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A-Level Biology > Module 4: Diversity > Flashcards

Module 4: Diversity Flashcards

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1
Q

biodiversity definition

A

variety in an ecosystem

variety of habitats and variety of ecosystems

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2
Q

species diversity definition

A

number of different species

number of individuals within each species

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3
Q

genetic diversity definition

A

variety of alleles in a species population

larger number of individuals in a species the larger the genetic diversity

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4
Q

benefits of high species diversity

A

stable ecosystem
each species is less likely to become extinct due to high genetic diversity
if a species does become extinct it won’t affect the food chain as there are other species available

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5
Q

how to measure species diversity for an area

A

species diversity index
takes into account the number of different species and how many individuals there are for each species
larger the species diversity index the larger the species diversity

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6
Q

how does deforestation lower species diversity

A 
deforestation removes trees for wood and space 
decreases plant species diversity 
less variety of habitats 
less variety of food sources 
decreases animal species diversity
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7
Q

how does agriculture/farming lower species diversity

A

deforestation to make space for the farm
only grow a few plants and keep a few animal species
selectively breed plants and animals
use pesticides to kill other species

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8
Q

classification definition

A

placing organisms into groups

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9
Q

what is hierarchical classification

A

large groups divided into smaller groups with no overlap

domain, kingdom, phylum, class, order, family, genus, species

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10
Q

what is binomial naming system

A

using genus name and species to name organism
genus name first in capital
species name second in lower case

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11
Q

species definition

A

group of individuals with similar characteristics that can interbreed to produce living fertile offspring

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12
Q

why are offspring from 2 different species mating infertile?

A

off spring will have an odd number of chromosomes
can’t perform meiosis
can’t produce gametes
therefore infertile

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13
Q

phylogenetic classification definition

A

based on evolutionary relationships

how closely related different species are and how recent a common ancestor they have

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14
Q

3 ways of comparing relationships between different species

A

dna hybridisation
amino acids sequence
protein shape

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15
Q

dna hybridisation

A 
compare the dna base sequence 
take dna from 2 species to be compared
radioactively label one of the dna
heat so both strands separate 
cool so single strands join together 
look for hybrid dna (one from strand a, one from strand b)
identify hybrid dna by 50% radioactivity 
heat hybrid dna to measure similarity

RESULTS:
higher temp required
more hydrogen bonds present 
more complementary base pairing 
more similar base sequence 
more similar the species
more closely related
more recent a common ancestor
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16
Q

amino acid sequence

A 
comparing AA sequence for the same protein (haemoglobin in mammals)
RESULTS:
more similar the aa sequence 
more similar the dna base sequence 
more similar the species 
more closely related
more recent a common ancestor
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17
Q

why is comparing the dna sequence better than comparing the amino acid sequence

A

dna sequence provides introns and the triplet code is degenerate

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18
Q

protein shape

A

comparing shape of same protein using immunological technique
comparing species a and b
take albumin from species a and place it in a blood of a rabbit
rabbit will make antibodies against albumin of species a
take these antibodies and place them in blood from species b
if albumin in species a has similar shape to albumin in species b then antibodies will bind to form antigen-antibody complexes, this will form a precipitate

RESULTS:
more precipitate 
more complexes
more similar shape 
more similar the species 
more closely related 
more common recent ancestor
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19
Q

variation definition

A

difference in characteristics between organisms

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20
Q

types of variation

A

intraspecific

interspecific

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21
Q

intraspecific variation definition

A

differences between organisms of the same species

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22
Q

interspecific variation definition

A

differences between organisms of different species

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23
Q

causes of intraspecific variation

A

genetic factors
same genes but different alleles
environmental factors

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24
Q

causes of interspecific variation

A

genetic factors
different genes and different alleles
environmental factors

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25
types of characteristics
continuous and discontinuous
26
properties of discontinuous characteristics
characteristics fall into certain groups with no overlap (blood group) determined by genetics only (a single gene)
27
properties of continuous characteristics
characteristics show a range (height) determined by genetics (a few genes, polygenes) and their environment
28
genetic diversity definition
genetic variation | variety of alleles within a population of a species
29
benefits of high genetic diversity
species able to adapt with changes in the environment | e.g. if a new disease arises some individuals will have the characteristic to survive and reproduce
30
what can lower genetic diversity
small population size | founder effect, genetic bottleneck
31
what is the founder effect
where numbers in population start low
32
genetic bottleneck
where numbers in population decrease
33
what is natural selection and adaptation
variation in population of species new allele arises due to random mutation environment applies a selection pressure on the population those with favourable alleles have a selection advantage, better adapted will survive and reproduce to pass on their favourable alleles if this happens for many more generations then that characteristic will become more common allele will become more frequent (adaptation)
34
2 types of selection
stabilising | directional
35
stabilising selection
when environment favours those with the most common characteristic those on extreme die out common characteristic will increase in proportion range (standard deviation) will reduce
36
directional selection
when environment favours those individuals with characteristic on one of the extremes this will become the most common characteristic over time normal distribution will shift to that extreme
37
gene definition
section of dna that codes for a protein | made out of introns and extrons
38
intron definition
non-coding dna | turns gene on or off
39
exon definition
coding part of dna | codes for a protein
40
how does a gene/exon code for a protein
made out of a sequence of bases each 3 bases code for 1 amino acid, triplet code sequence of bases determines sequence of triplet codes determines sequence of amino acids =polpeptide chain=primary structure then folds to secondary then tertiary then quaternary
41
properties of triplet code
degenerate= each aa has more than one triplet code non-overlapping= each base is only read once stops codes= occur at the end of sequence, don't code for an amino acid universal= same amino acids code for same protein everywhere
42
how does a mutation lead to a non-functional enzyme
``` change in basde sequence change in sequence of triplet code change in aa sequence change primary structure changes hydrogen/ionic/disulfide bonds changes tertiary structure changes active site shape substrate no longer complementary no longer form enzyme substrate complex ```
43
how is a protein assembled
transcription and translation
44
transcription definition
production of a single stranded complementary copy of a gene called mrna
45
translation defiition
use sequence of codons on mrna to assemble protein, trna brings in amino acids
46
dna vs rna
deoxyribose sugar vs ribose sugar thymine vs uracil double stranded vs single stranded one type vs two types (mrna and trna)
47
names of nucleotide bases
``` adenine thymine cytosine guanine uracil ```
48
what is mrna
messenger rna single stranded complementary copy of a gene carries the code for assembling protein (on dna called triplet code, on mrna called codon)
49
what is trna
transfer rna single stranded rna folded over into a clover leaf shape held together by hydrogen bonds between bases has aa attachment site on the top has 3 specific bases on the bottom (anti codon) anticodon binds to complementary codons on mrna
50
what is transcription
occurs in nucleolus of nucleus dna helicase breaks hydorgen bonds between complementary bases in the gene the double strand of the gene unwinds leaves 2 separate strands (1 coding and 1 template) complementary rna nucleotides bind to exposed bases on the template strand rna polymerase joins the sugar-phosphate backbone of rna strand leaves pre-mrna (containing introns and exons) copies of the introns are removed by splicing leaves mrna
51
what is translation
takes place on the ribosomes of rough endoplasmic reticulum mrna leaves nucleus via nuclear pore mrna attaches to a ribosomes complementary trna carrying specific amino acids bind to the codons on the mrna via their anti codon amino acids on trna are joined by peptide bonds
52
what does meiosis produce
4 genetically different cells | haploid
53
benefits of meiosis
produces gametes which are used in sexual reproduction | 2 gametes fuse to form a zygote which develops into an organism
54
stages of meiosis
interphase meiosis 1 meiosis 2 cytokinesis
55
process of meiosis
interphase: - g1:protein synthesis - S:dna replication - G2: organelle synthesis meiosis 1: - prophase 1:dna coils to form chromosomes, nucleus breaks down, spindle fibres form, crossing over occurs - metaphase 1: homologous pair of chromosomes line up at the equatoe and attach to spindle fibre via centrometre - anaphase 1: spindle fibres shorten and pull, homologous pair of chromosomes separate to opposite poles by independent assortment - telophase 1: chromosomes uncoil, nucleus reforms (2 nuclei) meiosis 2: - prophase 2: dna coils to form chromosomes, nucleus breaksdown, spindle fibres form - metaphase 2: chromosomes line up in middle of cell and attach to spindle fibres via centromere - anaphase 2: spindle fibres shorten and pull, centromere splits, sister chromatids move to opposite poles by independent assortment - telophase 2: chromatids uncoil, nucleus reforms, left with 4 genetically different nuclei cytokinesis: - separating each cell into 4, with a nucleus and organelles
56
how does meiosis produce variation
crossing over and independent assortment
57
crossing over
occurs in prophase 1 of meiosis 1 homologous pairs of chromosomes wrap around each other and swap equivalent sections of chromatids- produces a new combination of alleles
58
independent assortment
in anaphase 1 of meiosis 1- homologous pairs of chromosomes separate in anaphase 2 of meiosis 2- chromatids separate independent assortment produces a mix of alleles from paternal and maternal chromosomes in gamete
59
what happens to dna mass in meiosis
quarters
60
what happens to chromosome number in meiosis
halves
61
mutation definition
change in the dna sequence | 2 tpyes: chromosome mutation and gene mutation
62
what causes mutations
random | or due to mutagenic agents (chemicals, radiation)
63
chromosome mutation
in plants inherit more than one diploid set of chromosomes (polploidy) in animals homologous pair of chromosome do not separatew in meiosis either inherit one extra or one less chromosome (non-disjunction)
64
what is a gene mutation
change in the base sequence of dna | 2 types= substitution and insertion/deletion
65
substitution
replace one base for another changes one triplet code can be silent so new triplet code codes for same aa mis-sense codes for different aa s slightly different protein shape non-sense codes for stop codon so chain isn't produced
66
insertion and deletion
adding a base or deleting a base cause frameshift, all triplet codes after mutation changes so normal polypeptide chain/protein isn't produced
67
Prokaryotic DNA
Shorter Circular Not associated with histones No chromosomes
68
Eukaryotic DNA
Longer Linear Associated with his tones Form chromosomes
69
DNA in mitochondria and chloroplasts
Short Circular Not associated with his tones
70
What do courtship behaviors allow individuals to do
``` Recognize members of their own species Identify a mate capable of breeding Form a pair bond Synchronize mating Become able to breed ```
71
Recognizing members of their own species
To ensure mating only takes place between members of the same species so they can produce fertile offspring
72
Identify a mate that is capable of breeding
Both partners need to be sexually mature, fertile and receptive to mating
73
Form a pair bond
Lead to successful mating and raising of offspring
74
Synchronize mating
So it takes place where there is the maximum probability of the egg and sperm meeting
75
Become able to breed
Bringing a member of the opposite sex into a physiological state that allows breeding to occur
76
Artificial classification
Divides organisms due to characteristics that are useful at the time Analogous characteristics Same function but not the same evolutionary origins
77
Bacteria
``` Absence of membrane bound organelles Unicellular Ribosomes are 70 s which are smaller Cell walls present and made of Murein Single loop of dna no histone ```
78
Archaea
Differ from bacteria as Genes and protein synthesis are similar to eukaryotes Membranes contain fatty acid chains with ester bonds to glycerol No murein in cell walls More complex rna polymerase
79
Eukarya
Cells have membrane bound nucleus and organelles Membranes containing fatty acids with ester bonds to glycerol Not all possess cell wall but if they do there is no murein present Ribosomes are larger 80s
80
3 domains i should know
Bacteria Archaea Eukarya

A-Level Biology (14 decks)

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