Ecosystems and sustainability Flashcards
(121 cards)
0
Q
Define population
A
All of the organisms of one species that live in the same place at the same time and can interbreed
1
Q
Define habitat
A
The place where an organism lives
2
Q
Define community
A
All the populations of different species that live in the same place at the same time and can interact withal each other
3
Q
Define ecosystem
A
Any group of living organisms and non living things occurring together that have interrelationships
4
Q
What are the 3 components of an ecosystem?
A
A habitat, a population and a community
5
Q
Define niche
A
The role that each species plays in an ecosystem
6
Q
Why is it impossible to define a niche exactly?
A
Because every organism interacts with both non living and living things
7
Q
Give 3 examples of thing that help define a niche
A
What the species feeds on, what it excretes, how it reproduces etc.
8
Q
True or false
It’s impossible for two species to occupy the exact same niche
A
True
9
Q
Define biotic factors and give 3 examples
A
The effect of living components in an ecosystem
Predation, disease and food supply
10
Q
Define abiotic factors and give 3 examples
A
The effect of non living components in an organism
PH, soil type and temperature
11
Q
Why do the population sizes in an ecosystem always slightly change?
A
Because all the organisms interact so the increase in death of one species will have a knock on effect on others
12
Q
What happens to other population sizes if the predator population increases?
What about if there’s low levels of nitrogen in the soil but nitrogen fixing plants live there?
A
The population size of the prey will decrease as more will get eaten
The nitrogen fixing plants will add more nitrogen into the soil allowing other plants to grow their which increases population sizes
13
Q
Give 2 examples of nutrient cycles where matter is recycled
Is energy recycled in an ecosystem?
A
The carbon cycle and the nitrogen cycle
No, it flows through the ecosystem
14
Q
What is at the start of nearly all food chains?
A
Plants
15
Q
What are producers? Consumers? Primary consumers? Secondary consumers? Tertiary consumers? Decomposes?
A
Plants and photosynthetic organisms (algae, bacteria) that supply chemical energy to other organisms
Animal and fungi that digest other organisms
Herbivores who eat plants
Carnivores
Carnivores who eat secondary consumers
Bacteria, fungi and some animals thy feed on waste material/dead organisms
16
Q
Define trophic level
A
The level at which an organism feeds in a food chain
17
Q
Define food web
A
Various different food chains thy interact with each other allowing us to see energy flows throughout an ecosystem
18
Q
Is energy lost at each trophic level?
A
Yes
19
Q
List two ways in which energy is lost between trophic levels
A
- Living organisms use energy in order to respire/carry out metabolic processes and the Betty is released as heat
- Energy remains in parts of dead organisms that consumers can’t digest, like bones, decomposes like fungi and bacteria then consume what’s left
20
Q
What is a pyramid of numbers?
A
It’s a visual representation of population sizes at each trophic level (the populations decrease higher up the pyramid)
21
Q
What is a pyramid of biomass?
Name 2 ways in which you can measure biomass
A
When the area of the bars in the pyramid is proportional to the dry mass of all the organisms a that trophic level
You can measure dry mass by collecting the organisms and putting them in an 80 degrees oven until all the water has evaporated from them. This is very destructive
You can also measure biomass via looking at the wet mass of organisms
22
Q
List two ways in which you can measure the efficiency of energy transfer between organisms
A
By creating a pyramid of biomass or a pyramid of energy
23
Q
How do you collect data in order to create a pyramid of energy?
A
You burn the organisms in a calorimeter and then work out how much heat energy is released per gram. It’s calculated via the rise in temperature of a known mass of water
24
List a limitation for pyramids of numbers
And 2 pyramids of biomass
And 4 for pyramids of energy
Counting the number of organisms doesn't provide an accurate picture about how much living tissue exist sat each level
It's very destructive and different species may release different amounts of energy per unit mass
It's destructive, time consuming and only provides a snapshot of data. Also populations sizes fluctuate so this might create a distorted idea of energy transfer
25
What is the best method of discovering energy transfer in an ecosystem?
The best method is looking at the rate at which energy passes through each tropic level. This is an pyramid of energy flow.
26
What is the rate of energy flow called?
| How is this measured?
Productivity
It's measured by looking at how much energy is available at a particular tropic level per unit area in a set time. It's measured via mega joules (1000 kj)
27
What is primary productivity?
What about gross primary productivity?
And net primary productivity?
The total amount of energy fixed by photosynthesis aka the net flux of carbon from the atmosphere to plants in a set time. It's measured in MJ m-2 yr-1
The rate at which plants convert light energy into chemical energy
The remaining energy, not including the energy that's lost when the plant respires/when the energy is less available to consumers. Aka the rate at which carbohydrate accumulates in plant tissue measured via dry mass in kg ha-1 yr-1
28
What is the formula for net primary productivity?
Primary productivity - respiratory heat loss
29
Why is knowing the net primary productivity (NPP) useful?
Because it tells us the amount of energy available to heterotrophs and is therefore an important factor in determining the amount of biomass an ecosystem can support.
30
How much sunlight energy that reaches the earth is used for photosynthesis?
Less than 1%
31
List 5 reasons why some sunlight isn't used for photosynthesis
Because it's reflected by clouds, it's reflected by the earth, it's used to heat the earth, it's used to evaporate water and it's the wrong wavelength for chlorophyll to absorb it
32
List 7 ways in which NPP can be improved
1. Plant the crops early to provide a longer growing season meaning they harvest more light
2. Irrigate crops and breed drought resistant strains
3. Greenhouses increase temperature and therefore increase the speed of chemical reactions
4. Crop rotation to ensures the soil contains nutrients and nitrogen fixing crops can replenish the levels of nitrates
5. Use pesticides to stop pests reducing the dry mass and energy. Breed pest resistant plants or modify them with bacillus thuringiensis which is resistant against bollworm to increase yield
6. Use fungicide or breed plants to be resistant to fungal infections like rhizomania in sugar beet. Potatoes have been genetically modified to be resistant to potato blight
7. Use herbicides to reduce competition against weeds
33
List 6 ways in which fungal infections can reduce the yield in plants
1. They can cause root rot which reduces water absorption
2. They can damage xylem vessels which can interfere with water transport
3. They can damage phloem tubes which can interfere with translocation
4. They can damage foliage via wilt
5. They can cause blight which interferes directly with photosynthesis
6. They can damage flowers and fruit interfering with reproduction
34
Is the transfer of energy between producers and consumers efficient?
No
35
List 5 reasons why the transfer of energy between producers and consumers is inefficient
1. Some plants die
2. Consumers don't eat every part of the plant
3. A lot of the plant is egested in faeces
4. A lot of the stored energy in plants is used to keep the consumer alive
5. Not everything consumers eat is digested
36
List 5 ways in which humans can manipulate energy transfer between producers and consumers
1. Harvesting animals before adulthood minimises a loss of energy from the food chain (from plants)
2. Treat animals with steroids so that they grow quicker
3. Use selective breeding so that the high yield animals pass on their traits
4. Treat animals with antibiotics to avoid energy loss from fighting off pathogens
5. Minimise grazing and movement so that more energy is used to build muscle and keep the temperature constant
37
Define succession
A directional change in a community of organisms over time
38
What is primary succession and give an example of it
The development of a community from bare ground
Example: Algae and lichens can live on the bare rock, these are the pioneer community. As the rock erodes and dead and rotting organisms build up, enough soil is produced for plants like mosses and ferns to grow. These succeed the algae and lichens. Larger plants then succeed the smaller plants and a final stable climax community is produced. These are often woodlands
39
What is secondary succession?
When succession occurs on a previously colonised but disturbed/damaged habitat
40
What is unique about succession in sand dunes?
The fact that they display all the stages of succession at the same place at the same time
41
Because sand dunes display all the stages if succession at the same time, where is the first stage of succession found and where is the last stage found?
The first stage is found just above the high water mark
| The last stage is found much further away from the sea
42
Describe the 4 stages of succession in sand dunes
1. Pioneer plants like sea rocket are prickly sandwort colonise in the sand just above the high water mark. They are able to tolerate sea water spray, lack of water and unstable sand
2. Wind blown sand builds up around the base of the plants forming embryo dunes. As the dune gets bigger, sea sandwort and sea crouch grass colonise it. Sea crouch grass have underground stems that stabilise the ground
3. The increased stability allows more nutrients to accumulate which means sea spurge and marram grass can grow there. Marram grass traps sand as it grows, making the dune increase in size as it moves up the beach
4. As nutrients build up, hare's foot clover and other legumes colonise. The bacteria in their root nodules add nitrates to the soil, which allows sand fescue to grow there.
43
Define quadrat
A square frame that defines the sample area, it's used for studying ecosystems
44
Why do ecologists study ecosystems?
To find out whether abundance and distribution of a species is related to abiotic or biotic factors
45
What 2 types of data can you collect from a quadrat?
The distribution (the presence or absence of each species) and the abundance (estimate/count the number of individuals in a quadrat)
46
Instead of counting all of the individuals, what can ecologists do to estimate the amount of individuals within a quadrat?
Calculate/estimate the percentage cover by just looking at it or via point frame which involves sticking a needle in the ground and record each species that touches the needle
47
How do you avoid biasing a quadrat sample to ensure that the sample is an accurate representation of the whole habitat? 2 ways
You randomly position the quadrats across the habitat by using random numbers to plot coordinates
You take samples at regular, set distances and sample each part to the same extent
48
How do ecologists work out how many quadrats they need to sample?
By doing a pilot study where they take samples from across the habitat and make a cumulative frequency table. They then plot the cumulative frequency against the quadrat number and when the curve levels off (you stop in ding new species) then that tells you the minimum amount of quadrats to use
49
How do ecologists work out how big their quadrats should be?
You count the number of species in larger and larger quadrats. You then plot this on a graph: x-axis = quadrat area. Y-axis = number of species found. When the curve levels off then that's the size you should use
50
What's the formula for estimating population sizes of a species?
Mean number of individuals of the species in each quadrat divided by the fraction if the total habitat area covered by a quadrat
51
What is a systematic way of looking for changes in vegetation across a habitat instead of using quadrats? This method measures vegetation in a certain direction
Use transects
52
How do you use a transect?
A line is taken across a habitat via a tape measure and samples are taken at regular intervals. The distance between samples depends of the length of the line and the density of plants
53
What doe a transect and quadrat measure?
The abundance and distribution of a number of species in a habitat
54
Why are the 2 transect methods?
Line transect which is when you make a note of which species is touching the tape at regular intervals
A belt transect which is when you use an interrupted belt transect (place a quadrat next to the tape at regular intervals) or you use a continuous belt transect (place a quadrat against the line and move it along the line after looking at each quadrat
55
What is dead/waste material broken down by?
Decomposers which are microorganisms like fungi and bacteria
56
Bacteria and fungi feed in a different way to normal organisms, how do they feed differently?
They're saprotrophs and they feed saprotrophically, this means they secrete enzymes onto the dead material and the enzymes digest the food into small molecules. The organism then absorbs this and the molecules are stored and respires
57
How are nitrogen atoms recycled?
| Bacteria help recycle nitrogen, what 4 processes do they do to achieve this?
Thy are recycled via biotic and abiotic components in an ecosystem
Bacteria are involved in ammonification, nitrogen fixation, nitrification and denitrification
58
Why is nitrogen essential for living things?
Because nitrogen is needed in order to make proteins and nucleic acids
59
What percentage does nitrogen gas make up of the earth's atmosphere?
79%
60
Is nitrogen reactive or unreactive?
| What does this mean?
It's unreactive meaning that plants can't use it directly
61
Because plants can't use nitrogen has directly, what do they do?
They use fixed nitrogen like ammonium ions or nitrate ions.
62
Nitrogen fixation is a vital process in the nitrogen cycle, list 3 ways in which nitrogen is fixed.
It's fixed via lightening strikes, the Haber process or by nitrogen fixing bacteria
63
Describe nitrogen fixing bacteria in detail
They live freely in the soil and fix nitrogen gas from the air in the soil and use it to manufacture amino acids. Rhizobium lives inside root nodules of peas and beans, it has a mutualistic relationship with them as they receive carbon compounds like glucose and give fixed nitrogen. Rhizobium fixes nitrogen in aerobic conditions as leghaemoglobin in the nodules absorb oxygen. Rhizobium uses nitrogen reductase to refuse nitrogen gas to ammonium ions
64
Nitrification is an important process in the nitrogen cycle, describe the process
It involves chemoautotrophic bacteria in the soil that absorb ammonium ions. Ammonium ions are released by bacteria involved in the putrefaction of proteins found in dead matter. The chemoautotrophs obtain their energy by oxidising ammonium ions to nitrites and then oxidising nitrites to nitrates. Nitrosomonas and nitrobacter are involved in this. The oxidation requires oxygen so it only occurs in well aerated soils. Nitrates are then absorbed by plants to make nucleotides
65
Denitrification is an important process in the nitrogen cycle, describe the process
Bacteria convert nitrates back to nitrogen gas. When some bacteria are in anaerobic conditions (waterlogged soil) then they can use nitrogen as a source of oxygen for respiration. This produces nitrogen gas and nitrous oxide.
66
Define carrying capacity
The maximum population size that can be maintained over a period of time in a particular habitat
67
Define: "the oscillation of a population size"
The regular swing back and forth of population sizes in a regular pattern
68
Finish the sentence
| The size of a population depends on the balance between...
...mortality rates and reproduction rates
69
What are the 3 phases of population growth?
The lag phase
The log phase
The stationary phase aka carrying capacity
70
Why does a population reach a carrying capacity?
Because the habitat can't support a larger population which means that the mortality rate is equal to the reproduction rate. This happens because of limiting factors like availability of food, water, light or because of predators, pathogens, competition etc.
71
When a population is at its carrying capacity, does it fluctuate or is it completely stable?
It fluctuates slightly in response to small environmental changes
72
Define predator
An animal that hunts other animals for food
73
List 4 things that happen after a predator's population size increases and more prey are eaten. All things are to do with population
The prey population decreases and there is less food available to predators
Fewer predators survive due to the decrease in prey so their population size decreases
Fewer prey are eaten so their population size increases
With more prey, there's more food for predators and their population size increases again
74
Are predator population sizes drastically affected by one species of prey not being easily available?
And do prey population sizes drastically decrease just because of predators?
No because they hunt more than one species
| No a lack food is also responsible
75
Define competition
When resources aren't present in adequate amounts to satisfy the needs of all individuals who depend on the resources
76
What are the two types of competition?
Interspecific competition
| Intraspecific competiton
77
Complete the sentence
| As the intensity of competition increases, the rate of...
...reproduction decreases and the rate of mortality increases
78
Why does reproduction decrease and mortality increase when there is intense competition?
Because some organisms don't have enough resources to reproduce and some organisms don't have enough resources to survive
79
Define intraspecific competition
| What about inter?
Competition between individuals of the same species
| Competition between individuals of a different species
80
When there's intraspecific competition, what determines which individuals succeed and survive?
Natural selection aka the ones that are best adapted to obtaining food survive and reproduce
81
When does intraspecific competition occur?
When resources are limited and the population growth stops increasing rapidly. It occurs just before the stationary phase
82
Does intraspecific competition in the stationary phase keep the population stable?
Yes because if the populations drop there is less competition and if they rise then there is more competition which brings it back to normal
83
Does interspecific competition affect population sizes?
| Does it affect the species distribution in an ecosystem?
Yes and yes
84
Describe the experiment about interspecific competition in detail
What did the scientist conclude?
What is the principle called?
Two species were involved: paramecium Aurelia and paramecium caudatum. The two species were grown together and separately. PA obtained food more successfully meaning that PC died out. This meant that PA grew its population faster when separate and when with PC.
He concluded that when there's more overlap between environmental niche's then there's more intense competition. If their in environmental niche was too similar then one species would become extinct and be out competed.
This conclusion is called the competitive exclusion principle
85
What does the competitive exclusion principle explain?
It explains why particular species only grow in particular places to ensure that their environmental niches are different
86
Does intense interspecific competition always result in extinction?
Explain. 2 things with an example for the second point
1. Because it can result in one population being much smaller but still relatively stable
2. Because many variables act as limiting factors but they all change on a daily basis or on a yearly basis. For example an experiment on flour beetles supported the competitive exclusion principle but if the temperature was changed then then dominating population reversed
87
Define coppicing
Cutting a tree trunk close to the ground to encourage new growth
88
Finish the sentence
| Because human population size is increasing exponentially humans have to...
...use more intensive methods to exploit the environment, this destroys ecosystems, reduces biodiversity and is completely unsustainable.
89
There needs to be a balance between conservation and gaining resources in terms of wood in order to be sustainable. Give 2 examples of sustainable management in terms of wood and explain the benefits
Coppicing and pollarding and felling (not that sustainable)
| Biodiversity is maintained, wood and timber companies are financially secure and there is a sustainable supply of wood
90
Explain what coppicing is
It's when you harvest wood but still keep the tree alive. You cut the trunk of a deciduous tree close to the ground and ten allow several new shoots to grow from the trunk. When the stems mature, they can then be used for fencing, firewood and furniture. The coppice cycle can be repeated many times
91
Explain what pollarding is
It's when you cut the trunk higher up which is useful when deer live near by as it stops the deer eating the new shoots.
92
Explain rotational coppicing
| Talk about 'standards'
It's when you divide the wood into sections and coppice one section each year which provides a continuous supply of wood. When the first section is coppiced again years later, all the shoots will have matured. The length of rotation can vary depending on the tree.
Standards are trees that aren't coppiced for a long time meaning the stems grow larger and supply large bits of wood.
93
Describe the main advantage of rotational coppicing
It's good for biodiversity as the coppiced woodland allows more light in which increases the number and diversity of species
94
Give 2 examples of small scale timber production and give 2 examples of large scale timber production
Coppicing and pollarding
| Clear-felling and selective cutting
95
Explain clear felling and describe it's disadvantages
Clear-felling is when you chop down all the trees in a certain area and it's rarely practised in the UK.
Disadvantages: it destroys habitats, it reduces biodiversity, it reduces soil mineral levels, it leaves the soil susceptible to erosion and it increase the chance of soil running into waterways which pollutes them
96
How does clear-felling increase the chance of soil running off into waterways?
Because trees remove water from the soil which prevents soil being washed away and trees maintain soil nutrient levels so without them there is more surface run off
97
Some sections of woodland are left for 50-100 years before being felled, why is this bad and why is this good?
It's bad because it's not cost effective and it's good because it increases biodiversity
98
What are the three principles for modern sustainable forestry?
Any tree that's harvested is replaced by another tree via natural growth or via plantation
The forest as a whole must maintain its ecological function in terms of biodiversity, climate, mineral and water cycles
Local people should derive benefit from the forest
99
Briefly describe selective cutting
It's when you only remove the largest, most valuable trees and the habitat is broadly unaffected
100
If each tree supplies more wood then fewer need to be harvested. To ensure that trees supply a lot of wood, foresters do what? 3 things
Control pests and pathogens
Only plant particular tree species where they know they'll grow
Position the trees at the optimal distance apart from each other, which reduces competition
101
Define conservation
The maintenance of biodiversity, genetic diversity, habitats and ecosystems
102
Does conservation keep the habitat natural?
Not necessarily it does what ever it needs to in order to maintain biodiversity
103
Does human population help biodiversity or does it threaten it?
It threatens it
104
List 3 ways in which humans threaten biodiversity
1. Over exploitation of wild populations for food, sport and commerce
2. Habitat disruption and fragmentation due to agricultural practises, pollution and widespread building
3. Species that are deliberately or accidentally introduced into an ecosystem and they out compete the native species
105
Describe the ethical issues of conservation
For: it needs to happen because every species has it's own right to exist and humans have an ethical responsibility to look after them
Against: conservation is subjective and some processes need to occur for economics even if they are against conservation
106
Give 3 examples of how other species can provide a direct economic value
1. They can be valuable food sources that can be genetically modified to have a high yield/resistance
2. They are valuable sources of potential beneficial resources like undiscovered drugs
3. Natural pest predators are valuable biological control agents which are better than using pesticides
107
Give 3 examples of animals having an indirect economic value
1. Wild insect species that pollinate crop plants
2. Communities that maintain water quality, soil and the breakdown of waste products
3. Biodiversity which increases climate stability, which reduces the amount of drought/flooding
108
Give an example of when biodiversity can have a social and financial value
Ecotourism and recreation in the countryside due to aesthetic values (it looks nice)
109
What is preservation and how is it different to conservation?
When biodiversity is maintained by protecting areas of land in their untouched form
It's different because it keeps the habitat natural and in its biological form
110
What is so unique about the Galápagos Islands?
Their isolation and small population sizes provide optimal conditions for rapid evolutionary change. They're one of the most conserved tropical archipelagos and house animals like finches, tortoises and iguanas
111
Who allocated the Galápagos Islands with the world heritage site?
The United Nations
112
What percentage of vertebrate and plant species are endangered in the Galapagos?
50% of vertebrates
| 25% of plants
113
What three things has increased Galapagos' population size?
Developing tourist trade
Increased demand for marine products like sea cucumbers
Economic problems in Ecuador
114
List 5 problems with the increased population on the Galápagos Islands
More demands for water, energy and sanitation
More waste and pollution
More demand for oil
More building and using land for agriculture
More destruction and fragmentation of habitats
115
What tree has almost been eradicated from san Cristobal?
Scalesia trees
116
List 5 species that have been over exploited in the Galápagos Islands
```
Whales
Seals
Tortoises
Sea cucumber
Sharks
```
117
What has been done to help replenish the depletion in tortoises in the Galápagos?
The Charles Darwin research station began a captive breeding programme
118
What species have humans brought to the Galápagos Islands?
| What effect has this had?
Goats, red quinine tree, cats, insects, malaria, bird flue, fruits and vegetables
Red quinine trees out compete Scalesia trees and they spread rapidly
Goats are destructive an ruin the habitat via grazing and it out competes the giant tortoise
Cats hunt lizards and iguanas
119
What has been done to reduce the effects of new species in the Galápagos Islands?
They've started a quarantine system on arriving boats/tourists
Natural predators have been used to reduce pest populations
Culling has been used against goats and pigs
120
What methods have people used to reduce human damage to the Galápagos Islands?
They have introduced an educating campaign for new arrivals and encourage sustainable management
