1
Q
what is a niche?
A
the role of an organism within an ecosystem
2
Q
what is a habitat?
A
The place where an Organism lives.
3
Q
What is the population?
A
All the organisms of one species in a habitat.
4
Q
What is a producer?
A
An Organism that produces organic materials using sunlight energy.
5
Q
What is a consumer?
A
An Organism that eats other organisms.
6
Q
What is a decomposer?
A
An Organism that breaks down dead or undigested organic material.
7
Q
What is a trophic level?
A
a stage in a food chain occupied by a particular group of organisms.
8
Q
What is an ecosystem?
A
All the organisms living in a certain area and all the non living conditions found them.
9
Q
What are biotic factors?
A
The living features of an ecosystem.
10
Q
What are abiotic factors?
A
For non living features of any.
11
Q
What are examples of biotic factors?
A
- food
- competition
- territory
- predation
- disease
12
Q
What are examples of abiotic factors?
A
- temperature
- rainfall
- soil
- pH
- salinity
13
Q
What are examples of ecosystems?
A
- rock pool
- playing field
- tree
14
Q
How is energy stored within an ecosystem?
A
as biomass
15
Q
What happens to energy and biomass locked up in things that can’t be eaten?
A
They are broken down by decomposers and recycled back into the ecosystem.
16
Q
What is a food chain?
A
A single line showing energy transfer.
17
Q
What is a food web?
A
Multiple food chains connected together.
18
Q
Why is not all energy/biomass transferred to the next trophic level?
A
- some is never taken in in the first place as plants cant absorb all wavelengths
- some is lost to the environment during respiration or body heat
- some is used for growth or stored as biomass
19
Q
What is the equation for energy efficiency?
A
(energy
transferred/ energy intake) X 100
20
Q
How would you calculate the energy transfer between trophic levels?
A
calculate the difference between the amount of energy in each level
21
Q
How can you calculate the amount of energy in a trophic level?
A
- measuring dry mass of organisms
22
Q
What human activities can increase for transfer of energy through an ecosystem?
A
- herbicides
- fungicides
- insecticides
- natural predators
- fertilisers
23
Q
What are the features of waterlogged soil?
A
little oxygen
24
Q
What is the function of soil?
A
PROVIDES:
- water
- nutrients
- anchorage
25
what are the features of clay soil?
- few air spaces
- retains water
- floods easily
26
What are the features of sandy soil?
- lots of air spaces
- doesnt store water
27
What is Loam Soil?
A mix of clay and sandy soil.
28
Why do plant roots need oxygen?
For respiration so there is enough ATP produced for active transport so minerals can be pumped into the plant.
29
what is biomass?
the mass of living material present in a particular place or in particular organisms
30
what are the 2 methods for measuring biomass?
- mass of fresh material present
- dry mass
31
why may measuring biomass by recording mass of fresh material present be used?
- easiest method
BUT unreliable as mass of water varies greatly
32
why may measuring biomass by recording dry mass be used?
- most accurate
BUT organism must be killed and baked in an oven at 80 degrees
33
what units are used for measure biomass in areas of land?
g m^-2
34
what units are used for measure biomass in areas of water?
g m^-3
35
what units are used for measure biomass in each trophic level?
KJ m^-2 yr^-1
36
why is biomass measured at each trophic level per year?
it allows for seasonal changes in photosynthesis and feeding patterns
37
what is the equation for ecological efficiency?
(biomass at higher trophic level) / ( biomass at lower trophic level)
X100
38
what is gross primary productivity?
the rate that plants convert light energy into chemical energy through photosynthesis
39
what is net primary productivity?
the proportion of energy from the sun which remains to enter the food chain (1-8%)
40
why do producers only convert 1-3% of the sunlight absorbed into chemical energy?
- not all solar energy is used for photosynthesis
- limiting factors for photosynthesis
- some is lost through photosynthetic reactions
41
what is the equation for net production?
gross production - respiratory losses
42
what are methods for improving primary productivity?
- greenhouses
- irrigation
- pesticides/ herbicides/ fungicides
- crop rotation
- fertilisers
43
how do greenhouses and irrigation improve primary productivity?
increase rate of photosynthesis as limiting factors are reduced
44
how do pesticides/ herbicides/ fungicides improve primary productivity?
- reduce loss of biomass
45
how do crop rotation and fertilisers improve primary productivity?
increase nutrient in soil so yields are improved
46
what is secondary productivity?
the amount of biomass produced by the primary consumer
47
what are methods for improving secondary productivity?
- harvesting young animals
- limiting movement
- maintain a warm environment
- treatment with antibiotics
- selective breeding
48
why does limiting movement and maintaining a warm environment improving secondary productivity?
maximises energy used for growth
BUT disease can spread quickly
49
why does treating organisms with antibiotics improve secondary productivity?
prevents sickness which uses energy
BUT it could cause antibiotic resistance
50
what are examples of carbon stores?
- atmosphere
- sedimentary rock
- fossil fuels
- soil
- vegetation
- dissolved in oceans
51
outline the carbon cycle
- carbon is removed from the atmosphere by autotrophs during photosynthesis
- carbon stored in sedimentation
- repsiration releases carbon into atmosphere
- carbon passed between organisms in feeding
- combustion releases carbon
52
what is succession?
the process of ecosystems changing over time
53
what are the features of a pioneer species?
- produce large quantities of easily dispersible seeds or spores
- rapid germination of seeds
- ability to photosynthesise
- ability to fix nitrogen
- withstand extreme conditions
54
what is the process of primary succession?
1. pioneer species colonises bare ground, they dies and release minerals
2. as plants die + decompose soil deepens, larger plants survive
3. diversity increases, smaller plants are outcompeted
4. climax vegetation
55
what is primary succession?
where species colonise somewhere that didnt use to be a habitat (bare ground)
56
what is secondary succession?
where succesion takes place on a previously colonised but disturbed or damaged habitat such as after a forest fire
57
what is deflected succession?
when human activity prevents succession from running its course
e.g. sheep grazing to prevent grassland from developing into woodland
58
what does deflected succession form?
a plagioclimax community if repeatedly managed
59
what bacteria are involved in nitrogen fixation?
- azotobacter
- rhizobium
60
What are azotobacter bacteria?
- free living bacteria found in soil
- they produce ammonia by fixing nitrogen gas
61
what are rhiobium bacteria?
- mutualisitic bacteria found in root nodules of legume plants
62
what happens during nitrogen fixation?
- nitrogen gas is converted into ammonium ions
63
what type of reaction is carbon fixation?
reduction
64
what is the formula for ammonium ions
NH4 +
65
what bacteria are involved in nitrification?
- nitrosomonas bacteria
- nitrobacter bacteria
66
what type of reaction occurs in nitrification?
oxidation
67
what do nutrosonomnas bacteria do?
- convert ammonium ions into nitrite ions
- they gain energy from this reaction
68
what is the formula for nitrite ions?
NO2 -
69
what do nitrobacter bacteria do?
- convert nitrite ions into nitrate ions
70
what is the formula for nitrate ions?
NO3 -
71
what is needed for nitrification?
- oxygen
- soil requires air pockets
72
what is ammonification?
- production of ammonia from organic compounds
e.g. urea
73
what organisms carry out ammonification?
saprobiotic microorganisms
74
what are saprobiotic organisms?
- fungi and bacteria
- they secrete enzymes onto their food, for it to digest externally, they then absorb the products.
75
what is denitrification?
- converting soil nitrates to nitrogen in the atmosphere
76
What conditions are required for denatrification?
- anaerobic
- water logged soil
77
Why is denitrification bad?
- removes nitrates from the soil so there is less for plants
78
How can denitrification be avoided?
aerating soil
79
What bacteria carry out denitrification?
- denitrifying (anaerobic) bacteria
OCR A BIOLOGY
flashcards
Decks in class (27)
# Cards
-
practicals41
-
2.1 cell structure33
-
2.2 biological molecules61
-
2.3 nucleic acids37
-
2.4 enzymes57
-
2.5 biological membranes86
-
2.6 cell division, diversity and differentiation110
-
3.1 exchange surfaces37
-
3.2 transport in animals47
-
3.3 transport in plants83
-
4.1 communicable diseases221
-
4.2 Biodiveristy58
-
4.3 - classification & evolution72
-
5.1 Communication and homeostasis47
-
5.2 Excretion114
-
5.3 neuronal communication40
-
5.4 Hormonal Communication42
-
5.5 Animal Responses73
-
5.5 Plant Responses54
-
5.6 Photosynthesis76
-
5.7 Respiration75
-
6.1 cellular control67
-
6.2 variation68
-
6.3 manipulating genomes66
-
6.4 - Cloning and Biotechnology104
-
6.5 - Ecosystems79
-
Populations & Sustainability30
