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Year 13 Biology > 6.6 - Populations And Sustainability > Flashcards

6.6 - Populations And Sustainability Flashcards

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1
Q

Exponential (log) phase characteristics

A 
Reproductive rate > death rate
Population size increases rapidly
Plenty of resources, e.g. food (little competition)
Little disease 
Few predators
No overcrowding
Low environmental resistance
low environmental resistance (biotic and abiotic factors which limit population growth)
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2
Q

4 stages of a population growth curve

A

Lag phase
Exponential phase (log)
Stationary phase
Death phase

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3
Q

Stationary phase characteristics in a population growth curve

A

reproductive rate = death rate - population size, remains stable

  • habitat cannot support larger population
  • it has reached its carrying capacity (k)
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4
Q

Lag phase characteristics in a population growth curve

A

reproductive rate is slow

  • population size is small
  • takes time for dispersed individuals to find each other to mate
  • acclimatising to habitat
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5
Q

Where are each of the stages in the population growth curve found?

A

1st(start of graph)
Lag phase

2nd(high population growth)
Exponential phase (log)

3rd (end of graph)
Stationary phase
No changes - population constant - has reached carrying capacity

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6
Q

Limiting factors that can affect population size

A
  • food
  • water
  • space
  • light
  • oxygen
  • effects of predators
  • disease
  • competition
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7
Q

Two types of strategists

A

K-strategists

R-strategists

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8
Q

Info about K-strategists

Give an example

A 
Low reproductive rate
Late reproductive age
Large body mass
Long life span
Slow development

E.g. humans, mammals like elephants, etc.

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9
Q

Info about R-strategists

A 
Quick development 
Short life span
Small body mass
High reproductive rate
Early reproductive age

E.g. fruit flies, some insects

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10
Q

What is carrying capacity?

A

Maximum no. of individuals in a population surrounded by a particular habitat

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11
Q

Why do some species exceed their carrying capacity?

- effects of exceeding carrying capacity

A

Due to a rapid reproductive rate
Once exceeded
There may be insufficient resources to maintain population
Some organisms may die

Buildup of waste products can also cause death

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12
Q

Describe and explain the relationship between the two organisms:
- Explain why
(3 Marks)

A
  • prey population increases when predator number is low
  • and when there are few limiting factors, such as a low environmental resistance
  • more prey = more food for predators
  • population of predators increases after a lag time
  • prey eaten by predators = prey numbers decrease
  • less food for predators
  • fewer survive and predator numbers decrease
  • Cycle repeats
  • carrying capacity is higher for prey populations than predators
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13
Q

What is intraspecific competition

A

Competition within a species

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14
Q

Why intraspecific competition occurs

A
  • as environmental pressures increases (factors become limiting)
  • competition increases
  • those best adapted survive, reproduce and pass on the genes/alleles (others die)
  • keeps the stationary phase fairly stable
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15
Q

What is interspecific competition?

A

Competition between two or more different species

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16
Q

What does this graph show?

A

Shows two species growing alone - no competition between them

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17
Q

What does this graph show?

A

Shows interspecific competition between the two species

  • increase in population of one species causes a decline in population of other species
  • one species more adapted - able to gain more food than other species - e.g. more light for photosynthesis
  • one species outcompeted
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18
Q

What is competitive exclusion

A

Explains why particular species only grow in certain places - or fill different niches

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19
Q

Explain why the competitive exclusion principle does not always apply in natural ecosystems

A
  • because of effects of other variables acting as limiting factors
  • variation between individuals in each species can lead to (natural) selection
  • so that the two species evolve to be slightly different
  • in effect the two species are not competing in exactly the same niche
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20
Q

How does increasing human population threaten biodiversity

A

Over-exploitation of wild populations for food
Disrupting habitats with urbanisation and pollution
Introducing non-native species which completely exclude native species - e.g. red squirrels and grey squirrels

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21
Q

Dynamic preservation def

A

Preservation of organisms or environments that are at risk from human activity.
This requires management and the creation of new habitats, which may need reclamation of land

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22
Q

What could be done to conserve a species or habitat

A

Conservation can involve:

  • establish protected areas - SSIs
  • National Parks
  • can provide legal protection for endangered animals or plants
  • can also take place ex-situ in places such as zoos or botanical gardens
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23
Q

Strategies for conservation and preservation of species

A
  • Reclaim ecosystems by reversing effects of human activity (likely to take a long time)
  • raise carrying capacity - by providing more food
  • move individuals to enlarge populations or create corridors which provide pathways
  • these connect fragmented habitats
  • allow species to move between them
  • restrict dispersion of individuals - by fencing
  • control predators and poachers
  • vaccinate individuals against disease
  • preservation of habitats by protecting against pollution or disruption (coppicing, grazing)
  • restricting succession
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24
Q

Large scale timber production info

- what are the consequences of this?

A

Clear-felling is completely cutting down all of the trees in an area.
It is for large scale timber production.

Trees take up water from the soil which stops the soil being washed away (soil erosion) and polluting rivers.
They keep nutrient levels in balance in the carbon and nitrogen cycle.
Clear-felling leads to the opposite

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25
Q

Sustainable production def

A

Harvesting in amounts which leave sufficient organisms to grow and replenish what has been harvested. It can be carried on indefinitely via replanting, coppicing, etc.

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26
Q

How forestry of large timbers can be made sustainable

A

Replant a tree for every one harvested
Whole woodland must maintain its ecological function of biodiversity, climate, mineral and water cycles
Local people should benefit from the forest

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27
Q

To ensure each tree yields the maximum amount of wood when cut down (and mean fewer trees need to be felled) foresters:

A

Control pests and pathogens
Only plant tree species which will grow well in the area
Plant trees optimal distances apart to prevent too much competition for light, water, minerals

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28
Q

What balance is needed in sustainable forestry of large timbers?

A

A balance between making money and supplying plenty of wood and maintaining biodiversity.

29
Q

What is coppicing?

Info about coppicing

A

Cutting a tree trunk close to the ground to encourage several new, thinner, stems to grow.

Once they have grown, the new stems will be cut.
All this thin wood can be used for furniture, firewood etc,
But the trees don’t die and so no replanting is needed
More branches grow, no trees block sunlight
No succession
So biodiversity maintained

30
Q

How rotational coppicing is carried out

A

Woodlands are divided up and different sections are coppiced on different years.
This means each section is at a different stage and coppicing can be done to provide a continuous supply of wood each year.
By the time they are ready to coppice the first section again, the shoots should have regrown and be ready to be re‐cut.

31
Q

What is pollarding?

A

Cutting trees at higher points/higher up to avoid herbivores

32
Q

Two methods to manage fish stocks

A

Fisheries - capture fisheries

Aquaculture

33
Q

What is aquaculture?

A

Reference to sustainable breeding, rearing, and harvesting of plants and animals in all types of water environments - controlled by humans.
These include ponds, rivers, lakes and the ocean
- allows sustainable fish stocks and harvesting of fish - as harvesting numbers can be controlled

34
Q

Benefits of aquaculture

A
  • restricts imports on oceanic fish stocks
  • expected to feed more people than traditional fishing in future
  • cheap and plentiful protein source for an increasing human population
35
Q

Conservation def

A

The active management of an ecosystem

36
Q

Preservation def

A

Protection of an ecosystem from interference (via human impact) so that it remains in its original state

37
Q

Disadvantages of aquaculture rather than ‘capture fisheries’

A

Populations susceptible to pests and pathogens

Possible cause of pollution

38
Q

3 main principles for sustainable management by the marine stewardship council

A
  1. Over‐fishing must be avoided to stop extinction of species (aim to maintain the population at its and only harvest excess numbers).
  2. No permanent damage to local habitats (maintains structure and function of ecosystem).
  3. Always comply with local, national and global regulations (be flexible with these).
39
Q

Advantages of capture fisheries

A

High economic value (sales and jobs)

40
Q

What are ‘capture’ fisheries?

A

Kemnd

41
Q

Economic reasons to maintain natural habitats

A

To support a sustainable timber industry

42
Q

Social reasons to maintain and protect natural habitats

A

Provide an environment for a human population to relax/exercise

43
Q

Ethical reasons to conserve natural habitats

A

All animals have a right to life

44
Q

What are ‘capture fisheries’?

A

the process of gathering and removing fish from the place in which it has grown,

Refers therefore to fishing and catching wild fish and shellfish.

45
Q

What does managing an ecosystem in a sustainable way mean?

A
46
Q

Describe the ecosystem of the Terai region of Nepal

A

Densely populated

• Home to endangered species - Bengal tiger , one-horned rhino

47
Q

State two ways in which humans use the Terai region in Nepal

A
  • expansion of agriculture in forested areas
  • grazing of farm animals
  • over-exploit forest resources
48
Q

Explain how sustainable forestry and agriculture practices are being used in the Terai region to maintain biodiversity, while also meeting the needs of the local population

A

WWF + Nepal government work together
• people have right to exploit forest and have responsibility to look after it
• create forest corridors between national parks
° help tigers survive and disperse
• Help cqunteract illegal poachers
• Wwf introduce biogaa Plants + wood eff. stores - reduce firewood demand
• construct waterholes, monitor endangered species, eradicate invasive species

49
Q

Threat to biodiversity - spruce and pine in conifer plantations support limited biodiversity - solution

A
50
Q

Threat to biodiversity

A
51
Q

Threat to biodiversity

A
52
Q

Threat to biodiversity

A
53
Q

Threat to biodiversity

A
54
Q

Threat to biodiversity

A
55
Q

Threat to biodiversity

A
56
Q

7 different case study areas

A 
Masai Mara
Peat Bogs
Galápagos Islands
Terai Region
Antarctica
Lake District
Snowdonia National Park
57
Q

Info about Terai region - Nepal

A
58
Q

Info about Masai Mara

A
59
Q

Info about Galápagos Islands

A
60
Q

Info about The Antarctic

A
61
Q

Info about Lake District

A
62
Q

Info about Snowdonia National Park

A
  • attracts walkers and climbers
  • good footpaths maintained so that rare plants not trodden on
  • gutters take water from paths - can be blocked by rubbish and dropped by walkers
  • workers clean rubbish to prevent path erosion
  • national park employees work with farmers to reduce sheep grazing on mountain
  • as sheep graze very low to ground, can leave landscape very barren
  • reduction of grazing gives rare plants better chance of survival
  • feral goats are a problem with grazing, so numbers and locations are monitored each year
  • farmers encouraged to plant hedges and conserve ancient woodland
  • moorland and big also part of Snowdonia landscape
  • these provide habitats and nesting sites for rare birds
  • use of wetland leads to humans having impact - needs to be controlled
63
Q

Peat bogs are ecosystems that contain unique communities of invertebrates, bird species, and wetland plants.
Sphagnum mosses represent a vital part of peat bog ecosystems. These species of moss require a high soil moisture content.
Almost all of the peat bogs in the UK have been affected by human activity. The following management activities were planned in a peat bog ecosystem:
the planting of a small area of conifer trees at the edge of the peatland a ban on the extraction of peat for use as compost
reintroduction of natural sphagnum mosses
the construction of a ditch as a flood prevention measure
extended grazing by cattle and a large flock of sheep
managed burning to create new growth for livestock grazing
the construction of a boardwalk to replace several sets of footpaths
(i) Suggest improvements that could be made to these plans.
Explain why your improvements would help conservation of the peat bog ecosystem.
(3 Marks)
(ii) Explain why the preservation of

A

(i)

(ii) (idea that) preservation

64
Q

Preservation alt. Def

A

Leaves ecosystems without human interference

65
Q

Conservation alt. def

A

When ecosystems are damaged, and need restoration and management from humans

66
Q

Impact by humans on Snowdonia and solutions

A

Farmers dig open drainage ditches to dry land
- this causes poor water quality in rivers
- rain flows quickly through habitats
- increases flood risk
Solution: block drainage ditched with hay bales to mitigate effect

67
Q

Social and economic reasons for conservation

A

Many plant and animals species provide a valuable food source
Genetic diversity in wild populations may be needed in future to breed for more adapted animals and plants - e.g. disease resistance, increased yield, drought resistance etc.
- as well, different alleles or genes may have potential future uses - e.g. in medicine
Natural environments are a valuable source medicines - e.g. drug production
Natural predators of pests can act as biological control agents
- better than causing pollution with artificial chemicals/pesticides

Aesthetic reasons - e.g. different breeds of animals/pets look nice, etc.

Economic:
- ecotourism is a source of money

68
Q

Ethical reasons for conservation

A
  • humans have ethical responsibility to look after animals

Year 13 Biology (19 decks)

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