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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
Q

types of characteristics

A

continuous and discontinuous

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26
Q

properties of discontinuous characteristics

A

characteristics fall into certain groups with no overlap (blood group) determined by genetics only (a single gene)

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27
Q

properties of continuous characteristics

A

characteristics show a range (height) determined by genetics (a few genes, polygenes) and their environment

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28
Q

genetic diversity definition

A

genetic variation

variety of alleles within a population of a species

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29
Q

benefits of high genetic diversity

A

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

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30
Q

what can lower genetic diversity

A

small population size

founder effect, genetic bottleneck

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31
Q

what is the founder effect

A

where numbers in population start low

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32
Q

genetic bottleneck

A

where numbers in population decrease

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33
Q

what is natural selection and adaptation

A

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
Q

2 types of selection

A

stabilising

directional

35
Q

stabilising selection

A

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
Q

directional selection

A

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
Q

gene definition

A

section of dna that codes for a protein

made out of introns and extrons

38
Q

intron definition

A

non-coding dna

turns gene on or off

39
Q

exon definition

A

coding part of dna

codes for a protein

40
Q

how does a gene/exon code for a protein

A

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
Q

properties of triplet code

A

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
Q

how does a mutation lead to a non-functional enzyme

A 
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
Q

how is a protein assembled

A

transcription and translation

44
Q

transcription definition

A

production of a single stranded complementary copy of a gene called mrna

45
Q

translation defiition

A

use sequence of codons on mrna to assemble protein, trna brings in amino acids

46
Q

dna vs rna

A

deoxyribose sugar vs ribose sugar
thymine vs uracil
double stranded vs single stranded
one type vs two types (mrna and trna)

47
Q

names of nucleotide bases

A 
adenine
thymine 
cytosine 
guanine
uracil
48
Q

what is mrna

A

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
Q

what is trna

A

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
Q

what is transcription

A

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
Q

what is translation

A

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
Q

what does meiosis produce

A

4 genetically different cells

haploid

53
Q

benefits of meiosis

A

produces gametes which are used in sexual reproduction

2 gametes fuse to form a zygote which develops into an organism

54
Q

stages of meiosis

A

interphase
meiosis 1
meiosis 2
cytokinesis

55
Q

process of meiosis

A

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
Q

how does meiosis produce variation

A

crossing over and independent assortment

57
Q

crossing over

A

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
Q

independent assortment

A

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
Q

what happens to dna mass in meiosis

A

quarters

60
Q

what happens to chromosome number in meiosis

A

halves

61
Q

mutation definition

A

change in the dna sequence

2 tpyes: chromosome mutation and gene mutation

62
Q

what causes mutations

A

random

or due to mutagenic agents (chemicals, radiation)

63
Q

chromosome mutation

A

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
Q

what is a gene mutation

A

change in the base sequence of dna

2 types= substitution and insertion/deletion

65
Q

substitution

A

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
Q

insertion and deletion

A

adding a base
or deleting a base
cause frameshift, all triplet codes after mutation changes so normal polypeptide chain/protein isn’t produced

67
Q

Prokaryotic DNA

A

Shorter
Circular
Not associated with histones
No chromosomes

68
Q

Eukaryotic DNA

A

Longer
Linear
Associated with his tones
Form chromosomes

69
Q

DNA in mitochondria and chloroplasts

A

Short
Circular
Not associated with his tones

70
Q

What do courtship behaviors allow individuals to do

A 
Recognize members of their own species 
Identify a mate capable of breeding 
Form a pair bond 
Synchronize mating 
Become able to breed
71
Q

Recognizing members of their own species

A

To ensure mating only takes place between members of the same species so they can produce fertile offspring

72
Q

Identify a mate that is capable of breeding

A

Both partners need to be sexually mature, fertile and receptive to mating

73
Q

Form a pair bond

A

Lead to successful mating and raising of offspring

74
Q

Synchronize mating

A

So it takes place where there is the maximum probability of the egg and sperm meeting

75
Q

Become able to breed

A

Bringing a member of the opposite sex into a physiological state that allows breeding to occur

76
Q

Artificial classification

A

Divides organisms due to characteristics that are useful at the time
Analogous characteristics
Same function but not the same evolutionary origins

77
Q

Bacteria

A 
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
Q

Archaea

A

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
Q

Eukarya

A

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
Q

3 domains i should know

A

Bacteria
Archaea
Eukarya

A-Level Biology (14 decks)

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