Ecology And Populations Flashcards

0
Q

How are ecosystems dynamic

A

Population sizes rise or fall because the living things have interrelationships and so a change in one population affects another

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1
Q

What is an ecosystem

A

A group of living organisms and non living things living together, and the relationships between them

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2
Q

What’s a biotic factor

A

A living feature of an ecosystem, eg predators or availability of food

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3
Q

What’s an abiotic factor

A

A non living feature of an ecosystem, eg temperature or water availability

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4
Q

What’s a producer

A

An organism which produces organic molecules using light energy, eg plants

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5
Q

What’s a consumer

A

An organism that eats another, eg birds, animals

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6
Q

What’s a decomposer

A

An organism that feeds on waste material and dead organisms

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7
Q

What’s a trophic level

A

The level at which an organism feeds

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8
Q

How is energy transfer shown

A

Food chains show how energy is transferred. The arrows show the direction of energy transfer. Organisms tend to be part of multiple food chains, so this can be shown as a food web

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9
Q

How can a pyramid of biomass be used to measure energy transfer

A

The area of the bar represents the dry mass of the organisms - usually ecologists just calculate this from the wet mass

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10
Q

How can pyramids of energy be used to measure energy transfer

A

They show a measure of how much heat energy is produced per gram of an organism!

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11
Q

What’s productivity

A

The rate at which energy passes through each trophic level

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12
Q

What’s gross primary productivity

A

The rate at which plants convert light energy into chemical energy

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13
Q

What’s net primary productivity

A

The amount of energ actually available to the primary consumer

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14
Q

Explain why energy transfer is never 100% efficient

A

Some energy is lost at each trophic level. Living organisms carry out life processes, eg respiration. Energy remains stored in dead organisms and waste material, which is then only available to decomposes. Some parts of organisms can’t be digested by consumers

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15
Q

What are the 6 ways we can improve primary productivity

A

Light, water, temperature, nutrients, pests, competition

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16
Q

How can humans stop light reducing primary productivity

A

Plant crops earlier in the year to maximise natural light, or plant under light banks

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17
Q

How can humans stop water reducing primary productivity

A

Irrigate crops, drought resistant crops eg wheat in Australia

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18
Q

How can humans stop temperature reducing primary productivity

A

Planting earlier to increase the growing season before its too cold to grow crops

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19
Q

How can humans stop nutrients reducing primary productivity

A

Crop rotation, including nitrogen fixing plants eg peas and beans, fertilising the soil

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20
Q

How can humans stop pests reducing primary productivity

A

Pesticides, pest resistant crops

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21
Q

How can humans stop competition reducing primary productivity

A

Use herbicides to limit competition from weeds

22
Q

What are the 5 ways to improve secondary productivity, explain why for each one

A

Harvest animals before adulthood as more of the energy in the young is invested into growing. selective breeding eg faster growth rates, high milk yield. , antibiotics, to avoid energy loss to pathogens or parasites. no grazing to avoid loss of energy through movement, heating so energy isn’t used to regulate body temperature

23
Q

Define primary succession

A

The development of a community from bare ground

24
Describe an example of primary succession
Surtsey, Iceland. Formed in 1960 by a volcanic eruption. Algae and lichens begin to live on bare rock - pioneer community. Erosion of rock, build up of dead organisms produces enough soil for mosses and ferns which replace the pioneer community. Similarly, larger plants succeed these until a final stable community is reached, called a climax community
25
How can quadrats measure distribution and abundance
Can record distribution, presence of a species, or abundance, number of a species or percentage cover
26
How do we use a quadrat
Take samples from a range of areas to reduce bias. Use a cumulative frequency graph to tell you how many samples you need to use. Population size of a species is average number of individuals in a species divided by the fraction of total habitat area
27
How can we use a transept to measure distribution and abundance
It's a line taken across a habitat. Sample regular intervals along the line. Line transect is which species is touching the tape and belt transect is where you place a quadrat next to the line, can be interrupted or continuous
28
Describe the role of decomposers
Bacteria and fungi are saprotrophic which means they secrete enzymes onto dead/waste material, these enzymes digest the material into small molecules, which are absorbed by the organism and respired to produce energy
29
Describe nitrogen fixation
Can occur through haber process and lightning but most occur due to nitrogen fixing bacteria. Many live in the soil and fix nitrogen gas within it, some such as rhizobium live in the roots of peas and beams. Mutualistic relationship as bacteria give fixed nitrogen and recieve glucose in return. The bacteria use an enzyme, nitrogen reductive, to reduce nitrogen has to ammonium ions used by the host plant.
30
Describe nitrification
Happens when chemoautotrophic bacteria in the soil absorb ammonium ions which are released by bacteria. Chemoautotrophic bacteria get their energy by oxidising ammonium ions to nitrates, eg nitrosomonas bacteria, or by oxidising nitrites to nitrates, nitrobacter bacteria
31
What does rhizobium bacteria do
Live in the roots of peas and beans and fix nitrogen
32
What does nitrosomonas bacteria do
Oxidise ammonium ions to produce nitrates
33
What does nitrobacter bacteria do
Oxidise nitrites to form nitrates
34
Describe denitrification
Conversion of nitrates back to nitrogen gas, when bacteria are grown without oxygen eg in waterlogged soil, they use nitrates as a source of oxygen for their respiration and produce nitrogen gas and nitrous oxide
35
Define carrying capacity
The maximum population size that can be maintained over a period of time in a particular habitat
36
Define intraspecific competition
Competition between individuals of the same species, resources become limiting so the best adapted individuals survive to reproduce
37
Define interspecific competition
Happens between individuals of different species, and affects both population size and species distribution
38
What are the three phases of population growth
Lag phase - only a few individuals so reproduction rate is low. Log phase - resources plentiful, rate of population growth is fast. Stationary phase - population size levelled out at carrying capacity, population fairly stable but fluctuates slightly due to environmental factors
39
Give examples of limiting factors
Food, shelter, water, light, oxygen, shelter, nesting spaces, predators
40
Describe the 5 stages of predator prey relationships
1. When the predator population increases, more prey are eaten. 2. The prey population get smaller, so there's less food for the predators. 3. Fewer predators can survive so their population size decreases. 4. Prey population increases as less are eaten. 5. With more prey, predator population increases again and the cycle starts again.
41
Define conservation
Involves the maintainence of biodiversity, and maintaining a varie of habitats and ecosystems
42
Define preservation
protecting areas of land, unused by humans, in their untouched form
43
Describe small scale timber management
Coppicing, pollarding which is similar but higher up so deer don't eat the new shoots. Rotational coppicing often used to supply of timber every year. Standards are trees left to grow larger to meet demands for larger pieces of timber
44
Describe large scale timber management
Clear felling no longer done as reduced soil mineral levels, destroyed habitat and soil erosion leading to river pollution. Selective cutting leaves each area fairly unaffected. If each tree produces more wood, less trees will need to be cut down to meet timber demands. To achieve this plant tree species where they'll grow well. Control pests and pathogens. Position trees optimally
45
What are the three principles of modern sustainable forestry
Any tree harvested must be replaced. Must maintain biodiversity and natural cycles. Locals should benefit from the forest.
46
Describe ethical reasons for conservation
Every living thing has a right to survive. We are ethically responsible for conserving species
47
Describe economic reasons for conservation
Indirect value, eg insects polluting crops helps farmers. Direct benefit eg harvesting fur or meat etc
48
Describe social reasons for conservation
Provide a valuable food source. Benefits to medicine. Allows for recreation eg hiking or birdwatching or both simultaneously
49
Why is conservation dynamic
It changes with the needs of the environment or species in question. It uses management and sometimes involves reclamation of land for habitats
50
Describe habitat disturbance in the galapagos
Oil spill in 2001 harmed marine and coastal ecosystems increased pollution, building, conversion of land for agriculture has destroyed habitats, forests of Salesia trees destroyed for this use
51
Describe over exploitation in the galapagos
200,000 tortoises killed in 50 years and made the pinta tortoise extinct. Fishing has left populations depleted and over 150,000 sharks killed for their fins including 14 species listed as endangered
52
Describe introduced species in the Galapagos
Red quinine trees introduced and eradicated cacaotillo shrubs. Goats outcompete tortoises for grazing and turn forests into grassland, leading to soil erosion.
53
Describe the preventative methods introduced in the Galapagos to minimise the effect of introduced species
Quarantine system, tourists searched for foreign species. Culling, eg feral pigs and feral goatees. 40% coastal zones allow no extraction of resources