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Higher Biology > Unit 3 > Flashcards

Unit 3 Flashcards

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1
Q

What do density-dependant factors include?

A
  • competition for nutrients
  • the transmission of disease
  • the level of predation
  • the build-up of toxic wastes
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2
Q

what is population density?

A

the number of individuals present per unit area (or volume) of a habitat

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3
Q

What happens when a population density increases?

A

each individual has access to fewer resources

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4
Q

What is our human populations dependant upon?

A

sufficient and sustainable food production from the harvest of a relatively narrow range of crop and livestock species

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5
Q

What is food security?

A

the ability of human populations to access food of sufficient quality and quantity

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6
Q

What do humans rely on to increase crop yields worldwide?

A

use of fertilisers and pesticides

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7
Q

Why must agriculture methods change?

A

to minimise the damage and degradation of natural resources

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8
Q

What do autotrophs (producers) use the light from the sun for?

A

to synthesise sugars and other organic compounds, which they use as fuel for cellular respiration and building materials for growth.

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9
Q

What do autotrophs include?

A

plants and algae

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10
Q

What is Arable land?

A

land which is suitable for growing crops

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11
Q

What do agricultural productions depend on?

A

factors that control plant growth

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12
Q

Factors that affect plant growth include:

A
  • temperature

- moisture

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13
Q

What does the level of soil nutrients affect?

A

productivity and yield of crop plants

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14
Q

What do water irrigating systems do?

A

increase the availability of water

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15
Q

What do greenhouse and polythene tunnels do?

A

provide shelter and controls the temperature and wind exposure

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16
Q

What do fertilisers do?

A

improve soil mineral levels

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17
Q

Factors to improve efficiency include:

A
  • breeding of higher yielding cultivars
  • protection of crops from pests
  • protections of crops from diseases
  • protections of crops from competition
  • use of fertilisers
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18
Q

what is a Cultivar?

A

(Cultivated Variety)

a plant selected for desirable characteristics

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19
Q

Problems associated with upkeep of livestock ;

A

livestock produce less food per unit area than plant crops due to loss of energy between trophic levels.

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20
Q

How much energy is lost between each level?

A

90%

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21
Q

Why are food chains relatively short?

A

because of the inefficiency of energy transfer along the chain

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22
Q

Energy enters most ecosystems as what?

A

sunlight

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23
Q

What is Net Assimilation?

A

Increase in mass due to photosynthesis - loss due to respiration

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24
Q

How can net assimilation be found?

A

by measuring the increase in dry mass per unit leaf area

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25
Q

What is productivity?

A

the rate at which plants accumulate or generate new biomass over a period of time.

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26
Q

what is productivity measured in?

A

grams per square metre per year

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27
Q

What is of low economic value?

A

a wheat stalk

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28
Q

What is of high economic value?

A

a kernel

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29
Q

What is a biological yield?

A

the total biomass produced

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30
Q

what is a economic yield?

A

the biomass of the desired product

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31
Q

What is harvest index?

A

Dry mass of biological yield

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32
Q

What absorbs sunlight?

A

a plants leaves

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33
Q

What is the energy of sunlight converted to?

A

chemical energy of food

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34
Q

Where does photosynthesis occur?

A

chloroplasts

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35
Q

What is the equation for photosynthesis?

A

carbon dioxide + water + light energy —-> glucose + oxygen

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36
Q

Light is a form of energy known as what?

A

electromagnetic energy

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37
Q

What 3 things can happen to light when it hits an object?

A
  • reflected
  • transmitted
  • absorbed
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38
Q

Substances that absorb light are known as what?

A

pigments

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39
Q

Why does a leaf appear green?

A

contains the pigment chlorophyll

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40
Q

Where is the chlorophyll contained within?

A

Thylakoid membrane

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41
Q

What is the space within the chloroplast called?

A

stroma

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42
Q

The ability of a pigment to absorb various wavelengths of light can be measured with what?

A

Spectrophotometer

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43
Q

what does an absorption spectrum show?

A

the “amount” of light energy absorbed by a pigment at each wavelength

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44
Q

What are the 4 main photosynthesis pigments?

A
  • chlorophyll a
  • chlorophyll b
  • carotene
  • xanthophyll
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45
Q

What are the Carotenoids made up of?

A

carotene and xanthophyll

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46
Q

What are accessory pigments?

A

broadened or extended range of wavelengths absorbed by the leaf

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47
Q

What is an action spectrum?

A

shows the rate of photosynthesis at each wavelength

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48
Q

What drives the rate of photosynthesis to the greatest extent?

A

red and blue light

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49
Q

What are “packets” of energy known as? (light)

A

photons

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50
Q

What are the two processes in photosynthesis?

A
  • light reactions

- Calvin cycle

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51
Q

Where does the first process take place?

A

Thylakoid membrane

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52
Q

What is split to provide a source of electrons and protons(H+) and oxygen?

A

Water

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53
Q

What does the light absorbed by the chlorophyll do?

A

drives the transfer of the electrons and hydrogen ions to an acceptor

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54
Q

what is the name of the acceptor in the first process of photosynthesis? and what is its function?

A

NADP+

temporarily stores the electrons and hydrogen ions

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55
Q

What generates ATP?

A

light reactions

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56
Q

What is photophosphorylation?

A

the addition of a phosphate group to ADP, during the light stages

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57
Q

What are photosystems?

A

Chlorophyll molecules that are situated along protein complexes

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58
Q

What is light said to do to the electrons?

A

“excite”’

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59
Q

What are “high-energy” electrons transferred across to generate ATP?

A

electron transport chains

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60
Q

What happens to oxygen during the light reactions?

A

it is evolved

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61
Q

What happens to hydrogen during the light reactions?

A

transferred to the coenzyme NADP

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62
Q

What happens to NADP when it is reduced ?

A

NADPH

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63
Q

What happens during the electron chain stage?

A

protons are pumped into the thylakoid lumen, providing the driving force for synthesis of ATP via ATP synthase

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64
Q

What is the role of NADPH?

A

“‘shuttles” the energy to the Calvin cycle

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65
Q

What else is energy used for?

A

photolysis

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66
Q

Where does the Calvin cycle take place?

A

the Stroma

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67
Q

What does the Calvin cycle use the products of the light reactions for?

A

to synthesise sugar from CO2

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68
Q

What are the 3 phases of the Calvin cycle?

A
  • carbon fixation
  • reduction
  • regeneration of RuBP
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69
Q

What is the equation for carbon fixation?

A

RuBisCO

RuBP + CO2 ————-> 3 - PGA

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70
Q

What is the equation for reduction?

A

ATP ————————-> ADP
3 -PGA ——————–> G3P
NADPH ———————> NADP

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71
Q

What does RuBP stand for?

A

Ribulose Bisphosphate

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72
Q

What does 3-PGA stand for?

A

3-phosphoglycerate

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73
Q

What does G3P stand for?

A

Glyceraldehyde-3-phosphate

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74
Q

what happens to the remaining 5 molecules of G3P?

A

recycled

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75
Q

What is the starting material for metabolic pathways that synthesise organic compounds?

A

G3P

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76
Q

Examples of organic compounds?

A

Glucose, sucrose, cellulose and starch

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77
Q

What does intensive farming reduce?

A

species diversity

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78
Q

What is a weed?

A

any plant that grows where it is not wanted

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79
Q

What are the 2 types of weeds?

A
  • annual

- perennial

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80
Q

What is an annual weed?

A

completes its life cycle in 1 year

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81
Q

Properties of an annual weed:

A
  • rapid growth
  • short life cycle
  • high seed output
  • long-term seed viability
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82
Q

Give an example of an annual weed.

A

chickweed

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83
Q

What is a perennial weed?

A

persists from one year to the next

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84
Q

Properties of a perennial weed

A
  • storage organs

- reproduce vegetatively

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85
Q

Give an example of a perennial weed

A

Dandelion

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86
Q

What are the 3 invertebrate groups which are crop pests? and give an example

A
  • Insect (aphid)
  • Nematode worms (potato cyst)
  • Mollusc (snail)
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87
Q

What does a plant disease alter?

A

plants growth, appearance or function

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88
Q

What do pathogens include?

A

bacteria, fungi and viruses

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89
Q

How are most pathogens transmitted?

A

by invertebrates

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90
Q

What 2 factors are important to the success of the pathogen?

A

temperature and moisture

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91
Q

What are the results of a pathogen?

A
  • reduction in plant health
  • a lower productivity
  • poorer yield of crop
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92
Q

What does the genetic uniformity of the crops create?

A

a population that is at a high risk of any pest

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93
Q

What creates a uniform habitat?

A

large scale monocultures

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94
Q

Examples of cultural practises

A
  • ploughing
  • time of sowing
  • weeding
  • removal of crop residue
  • crop rotation
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95
Q

What are the 2 types of chemical agents?

A
  • selective

- systemic

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96
Q

examples of chemical agents and their actions

A
  • Herbicide (kills weeds)
  • pesticide ( pests)
  • Insecticide (insects)
  • Molluscicide ( molluscs)
  • Nematocide (nematodes)
  • Fungicide (fungi)
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97
Q

What does a systemic herbicide do?

A

destroys the whole plant

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98
Q

What does a selective herbicide do?

A

will only kill broad-leaved plants

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99
Q

What are the optimal conditions for fungal growth?

A
  • high humidity
  • high moisture levels
  • moderate temperatures
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100
Q

Why are air temperatures and humidity levels monitored every hour?

A

predict the most suitable time to spray crops with fungicides

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101
Q

What is the Smith Period?

A

the period when a crop plant is at greatest risk to infection

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102
Q

What should plant protection chemicals be?

A

specific, short-lived and relatively safe

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103
Q

What happens to toxic molecules as they are passed along the food chain?

A

become more and more concentrated at each level

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104
Q

What Is a toxic pesticide?

A

DDT

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105
Q

What effect does biomagnification have?

A

relatively harmless pesticides can become rapidly lethal in top predators

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106
Q

What is biomagnification?

A

chemicals build up in the cells of the organism and increase in concentration at each transfer

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107
Q

What is bioaccumulation?

A

build up in the cells of organisms to a higher concentration than in the surrounding environment

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108
Q

What is persistence?

A

not broken down in the bodies of the organisms

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109
Q

What is resistance?

A

organisms which are not affected by the pesticide

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110
Q

What is a biological control?

A

the control of a pest population through the deliberate introduction of another organism that is a potential threat or “enemy”

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111
Q

What are 3 types of biological controls? and give some examples

A
  • Predator (aphid–ladybug)
  • Parasite (whitefly)
  • Pathogen (leaf eating caterpillar)
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112
Q

What are the risks of biological control?

A
  • introduced species may become pests
  • may introduce disease and parasites
  • may disrupt food webs and food chains
  • may out-compete native species and reduce biodiversity
  • may eat and destroy native plants
  • acts as predators to native species
113
Q

What does integrated pest management involve?

A

a combination of techniques to lower pest populations and reduces the need for pesticides

114
Q

what will most IPM programmes combine?

A

cultural, chemical and biological controls together

115
Q

How can an animals wellbeing be measured?

A

through observations of their displayed behaviours

116
Q

What are the 5 Freedoms of animal welfare?

A

Freedom from

  • hunger and thirst
  • discomfort
  • pain, injury and disease
  • fear and distress
  • freedom to express normal behaviour
117
Q

What do the 5 Freedoms require?

A
  • set of environmental conditions

- can initially be very expensive

118
Q

Benefits of animals reared in stress free and improved living conditions?

A
  • grow better
  • breed more successfully
  • produce higher quality products with greater yields
119
Q

In the UK, who is the additional cost passed onto?

A

the consumer

120
Q

What do ethics refer to?

A

moral values and rules

121
Q

What are the unacceptable standards which an animal should not face?

A

overcrowding, hygiene and poor quality food

122
Q

What are the ethical impacts of a good animal welfare?

A
  • better quality of life
  • less stress
  • natural behaviours
  • less susceptible to disease
123
Q

What are the ethical impacts of a poor animal welfare?

A
  • poor quality of life
  • stressed behaviours
  • invasive treatments
124
Q

What do behavioural indicators include?

A
  • stereotypy
  • misdirected behaviour
  • failure in sexual and reproductive behaviour
  • altered level of activity
125
Q

What is Ethology?

A

the study of animal behaviour in its natural or semi-natural setting

126
Q

What is an Ethogram?

A

a list of all observed behaviours and the length of time an animal displays these.

127
Q

What word describes “ the attribution of human motivation, characteristics or behaviour to non-human animals” ?

A

Anthropomphism

128
Q

What is important when observing an animals behaviour?

A

not to draw conclusions based on parallels with human behaviour

129
Q

What kind of test can be set up to establish the conditions an animal “prefers”’?

A

preference tests

130
Q

What drives an animal to behave or act in a particular way?

A

Motivation

131
Q

What is motivation?

A

the process that arouses and directs an animal’s behaviour to satisfy on of the basic needs

132
Q

What is the definition of Symbiosis?

A

a co-evolved intimate relationship between members of two different species

133
Q

What are larger organism knows as?

A

host

134
Q

What are smaller organisms knows as?

A

symbiont

135
Q

what is Parasitism?

A

When a parasite lives within the host organism or on the surface

136
Q

How does the parasite benefit from living in the host or on the surface of it?

A

it receives energy or nutrients from the host

137
Q

How is host harmed by parasitism?

A

by the loss of nutrients

138
Q

Transmission of parasites to new hosts involves what? (3)

A
  • direct contact
  • resistant stages
  • use of a vector
139
Q

What is Direct contact?

A

When the parasite is passed directly from one host to another; when the two hosts come into close physical contact with one another

140
Q

What are resistant stages?

A

when parasites can survive through extreme conditions, can survive out with their host for some time

141
Q

What is a vector?

A

an intermediate organism that transfers a parasite from one host to the next

142
Q

What does a life cycle of a parasite require?

A

two or more hosts for completion

143
Q

What kind of metabolism do parasites have?

A

very limited

144
Q

What is Mutualism?

A

an interdependent relationship that benefits both species

145
Q

What 2 cells display similarities with bacteria?

A

mitochondria and chloroplasts

146
Q

What does the endosymbiont theory state?

A

an early ancestor of eukaryotic cells engulfed an oxygen-using non photosynthetic prokaryotic cell, eventually the engulfed cell formed a relationship with the host cell

147
Q

What is an endosymbiont?

A

a cell living within a cell

148
Q

The difference in DNA between chloroplast and nucleus

A

Chloroplast has circular DNA and nucleus has linear DNA

149
Q

What is artificial selection?

A

a form of selection in which humans actively chose which traits should be passed onto offspring

150
Q

Animal and plant hereditary has been manipulated to improve what?

A

plant crops
animal stock
and to support sustainable food production

151
Q

Breeder develop improved crops and animals with what traits?

A
  • higher food yields
  • higher nutritional values
  • pest resistance
  • disease resistance
  • ability to thrive in particular environmental conditions
152
Q

What can GM plants increase?

A

the quality and quantity of food

153
Q

What to field trials involve?

A

breeders conducting a series of trials in their pursuit of developing new varieties.

154
Q

Where will a field trial be carried out?

A

carried out in the organism’s natural environment

155
Q

Why are field trials carried out?

A

to compare the performance of different cultivars or treatments and to evaluate GM crops.

156
Q

In a field trial, the area of land will be divided into what?

A

equally sized plots

157
Q

What factors must be considered when planning field trials ?

A
  • selection of treatments
  • number of replicates
  • randomisation
158
Q

What does the selection of treatments ensure?

A
  • this ensures there is a fair comparison
159
Q

What does the number of replication ensure?

A

several replicates take account of the variability within the sample

160
Q

What does randomisation eliminate?

A

eliminates bias when measuring treatment effects

161
Q

What is inheritance? (or heredity)

A

The transmission of traits from one generation to the next

162
Q

What is genetic variation a consequence of?

A

sexual variation

163
Q

What does variation contribute to?

A

evolution through the process of natural selection

164
Q

What is outbreeding?

A

the mating of unrelated or distantly related members of a species

165
Q

Plants that are cross-pollinated are known as what?

A

outbreeding

166
Q

Animals that rely on sexual reproduction will be what?

A

outbreeding

167
Q

What is inbreeding?

A

the mating of closely relate organisms

168
Q

When does inbreeding occur?

A

when plants or animals have been selected by humans in breeding programmes.

169
Q

What happens during the breeding programmes? and what does it lead to?

A

selected animals or plants are bred for several generations until the population breeds “true” o the desired trait.
leads to the loss of heterozygotes

170
Q

What is a gene?

A

The unit of heredity that controls a characteristic

171
Q

What is a Genome?

A

The combination of genes that is possessed by an organism e.g. BB, Bb, bb

172
Q

What is a phenotype?

A

the physical attributes that are observed e.g. black coat in Guinea pig

173
Q

What are alleles ?

A

Different forms of a gene

174
Q

what is the meaning of Homozygous?

A

when an organism possesses two identical alleles of a gene e.g. BB or bb

175
Q

what is the meaning of Heterozygous?

A

When an organism possesses two different alleles of a gene e.g. Bb

176
Q

What is dominant ?

A

the allele that is expressed in the phenotype

177
Q

What is recessive ?

A

the allele that is only observed in the phenotype, if homozygous

178
Q

What is polygenic?

A

a characteristic controlled by the alleles of more than one gene e.g. height

179
Q

What are variations?

A

Differences observed in members of the same species

180
Q

What are discrete variations?

A

when the differences are clear cut and can be used to divide up a group e.g. blood group

181
Q

What are continuous variations?

A

when the differences are not clear cut and they show a wide range of values eg. height

182
Q

Avoiding inbreeding:

A

some flowering plants possess mechanisms to promote outbreeding and avoid inbreeding

183
Q

summary of inbreeding (self-pollinating plants)

A
  • self-fertilisation
  • homozygosity promoted
  • recessive, deleterious alleles normally eliminated by natural selection
184
Q

Summary of outbreeding (cross-pollinating plants and animals)

A
  • cross-fertilisation
  • heterozygosity promoted
  • recessive, deleterious alleles be present but “masked” by dominant alleles
185
Q

What is inbreeding depression?

A

this accumulation of deleterious recessive alleles

186
Q

What does inbreeding depression result in?

A

loss in vigour, size, fertility and yields

187
Q

How does natural selection reduce inbreeding depression in self-pollinating plant species?

A

by eliminating deleterious alleles

188
Q

In outbreeding species, how is inbreeding depression avoided?

A

by selecting from the desired characteristics while maintaining an otherwise genetically diverse population

189
Q

How do you overcome inbreeding depression?

A

breeders will introduce new alleles to plant and animal lines by crossbreeding with another organism possessing a different desirable characteristic

190
Q

What process is required to maintain the new breed?

A

backcrossing

191
Q

What are F1 hybrids?

A

the individual resulting from a cross between genetically dissimilar members of the same species .

192
Q

What do F1 hybrids creates?

A

a relatively uniform heterozygous crop

193
Q

what do F1 hybrids often exhibit? and what is this known as?

A

increased vigour, yield and fertility

- known as hybrid vigour

194
Q

What can the F2 be used for?

A

a source of new varieties

195
Q

What is a test cross?

A

a cross that is used to identify unwanted individuals with heterozygous alleles

196
Q

Agricultural scientists have developed mechanisms that can identify what?

A

a selected gene or a desirable characteristic, remove it and introduce it to another organism.

197
Q

Agricultural applications:

A
  • breeding
  • quality
  • disease resistance
198
Q

What is genetic engineering rapidly replacing?

A

Traditional plant-breeding programmes

199
Q

some transgenic plants have been endowed with desirable traits such as what?

A

delayed ripening and resistance to disease and spoilage

200
Q

What are the 4 traits in agriculture applications in GM crops?

A
  • herbicide resistance
  • pest resistance
  • salinity resistance
  • improved nutritional value
201
Q

What does social behaviour consist of?

A

a set of interactions among individuals of the same species

202
Q

What is the benefit of living in groups?

A

it increases the frequency of interactions between individuals

203
Q

All behaviours associated with conflict is known as what?

A

Agonistic behaviours

204
Q

What kind of behaviour signifies submission?

A

appeasement behaviour

205
Q

What does appeasement behaviour replace?

A

replaces actual attack and defence, and therefore decreases the risk of injury and reduce the energy expenditure involved in resolving conflict

206
Q

What is a disadvantage about living in close contact?

A

risks the rapid spread of parasites and disease.

207
Q

An advantage about social groups:

A

safer from predators

208
Q

What is increased survival a result of?

A

increased protection

209
Q

What 3 factors do social behaviours include?

A
  • social hierarchies
  • cooperative hunting
  • cooperative defence (social defence)
210
Q

What is social hierarchy?

A

a social structure in which members of a group are organised into a linear ranking, with each animal dominant over those below it and submissive to those above it in the hierarchy.

211
Q

How is the hierarchy established?

A

by fighting or display behaviour

212
Q

Which special privileges does a dominant wolf “earn”?

A
  • first choice of food
  • first choice of mate
  • best sleeping area
213
Q

What are the benefits of social hierarchy?

A
  • reduces conflict and aggression, real fighting is kept to a minimum and serious injury is avoided
  • reduces energy loss
  • the most dominant animal gets to eat first, ensuring it survives
214
Q

What is cooperative hunting?

A

when a group of animals work together to catch and share their prey

215
Q

What are the benefits of cooperative hunting?

A
  • increases the chances of actually attacking and killing the prey
  • larger prey can be caught, with less pursuit time per individual
  • reduced energy expenditure per individual
  • subordinate animal may gain more food than by foraging or hunting alone
  • food sharing will occur as long as the reward for sharing exceeds that for foraging individually
216
Q

What is social defence?

A

“safety in numbers” meaning “more eyes” on the lookout

217
Q

Benefits of social defence:

A
  • warns groups of danger
  • protection of offspring
  • reduces success of the predator
  • provides protection for most of the herd
218
Q

What is altruism?

A

when an animal behaves in a way that is disadvantageous to itself, a donor and beneficial to another animal, a recipient
- unselfish behaviour

219
Q

What does altruistic behaviour in related animals (kin) increase?

A

increases their “fitness” of the parents, as the survival of their offspring into the next generation maximises their “genetic representation” on the population

220
Q

What variables affect altruism?

A
  • the benefit of the recipient
  • the cost of the altruist (donor)
  • the relatedness of the donor and the recipient
221
Q

What does relatedness mean?

A
  • the probability that 2 individuals share an allele to recent common ancestry
222
Q

What is kin selection?

A

Natural selection that favours altruism by enhancing the reproductive success of relatives

223
Q

What does an animal increase by helping close relatives?

A

increases its genetic representation in the next generation

224
Q

What does reciprocal altruism involve?

A

one individual, at some cos to itself, giving help to another provided that there is a very real prospect of the favour being returned

225
Q

Examples of social insects;

A

honey bees, wasps, ants and termites

226
Q

give an example of kin selection in social insects:

A

most members of the colony are workers who cooperate with close relatives

227
Q

What are keystone species?

A

species that hold a vital role in an ecosystem

228
Q

What are primates?

A

a large diverse group of mammals that include monkeys, apes and humans

229
Q

Name a key feature to primate behaviour?

A

the extended period of parental care

230
Q

what are the 3 types of behaviours in primates?

A
  • alliance
  • ritualistic display
  • appeasement
231
Q

What is alliance behaviour? (description)

A

the more allies, the greater chance of being dominant

232
Q

What is ritualistic display?

A

this intimidates other males

233
Q

What does appeasement reduce?

A

aggression

234
Q

What is taxonomy?

A

the classification and naming of organisms into an ordered system

235
Q

What are the factors affecting the complexity of the social structure?

A
  • ecological nice
  • the distribution of resources
  • taxonomic group
236
Q

What is extinction?

A
  • the process in which organisms die out

- natural phenomenon

237
Q

When will extinction occur?

A

if the birth rate is less than the death rate over an extended period of time

238
Q

What is mass extinction?

A

a rapid decrease in the numbers of species present over a period of time

239
Q

What does mass extinction show?

A

an increases extinction rate over and above the “‘normal background” level

240
Q

Large land animals are known as what?

A

Megafauna

241
Q

What are the major causes of ecosystem degradation?

A
  • deforestation
  • over hunting
  • over fishing
  • pollution
242
Q

What is the impact of deforestation?

A
  • more CO2
  • fewer habitats
  • loss of food sources
243
Q

What is the impacts of over hunting?

A
  • declining numbers (of whale populations and elephant herds)
244
Q

What is an impact of overfishing?

A

reduced numbers

245
Q

What are the impacts of pollution?

A
  • contribution to greenhouse gases

- leads to eutrophication

246
Q

What are the three levels of biological diversity ?

A
  • genetic diversity
  • species diversity
  • ecosystem diversity
247
Q

What is genetic diversity?

A

the number and frequency of alleles in a population

248
Q

What is species diversity?

A

the number of different species in an ecosystem (species richness) and the proportion of each species in the ecosystem (relative abundance)

249
Q

What is ecosystem diversity?

A

the number of distinct ecosystems within a defined area

250
Q

what do biogeographic factors contribute to?

A

the range of diversity observed in biological communities

251
Q

What is a true island?

A

land mass permanently surrounded by water

252
Q

What is a habitat island?

A

an isolated area on land surrounded by environment not suitable for the “island species”

253
Q

What factors determine numbers on a island?

A
  • the rate at which a new species migrate to it

- the rate at which they become extinct on the island

254
Q

What happens as the number of species on the island increases? and why?

A

the immigration rate of the new species deceases because any individuals reaching the island are less likely to represent a species that is not already present

255
Q

why do extinction rate on the island increase?

A

due to increased competition

256
Q

What is relative abundance ?

A

number on an organism compared with others in a community

257
Q

What are the 4 main categories of threats to biodiversity?

A
  • overexploitation (over harvesting)
  • habitat loss
  • introduced species
  • global change
258
Q

What is overexploitation?

A

the harvesting of natural resources

259
Q

What does overexploitation involve?

A

the resources being harvested at a rate faster than they can be replaced

260
Q

Give two types of overexploitation:

A
  • overhunting

- overfishing

261
Q

What does the loss of genetic diversity cause?

A

the reduction of a population to below a level that is unlikely to recover

262
Q

What is the “bottleneck effect”?

A

when a small population lose the genetic variation necessary to enable evolutionary responses to environmental change

263
Q

What does inbreeding in small populations result in?

A

poor reproductive rates

264
Q

What is the single greatest threat to biodiversity?

A

human alteration of habitats

265
Q

What does the process of fragmentation of a habitat result in?

A

the formation of several habitat fragments whose total surface area is less than that of the original habitat

266
Q

What is habitat fragment?

A

a small area of isolated habitat resulting from fragmentation

267
Q

What does degradation of the edges lead to?

A

a proportionate decrease in size of the fragment and further loss of habitat

268
Q

What is a possible solution to habitat fragmentation?

A

to link isolated fragments with habitat corridors

269
Q

What is a habitat corridor?

A

a narrow strip of land to connect the disconnected fragments

270
Q

What do habitat corridors allow?

A

allow species to feed, mate and recolonize habitat after local extinctions

271
Q

What is a benefit of habitat corridors on biodiversity?

A

it provides access to other areas of habitat to increase gene flow and provides a route for species to reach the same food source

272
Q

What are the problems with multiple corridor options?

A
  • can be dominated by “edge” effects
  • can increase the risk of parasitism
  • can increase the spread of disease
  • can facilitate the dispersal of invasive species
273
Q

what are introduced species?

A

species that humans have moved intentionally or accidentally from the species native locations to new geographic regions

274
Q

What are the benefits of introduced species?

A
  • free from predators, parasites and pathogens that limit their populations in their native habitats
275
Q

Definition of naturalised:

A

lives and breeds in the wild in its new habitat/ecosystem

276
Q

What are invasive species?

A

naturalised species that spread rapidly and eliminate native species

277
Q

When does hybridisation occur?

A

when members of two different species mate with one another and produce viable offspring

278
Q

What are the two contributing factors to anthropogenic climate changes?

A
  • the burning of fossils has increased levels of CO2

- the felling of trees which reduces the number of plants photosynthesising

279
Q

What are the 5 effects of climate change ?

A
  • change in distribution and abundance of species
  • change in timing of seasonal events
  • changes in composition of plants and communities
  • habitat loss
  • increased sea temperature

Higher Biology (4 decks)

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