Populations And Ecosystems Flashcards
1
Q
Ecology:-
A
The study of the interrelationships between organisms and their environment.
2
Q
Ecosystem:-
A
A balanced community of interdependent species and their habitats inc. both living (biotic) and non-living (abiotic) elements.
3
Q
ECPI size order:-
A
Ecosystem➡️community➡️population➡️individual organism ⬇️
Habitat➡️niche
4
Q
Community:-
A
Consists of populations of different species which live in the same place at the same time and interact with one another.
5
Q
Habitat:-
A
Where a population lives.
It will have biotic and abiotic features which separate it from other habitats.
6
Q
Ecological niche:-
A
The role + position of a population within its environment.
It can be defined as the sum total of biotic and abiotic resources used by a population in its habitat.
7
Q
Population increase/decrease:-
A
Depends on balance of birth/death rate and immigration/emigration.
8
Q
Interspecific competition:-
A
Comp for resources between members of different species occupying the same niche in an ecosystem. Long term, one outcompetes the other. One pop decreases whilst the other continues to increase.
9
Q
Intraspecific comp:-
A
Comp between individuals of same species for same resources. Density dependent:- greater pop = more fail to survive.
Survival of fittest.
Stabilising effect on population size.
10
Q
Intraspecific comp stabilising effect:-
A
- Pop decrease➡️less intraspecific comp➡️pop increase
* pop increase➡️more intraspecific comp➡️pop decrease
11
Q
Predator-prey intereliant cyclic changes:-
A
- prey no. always higher than pred as over 99% energy is lost between trophic levels- high biomass ensures higher trophic level support.
- delay/lag between pred/prey rise/fall.
- prey pop inc= more pred food so pred pop inc. More prey will be eaten, decing its pop, causing the cycle.
12
Q
Flora sampling techniques:- (3)
A
Random quadrat
Line transect
Belt transect
*all use Simpson’s diversity index.
13
Q
Fauna sampling techniques:-
2
A
- Kick-sampling (for aquatic) Simpson’s diversity index.
* capture-mark-recapture (for terrestrial) Lincoln index.
14
Q
Macronutrients:-
A
Compose 95% of living matter:- carbon,hydrogen, nitrogen, oxygen, phosphorus and sulfur (CHNOPS).
Needed in large amounts by green plants.
15
Q
Trace elements:-
A
Only needed in minute amounts e.g zinc, manganese, iron, copper, boron.
If lacking, plants will decelop deficiency symptoms.
16
Q
Detritus:-
A
Fragments of dead and decaying matter.
17
Q
Detritivores:-
A
Shred up detritus into minute particles that deconposers can act upon. Would take much longer otherwise. Inc. worms, woodlice and maggots.
18
Q
Decomposers:-
A
Release enzymes that break down food by extracellular digestion. Absorb digested products in simalar way to that of our gut. Use it for growth and energy. Nutrients can be passed on by consumption of decomps or release into soil/water. (Fungi + bacteria)
19
Q
4 bacteria types in nitrogen cycle:-
A
- decomposing bacteria.
- nitrifying.
- nitrogen-fixing.
- denitrifying.
20
Q
Decomposing bacteria:-
A
- Along w/ fungi, decomp dead 🌱s and animals, faeces + urine into simpler molecules.
- complex molecules such proteins, AAs and urea are broken down and released to the environment in the form of ammonium ions (NH4^+)- ammonification.
21
Q
Nitrifying bacteria:-(2)
A
Convert ammonium ions into nitrates, under aerobic conditions, oxidises to nitrite. Nitrite is oxidised to nitrate by nitrobacter- nitrification.
Nitrates formed can be absorbed bu plants and so make proteins and nucleic acids and enter the food chain.
22
Q
Nitrogen fixing bacteria:-
A
Take nitrogen gas out of the air and convert it into organic form.
23
Q
Free-living nitrogen fixing micro orgs:-
A
These, such as Azotobacter and Nostoc, a cyanobacteria found in freshwater, account for 90% of nitrogen fixation.
24
Q
Rhizobium (nitrogen fixing)
A
Found in roots of legume plants such as peas, beans, clover and gorse. Roots swell to form root nodules. Mutualistic relationship- bacterium fixes nitrogen and gives plant source of nitrogen, bacterium obtains carbohydrate from host plant.
25
Denitrifying bacteria:-
Get energy source by converting nitrates and ammonium ions back into nitrogen gas. Occurs in absence of oxygen e.g in water logged soils. Source of energy for Pseudomonas and Thiobacillus.
26
Biotic index:-
A number calculated to descrive a particular feature of a population.
27
Lincoln index:-
Capture organisms, mark them and return them. Allow them to mix w/ other members of population. take second sample and record no. of marked and unmarked.
28
Lincoln index equation:-
Population size= (number in first sample x number in second sample)/(number of marked individuals recaptured.
29
Improving Lincoln Index source of error- marking could affect behaviour of organisms or its predators:-
Use marking that is only visible in UV light.
30
Improving Lincoln Index source of error- markings could br lost between the two collections:-
Use not water soluble marks
31
Improving Lincoln Index source of error- the animal may not fully integrate back into its community:-
Leave as long as reasonable
32
Improving Lincoln Index source of error- some organisms may be better at avoiding capture:-
Very diligent searching
33
Improving Lincoln Index source of error- may be immigration/emigration in population between two samples
Choose isolated population
34
Basic nutrient cycle:-
•Abiotic environment:-
Simple inorganic CO2/N2/H2O.
➡️fixed by producers➡️plants + animals•biotic enviro, complex organic carbs/proteins/lipids.
➡️broken down by decomposers➡️soil/H2O/atmos. Back at start.
35
Carbon cycle (4):-
* inorganic CO2 = C source, released into atmosphere by respiration and fossil fuel combustion.
* carbon fixed into complex org mols by photosynthesis e.g AA, DNA/RNA, ATP.
* CO2 released by resp when animals eat plants.
* if plants/animals die, decomped by saprotrophs (microorgs) in soil. Released C mols are passed through food chains and eventually returned to enviro as simple inorg mols.
36
3 main processes in carbon cycle:-
* photosynthesis.
* respiration.
* combustion (release in factories).
37
2 main factors leading to rise in CO2 levels:-
* burning of fossil fuels releasing locked CO2.
| * deforestation removing large quantities of photosynthesising biomass.
38
Carbon footprint:-
The total amount of CO2 attributable to the actions of an individual or a product or service over the period of a year.
39
Direct emissions:-
E.g. Energy used at home + by transport.
40
Indirect emissions:-
E.g CO2 emissions as a result of goods and services consumed.
41
4 stages of nitrogen cycle:-
Nitrogen fixation.
Ammonification.
Nitrification.
Denitrification.
42
Nitrogen fixation:-
Inorganic nitrogen gas taken from atmos and fixed into NH3 by N fixing bacteria. Dissolves to form NH4+.
Absorbed by plant roots to make organic N comps.
43
Ammonification:-(3)
* decomposers result in dead plants and animals, faeces and urine into ammonia.
* decomp nitrogenous org matt by saphrotropic digestion, breaking down into AAs.
* amino group removed and hydrogen group added to form NH3.
44
Nitrification:-(4)
* ammonia converted to nitrite ions by nitrosomonas bacteria.
* nitrite ions converted to nitrate ions by nitrobacter bacteria.
* bacteria require aerobic conditions.
* nitrate ions taken up by plants via facilitated diffusion or active transport and are used to form aa/proteins.
45
Denitrification:-
* nitrogen is lost from ecosystems.
* problem in water logged soils whete air spaces become filled with water-anaerobic. Only anaerobic bact can survive (pseudomonas) which convert nitrates and NH4 ions back to N which is then lost to atmos.
46
Nitrogen can be lost from ecosystems by (2):-
* leaching-run off after heavy rainfall as nitrates are water soluble.
* harvesting crops- nitrogenous compounds are removed from soil.
47
Measures to prevent N2 loss/improve N circulation:- (4)
* iniorganic fertilisers (containing instantly absorbable nitrates.
* organic fertiliser (manure) containing dead materials which breaks down to ammonium comps and converts to nitrates.
* planting leguminous plants (has rhizobium)
* maintaining aerobic conditions in soil ploughing to break up soil and digging drainage ditches around field edges.
48
Eutrophication definition:-
The artificial enrichment of aquatic habitats by excess nutrients, often caused by run off of fertilisers, resulting in a reduction in water's oxygen level.
49
Simpson's diversity index equation:-
1-((sum of n(n-1))➗(N(N-1)
n= number in each species.
N=total number of organisms.
50
Population growth curve and 4 stages:-
* Lag phase (flat bit at bottom).
* log (exponential) phase- growing, steep grad.
* stationary phase- flat, max.
* death (decline) phase.
51
Lag phase:-
Lasts from few mins to few years. V. Slow as few individuals so little growth. Period of prep for growth so indivs undergo:- finding food, finding a mate and, in bacteria, metabolic activity. Organisms need to reach sexual maturity.
52
Log phase:-
```
Rapid growth as little environmental resistance and preds/disease.
•more individuals for reprod.
•birth rate>death rate.
•immigration>emigration
•in bacteria, constant rate of cell div.
```
53
Stationary phase:-
```
Steady growth rate:-
•birth=death rate
•immi=emi
•enviro resistance occurs
•when enviro is saturated with a species, it is said to have reached its carrying capacity (K on graph).
```
54
Carrying capacity:-
The limit to the number of individuals that an area can support.
55
Death/decline phase:-
* death rate>birth
* emi>immi
* rate will be increased by depletion in resources and preds/disease
56
Density dependent factors:-
Effect depends on pop size e.g disease, depletion of food resources. Carrying capacity therefore dependent on resources available in environment.
57
Density independent factors:-
Effect on population is the same regardless of pop size e.g tenp/ph/volcanic eruption.
58
Set point:-
Optimum population which is fluctuated about.
59
Negative feedback:-
When there is a change in a monitored variable, a response is triggered to counteract the initial fluctuation.
Regulate population oscillations.
60
Population size equation:-
(Birth rate + immigration)-(death rate + emigration)
61
Biotic factors:-
Predation, disease, etc
62
Abiotic:-
Volcanic eruptions, light intensity, flooding, etc
63
Population:-
A group of individuals of the same species living in the same habitat.
64
Diversity index number meaning:-
Greater number = more diverse. Number should always be between 0 and 1.
65
Pyramid of numbers:-
Number of organisms at each trophic level shown..
66
Pyramids of biomass:-
Show biomass of organisms at each trophic level (kg m^-2).
| Don't take into account time so temporary pop variation could cause irregular shape.
67
Pyramid of energy:-
Most accurate way of repping feeding relationships. KJ/m^2/year.
Difficult to collect data as would require incineration of living material.
68
Sun:-
Source of energy for most ecosystems. Green plants absorb solar energy and photosynthesise, converting light energy into chemical energy which is then available to organisms in ecosystem.
69
Primary producer:-
Organism that converts light into chemical energy. At base of food chain.
70
Primary consumer:-
Feed on primary producers. Herbivores.
71
Secondary consumers:-
Feed on primary consumers. Carnivores.
72
Energy transfer inefficient in ecosystem:-
Approx 10% from each trophic level transferred to biomass and available to next trophic level. Therefore, rarely more than 5 level.
73
Energy lost by:-(3)
* respiration.
* egestion e.g of undigested cellulose.
* excretion.
74
Gross primary productivity:-
Rate at which plants convert light energy into chem energy/ organic mats such as carbohydrates.
Measured kJm^-2year^-1 and is approx 0.2% of incident global sunlight.
75
Net primary productivity:-
The potential food (biomass) available to heterotrophs in ecosystems (approx 0.1% of incident global sunlight).
76
NPP equation:-
GPP - R.
| R = resp.
77
Secondary consumer efficiency:-
May be higher e.g. 20%
| As protein is easier to digest than cellulose.
78
Sucession definition:-
The change in structure and species composition of communities over time.
79
Primary sucession:-
Refers to the intro of plants and animals into areas that haven't previously supported a community.
Usually starts w/ bare rock or sand such as behind a retreating glacier, after a volcanic eruption, on a new sand dune, etc.
80
Secondary sucession:-
Reintrocof orgs into a bare habitat that has previously been occupied by plants and animals. E.g if original vegetation is removwd by a fire.
81
Six seres in sucession:-
| Use Beer Pong Causes Horrific Shots for Cameron.
* bare ground
* pioneers (lichens)
* colonisers (mosses, ferns)
* herbaceous plants (grasses)
* shrubs (shrubs, bushes)
* climax (trees)
82
Woodland primary sucession:-
* bare ground colonisation - algae and lichens.
* erosion, death and decay of these leads to simple soil dev + provides conditions for colonisers to grow.
* further decay improves soil for grasses.
* soil builds up, deep rooted shrubs and eventually, trees, start to appear.
* when wood is formed, climax community. Stable.
83
Invertebrate vs mammals/birds energy floe:-
Mammals/birds pass on more as they are warm blooded so require lower resp rare for heat production and therefore use up less glucose.
84
Facilitation:-
•interactions where at least one benefits.
85
Eutrophication 1:-
Fertilisers containing nitrates and phosphates are leached from land into neighbouring water courses as they are highly soluble.
86
Eutrophication 2:- Previous= Fertilisers containing nitrates and phosphates are leached from land into neighbouring water courses as they are highly soluble.
Abundance of nutrients promotes surface algae growth- algal bloom. This turns the water green and restricts light penetration to lower levels of the water body.
87
Eutrophication 3:- Prev= Abundance of nutrients promotes surface algae growth- algal bloom. This turns the water green and restricts light penetration to lower levels of the water body.
Bottom dwelling plants can't photosynthesise and therefore die. There is a general decrease in animal species diversity as they rely on the plants for food and shelter.
88
Eutrophication 4:- Prev= Bottom dwelling plants can't photosynthesise and therefore die. There is a general decrease in animal species diversity as they rely on the plants for food and shelter.
Short lived algae die and are decomped by saphrotrophic bacteria which use a lot of oxygen, creating a high biochemical oxygen demand (BOD).
89
Eutrophication 5:- Prev= Short lived algae die and are decomped by saphrotrophic bacteria which use a lot of oxygen, creating a high biochemical oxygen demand (BOD).
Water in all but very levels becomes deoxygenated, so fish and other species requiring oxygen die.
90
Eutrophication 6:- Prev= Water in all but very levels becomes deoxygenated, so fish and other species requiring oxygen die.
Anaerobic bacteria in water reduce nitrate to nitrite, both of which are toxic compounds.
91
EU water toxicity limit:-
11.3 parts per million
92
Legislation farmers must follow to reduce nitrate quantity released (3):-
* restrict fertiliser applied and only fertilise when crops are actively growing.
* leave a strip at least 10m wide next to water courses.
* drainage ditches which may prevent run off can also reduce biodiversity- needs to be used with caution.
93
Problems caused by excess nitrates in soils:-(2)
* reduced species diversity on grasslands.
| * increased growth of grasses and nettles which shade out smaller plants.
94
Light energy not all absorbed by leaf:-(3)
* light can be transmitted through leaf and not strike the chlorophyll.
* light can be reflected from leaf surface.
* light can be not absorbed:- chlorophyll only absorbs red and blue wavelengths of light.
95
Biofuel disadvs:-(3)
* energy is used in farming + processing the frops. Can possibly make biofuels as polluting as petroleum based.
* widespread use would reduce habitat for 🌱 and animal species, leading to further biodiversity loss.
* if increased proportions of food crops are used for fuel, it will push up food prices for less wealthy countries.
