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Edexcel SNAB A Level Biology > Topic 4 - Biodiversity and Natural Resources > Flashcards

Topic 4 - Biodiversity and Natural Resources Flashcards

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1
Q

What is a species?

A

A group of organisms with similar morphology, physiology and behaviour, which can interbreed to produce fertile offspring and which are reproductively isolated from other species

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2
Q

What is a habitat?

A

The area inhabited by a particular organism/species

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3
Q

What is a population?

A

A group of interbreeding individuals within an area

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4
Q

What is a community?

A

All the various populations within a habitat

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5
Q

What is an ecological niche?

A

The way an organism uses/exploits it’s environment

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6
Q

What does a niche include?

A
  • interactions with other organism
  • interactions with the non living environment
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7
Q

What will happen if 2 species try to occupy the same niche?

A

They will compete with each other and one species will inevitably be more successful and outcompete the other

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8
Q

What is a behavioural adaptation?

A

Actions taken by organisms to survive or reproduce

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9
Q

What are some examples of behavioural adaptations?

A

Possums playing dead if threatened by predator
Plants turning leaves to sun to maximise photosynthesis

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10
Q

What is a physiological adaptation?

A

A feature of the internal workings of organisms that help them to survive of reproduce

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11
Q

What are some examples of physiological adaptations?

A

Brown bears hibernate and lower rate of metabolism to conserve energy
Bacteria produce antibiotics to kill threatening bacteria

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12
Q

What is a structural adaptation?

A

Structural features of organisms for survival/reproduction

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13
Q

What are some examples of structural adaptations?

A

Otters have a streamlined shape to glide through water
Whales have a layer of blubber for insulation

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14
Q

What is evolution?

A

A change in allele frequency over time

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15
Q

How does natural selection occur?

A
  1. A population has a naturally occurring genetic variation, with new alleles created through mutation
  2. A selection pressure occurs in the environment
  3. Survival of the fittest - advantageous allele
  4. Organisms with the allele are more likely to survive, reproduce and so produce offspring
  5. Their offspring are more likely to have the allele, so it becomes more common in the population
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16
Q

What is speciation?

A

The formation of a new species

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17
Q

What must happen for speciation to occur?

A

Reproductive isolation

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18
Q

How does geographical isolation lead to speciation?

A
  1. geographical isolation (mountain, river etc) prevents a group of individuals from breeding with the rest of the population
  2. over time the 2 groups become less like each other as they respond to different selection pressures and random mutations accumulate
  3. eventually, 2 groups cannot interbreed to produce fertile offspring
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19
Q

What is a gene pool?

A

All the alleles of all the genes present in a population

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20
Q

What is the benefit of having a bigger gene pool?

A

Populations with a bigger gene pool are said to have a greater genetic diversity - they are more likely to possess alleles that allow them to survive

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21
Q

What is the Hardy Weinburg equation used for?

A

To see if there has been a change in allele frequency over time

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22
Q

What is the Hardy Weinburg equation?

A

q squared (freq of homozygous recessive individuals) + 2pq (freq of heterozygous individuals) + p squared (freq of homozygous dominant individuals) = 1
p + q = 1

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23
Q

What are the conditions/assumptions of the Hardy Weinberg equation?

A
  • random mating
  • infinitely large population
  • no migration, mutation or natural selection
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24
Q

What factors determine the ability of a population to adapt to new conditions?

A
  1. strength of selection pressure
  2. size of gene pool
  3. reproductive rate of organism
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25
Q

What is biodiversity?

A

The variety of species in an ecosystem/community/habitat
The variety of alleles in a gene pool

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26
Q

What are the 3 levels to assess biodiversity?

A
  • number and range of different ecosystems/habitats
  • number of species and their relative abundance
  • genetic variation within each species
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27
Q

What is endemism?

A

a species only found in one geographical location

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28
Q

What is species richness?

A

The number of a species present in a given habitat

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29
Q

What is species evenness?

A

The relative abundances of different species within a community

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30
Q

What is the equation for the Index of Diversity?

A

D = N(N-1)/Σn(n-1)
where N = number of organisms in the habitat
and n = number of organisms of each species
High D value = greater biodiversity

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31
Q

What is a biodiversity hotspot?

A

Areas of particularly high biodiversity

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32
Q

What does the Heterozygosity Index measure?

A

Genetic diversity within a species

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33
Q

What is the equation for the Heterozygosity Index?

A

H = number of heterozygotes/number of individuals in the population

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34
Q

What is genetic diversity?

A

The variety of the alleles in the gene pool of a species or population

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35
Q

What can you look at to measure genetic diversity?

A

Genotype - genetic makeup of an organism
Phenotype - observable characteristics of an organism

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36
Q

Where does genetic diversity come from?

A

Mate selection, random fertilisation, chromosome mutations, meiosis

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37
Q

What information should you collect for studies of biodiversity?

A
  • presence of endemic/rare species
  • use of a diversity index
  • genetic diversity of populations
  • species richness
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38
Q

What is classification, and why do we classify organisms?

A

The process by which scientists group living organisms
Allows us to look at evolutionary relationships

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39
Q

What is the order of the hierarchy of classification?

A

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

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40
Q

What is phylogeny?

A

The study of the evolutionary history of groups of organisms

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41
Q

What is molecular phylogeny?

A

The study of molecular differences in DNA/RNA of proteins. It looks at evolutionary relationships

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42
Q

What are phylogenetic trees?

A

Representation of evolutionary relationships based on molecular differences accumulated over time

43
Q

What were the 5 traditional kingdoms?

A

Plantae
Fungi
Animalia
Protoctista
Prokaryotae

44
Q

What are the 3 newer domains?

A

Archaea
Bacteria
Eukaryota

45
Q

Why were the 3 domains created?

A

To create 2 separate bacteria categories - molecular phylogeny had determined that archaea and bacteria were more distantly related than initially thought

46
Q

What is the structure and function of a plant cell wall?

A

Composed of cellulose
Provides cell with structural support

47
Q

What is the structure and function of the middle lamella?

A

Outermost layer of cell, produced between adjacent new cells
Holds cell walls together by acting like a sticky glue

48
Q

What is the structure and function of the plasmodesmata?

A

Narrow threads of cytoplasm connecting cytoplasm of neighbouring cells (cytoplasmic connection)
Allows efficient exchange of signalling molecules between neighbouring cells (allows transport/communication)

49
Q

What is the structure and function of a pit?

A

Thin region of the cell wall
Facilitates the transport of substances

50
Q

What is the structure and function of a chloroplast?

A

Double membrane with thylakoids containing chlorophyll in stacks called grana
Site of photosynthesis

51
Q

What is the structure and function of an amyloplast?

A

Small membrane bound organelles containing starch granules
Store starch and synthesise it

52
Q

What is the structure and function of the vacuole and tonoplast?

A

Vacuole - cell sap filled sac, tonoplast is the membrane that surrounds it
Vacuole keeps cell turgid, tonoplast regulates ion movements around cell

53
Q

What 3 basic principles do plant cells use to build structures?

A

Strong cell walls from cellulose
Columns and tubes made from specialised cells
Stiffen some of these cells with lignin

54
Q

What is cellulose?

A

A polysaccharide made up of beta glucose units

55
Q

How do 2 beta glucose molecules join?

A

Via a condensation reaction
B glucose molecules are rotated alternately through 180 dgrees, creating a 1-4 glycosidic bond

56
Q

What is a cellulose microfibril?

A

A bundle of around 60-70 cellulose molecules

57
Q

What is the structure of a cellulose microfibril?

A

Parallel chains of cellulose polymers
H bonds form between the neighbouring molecules due to hydroxyl groups

58
Q

What holds cellulose microfibrils together?

A

Hemicellulose and pectins (short polysaccharides) which bind to the cellulose and each other

59
Q

What is the xylem and how is it adapted for it’s function?

A

Long tube like structure formed from dead cells placed end to end for the transport of water and mineral ions
Adaptations: hollow lumen, no end walls (allows mass flow), thickened with lignin (strength to withstand hydrostatic pressure), pits allow lateral movement of water (in case of air bubbles)

60
Q

What happens in mature lignified xylem cells?

A

They are dead

61
Q

What is the phloem and how is it adapted to it’s function?

A

A transport tissue made of sieve tube elements joined together for the transport of sucrose and other dissolved nutrients
Adaptations: sieve cells have no nucleus or other organelles (maximises space for translocation), they have a companion cell which provide the energy for active transport (lots of mitochondria), sieve pores allow continuous movement, plasmodesmata links sieve tubes to companion cells

62
Q

What is the difference between mature phloem and xylem cells?

A

Mature phloem contain living cells, unlike mature xylem which are dead

63
Q

What is the sclerenchyma and how is it adapted to it’s function?

A

Support fibres made of bundles of dead cells thickened with lignin - provides mechanical support
Adaptations: lignification of cell wall, hollow inside, dead cell

64
Q

Why would the structure of sclerenchyma make these fibres useful to make rope?

A

Thick lignin walls for strength
Lignin makes them waterproof
Flexible so do not break easily
Light because they are hollow

65
Q

Why are plant fibres so strong?

A

Due to factors affecting the cell wall:
- the arrangement of microfibrils in a mesh like pattern
- secondary thickening (development of a secondary cell wall which contains lignin)

66
Q

How is water transported in the xylem?

A

Transpiration stream: water is pulled up as it evaporates out of the stomata due to the tension of the H bonds and cohesive forces

67
Q

How are inorganic ions transported by the xylem?

A

The movement of water through the xylem provides a mass flow system for transport

68
Q

Why are plant fibres useful to humans (and give an example of how they’re used)?

A

They are very strong
Ropes and fibres

69
Q

Why are plant fibres sustainable?

A

Less fossil fuels used
Can be replanted for next generation (resources made available for future generations)
Plant fibres are biodegradable
Cheaper and easier to grow and process

70
Q

How can starch contribute to sustainability?

A

Can be used to make bioplastics, which are more sustainable as crops can be regrown and there are no fossil fuels
Can make fuel from starch

71
Q

How can the use of starch (over plastic) contribute to sustainability?

A

Starch is a renewable resource, plastic is derived from oil which is a non renewable resource

72
Q

What is the importance of water to plants?

A
  • Solvent properties (can transport dissolved substances)
  • Thermal properties (cools and heats slowly to avoid rapid changes in internal temp)
  • Density/freezing (ice is less dense than water as water expands as it freezes)
  • Cohesion and surface tension (H bonds keep water molecules in a column in xylem vessels)
73
Q

What is the importance of water and different inorganic ions to plants?

A

Water - photosynthesis, transport medium, turgidity, temp regulation
Mg ions - production of chlorophyll (yellow leaves, plants smaller)
Nitrate ions - plant growth, DNA and protein synthesis (stunted growth)
Ca ions - cell wall growth (middle lamella - leaves cannot grow fully without)

74
Q

What are the conditions required for bacterial growth?

A
  • nutrients (materials to grow and respire)
  • oxygen (if respiring aerobically)
  • optimum temp/pH to allow correct enzyme function
75
Q

What 2 things must new drugs be tested for?

A

Efficacy
Side effects

76
Q

Why are healthy volunteers in a drug trial given different doses of the drug or placebo?

A

Check for side effects, different doses to determine safe dose, placebo to ensure side effects were due to drug

77
Q

Why are placebos used to test the efficiency of new drug treatments?

A

Placebo = inactive substance
Used as a control
So that psychological effect does not take place (placebo effect)

78
Q

What did William Withering do with foxglove?

A

Used it to treat dropsy - contains drug digitalis. However foxglove can be poisonous so he tried out different doses on his dropsy patients to find a ‘safe’ dose

79
Q

What are the stage of drug testing today?

A

Pre-clinical - animal and lab studies
PHASE I - small group of healthy volunteers
PHASE II - small group of volunteer patients who need the drug
PHASE III - large number of patients split into 2 groups (double blind). If successful, becomes licensed
Post licensing - begin development of new drug

80
Q

What is a double blind trial?

A

One set of patients receives real drug, other set = placebo
Neither doctors or patients know whether they have received placebo or real drug to remove the bias from results

81
Q

What is a placebo?

A

A dummy drug to ensure there is not just a ‘placebo’ effect

82
Q

How is contemporary drug testing protocol an improvement on the trial used by William Withering?

A

SAFER - pure drug rather than extract, pre testing on cells/animals rather than people, legislated by regulations
MORE VALID - placebo, double blind, controlling factors in cohort
MORE RELIABLE - more people tested, analysed statistically

83
Q

What is conservation?

A

The wise use of natural resources and planning and carrying out action to preserve and protect living and non-living resources

84
Q

What are the 2 approaches to conservation?

A

In-situ - conserving species in it’s natural environment
Ex-situ - conserving a species by taking it out of it’s natural environment

85
Q

What happens when a species goes extinct?

A

There is an overall decrease in biodiversity

86
Q

What is an endangered species?

A

One that is threatened with extinction

87
Q

What is a seed bank?

A

A facility that conserves plant diversity by drying and storing seeds in a temperature controlled environment

88
Q

Why do we need seed banks?

A

25% of Earth’s plant population will disappear over next 50 years.
Save genetic material, plants are essential for animal survival and are a carbon sink

89
Q

What are the stages of seed bank storage?

A

Seed collected, transferred to seed bank and unpacked and checked.
Seed cleaned and identification checked
Seeds are dried and packed
Seeds stored at -20 degrees C
Periodic germination trials to check seed viability

90
Q

What are the advantages of seed banks?

A

Less labour intensive, more cost effective, makes seeds less vulnerable
Ensures future food security, conserves genetic diversity, protects from natural disasters/mismanagement

91
Q

What are the disadvantages of seed banks?

A

Testing seeds is time consuming and expensive, some seeds are difficult to collect

92
Q

How are seeds selected for storage in the seed bank?

A

From different plants to provide genetic variation, X rayed to ensure/check viability

93
Q

What conditions are seeds stored at in seed banks and why?

A

Cool and dry
- reduce enzyme activity
- prevent germination/keep seed dormant
- reduce growth of microbes
- decrease rate of decomposition

94
Q

Why is it better to store seeds than fully grown plants?

A
  • seeds are smaller so more can be stored
  • seeds can be stored for a longer time (dormancy)
  • do not require maintenance in the same way as growing plants
  • reduced cost
95
Q

How can zoos help conservation?

A
  • scientific research
  • captive breeding to increase number in the wild
  • reintroduction programmes
  • education
96
Q

What are the disadvantages of zoos?

A

Ethical concerns, captive breeding can lead to genetic drift and loss of genetic diversity, scientific data unreliable due to captivity conditions, certain animals may not breed in captivity

97
Q

What are the advantages of reintroduction programmes?

A

Prevents extinction, rebalance ecosystems, restore habitats

98
Q

What are the disadvantages of reintroduction programmes?

A

New organisms may carry disease, a struggle to readjust to the wild and therefore may die.

99
Q

How does the scientific community critically evaluate new theories?

A
  • theories communicated to scientific community
  • peer review
  • checking of evidence to ensure its validity
100
Q

Why would you use systematic sampling instead of random sampling?

A

Due to presence of environmental gradient

101
Q

How can differences in primary structure of a protein be used to produce phylogenetic trees?

A
  • determine sequence of amino acids
  • determine number of similarities/differences in amino acid sequence
  • greater number of differences = less related species are
102
Q

How do zoos play a role in animal conservation?

A
  • research (improving health, developing genetic database)
  • education (conservation)
  • repopulation (captive breeding and reintroduction programmes)
  • protection (from poachers)
103
Q

How do captive breeding programmes in zoos maintain genetic diversity of captive populations?

A
  • animals carefully selected to prevent breeding between closely related individuals
  • stud book used to select individuals for mating (preventing inbreeding)
  • exchange of animals between zoos

Edexcel SNAB A Level Biology (9 decks)

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