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A Level Biology (SNAB) > Topic 4 > Flashcards

Topic 4 Flashcards

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1
Q

Biodiversity

A

Variety of living organisms in the area

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2
Q

Species diversity

A

The no. of different species & abundance of each specie within a given area

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3
Q

Genetic diversity

A

Variation of alleles within a species (e.g. blood type = three alleles)

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4
Q

Endemism

A

Species unique to a single place

e.g. Giant tortoise = endemic to Galapagos islands

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5
Q

Anthropogenic affect on biodiversity

A

Reduced via farming and deforestation

- conservation = important, especially for endemic species

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6
Q

Natural Selection

A

The pressure that causes groups of organisms to change over time

  • > adaptation
  • > evolution
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7
Q

Habitat

A

Where organisms live

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8
Q

Measuring species diversity in a habitat

A
  1. count no. of different species = species richness (no. = indication of abundance)
  2. count no. of different species + abundance of them
    - > index of diversity equation to calculate diversity

note: compare + note change

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9
Q

Sampling (method)

A
  1. area
  2. random sample (avoid bias)
  3. count no. of each species
    - plants = quadrat
    - insects (flying) = sweepnet (net on a pole)
    - insects (ground) = pitfall trap
    - aquatics = net
  4. repeat
  5. estimate
  6. sample different habitats using same technique
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10
Q

Measuring genetic diversity (within a species)

A

To measure look at:

  1. Phenotype = observable characteristics
    - different types -> idea of alleles
    e. g. greater genetic diversity for eye colour in northern Europe than rest of the world
  2. Genotype = DNA samples taken & sequence of base pairs analysed
    - base order in different alleles differs slightly
    - sequencing DNA -> look at similarities + differences
    - measure no. of different alleles for one characteristic
    - look at heterozygosity index
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11
Q

Gene pool

A

complete set of alleles in population

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12
Q

Diversity within a species

A

Diversity within a species = variety shown by individuals/population
- variation -> alleles

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13
Q

Genetic diversity

A

Variety of alleles in gene pool

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14
Q

Heterozygosity Index

A

Measures genetic diversity

  • two different alleles at particular locus
  • higher proportion of heterozygotes -> greater genetic diversity
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15
Q

Heterozygosity Index Equation

A

H = (no. of different alleles at particular locus) / (no. of individuals in population)

  • > average value for H at many loci
  • estimate diversity in whole genome of population
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16
Q

Index of Diversity

A

D = ( N ( N-1 )) / ( Σn ( n-1 ))

-> higher number = more diverse; compare different habitats

D = Index of diversity
N = total number or organisms of all species
n = total number of organisms of one species
Σ = sum of
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17
Q

Niche

A

Role of species within a habitat
Only occupied by one species -> competition
- interactions with living organisms & environment

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18
Q

Niche: Common Pipistrelle Bat

A

British farmland bat
- open woodland, hedgerows, urban
Flies & catches insects
- echolocation: frequency = 45 kHz

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19
Q

Niche: Soprano Pipistrelle Bat

A

British woodland bat
- close to lakes + rivers
Flies & catches insects
- echolocation: frequency = 55 kHz

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20
Q

Organism adaptation to niche

A
  1. Behavioural
  2. Physiological
  3. Anatomical
    note: increase survival
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21
Q

Organism adaptation to niche: Behavioural

A

Ways an organism acts

  • Possums -> play dead
  • Scorpions -> ‘dance’ before mating
  • > ensures (likelihood of) same species mating
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22
Q

Organism adaptation to niche: Physiological

A

Processes inside an organism’s body

  • brown bears -> hibernate (lower metabolic rate) as food scare over winter
  • some bacteria are antibiotic resistance (ensures survival over though who are not)
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23
Q

Organism adaptation to niche: Anatomical

A

Structural features of an organism’s body

  • otters = streamlined -> glide through water
  • whales = thick blubber layer -> warm in cold sea (location of food source)
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24
Q

Evolution -> increases adaptation

A
  1. Mutation -> new alleles -> phenotype variation
  2. Selection pressure (predation/disease/competition) -> survival struggle
  3. no advantageous allele -> die -> survival struggle
    - > better adaptation -> increased survival -> more likely to reproduce -> pass on allele
    - > allele population increases overtime
    - > evolution
    - > Charles Darwin = natural selection
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25
Q

Evolution: Peppered Moths

A 
Variation in colour (light + dark)
1800's = more light coloured
- pollution -> blackened trees
- dark = more camouflaged
- light -> predation (stood out)
-> (overtime) dark moths = more common
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26
Q

Speciation

A

Development of a new species (genetically distinct),
via:
1. Reproductive isolation
- Seasonal changes = develop different flowering/mating seasons; sexually active at different times
- Mechanical changes = genitalia altered
- Behavioural changes = courtship rituals alter
2. Random mutation
3. Geographical isolation
- physical barrier divides population
- conditions either side of barrier differ slightly
- selection pressure -> different characteristics become more common
-> allele frequencies change
-> independent mutations not spread through population
-> change in phenotype frequencies

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27
Q

Species

A

Group of similar organisms that can reproduce to produce fertile offspring

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28
Q

Evolution

A

Change in allele frequency

  • percentage calculated by Hardy-Weinberg principle
  • new alleles = gene mutation
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29
Q

Hardy-Weinberg principle

A

Predicts allele frequencies will not change over time

Certain conditions:

  • large population
  • no immigration
  • no migration
  • no mutations
  • no natural selection
  • random mating
30
Q

Hardy-Weinberg equation (predict allele frequencies)

A

p + q = 1

  • p = frequency of dominant allele
  • q = frequency of recessive allele
31
Q

Hardy-Weinberg equation (Gentotype + Phenotype frequency)

A

p^2 + 2pq + q^2 = 1

  • p^2 = frequency of homozygous dominant genotype
  • 2pq = frequency of heterozygous genotype
  • q^2 = frequency of homozygous recessive genotype
32
Q

What is an indication of a population evolving

A

Allele frequencies

33
Q

Classification

A

Grouping together similar organisms

34
Q

Taxonomy

A

Science of classification (naming + organising)

8 taxonomic groups

35
Q

Taxonomic groups

A
  1. Domain
  2. Kingdom
  3. Phylum
  4. Class
  5. Order
  6. Family
  7. Genus
  8. Species
36
Q

Species naming

A

Binomial word
1st = genus
2nd = species

37
Q

5 Kingdoms

A

= all organisms

  1. Prokaryotae (monera)
  2. Protoctista
  3. Fungi
  4. Plantae
  5. Animalia
38
Q

Prokaryotae (monera) Kingdom

A

Bacteria

  • Prokaryotes
  • Unicellular
  • No nucleus
  • x < 5μm
39
Q

Protoctista Kingdom

A

Algae, Protozoa

  • Eukaryotic Cells
  • water (emvironment)
  • single-celled
  • simple multicellular
40
Q

Fungi Kingdom

A

Moulds, Yeast, Mushrooms

  • eukaryotic
  • chitin cell wall
  • saprotrophic
41
Q

Plantae Kingdom

A

Moses, Ferns, Flowering plants

  • eukaryotes
  • multicellular
  • cellulose cell wall
  • photosynthesise
  • chlorophyll
  • autotrophic
42
Q

Animalia Kingdom

A

Nematodes, Molluscs, Insects, Fish, Reptiles, Birds, Mammals

  • Eukaryotes
  • Multicellular
  • no cell walls
  • heterotrophic
43
Q

Heterotrophic

A

Consume plants and animals

44
Q

Autotrophic

A

Produces own food

45
Q

Saprotrophic

A

Absorb substances from dead/decaying organisms

46
Q

Three domain system

A

New data (molecular phylogeny) -> new taxonomic groupings

Domains = Superkingdoms, above kingdoms in hierarchy:

  1. Archaea
  2. Bacteria
  3. Eukaryota

Prokaryotae -> Archaea + Bacteria (more distantly related)
Other 4 Kingdoms -> Eukaryota

47
Q

Molecular Phylogeny

A

MP = looks at molecules to see how closely related an organism is

Phylogeny = study of molecular history of organism groups

48
Q

Conservation (reason)

A 
Species extinction (or loss of species genetic diversity) -> loss of global biodiversity
Counteract + reintroduce
49
Q

Seedbanks

A

Stores seeds from different plant species
Helps to conserve genetic diversity
- cool + dry conditions needed for storage
- Testing for viability (planted -> grown -> seeds harvested)

50
Q

Seedbanks (+/-)

A 
\+ Cheaper = seeds
\+ large number -> less space
\+ less labour
\+ stored anywhere
\+ less likely to be damaged (disease, natural disaster)
  • Viability testing -> expensive + time consuming
  • too expensive to store all seeds + test regularly
  • difficult to collect some seeds (remote locations)
51
Q

Zoos (captive breeding programs)

A

Animals bred in controlled environment

  • problems breeding outside natural habitat
  • > hard to recreate
  • e.g. Pandas do not breed as successfully
  • considered cruel

Reintroduced into wild

  • e.g. Californian Condor = 22 birds left -> 300 (half reintroduced)
  • help habitat restoration + reliance of/on other organisms
  • could bring new diseases
  • may not behave as if raised in the wild (decreased survival likelihood)
52
Q

Scientific Research + Education (Seedbanks + Zoos)

A

Seedbanks -> study successful growing methods

  • medical research (no removing wild population)
  • limits data to interbred population (small)
  • > provide training + local seedbanks
  • > Millenium seedbanks = in own country

Zoos -> increase knowledge of behaviour, physiology & nutritional needs

  • nutritional + reproductive studies (not possible in the wild)
  • Captivity -> may act different
  • > increase enthusiasm for conservation (up close interactions)
53
Q

Cell Wall

A

Rigid structure that surrounds plant cells & supports them
- Mainly made of carbohydrate Cellulose

54
Q

Middle Lamella

A

Outer most layer of cells, acting as an adhesive to stick adjacent cells together, giving them stability

55
Q

Plasmodesmata

A

Channels in cell walls that link adjacent cells together

- allows transports of substances and communication between cells

56
Q

Pits

A

Cell wall regions that are very thin, and arranged in pairs (lined up with adjacent cell)
- allows transport of substances between cells

57
Q

Chloroplast

A

Small Flat structures
Double Membrane
Inside = thylakoid membranes (-> stacked = granum)
Grana linked by lamella = thin flat pieces of thylakoid membrane
Stroma = thick fluid inside
- where photosynthesis occurs: grana (light dependent) & stroma (light independent)

58
Q

Amyloplast

A

Small organelle enclosed by membrane
Contains starch granules
- stores starch grains
- converts starch -> glucose

59
Q

Vacuole

A

Compartment containing cell sap, surrounded by a Tonoplast (membrane)

  • cell sap = water, enzymes, minerals, waste
  • keeps cell turgid
  • breakdown + isolation of unwanted chemicals
60
Q

Tonoplast

A

Membrane that surround vacuole

- controls what enters + leaves

61
Q

Xylem Vessels

A
  1. function = water + mineral ion transport (up the plant)
    - > provide support
  2. long tube like structures, formed from dead cells joined end to end
    - formed in bundles
  3. cells = longer than wide
    = hollow lumen (no cytoplasm)
    = no end walls
    -> unitterupted tube for transport through middle
  4. walls = thickened with woody substance = lignin
    - > helps support
  5. Water + mineral ions move in/out via pits in the wall (no lignin present)
62
Q

Sclerenchyma Fibres

A
  1. provide support
  2. bundles of dead cells running vertically up the stem
  3. Cells = longer than wide
    = hollow lumen
    = have end walls
  4. cells thickened with lignin
    - more cellulose (than other plant cells)
    - no pits
63
Q

Phloem Tissue

A
  1. Transports organic solutes (e.g. sucrose) from where there made in plant -> needed
    = TRANSLOCATION
  2. Arranged in tubes (non-supportive)
  3. Sieve tube elements = living cells with no nucleus
    - joined end to end -> sieve tubes
    - thin cytoplasm layer
    - few organelles
  4. ‘Sieve’ = end wall
    - lots of holes -> solutes
  5. Sieve Plates =through which the cytoplasm of adjacent cells is connected via holes in the plates
  6. Companion cells = living function for themselves & sieve cells
    - energy
    - active transport
    - all sieve tube elements have companion cell as without nucleus + other organelles they cannot survive
64
Q

Vascular Bundels

A

Xylem + Phloem grouped together

  • sclerenchyma fibers associated
  • present in (plant) stem

note: Xylem = inside
Phloem = middle
sclerenchyma = outside

65
Q

Starch

A

Main energy source in plants

  • Cells = energy from glucose; excess -> starch
  • Starch = amylose + amylopectin
  • insoluable in water -> good for storage (does not alter osmotic potential
66
Q

Cellulose

A

Major component of plant cell walls

  • long unbranched chains of Beta glucose
  • joined via 1-4 glycosidic bonds
  • bonds = straight -> chain = straight
  • 50 to 80 chains
  • linked via ( many) hydrogen bonds
  • > strong threads = Microfibrils
  • > structural support
67
Q

Plant Fibres = Strong, because…

A
  1. Arrangement of microfibrils = net like in cell wall
  2. Secondary thickening of cells walls
    - structural (xylem + sclerenchyma) cells finish growing
    -> second cell wall between original + cell membrane
    = thicker + more lignin
68
Q

Microfibril

A

50 to 80 cellulose chains linked via hydrogen bonds

69
Q

Drug Testing (modern method)

A
  1. Computers model potential effects
  2. Tests carried out on human tissues in lab
  3. Tested on live animal(s)
  4. Clinical (human) trials: three phases
70
Q

Phases of clinical trials

A
  1. New drug
    - small group of healthy individuals
    - safe dosage
    - side effects
    - body’s reaction
  2. Larger group
    - includes patients
    - test effectiveness
  3. Drug compared to existing treatment
    - tests on hundred to thousands of patients
    - > large sample = more reliable results
    - patients randomly split into two groups
    - > double blind study + placebos
    - > new drug + existing drug

note:
double blind study = neither patient nor doctor knows who has what
- reduces bias (perception + want)

71
Q

Digitalis soup (Trial + Error)

A

William Withering (1700s) chance observation of patient treated with traditional foxglove remedy

  • Foxglove extract -> dropsy treatment (swelling caused via heart failure)
  • drug = Digitalis
Foxgloves = poisonous
- tested different versions with different concentrations of digitalis
= Digitalis Soup
-> too much = poison
-> too little = no effect
-> trial + error -> treatment discovered

A Level Biology (SNAB) (10 decks)

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