Paper 4 Flashcards
0
Q
Population
A
All the organisms of one species in a habitat
1
Q
Habitat
A
The place where an organism lives
2
Q
Community
A
All the Populations of different species living in a particular area and all the abiotic conditions
3
Q
Abiotic conditions
A
Non-living features of an ecosystem e.g. Temp
4
Q
Biotic conditions
A
Living features of an ecosystem e.g. Predators
5
Q
Niche
A
The role of a species within its habitat e.g. What it eats
6
Q
Species abundance
A
Number of individuals of one species in a particular area
7
Q
Species frequency
A
Number of samples a species is found in
8
Q
Percentage cover
A
How much of the area is covered by a species
9
Q
Species distribution
A
Where a particular species is within the area investigated
10
Q
Random sampling…
A
Avoids bias
Repeat - reliable and representative
Random number generated
Number of individuals estimated
11
Q
Pitfall traps
A
For ground insects
Insects fall in and can’t escape
Sample can be affected by small predators
12
Q
Pooters
A
For ground insects
When inhaling through shorter tube, air is drawn through the longer tube, sucking the insect into the jar
Can take a long time to get and large sample - some species may be missed
13
Q
Quadrants
A
For plant populations
Measure species frequency or % cover (more than half - quick)
Large plants and trees need large quadrats
14
Q
Transects
A
For plant populations
Line transact - touch; interrupted transact - take measurements at intervals
Shows how plants are distributed across and area
15
Q
Beating trays
A
For insects in vegetation Sheet/tray(white) under plant/tree Shaken to make insects fall Large samples - good estimates Only insects that fall easily
16
Q
Mark-release-recapture
A
For mobile species
Capture a sample and count, Mark, release
Wait appropriate time (1 week) and take second sample and count how many marked. Repeat.
Total popn size = (number in first sample x number in second sample)/number marked in second sample
17
Q
Assumptions for Mark-release-recapture
A
Enough time to mix back in
Marking doesn’t affect chances of survival and is still visible
No changes in popn size due to births, deaths and migration
18
Q
Interspecific competition
A
Between different species
- compete for the same resources
- less available to both populations - limited pops
- less energy for growth and reproduction eg red/grey squirrels
- one may be better adapted - outcompeted
19
Q
Intraspecific competition
A
Competition within a species
- population increases, so more organisms competing for same space and food
- food and space limiting so popn declines
- smaller popn - less competition and popn grows
20
Q
Predation
A
- as prey popn increases, more food for predators
- predator popn grows and more prey eaten so prey popn decreases
- less food so popn decreases
- other factors involved eg food for prey
21
Q
Nutrient cycles
A
Inorganic molecule or ion ➡️ absorption ➡️ organic molecule on producers (death) ➡️ organic molecule in consumers ➡️ organic moe,duke in saprobionts ➡️ extra cellular digestion (respire + CO2) decomposition
22
Q
Carbon cycle
A
CO2 in atmosphere and water ➡️ photosynthesis ➡️ carbon compound in plants (respiration and decomposition) ➡️ feeding and digestion ➡️ carbon compound in animals (respiration) ➡️ decomposition ➡️ carbon compound in saprobionts (respiration) ➡️ carbon in fossil fuels ➡️ combustion
23
Q
Global warming
A
The increase in average global temp over the last century caused by human activity, enhancing greenhouse effect
24
Effects of global warming
- different rainfall patterns and changes to seasonal weather patterns
- increase in crop yields (CO2)
- life cycles and numbers (warmer and wetter) of some insects may change - larvae stage quicker as higher metabolism.
- could affect distribution and numbers of many wild animals and plant species - more wide (warmer temps) or less wide (coolers temps)
25
Nitrogen cycle
Atmospheric nitrogen ➡️ nitrogen fixation (nitrogen fixing bacteria - mutualistic relationship with plants (nitrogen compounds for carbohydrates) ) ➡️ ammonia ➡️ ⚪️ammonia compounds in soil ➡️ nitrites in the soil ➡️ nitrates in the soil ⚪️ (nitrification by aerobic nitrifying bacteria) denitrification by anaerobic denitrifying bacteria to ammonia ➡️ absorption and assimilation by active transport ➡️ nitrogen compounds in plants (DNA, RNA, amino acids and proteins) ➡️ nitrogen compounds in animals ➡️ urea/ excretion and death (ammonification - saprobiotic bacteria and fungi) to ammonia ➡️ ammonium compounds in soil or atmospheric nitrogen.
26
Leaching
Water-soluble compounds in the soil are washed away by rain or irrigation systems - often into nearby ponds and rivers.
27
Eutrophication
- nitrates leached from fertilisers fields stimulate growth of algae
- large amounts block light to plants below
- plants die - can't photosynthesise enough
- bacteria feed on dead plant matter
- reduce oxygen concentration - aerobic respiration of bacteria
- fish and other organisms die due to lack of dissolved oxygen
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Succession
The process by which an ecosystem changes over time
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Primary succession
On newly formed or exposed land eg new rock surface from volcanic eruption
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Secondary succession
Land is cleared of all plants but soil remains eg after forest fire
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Pioneer species
Colonise new land eg lichen from seeds and spire and are specialised to do so
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Climax community
The final serial stage in which the ecosystem is supporting the largest, most complex community of plants and animals it can - it won't change much more - in a steady state
33
Plagioclimax
Human activities preventing succession eg regularly mown field
34
Glycolysis: where and what?
- cytoplasm
- glucose into phosphorylated glucose (ATP➡️ADP+Pi)
- 2x triose phosphates
- to pyruvate (NAD➡️NADH; ADP+Pi➡️ATP x2)
- 2 ATP produced by substrate level phosphorylation
35
link reaction
- mitochondrial matrix
- pyruvate oxidised by coenzyme A to produce CO2 (decarboxylation)
- NAD reduced to NADH and acetyl coenzyme A produced
36
krebs cycle
- mitochondrial matrix
- acteyl coenzyme a combines with a 4 carbon compound (oxaloacetate) to produce a 6 carbon compound (citrate)
- cycle of reactions - 2CO2, 1 ATP (substrate level phosphorylation), 3 NADH and 1 FADH2 produced per cycle
- to a 4 carbon compound (succinate) then to oxaloacetate
37
electron transport chain
- inner mitochondrial membrane (cristae)
- NADH oxidised to NAD releasing electrons
- electrons transfer down ETC as they reduce electron carriers by gain of electrons
- energy released that is used to take H+ ions into inter-membrane space
- H+ ions pass back through membrane, into matrix, through a protein channel and ATPase and energy used to combine ADP+Pi(phosphate) to ATP
- 3 ATP per NADH and 2 per FADH2
- oxygen is the final electron acceptor and combines with H+ to form water
- 34 ATP produced by oxidative phosphorylation
38
why is ATP good?
- universal energy carrier and store of energy
- immediate energy source
- water soluble/easy transportation from respiration
- binds between phosphate groups unstable and have low Ea so easily broken, releasing lots of energy
- releases energy in small/suitable amounts - not too much at once for body to cope
- immediate energy compound - energy available rapidly
- easily broken down in a single reaction (hydrolysis)
- easily reformed/regenerated (condensation)
- phosphorylates substances to make more reactive
39
Anaerobic respiration in mammalian muscles and other organisms
glucose ➡️ pyruvate (2 ATP and 2 NADH) ➡️ 2 lactate causing fatigue and cramp
NAD regenerated
40
anaerobic respiration in yeast and some plant tissues
glucose ➡️ 2 pyruvate (2 ATP and 2 NADH) ➡️ 2 ethanol
| NAD regerated
41
Light-dependent reaction
1. Light energy excites and raises energy level of electrons in chlorophyll
2. electrons pass down electron transfer chain and reduce carriers
3. electron transfer chain has a role associated with chloroplast membranes - chemiosmosis
4. energy released as carriers decrease energy levels
5. ATP generated from ADP+P
in thykakoid membranes
42
photolysis
H2O ➡️ 2H+ + 2e- + 1/2O2
43
Light-independent reaction
CO2 is fixed by Ribulose bisphosphate (RuBP) and catalysed by the enzyme rubisco to an unstable 6C compound which immediately splits into 2 3C molecules of glycerate-3-phosphate (GP).
2 molecules of ATP from LDRs provide energy and 2 NADPH molecules from LDRs are oxidised to convert GP to Triose phosphate (TP) which can be converted go glucose, lipids or proteins.
ATP ➡️ ADP + Pi to form back to RuBP (5/6)
44
Inefficiency of producers
1-3%
1. light may not fall on chlorophyll molecule and pass straight through
2. limiting factors
3. reflected into space by clouds and dust
4. only certain wavelengths absorbed
5. energy lost as heat (resp) 20-50%
45
Inefficiency of consumers
10-20%
1. some parts not eaten
2. some parts not digested so lost in faeces
3. some energy lost in waste or excretory materials
4. heat loss from respiration and directly from body to environment eg muscle contraction
5. efficiency lower in older animals, herbivores and primary consumers
6. carnivores use more of their food than herbivores
46
Productivity
The total quantity of energy that the plants in a community convert to organic matter (gross productivity).
Plants use 20-50% of this energy in respiration, leaving little to be stored. The rate at which they store energy is called the net productivity = gross productivity - respiratory losses
47
Biomass
The total DRY mass of living material in a specific area at a given time
48
Pyramid of numbers
Numbers of different organisms at each tropic level in an ecosystem at any one time
+ data quick and easy to collect
- blocks difficult to scale - large numbers
- can be inverted when large organisms (in small numbers) or small organisms (large numbers)
49
Pyramid of biomass
Number of individuals x dry mass of each individual at each tropic level at any one time m2g-1
+ usually gives a pyramid
+ takes size into account
- data can take time to collect (kill to find mass)
- biomass not equivalent to energy value (fat more kJ than cellulose per g)
- can be inverted - any one time - standing crop not productivity
50
Pyramid of energy
Each block represents energy equivalent of organic material produced by each organisms in a set time kJm-2year-1
+ pyramid never inverted
+ portrays energy value of material making up biomass
+ solar energy can be added
+ compares productivity - time factor
- data difficult to collect - estimated. Found by burning.
51
Agricultural ecosystems
Made up of domesticated animals and plants used to produce food for mankind
52
Properties of a good pesticide
Specific
Biodegradable (non-toxic products)
Doesn't bioaccumulate
Cost effective
53
Biological control of pests
Beneficial action of predators, parasites, pathogens and competitors in controlling pests and their damage
54
Intensive farming increases production by
Restricting movement - less energy used in muscle contraction
Keep animals warm and inside to reduce heat loss and predation
Feed optimum level of nutrients - max growth and no wastage
Antibiotics in feed to prevent spread of disease
Selective breeding for high productivity
Slaughtered when young so more energy transferred to biomass
55
Gene
Length of DNA that codes for the production of a particular polypeptide sequence
56
Chromosome
Larger modules of DNA containing different genes
57
Allele
One form of a gene eg tall/short
58
Genotype
The genetic construction of an organism Gg
59
Phenotype
The observable characteristics of an organism green
60
Gametes
Reproductive cell that fuses with another during fertilisation
61
Homozygous
Allele on each chromosome is the same aq
62
Heterozygous
Alleles on each chromosome different AAA
63
Dominant
Allele of the heterozygote that expresses itself in the phenotype
64
Recessive
Two recessive alleles are needed for this characteristic to be expressed in the phenotype
65
Co-dominant
Two alleles contribute to the phenotype - both alleles contribute to the phenotype
66
Multiple alleles
A gene that has more than two possible alleles - dominance hierarchy
67
Autosomes
Non-sex chromosomes
68
Sex chromosomes
In humans, vertebrates insects, female XX (larger), males XY
69
Homogametic
Organism that produces gametes of the same type - XX
70
Heterogametic
Organism that produces gametes of different types - XY
71
Deme
Genetically isolated popn
72
Gene pool
All the alleles of all the genes in a popn at any one time
73
Allelic frequency
Number of times an allele occurs within a gene pool
74
Hardy-Weinberg principle
Can be used to calculate the frequencies of the alleles of a particular gene in a popn.
The proportion of dominant and recessive alleles of any gene in a popn remains the same from one generation to the next providing:
- no mutations arise
- popn is isolated (no flow of alleles in or out)
- no selection
- popn is large
- mating is random
P^2 + 2pq + q^2 = 1 = p + q
Homozygous dominant frequency (AA) p^2
Homozygous recessive frequency (aa) q^2
Heterozygous individuals frequency (Aa) 2pq
75
Natural selection
1. Within a popn there are more than one phenotypes, resulting from genetic variation in the genotypes
2. There is differential reproductive success between the phenotypes
3. Organisms with greater reproductive success leave more offspring that those with less and will pass on their favourable alleles to their offspring
4. The frequency of the successful alleles will increase in the popn.
76
Directional selection
1. Response to changing environmental conditions
2. Changes selection pressures - different phenotypes and combination of alleles favoured
3. Selection pressure moves the phenotype and allele frequencies to one extreme
4. Brings about evolutionary change
77
Stabilising selection
1. Response to optimal, unchanging environmental conditions
2. Competition not severe
3. Selection operates against extreme values, eliminating them from a popn
4. Maintains phenotype stability
Few values at extremes - majority in the middle
78
Speciation
The evolution of a new species from an existing species
1. Species are kept apart by geographical isolation or reproductive isolation
2. Different environmental conditions cause a change in the gene pools due to directional selection
3. Even when habitats merge again, new species kept apart by isolating mechanism
79
Species
A group of individuals with similar genes and capable of breeding and producing fertile offspring. Belong to the same gene pool.
