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OCR A level Biology > 6.3.2 - Population and Sustainability > Flashcards

6.3.2 - Population and Sustainability Flashcards

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1
Q

Stages on population graph

A

Slow growth
Rapid growth - resources plentiful, reproductive rate > mortality rate
Stable state (no growth) - mortality = reproduction
Cannot support a larger pop. due to carrying capacity, small fluctuations

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2
Q

Populations can

A

Remain stable
Rise or fall suddenly
Oscillate up and down w. the reg. pattern

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3
Q

Types of limiting factors

A

Density dependent

Density independent

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4
Q

Density dependent

A

Factors that affect pop. the more they increase in size e.g resources, predators, intra and inter spp comp.
These limiting factors place the carrying capacity on population size

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5
Q

Density independent

A

Factors that affect the the same proportion of the population regardless of size

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6
Q

Types of strategists

A

k and r

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7
Q

K selection

A 
Offspring have a high prob of survival 
Heavy parental care and nurturing
Larger organisms
Much lower reproductive rate
Young are altricial, longer lifespans and have overlapping generations
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8
Q

Altricial

A

Born in an undeveloped state and requiring care and feeding by the parents

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9
Q

R selection

A

Produce many low effort organisms
Species grow rapidly
Found in less competitive and low quality environments
Young are precocial
High of mortality so start reproducing earlier
Non overlapping generations, shorter lifespans
Boom and bust (cyclical)

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10
Q

Precocial

A

Born in an advanced state and able to feed itself almost immediately

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11
Q

Predator prey interactions

A

When predator pop increases, more prey eaten
Prey pop decreases, less food available for predator s
W/ less food, fewer predators survive so their pop. decreases
W/ fewer predators, fewer prey are eaten so their pop. increases
More prey = more food, predator pop. increases
Two populations are in eqm and stable due to -ve feedback

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12
Q

When does competition occur

A

When there are not enough resources to satisfy all of the organisms that depend on them

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13
Q

How does intraspp comp affect population

A

Population drops –> comp. reduces –> pop. increases –> pop. drops (oscillates)

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14
Q

Examples of interspp comp. affecting population

A

Red and grey squirrels - Invasive species
May leads to extinction of one species
Greater specialisation to avoid competition
Change in distribution of the species

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15
Q

Where does invasive species have a largest effect

A

Islands

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16
Q

Competitive exclusion principle

A

2 competitive species cannot coexist at the same population level esp if ones staring population is higher than the other

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17
Q

Preservation

A

Keeping habitats/species as they are now (assuming they are currently undisturbed)
Focuses on eliminating any human effects on ecosystems

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18
Q

Conservation

A

Active management of ecosystems by humans to maintain biodiversity
Involves management of ecosystem so that natural resources can be used sustainably and reclamation

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19
Q

Reclamation

A

Restoring ecosystems that have been damaged/destroyed

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20
Q

Threats to biodiversity

A

Over-exploitation of ecosystems by humans
Habitat disruption and fragmentation
Intro of invasive species by humans that outcompete native species to extinction

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21
Q

Potential management strategies

A 
Raise carrying capacity by increasing nutrients 
Move individuals to enlarge pop
Encourage natural dispersion using dispersion corridors  between fragmented habitats 
Fencing 
Controlling predators and poachers
Vaccinate individuals 
Prevent pollution/disruption 
Intervene to restrict succession
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22
Q

Ethical reasons to conserve

A

Moral responsibility
All organisms have a right to live
Every species has value in and of itself

23
Q

Why does interspp competition have diff effects in the wild

A

Species may migrate
Other biotic and abiotic effects on the organism
Availability of resources vary
Organisms may not have exactly overlapping niches

24
Q

Small scale timber production

A

Coppicing

Pollarding

25
Q

Sustainable management

A

Carrying out processes indefinitely w/out damaging the ecosystem

26
Q

Coppicing

A

Stem of deciduous tree is cut close to ground
New shoots grow from the cut surface
Mature into narrower stems
Happens cyclically

27
Q

What is coppicing used for

A

Fencing
Firewood
Furniture

28
Q

Pollarding

A

Sim technique to coppicing

Only done higher up so that the animals cant eat the new shoots

29
Q

Negative of small scale timber production

A

Labour intensive

30
Q

Rotational coppcing

A

Divide wood into sections

Cut one each year

31
Q

Why is rotational copppicing good for diversity

A

Light is still able to reach forest floor as tress never grow tall enough –> increasing diversity of species
Can control succession (deflection - plagioclimax)

32
Q

Large scale timber production

A

Clear felling

Selective cutting

33
Q

Clear felling

A

Felling all the trees in one area destroying habitats on a large scale

34
Q

Drawbacks of clear felling

A

Decreases soil mineral level
Leaves soil susceptible to erosion
Takes 50-100 years of succession
Trees bind soil
Trees remove water from soil and stops it from being washed away
Trees maintain nutrient levels through their roles in the carbon and nitrogen cycle (decomposition)

35
Q

Selective cutting

A

Only cutting down the largest, most valuable trees

36
Q

How is tree growth encouraged for selective cutting

A

Controlling pests and pathogens
Only planting species where they will grow well
Position tress at optimum distance to decrease comp

37
Q

Aims of sustainability

A

Preserve the environment
Ensure resources are available for future generations
Allow all humans to live comfortably
Enable LEDCs to develop

38
Q

Modern sustainable forestry

A

Any tree harvested is replaced by another (naturally or planted)
Forest must maintain its ecological function
Local people must benefit from the forest

39
Q

Main principles of fisheries

A

Take place at a level that allows it to continue indefinitely (ideally carrying capacity and excess are harvested)
Must maintain structure, productivity, function and diversity of the ecosystem
Must adapt to changes in circumstances and comply w. local, national and international regulation

40
Q

Strategies put in place for fisheries

A

Large mesh sizes so only mature fish are caught
Limiting recreational/ commercial fishing to certain times of the year
EU common fisheries policy - Fishing quotas limiting no. of certain fish and where they can be caught

41
Q

Aquaculture

A

Farming fish
Restricts impacts on oceanic fish value
Allows susceptible fish species numbers to recover
But decreases genetic biodiversity

42
Q

Why do fish numbers fall

A

Too few adult fish left to breed and maintain fish numbers

43
Q

Scramble competition

A

Relies on all individuals finding food and nest sites by chance this allows natural selection as some may be better adapted than others

44
Q

Dominance hierarchy

A

Strongest, most dominant individuals breed and pass on their alleles - if there’s only 1 dominant individual there is likely to be less variation in the next gen.

45
Q

Why is preservation not enough to maintain biodiversity

A

Preservation only keeps the environment as it is
If the ecosystem has already decreased preservation doesn’t prevent further loss
Takes active intervention

46
Q

Masai Mara region

A

National reserve in Kenya
Combined needs for locals to run farms w/ larger land owner who use land to encourage conservation and generate income (ecotourism)

47
Q

Terai region

A

Home to Bengal Tiger (endangered)
Forest is under pressure due to increased agriculture and grazing
Comm forestry initiatives allow locals to exploit but also adopt responsibility
Marketing products made for forests also generates income

48
Q

Peat bogs

A

Peat takes 1000’s of years to accumulate
Ideal for Sphagum moss - feeding and stopping off points for migrating birds
Local level schemes aim to restore certain peat bogs and end commercial use

49
Q

Human activities affecting the Galapagos

A

Fishing and whaling have upset the marine ecosystem
Intro of new species e.g. goats (eat vegetation), rodents (damage eggs of natives), dogs and cats (chase and eat native)
Tourism
Scientific research
Increasing pop.

50
Q

Strategies to maintain the Galapagos

A 
Searching boats for foreign species
Using natural predators 
Culling feral goats 
Educating 
Captive breeding for tortoises 
Galapagos Marine Reserve
51
Q

Antartica

A

Overfishing of krill (keystone species)
Moinitor catch size
Whales protected by marine reseves
Sea birds protected by night fishing and during the non-breeding seasons

52
Q

Measuring distribution

A

Line or belt transects (systematic sampling)

53
Q

Measuring plant abundance

A

Randomly placed quadrats

No. of individuals in sample / Area of sample

54
Q

Measuring animal abundance

A

Capture, mark, release, recapture (all occurs in orig. sample area)
(no. in first sample * no in 2nd sample) / no. of recaptured marked individuals

OCR A level Biology (25 decks)

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