Topic 5 Flashcards
Ecosystem
All the organisms living in a particular area, as well as all the abiotic factors
Habitat
The place where an organism lives
Population
All the organisms of one species in a habitat
Population size
Number of individuals of one species in a particular area
Community
All the organisms of different species that live in the same habitat and interact
Abiotic factors
non-living features of an ecosystem
e.g. light, water, space, temp, chemical comp
Biotic factors
living features of an ecosystem
Abundance
Number of individuals of one species within a particular area
Distribution
Where a species is within a particular area
Ideal Abiotic Factors (mammals)
Mammals surrounding temperatures suitable for metabolic reactions (less energy required)
- faster growth and reproduction
Biotic Factors that cause variation in Population size / Abundance
- Interspecefic Competition
- Intraspecefic Competition
- Predation
Interspecefic Competition
Competition between species
- same resources
- > availability reduces
- > populations limited
Intraspecefic Competition
Within a species
- Population increase = pletiful resources
- competing organisms increase - Limits food + resources
- > begin decline - Smaller population
- > better reproduction
- grows again - = Carrying Capacity
Carrying Capacity
Maximum stable population
Predation
The link between predator and prey population size
- Prey population increases
- > more predator food
- predator population grows - Prey eaten
- > prey population falls - Less predator food
- > predator population decreases
Note: lack of prey food source causes downwards spiral of prey/predator population
Affect of Abiotic & Biotic factors on Distribution
Abiotic:
- Plants that only grow on south facing slopes in northern hemisphere
- > solar input = greatest
- plants that don’t grow near shoreline
- > too saline
- large trees do not grow in polar regions
- temperature = too low
Biotic: Adapted to ‘out compete’ = better chance of survival
Sampling
Investigate populations (abundance + distribution)
- choose area to sample (Random or non-random e.g. systemetic)
- count no. of individuals of each species
- repeat process -> indicator of whole habitat
- estimate
Frame Quadrats
Square frame divided into grid of 100 smaller squares
1m x 1m
- string attached across the frame
- no. of species recorded at each quadrat
- % cover of plant species -> if a square is more than half covered = 1 (quick method)
- large quadrats marked out by tape measure
Point Quadrats
Horizontal bar on two legs with holes at set intervals
- placed on ground at random points
- pins dropped through holes
- every pin touched is recorder (even if one plant touches multiple)
- no. of each species recorded
- % cover: no. of pins touching a given species
- > % of total pins dropped
- useful in low, dense vegetation
Transect(s)
Distribution measured along line(s)
- Line transect:
- tape measure placed along transect; species touching -> recorded - Belt transect:
- data collected along transect using fra, quadrats placed consecutively - Interrupted transects
- Measurement at set intervals (belt or line T)
- point quadrats placed at right angles at set intervals
Kite Diagram
Shows abundance + distribution
- abundance = thickness of kite shapes; symmetrical, %
- x-axis = distance (along transect)
- abiotic factors plotted (e.g. land surface)
- each ‘kite’ labelled with organism
Methods of measuring Abiotic factors within a habitat
- Climate:
- temperature = thermometer
- rainfall = raingauge (funnel + cylinder)
- humidity = electronic hygrometer (water vapour) - Oxygen availability (aquatic habitats):
- O2 dissolved in H2) = Oxygen sensor - Solar input = light sensor
- Edaphic factors (soil condition);
- pH = indicator liquid (soil, water + indicator)
- moisture content = % difference before + after drying - Topography:
- relief = height of the land (contours)
- aspect = slope direction (compass)
- slope angle = clinometer (string + weight attached to protactor centre)
Climate
Weather conditions of a region over a long time period
Edaphic
Conditions of soil
Measuring moisture content
Mass measured before + after being dried in oven at 80 - 100 C
- until constant mass
- percentage difference = moisture content
Succession
Ecosystem Change
- Primary = newly formed/ exposed land
- no soil + organic matter to start with
- e.g. volcanic eruption, lowered sea level - Secondary = cleared of plants/ pre-existent life
- soil remains
- e.g. forest fire / deforestation
Primary Succession
Species (pioneers) colonise new land surface Abiotic factors = hostile - no water retention (no soil) Pioneers (e.g. marram grass) die - microorganisms decompose (into) humus -> basic soil = less hostile -> water retained New organism die -> richer, deeper soil -> more minerals Species may change environment so it is less suitable for earlier species: - e.g. maram grass needs constant sand reburial to be healthy - sand sedge stabalises sand -> Rhizomes grow
Primary Succession (process)
- Pioneers colonise rocks
- e.g. lichens grow on -> break down rocks - Lichens die -> decompose -> thin soil
- mosses grow - Larger plants recquiring more water move in as soil thickens -> die -> soil deepens
- Shrubs + ferns & small trees grow
- out compete & become dominant species
- increased diversity - Soil = deep + rich -> support trees
- > dominant species
- > climax community
Rhizomes
Underground stems
Key aspects of primary succession
Each stage = better adapted
- out-competes
- dominant
- > ecosystem becomes more complex
- new species move in alongside -> increased biodiversity
- Final stage = Climax Community
Climax Community
The largest and most complex community that can be supported in a steady state
Secondary Succession
Already a soil layer present
Succession starts at a later stage -> pioneers = larger plants
Preventing Succesion
Artificially stopped = PLAGIOCLIMAX
- regularly mown field
- > growing plants cut by lawn mower
- > inhibits diversity
Particular Climax
Climatic Climax
Temperate Climax Community
- plenty of water
- mild temperatures
- little change between seasons
- climax community = large trees
Polar Climax Community
- little available water
- low temp
- massive seasonal changes
- climax community = herbs or shrubs
Phosphorylation
Adding phosphate to a molecule
Photophosphorylation
Adding phosphate to a molecule using light
Photolysis
Splitting (lysis) of a molecule using light energy
Hydrolysis
Splitting of a molecule using water
Redox Reaction
Oxidation + Reduction
- Reduction = gained electrons (alternatively, gained H/ lost O)
- Oxidation = lost electrons (lost H/gained O)
Animals need energy for …
Muscle contractions
Homeostasis
Protein Synthesis
DNA replication
Plants need energy for …
Photosynthesis
Active Transport
Cell division
Photosynthesis
Energy from light used to break apart strong bonds in H2O molecules
-> Hydrogen then stored in glucose by combining with CO2, releasing O2
Photosynthesis equation
6CO2 + 6H2O + Energy -> C6H12O6 + 6O2
ATP
Adenine Triophosphate = immediate energy source in cell (energy from glucose breakdown (respiration) used to make it)
- synthesised by ADP phosphorylation
- energy from glucose breakdown stored in phosphate bond
- catalysed by ATP synthase (enzyme)
Inorganic Phospahte
Single Phosphate
ATP use in cell
ATP carries energy around cell -> target (diffuses)
1. broken down via hydrolysis -> ADP + Pi
2. energy released from phosphate bond
3. ATPase catalyses reaction
ADP + Pi recycled
Chloroplasts
- Flattened organelles found in plant cells
- double membrane = chloroplast envelope
- keeps photosynthesis reactants close to reaction sites - thylakoids = fluid filled sacs
- large SA -> max light energy absorption
- stacked = Granum (linked by Lamella = thykakoid membrane)
- Lots of ATP synthase (for ATP in LDR) - Photosynthetic Pigments = coloured substances that absorbed light
- in thylakoid membrane
- e.g. chlorophyll a, b & carotene
- attached to protein - Two photosystems:
- PSI = 700 nm
- PSII = 680nm - Stroma = gel like substance
- contains enzymes, sugars and organic acids
- contains oil droplets
- LIR site
Three photosynthetic pigments
Chlorophyll a
Chlorophyll b
Carotene
Photosystem
Protein + Photosynthetic Pigment
Two phtosystems in chloroplasts:
- PSI = 700 nm
- PSII = 680nm
Stages of Photosynthesis
- Light Dependent Reactions (LDR):
- occurs in thylakoid membranes
- light energy -> photosynthetic pigments (photosystems) -> chemical energy
- > ADP + Pi -> ATP (transfers energy)
- > reduces NADP (reduced NADP) by transfering hydrogen when H2O is oxidised - Light Independent Reactions (LIR):
- occurs in stroma
- ATP + NADP reduced; supply energy + hydrogen
- CO2 -> glucose
Light Independent Reaction
Light energy used for three things:
- ADP + Pi -> ATP (photophosphorylation)
- Non-cylic
- Cyclic - NADP -> reduced NADP
- H2O -> protons, electrons, oxygen (photolysis)
Non-Cyclic Photophosphorylation
Photosystems linked to electron Carriers = Electron Transport Chain (ETC)
- light energy absorbed by PSII
- excites electrons in chlorophyll
- e-‘s excited to higher energy level
- high energy e-‘s move along ETC to PSI - Excited e-‘s leaving PSII must be replaced
- H2O -> H+, e- & O2 (photolysis)
- > H2O -> 2H+ + 1/2 O2 - excites e-‘s lose energy as they move along ETC
- energy used to transport protons into thylakoids -> higher H+ concentration that stroma
- > results in proton gradient across membrane
- protons go down gradient into stroma (using stalked enzyme ATP synthase that bypasses membrane)
- uses energy from ATP formation = chemiosmosis - Light energy absorbed by PSI
- e-‘s excited to higher energy level
- e-‘s transferred to NADP + H+ (from stroma)
- > reduced NADP
Cyclic Photophosphorylation
- Only uses PSI
- e-‘s from chlorophyll molecule passed back to PSI via electron carriers
- electrons recycled
- > repeatedly flow through PSI
- > no reduced NADP or O2
- > small amounts of ATP generated
Electron Carriers
Proteins that transfer electrons
Electron Transport Chain
Protein chain through which excited electrons flow
Light Dependent Reaction
= CALVIN CYCLE or Carbon Dioxide Fixation (CO2 fixed to organic molecule)
- Stroma = site
- Molecule = glyceraldehyde 3-phosphate (GALP) (3C)
= Ribulose biphosphaye (RuBp) (5C)
- ATP + reduced NADP recquired to keep cycle going
- starting compound (RuBp) regenerated
- enzyme = RUBISCO used for CO2 fixation
Calvin Cycle
- CO2 enters leaf via stromata -> diffuses into stroma
- combines with RuBp ( catalysed by RUBISCO)
- > unstable 6 carbon compound
- > breaks into 2 x glycerate 3-phosphate (GP) - 2x ATP hydrolysed for energy
- 2 x reduced NADP -> NADP for H+ ions
- > GP (x2) -> GALP ( x 12)
- some GALP converted into useful organic compounds (2)
- rest continues to regenerate RuBp (10) - RuBp regenerate requires ATP hydrolysis for energy
Calvin Cycle diagram (for 1 CO2 molecule)
ngng
Other organic substances produced by Calvin Cycle
- carbs = 2 x GALP (saccharides)
- lipids = glycerol (synthesized from GALP), fatty acids (synthesized from GP)
- amino acids (usually made from GP)
- nucleic acids = ribose (made from GALP)
Measuring energy transfer between Trophic levels
- Difference = dry mass (biomass) measurements
- dried at 80-100 C until reaches ‘constant mass’ (measured at intervals) -> water removed
- sample results multiplied by total population size = energy at trophic level
note: errors can be found in locating energy source
- accurately estimating = include all individuals at trophic level (e.g.different species)
Energy Transfer
- Roughly 90% of total available energy lost between trophic levels
- 60% never taken in:
- wrong wavelength, reflected, passes through
- hits wrong region e.g. bark
- parts uneaten; go to decomposers
- indigestible - 40% absorbed = gross productivity
- 30% ( 75% of GP) lost to environment
- > respiration = body heat (respiratory loss) - 10% goes to Biomass = Net productivity
Net Productivity
Amount of energy available to next trophic level
note:
- producers = net/gross primary productivity
How does energy mainly enter the ecosystem
Via producers (plants) storing light energy as biomass by means of photosynthesis
- transferred through consumers (primary, secondary etc)
- each stage = trophic level
Climate Change
Long term changes in global weather patterns
- natural variations as well as commonly being in reference to human changes (e.g. global warming, greenhouse effect)
Global Warming
Rapid increase in temperature seen over the last century, resulting in changes to seasonal cycles and rainfall patterns
Evidence of Climate Change (3)
- Temperature records
- Dendrochronology
- Pollen in peat bogs
Temperature Records
Measured since 1850’s (thermometers)
- reliable, but short term record
- > general trend of increasing temperature (even noting fluctuations)
Dendrochronology
Finding out the age of the tree, using its rings
- one ring within trunk per year
- thickness of ring dependent on climate when formed
- > warmer = thicker (better conditions for growth e.g. water + nutrients)
Cores taken through trunk: each ring dated + thickness recorded to indicate climate
- closest to bark = most recent
Pollen in Peat Bogs
Pollen preserved in peat bogs (acidic wetland)
- bogs accumulate in layers (age increases with depth)
- cores taken
- > extract pollen grains -> identify plant species
- only mature plants produce pollen (indicates plant species was successful during that period)
- similar plants to now are compared
- > indicates climate in that period (varies as climate changes)
- more warm attributed species -> indicates temp increase
note: indicates temp change over thousands of years
Anthropogenic causes of climate change
Enhance greenhouse effect (absorbs more outgoing enegy, so less is lost to space)
CO2:
- atmospheric concentration increased by 100ppm since mid-19th century
- stable for previous 10,000 years
- > natural sinks destroyed
- > fossil fuels burnt
CH4:
- atmospheric concentration doubled since mid-19th century
- levels stable for previous 850 years
- > fossil fuels
- > decaying waste increase
- > more cows
- > permafrost release
Data Extrapolation for Climate Change
Minimum, stable and maximum emissions are put into the global climate model
Issues:
- don’t know how emissions will change
- nor how much each will rise by
- natural causes (for change) are unknown
- don’t know how successful attempts at change are
- complex feedback systems with little understanding of climate impact
Increased Temperatures affect on rate of enzyme activity
Initial rate increase
- more heat -> more kinetic energy
- > faster moving molecules -> collisions increase + energy of collisions increase
Too high -> reaction stops
- enzyme’s molecules vibrate more
- x > 37 C (animals)
- x > 25 C (plants) -> vibrations break bonds for enzyme shapes
- > active site changes shape
- E-S complex cannot form
- enzyme = denatured
Increased Temperatures affect on life cycles, development & distribution
Some organisms:
- speed up metabolic reactions
- growth rate increases
- develop + progress through life faster
E.g Cyanobacteria = blue/green algae that photosynthesise
- some species produce toxin
- warmer water -> increased growth rate = more harmful algal blooms
Temperature becomes too high for others: - metabolic reactions slows - decreased growth rate - slower life cycle E.g. Wheat grown above 25 C develops fewer grains and yield fall E.g. Eggs of cold water fish (trout, salmon) develops best at low temps - will not hatch if too high - brown trout > 13 C; does not hatch
Changing Rainfall Patterns
Affects distribution
Ocotillo = desert plant
- dormant during dry periods
- reduced rainfall = less growth of new leaves
- > dormant for longer
Affect of altered Seasonal Cycles
Changing timing of the seasons:
-> red squirrels in Canada birthing 3 weeks earlier due to earlier food availability
Distribution:
- swallows live in South Africa & fly to different parts of Europe to breed at the start of spring
- earlier British spring = earlier flowers + insects
- > swallows arrive when little food is available
- reduced swallows born in Britain
- > those that migrate there eventually die out
Carbon Cycle
(insert diagram)
Photosynthesis = plants Respiration = plants, animals, decomposes Decomposition = plants + animals Combustion = fossil fuels
Increased Temperatures affect on Distribution
Global warming -> affects distribution (move, die out, or expand)
- alpines -> zone of growth moves higher up to cooler areas
- subtropical plankton -> found further north (sea surface temp in northern Atlantic increased)
- European butterflies -> shifted northward range
Metabolism
All the chemical reactions that take place in the cells to keep the organism alive, which is controlled via enzymes
Decreasing Atmospheric CO2 concentration
Biofuels - produced from (is/recently living) biomass
- crops (that are replanted after harvesting) waste used
- burnt -> releases CO2, but no net increase as equals the CO2 taken on during growth
Reforestation - planting new trees in existing forests that have been depleted
- CO2 sink
- > less CO2 in atmosphere
Pros/Cons of Biofuels
+ farmers can have government funding/subsidiaries
+ biofuel is cheaper for drivers
- potential to cause food shortages for consumer
- potential of forests being cleared for space (conservation issue)
Pros/Cons of Wind Turbines
+ can increase company sales (ethical perception)
+ electrically based (no CO2 increase)
- noise pollution
- ruin landscape
- birds killed by flying in
Evolution (definition)
Change in allele frequency
Isolation
Results in reduced gene flow, causing speciation
Two types:
- allopatric
- sympatric
Allopatric Speciation
Geographical isolation
Sympatric Speciation
Random mutations result in a change to mating phenotype
E.g. eukaryotes = diploid
- mutation -> increased chromosome no. = Polyploidy; so becomes reproductively isolated
- > no fertile offspring
- potentially asexually reproduce -> new organism
Note: more common in plants
Evidence of Evolution
- Genomics
2. Proteomics
Genomics
Using DNA technology to determine the base sequence of an organisms genome & the fluctuation of its genes
- allows comparisons
- organisms that genetically diverged more recently should have more similar DNA
E.g. chimps + humans = 94% same
Mice + humans = 84%
Proteomics
Study of proteins (size, shape & amino acid sequence)
- sequence coded for by DNA sequence in gene
- related organisms -> similar DNA sequence
- more recent divergence = more similar proteins
Scientific Validation
- Peer review
- Scientific Journals
- Conference’s
Peer Review
Peers read + review work
Check validity, ergo its supports conclusions
Check that the highest possible standard of experimentation has been conducted
Scientific Journals
Academic magazines which publish articles (peer reviewed)
Share new ideas, theories, experiments, evidence & conclusions
- repeat experiments
- check it can achieve same results with the same methods
- replication = reliable evidence
Conferences
Meetings to discuss work
- lecture or poster presentation
- face to face Q&A
- easy sharing + discussion method
