on mRNA , linking amino acids in second & third tRNA molecule 5. First tRNA released from amino acid and tRNA free to collect another amino acid from amino acid pool in cell, 6. Synthesis of polypeptide continues with detachment of tRNA until ribisomes reach stop codon. so mRNA , ribisomes & last tRNA seperate [completes polypeptide chain ] from joining of amino acids in condensation reaction
42
How many amino acids added until polypeptide chain built up?
15 (As amino acids chains less than 10-15-20 are called oligopeptides
43
Why can many identical polypeptide be assembled at the same time?
50 pass immediately behind first
44
What are functional proteins?
Complete final form of protein that can then be able to fulfil its role - either can be: • Single polypeptide chain • secondary/ tertiary/ quaternary protein structure
45
How many different tRNA are there?
60
46
What is mutation?
Change to the quantity or base sequence of DNA of organism
47
What is gene mutation?
Change to one or more nucleotide base /sequence of bases in DNA (changes in a gene)
48
What is base substitution?
Nucleotide in DNA molecule replaced by another nucleotide with different base (Changes bind formation ) affecting protein structure
49
Why does sometimes base substitution not affect polypeptide produced?
As some bases will still code for the same amino acid
50
What is the cause & consequence of a base deletion?
Nucleotide lost from normal DNA sequence = polypeptide not functioning properly = triplet sequence to be read differently
51
What is chromosome mutation?
Changes in structure / number of chromosomes Two forms: -change in chromosome sets -change in number of individual chromosomes
52
What is polyploidy mutation?
Chromosomes have 3 or more sets (usually have 2) when there are changes in chromosome sets
53
What is non disjunction mutation?
Occurred when chromosomes in homologous pair fail to seperate in meiosis / form a pair/ stay in one cell when there are changes in number of individual chromosomes =gametes have more/fewer chromosomes = offspring have more/ less chromosomes in body
54
What is meiosis?
Producing 4 daughter cells each with half number of chromosomes as parent cell
55
Why is meiosis important?
Halving of chromosomes from meiosis occurs so a constant number of chromosomes is maintained in the adult of the species , as during sexual reproduction the diploid number (46) (if they had a full set) would double in the cell So when two haploid gametes fuse at fertilization , a diploid number is restored. So the cell has a full set of chromosomes
56
What is procces of meiosis?
• (Meosis 1) homologous chromosomes pair up & chromatids wrap around eachother . [Equivalent chromatids portions exchanged in “crossing over” procces.] One chromosome on each pair go into one of two daughter cells • (meosis 2) chromatids move apart so four cells have been formed
57
How is genetic variation achieved in meiosis?
-Independent segregation of homologous chromosomes -variety from new genetic combination -genetic recombination by crossing over
58
What is genetic segregation of homologous chromosomes?
-chromosomes line along side homologous partner and arrange themselves randomly in line -one of each pair passes into each daughter cell based on how pairs are lined up in parent cell
59
How is variety from new genetic combination achieved?
Alleles of gene in homologous pair of chromosomes might differ So independent assortment of chromosomes produce new genetic combinations
60
How is genetic recombination by crossing over achieved ?
• chromatids of each pair became twisted around eachother • during twisting, tensions are created & portions of chromatids are broken of • broken portion rejoin with chromatid of homologous partner (recombination) • equivalent portion of homologous chromosomes that’s exchanged • new genetic combinations of maternal & paternal alleles produced
61
What does genetic diversity lead to?
Increase different alleles frequency) in species , which increases genetic diversity… so there is a high chance of survival to survive environmental change So enabling natural selection to occur
62
How does natural selection occur?
From organisms reproducing successfully Which affect the allele frequency in populations (limiting alleles passed on only to those in organisms that survive)
63
What is the procces of natural selection?
• in population there’s a gene pool containing a variety of alleles • a mutation of allele in gene pool leads to a new allele of gene (that’s mostly harmful but can be an advantage • the advantages alleles make individuals better adapted, increasing there survival =so obtain more resources = live longer= produce more offspring • new allele most likely passed on to nest generation , so individuals with advantages allele increases
64
What are the selection types?
Directional selection Stabilising selection Natural selection
65
What is directional selection?
Favours population that sway in one direction from mean population (changes populations characteristics) So The phenotype best suited to new [changed] conditions survive (either left or right of mean of normal distribution curve) (Population of distribution curve shifts more to one side, favouring extreme phenotype of population )
66
What is stabilising selection?
Favour average individuals ( preserves population changes) Phenotypes closest to the mean in normal distribution curve
67
What does natural selection cause?
Makes Species better adapted to environment Creates anatomical / physiological/ behavioural adaptations
68
What are agricultural ecosystems?
Farmers select species for particular quality to make them more reproductive
69
How does agricultural ecosystems reduce species diversity?
• reducing genetic variety of alleles passed on • reduces species • smaller areas unused becomes more competitive (not all species survive ) • use of pesticides
70
What practices reduce species diversity?
• removal of hedgerows • grubbing woodlands out • creating monocultures • filling ponds • draining marshes • over grazing land • use of pesticides & inorganic fertiliser • escape of effluent from silage stores • absence of crop rotation • lack of intercropping
71
What are the list of methods & techniques for conservation of species diversity?
• Maintaining beneficially shaped existing hedgerows • planting hedges • maintain & create ponds • leave wet corners on field • planting native trees • reduce use of pesticides • use of organic fertilisers • crop rotation (nitrogen fixing crop) • intercropping to control weeds • create natural meadows • leaving cutting of verges until after flowering • introduce conservation headlands
72
How can you compare observable characteristic to investigate genetic diversity? & limitations of this method
Each observable characteristic is determined by genes= Variety determine from number & variety of alleles of gene Limitations are that characteristic might be coded by more than one gene (=polygenic) & can be modified by environment
73
How can comparing DNA base sequences be used to investigate diversity ?
They determine the exact order of nucleotides on DNA -is operated by automatic machine that’s analysed by computers to produce data • by sampling DNA of its members ,sequences it to produce pattern of coloured bonds, then its analysed to compare with another of same species This determines evolutionary relationships between species as DNA base sequences would be more similar to closely related species
74
How can comparing mRNA base sequences be used to investigate diversity?
mRNA are complimentary from DNA strands there made from
75
How can comparing amino acid sequences be used to investigate diversity?
Close relations determine if whether these species have the same protein. Compare sequences by counting numbers of similarities or differences in each sequence
76
What is interspecific variation?
One species differ from another
77
What is intra specific variation?
Members of same species differ from eachother
78
What is random sampling method?
-divide study area into grid of number lines, use random numbers from a table to gain series of coordinates And then take samples at intersection of each coordinate pairs
79
Why is random sampling needed?
To avoid sampling bias and to remove potential sampling by chance
80
How do you further minimise chances when random sampling?
-using a larger sample size (more individuals selected, less percentage chance will influence = more reliable) -analyse data collected: use statistical tests to determine what extent chance influenced data (if variance is a result of chance is identified )
81
What is a gamete?
Reproductive cell of animal or plant
82
What is a gamete?
Reproductive cell of animal or plant

A level biology (8 decks)

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