4 ecology Flashcards
(168 cards)
1
Q
habitat
A
the type of environment in which an organism or groupn ormally lives
2
Q
food chain
A
a series of steps in whcih organisms transfer energy by eating and being eaten
3
Q
community
A
a group of interdependent organisms in habiting the same region and interacting with each other
4
Q
detritivore
A
an organism that ingests non living organic matter
5
Q
heterotroph
A
an organism that obtains organic molecules from other organisms
6
Q
consumer
A
an organism that ingests other organic matter that is living or recently killed
7
Q
autotroph
A
an organism that synthesizes its organic molecules from simple inorganic substances
8
Q
ecosystem
A
a community of organisms and their abiotic environment
9
Q
food web
A
a complex arrangement of interrelated food chains illustrating the flow of energy between interdependent organisms
10
Q
species
A
a group of organisms that can interbreeed and produce fertile offspring
11
Q
ecology
A
the study of relationships between living organisms and their environment
12
Q
population
A
a group of organisms of the same species who live in the same area at the same time
13
Q
saprotroph
A
an organism that lvies on or in non living organi matter, secreting digestive enzymes and absorbing digested products
14
Q
trophic level
A
the feeding level in a food web defined by the number of energy transfers away from the orgiinal source of energy
15
Q
species
A
a group of genetically similar living organisms that are able to interbreed and produce fertile offspring. Fertile offspring are those which can in turn interbreed and pass on their genes to another generation.
16
Q
autorophs
A
Organisms that are capable of making their own complex organic molecules from carbon dioxide and other simple compounds are called autotrophs
17
Q
heterotrophs
A
Organisms that obtain their organic compounds through feeding on other organisms are called heterotrophs.
18
Q
bacteria method of obtaining org molecules
A
Some autotrophic and some heterotrophic
19
Q
protocista method of obtaining org molecules
A
some autotrophicn and some heterotrophic
20
Q
fungi method of obtaining org molecules
A
heterotrophic
21
Q
plantae method of obtaining org molecules
A
mostly autotrophic
22
Q
animals method of obtaining org molecules
A
heterotrophic
23
Q
ingestin
A
the taking in of a substance
24
Q
Detritivores
A
heterotrophs that obtain their organic nutrients from detritus, which is waste or other organic debris, by internal digestion.
organisms that gain nutrients by feeding on dead organic material and breaking it into smaller organic molecules.
25
Symbiosis means
'living together' and refers to the following outcomes of interactions between populations.
26
mutalism
a type of symbiotic relationship where both organisms benefit.
27
Commensalism is a type of
symbiotic relationship where one organism benefits and the other is unaffected.
28
Parasitism is a type of
symbiotic relationship where one organism benefits and the other is harmed.
29
whats an ecosystem
a community interacting wit its abiotic environment
30
if sea organisms cant get the sun's energt what can they use
chemical energy
31
nutrient cycling
helps to move organic molecules and minerals through the food chain and back into the soil where they can be taken up by plants to re-enter the food chain.
32
mesocosm
an experimental tool that allows the experimenter to control the conditions in a small part of the natural environment. It can act as a model of a larger ecosystem, in which energy enters and leaves but matter does not.
33
adv of mesocosms
Treatments are easily replicated.
The effect of several environmental factors can be tested.
Food webs can be established.
Direct and indirect effects can be studied.
Contamination influence can be evaluated.
Constants can be controlled to see the effect of one environmental factor at a time.
The sustainability of an ecosystem can be tested.
34
types of mesocosm
aquatic and terrestial
35
chi sq
a statistical test to better understand communities and whether two populations are associated and dependent upon each other or not.
36
null hypothesis
the hypothesis that states that there is no association between the two populations being tested in the chi-squared test.
37
what type of data for chi sq
categorical
38
ecological frequency
the number of times a plant species occurs in a given number of quadrats. Frequency is usually expressed as a percentage and is sometimes called a Frequency Index.
39
how do you calculate expected freq
multiplying the row total by column total and dividing by the grand total
40
chi sq formula
x2=Σ (O−E)/2E
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Random sampling
necessary in order to obtain data that is random and unbiased.
42
X 2 calculated >X 2 critical:
H 0 is rejected and the variables are associated
43
X 2 calculated ≤ X 2 critical:
H 0 is accepted and the variables are not associated
44
The degrees of freedom is calculated by multiplying
the number of rows minus one by the number of columns minus one.
45
photosynthesis equation
6H2O+6CO2+Energy from the Sun→C6H12O6+6O2
46
respiration formula
6O2+C6H12O6→Energy in the form of ATP→6H2O+6CO2
47
what coudl energy from carbon compounds be used for
Nucleic acid and protein synthesis
Ion exchange across membranes
Cell division for reproduction, growth and repair
Movement of components within cells.
48
energy transfer between trophic levels
between 10 to 20%
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how is energy lost in trophic levels
movement, excretory products, faeces, heat and unconsumed materials
50
biomass
the mass of dried organic material which can be used as fuel in an ecosystem, expressed in terms of dry weight per unit area.
51
why does carbon accumulate at the bottom
its heavier than other components in the atmosphere
52
as pressure increases, the solubility of CO2
increases
53
CO2 combines with water to form
carbonic acid (H2CO3)
54
carbonic acid
is the molecule that forms when CO2 combines with water. This molecule is unstable and dissociates easily in water into hydrogen ions (H+) and hydrogen carbonate ions (HCO3-). The H+ that are released in this dissociation lower the pH of the water (makes it more acidic).
55
Land plants take up carbon dioxide as a gas through
their stomata
56
In aquatic plants, dissolved carbon dioxide enters how
diffuses into the leaves from the environment
57
In aquatic ecosystems carbon is present as:
Dissolved CO2 and bicarbonate ions
58
methane
a carbon molecule which is produced in anoxic conditions and can oxidise into carbon dioxide and water.
59
what produces methane from organic matter under anaerobic conditions
methanogenic archeans
60
methanogenic archeans
bacteria that are found in several anoxic environments and produce methane as part of the carbon cycle.
61
ruminants
mammals that have a mutualistic relationship with methanogenic archaeans that help them to digest cellulose from the cell walls in the plants they eat. This creates methane, which is released as gas from the mammal.
62
whats acetogenesis
Organic matter is first changed to organic acids and alcohol, such as ethanol, by a group of bacteria
63
hydrolysis by ruminants
Ruminants chew on plants breaking down the molecules, such as some carbohydrates, into smaller monomers (using their saliva)
64
Acidogenesis
the chemical process in which bacteria convert organic matter into organic acids and alcohol.
65
Acetogenesis
the chemical process in which bacteria convert organic acids and alcohol into acetate.
66
Methanogenesis
the chemical process in which methanogenic bacteria can produce methane through the reaction of carbon dioxide and hydrogen or through the breakdown of acetate.
67
how is peat formed
when organic matter is not fully decomposed because of acidic and/or anaerobic conditions in waterlogged soils.
68
what is peat
partially digested organic matter that forms in acidic, water-saturated soil. Peat contains large amounts of carbon and can be compressed into coal after time.
69
uses of peat
As a substitute for firewood for cooking and heating
To increase the moisture holding capacity of soil (that is rich in sand particles) in horticulture
To increase the water infiltration rate of soils rich in clay particles
To acidify soils for specific pot plants.
70
Methanogens are archaea that are:
Anaerobic organisms that obtain energy through the synthesis of methane from CO2 and H2 or acetate.
71
conditions required for peat formation
acidic conditions
lowpH
anaerobic condiitons (no O2)
72
fossil fuels
organic material that has been compressed over time, to form coal, oil and gas.
73
combustioin
a process of burning which releases CO 2 from organic material such as fossil fuels or biomass.
74
Calcium carbonate –
CaCO3 – an important source of carbon in the environment which makes up shells and exoskeletons and can eventually become porous sedimentary rock such as limestone.
75
what does calcium carbonate dissolve in
acid but not alkali
76
resevoir
a place where a certain element, such as carbon, has accumulated or pooled. Also, known as a sink when discussing nutrient cycling.
77
When carbon moves from one reservoir, or sink , to another it is called a
flux
78
flux
the process that moves an element from one reservoir or sink to another.
79
lithiosphere
the portion of the Earth that consists of the crust and upper mantle.
80
hydrosphere
the portion of the Earth that consists of water including oceans, lakes, ponds and rivers.
81
biota
the portion of the Earth that consists of the living organisms.
82
atomosphere
the layer of gases surrounding the Earth.
83
unit for carbon
the unit is gigatonnes (Gt): 10 15 g
84
For carbon, the cycling process involves:
A reservoir
An exchange pool
A biotic communityFor carbon, the cycling process involves:
85
Greenhouse gases
gases found in the atmosphere such as water vapour, carbon dioxide, methane and nitrous oxides, that contribute to the greenhouse effect.
86
water vapour
water found in the atmosphere in a gaseous form. It is the most abundant greenhouse gas.
87
carbon dioxide
a gas found in the atmosphere that is a main greenhouse gas. Carbon dioxide enters the atmosphere by respiration and decomposition as well as burning of biomass and combustion of fossil fuels. It is taken out of the atmosphere by the process of photosynthesis and absorption by water.
88
methane
a gas found in the atmosphere that is produced from methanogenic ruminant bacteria and saprotrophic bacteria.
89
nitrous oxides
a greenhouse gas that is formed both naturally and by humans, mainly through farming, industry and combustion of fossil fuels.
90
Two factors that determine how much a greenhouse gas will contribute to global warming are ______ ; Your answer here;and ______ ; Your answer here;.
Ability to absorb longwave radiation/abundance in atmosphere
91
summary of the greenhouse effect
1. Solar radiation, from the sun, spans the electromagnetic spectrum from approximately 100 to 4 000 nanometres (nm), with visible light comprising about 44% of its emissions. After passing through the ozone layer , the layer of the atmosphere that blocks UV radiation but is not considered a greenhouse gas, only short-wavelength radiation from the sun reaches the Earth's surface. Some of the short-wavelength radiation is reflected, but most passes through the greenhouse gases to the Earth’s surface.
2. The Earth absorbs some of this shortwave radiation while some is reflected. This absorbed radiation is then re-emitted, mainly as infrared (heat) , which is a longwave radiation (with a peak around 10 000 nm).
92
radiation
energy that may be a subatomic particle, for example an electron (gamma rays) or in the form of an electromagnetic wave, for example ultraviolet radiation.
93
solar radiation
energy from the sun that comes in the form of electromagnetic waves. This includes many types of waves such as visible light or ultraviolet light.
94
ozone layer
O 3 – is a layer of the Earth’s atmosphere that protects the Earth from ultraviolet radiation coming from the sun. It is not considered a greenhouse gas because it does not absorb longwave radiation.
95
UV radiation
ultraviolet radiation is a type of shortwave radiation coming from the sun, but is filtered out by the ozone layer of the atmosphere.
96
Long-wavelength radiation
also known as infrared light, a type of radiation that is emitted from the Earth and its atmosphere. Examples include, microwaves and radiowaves.
97
short wave radiation
this type of radiation comes from the sun in the form of visible light and ultraviolet light. It is absorbed by the Earth and re-emitted as long-wavelength radiation.
98
Infrared –
this type of long-wavelength radiation is given off from the Earth in the form of heat.
99
global warming
the warming of the Earth and its atmosphere due to the intensified greenhouse effect.
100
Why are oxides of nitrogen classed as greenhouse gases?
Oxides of nitrogen trap some of the longwave radiation emitted by the Earth’s surface.
101
The Earth ________ short-wavelength radiation from the sun and ______ long-wavelength radiation.
absorbs short wave
emits long wave
102
rise in temp effect on climate change
Higher global averages mean that the total amount of water that evaporates from oceans and lakes increases. More water in the atmosphere leads to heavier rainfall. Global warming can also have substantial effects on wind and ocean currents causing stronger hurricanes and typhoons.
103
rise in temp effect on rising seawater
Another consequence of the increased global temperature is the rising seawater temperature and the melting effect on the polar ice caps and glaciers around the world.
104
rise in temp effect on loss of habitat
The polar ice caps and glaciers are melting, decreasing ice habitats for some arctic organisms. Also, when these ice caps melt they cause a rise in sea levels, as mentioned above, destroying coastal habitats.
105
rise in temp effect on biotic factors
The warming of any habitat would change the species that live in the area and can cause changes to migratory patterns. Temperate species move into warmer arctic areas and compete with the arctic species. Arctic species need to adapt to competition and the change in temperature or emigrate to a new habitat. This would cause a change in the distribution of species, possibly a decrease in population sizes and, in extreme cases, extinction of species. As you learned in subtopic 4.2 , changes such as these could have severe impacts on the food chains of an ecosystem disrupting the food web and having a large impact on organisms in higher trophic levels. Other effects on the biota may be an increase in decomposition due to melting permafrost, which exposes saprotrophic bacteria to oxygen, releases methane, and, with an increase in temperature and moisture there will be an increase in pest species and pathogens.
106
Precautionary principle
also known as the burden of proof, this principle states that even without concrete evidence of a causal relationship, precautionary measures should be taken to ensure that humans are not causing detrimental harm to the environment or human health.
107
Precautionary principle
also known as the burden of proof, this principle states that even without concrete evidence of a causal relationship, precautionary measures should be taken to ensure that humans are not causing detrimental harm to the environment or human health.
108
If humans start to see devastating effects in the environment, such as melting ice caps, but not clear evidence suggesting that it is caused by human action, such as the burning of fossil fuels, which statement about the precautionary principle would be appropriate?
Because it is probable that combustion of fossil fuels are causing devastating environmental effects, people should be educated on the consequences and laws that require cleaner filtering systems for industries.
109
coral reefs
a ridge in the ocean where living coral polyps attach and secrete calcium carbonate. Coral reefs are typically very diverse places found in warm shallow waters.
110
Ocean acidification –
the drop in pH of the ocean due to the absorption of carbon dioxide, which forms carbonic acid. The H+ ions become dissociated from carbonic acid causing the water to become acidic.
111
Calcification –
the process used by molluscs, crustaceans, and corals to build their shells and exoskeletons using calcium carbonate.
112
nutrient cycle
soil
some nutreints lost due to leaching
some nutreints added as rock is weathered
biomass
nutrients taken up by plants
plants and organisms die
litter
layer of vegetation in surface of soil
nutrients released as plants rot
113
what is nutrient cycling
helps to move organic molecules and minerals through the food chain and back into the soil where they can be taken up by plants to re-enter the food chain.
114
whats a mesocosm
an experimental tool that allows the experimenter to control the conditions in a small part of the natural environment. It can act as a model of a larger ecosystem, in which energy enters and leaves but matter does not.
a tool used to model ecosystems in order to monitor and evaluate variables.
115
adv of using a mesocosm as an experimental tool
Treatments are easily replicated.
The effect of several environmental factors can be tested.
Food webs can be established.
Direct and indirect effects can be studied.
Contamination influence can be evaluated.
Constants can be controlled to see the effect of one environmental factor at a time.
The sustainability of an ecosystem can be tested.
116
types of mesocoms
aquatic and terrestial
117
what should you use as a mesocosm
sealed glass vessels
118
what does chi squared test
how likely it is that an obsered distribution is due to chance
119
what does the chi squared test test
null hypothesis (are the variables independent of eachother)
120
chi sq test
a statistical test to better understand communities and whether two populations are associated and dependent upon each other or not.
121
what type of data is used with chi sq test
categorical data (not linear but seperated into categories)
122
what is ecological frequency
the number of times a plant species occurs in a given number of quadrats. Frequency is usually expressed as a percentage and is sometimes called a Frequency Index.
123
how to calcualte ecological frequency
row total x column total
---------------------------------- = exp freq
grand total
124
whats expected frequency
the number of quadrats a population is expected to occupy in an area.
125
how to carry out chi sq
state null hypothesis (that two varibels are independent and unrelated)
state alternate hypothesis
calcualte degrees of freedom (no rows -1 x no columns -1
read the significance level at 5%
126
if the p value is less than 0.05 or 5%
then the variables are dependent or associated
127
if the p value is more than 0.05 or 5%
variables are independent or not associated
128
X 2 calculated >X 2 critical:
H 0 is rejected and the variables are associated
129
X 2 calculated ≤ X 2 critical:
H 0 is accepted and the variables are not associated
130
limitations of chi sq
The chi-squared test can only be used for categorical data.
The data must be raw data counts, not percentages, continuous data, or derived data.
The chi-squared test is not valid if the sample size is a small value, for example, one organism.
The chi-squared test cannot tell you what the association between the variables is, only if there is one.
131
random sampling
necessary in order to obtain data that is random and unbiased.
132
what causes the struggle or surival in populations
When there are too many individuals in a population (caused by overproduction of offspring) there is not enough sustenance or space to support the whole population This causes the struggle for survival.
133
in what type of porous rock would you expect to find high amoutns of calcium carbonate from the shells of molluscs and exoskeletons of crustaceans
sediemtnary rock
limestone
134
what is recycled in an ecosystem
carbon and nutreitns but not energy
135
Graphs illustrating the change in global temperatures over time often have many peaks and troughs. Suggest a term you could use to describe these peaks and troughs.
fluctuations
136
In a diagram showing a pyramid of biomass there may be another block on the primary consumer level in addition to herbivores. What does this additional block represent?
decomposers
137
Why are oxides of nitrogen (NOx) classed as greenhouse gases?
they trap some of the long wave radiation emitted by the earths surface. For a gas to contribute to the greenhouse effect it has to have the following property: it has to absorb longer wavelength radiation. Two other gases, methane and nitrous oxides (NO2 and NO) have that property and contribute. Please also refer to the section 4.4.2 for the explanation.
138
aim of setting up a mesocosm
establishing sustainability in the mesocosm
139
outline the criteria that should be used to assess whether a group of organismsi s a species
a organisms can potentially interbreed;
b to produce fertile offspring;
c same sequence of genes (on chromosomes) / same types of chromosomes;
d similar traits/phenotype/WTTE;
e same chromosome number/karyotype;
140
disucss the changes that occur in gene pools during speciation
a gene pool is all genes/alleles in an (interbreeding) population;
b gene pool splits/divides/separated during speciation;
c due to reproductive isolation (of groups within a species);
d temporal/behavioral/geographic isolation (can cause reproductive isolation);
e divergence of gene pools;
f allele frequencies change;
g natural selection different (in the isolated groups so there is divergence);
h different (random) mutations occur (in the isolated populations so there is divergence);
i speciation has occurred when differences between populations prevent interbreeding
141
discuss the process, including potential risks and benefits, of using bacteria to genetically modify plant crop species
Process:
a genetic modification by gene transfer between species;
b gene/Bt gene/DNA segment transferred from bacterium to plant/crop;
c gene/DNA codes for/responsible for desired protein/gene product;
d bacteria have/produce plasmids / gene/DNA inserted into plasmid;
e using restriction enzymes/endonucleases to cut DNA;
f using DNA ligase to join DNA;
g bacterium transfers (modified) plasmid to plant cell;
Benefits:
h increase crop yields / more food produced / less land needed to grow food;
i increase pest/disease resistance / use less pesticides/insecticides/fungicides;
j improves crops to be more nutritious/increased vitamin content;
k increased tolerance to saline soils/drought/high temperatures/low temperatures;
Risks:
l GM organisms could spread to sites (where they will cause harm);
m transferred gene could spread to other species / spread of herbicide resistance to
weeds;
n GM crops that produce pesticide could kill non-pest insects/monarch butterflies / insect
pests could develop resistance to pesticides/insecticides/Bt toxin
142
proteome
the entire set of proteins expressed by an organism at a certain time
143
how do you get rid of CO2
boil and cool the water
144
function of dna polymerase I
remove rna primer and replace it with dna
145
r group interactions stabilize...
further foldings of a polypeptide into teritary structure
146
how is the kidney involved in osmoregulation
a osmoregulation is regulation of water and solute/salt balance/solute concentrations;
b nephron (is the functional unit of the kidney/osmoregulates);
c ultrafiltration in glomerulus / glomerular filtrate collected by Bowman’s capsule;
d loop of Henle establishes/maintains hypertonic conditions in medulla;
e osmosis/reabsorption of water (from filtrate) in the collecting duct;
f brain/hypothalamus monitors blood solute concentration / pituitary secretes ADH;
g ADH secreted when solute concentration of blood is too high/hypertonic/when dehydrated;
h ADH increases permeability of collecting duct to water;
i ADH causes more aquaporins (in membranes of collecting duct wall cells);
j more water reabsorbed resulting in more concentrated/hypertonic urine/less volume of
urine;
k less/no ADH secreted when solute concentration (of blood) is too low/hypotonic;
l less water reabsorbed resulting in dilute/hypotonic urine/large volume of urine
147
describe the processes that cause water to move from the roots of plants to their leaves
a water moved/transported in xylem vessels;
b transported under tension/suction/pulled up (in xylem vessels);
c transpiration/loss of water (vapour) generates pulling forces/low pressure/tension;
d tension/pull generated when water evaporates from cell walls (in mesophyll);
e transpiration is loss of water vapour from leaf (surface)/stomata;
f cohesivity/cohesion in water due to hydrogen bonding/attractions between water
molecules;
g cohesion/WTTE so chain/column of water (molecules) doesn’t break/remains continuous;
h transpiration stream is a column of/flow of water in xylem from roots to leaves;
148
explain how polypeptides are produced by this process of translation
a mRNA is translated;
b mRNA binds with ribosome/with small subunit of
ribosome;
c tRNA-activating enzymes/aminoacyl tRNA synthetases
attach specific amino acid to tRNA;
d anticodon of 3 bases/nucleotides on tRNA;
e start codon/AUG on mRNA;
f tRNA carrying first amino acid/methionine binds to
P/peptidyl site (when large subunit binds);
g anticodon (on tRNA) binds to codon (on mRNA);
h complementary base pairing (between codon and
anticodon);
i tRNA for next codon binds to A site/amino acyl site;
j peptide bond forms between amino acids (on tRNAs)
at P and A sites;
k ribosome moves along mRNA to next codon/by three
bases/in 5’ to 3’direction;
l tRNA released from E/exit site;
m process/cycle repeats to elongate the polypeptide/until
stop codon is reached;
n release of polypeptide and mRNA/disassembly of
ribosome complex at stop codon;
149
outline how the roteins are digested and products of protein digeston absorbed in humans
a digested by peptidases/proteases;
b pepsin/pepsinogen/endopeptidase secreted by
stomach (lining)/digests proteins in stomach;
c pancreas secretes/pancreatic juice contains
endopeptidase/trypsin/peptidase;
d endopeptidase digest proteins/polypeptides to shorter
chains of amino acids/shorter peptides;
e amino acids absorbed by active uptake/transport;
f in small intestine/ileum;
g villi increase the surface area for absorption;
h absorbed into bloodstream/into capillaries;
150
Ecological role of saprotrophic bacteria
To digest dead organic matter and release nutrients from it
151
What type of organisms obtains nutrients from internal digestion of materials such as shed skin, hair, leaves, feathers etc
Detritivores
152
Ecosysten
Community and it's abiotic environment
153
What is a hybrid
An organism that is the offspring of two different species. The two parent species must be closely related, but often have different chromosome numbers, leading to an odd number of chromosomes in the hybrid offspring
154
What is recycled in an ecosystem
Carbon, nitrogen not energy
155
What is the aim of setting up a mesocosm
Establishing sustainability in the mesocosm
156
Methanogenic archaeans –
bacteria that are found in several anoxic environments and produce methane as part of the carbon cycle.
157
ruminants
mammals that have a mutualistic relationship with methanogenic archaeans that help them to digest cellulose from the cell walls in the plants they eat. This creates methane, which is released as gas from the mammal.
158
whatproduces vast amounts of methane
The gut bacteria in ruminants and other herbivores produce vast amounts of methane, which is released into the atmosphere.
159
stages of ruminant digestion
hydrolysis (chewing and breaking down molecules like carbs into smaller monomers)
acidogenesis (org matter changed to org acids and alcohol, such as ethanol, by a group of bacteria)
acetogenesis (bacteria convert org acids and alcohol into acetatec co2 and hydrogen)
methanogenesis ( methanogenic bacteria can produce methane either through the reaction of carbon dioxide and hydrogen (1) or through the breakdown of acetate (2), also known as methanogenesis.)
160
hydrolysis
the chemical process of breaking large polymers into dimers or monomers using water.
161
acidogenesis
the chemical process in which bacteria convert organic matter into organic acids and alcohol.
162
acetogenesis
the chemical process in which bacteria convert organic acids and alcohol into acetate.
163
methanogenesis
the chemical process in which methanogenic bacteria can produce methane through the reaction of carbon dioxide and hydrogen or through the breakdown of acetate.
164
oxidation of methane
Methane is oxidised in the upper layers of the atmosphere through the interaction of methane with hydroxyl radicals, which are highly reactive. The reaction produces CO2 and water. The complete oxidation of methane to carbon dioxide and water involves several steps and includes several intermediate compounds.
165
is the saprotrophic digestionof dead leaf matter and other organic debris anaerobic or aerobic
aerobic
166
how does peat form
there are some waterlogged areas where the stagnant water creates an anaerobic (no oxygen present) environment in which the saprotrophs cannot grow. The result is an environment that becomes progressively acidified over time. Any surviving saprotrophs die, and the remaining organic matter is only partially digested. New layers of leaf litter and other organic debris fall on top of this older layer of material, further compressing it. The result is peat. Peat exists across wide areas of our planet and can reach depths of 10m
.
167
uses of peat
As a substitute for firewood for cooking and heating
To increase the moisture holding capacity of soil (that is rich in sand particles) in horticulture
To increase the water infiltration rate of soils rich in clay particles
To acidify soils for specific pot plants.
168
waht type of rock is limestone
sedimentary or porous rock
