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A Level Biology (SNAB) > Topic 5 > Flashcards

Topic 5 Flashcards

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1
Q

What is an ecosystem?

A

Ecosystem = all the organisms living in a particular area and all the abiotic factors

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2
Q

What is a habitat?

A

Habitat = the place where an organism lives

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3
Q

What is a population?

A

Pop. = all the organisms of one species in a habitat

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4
Q

What is a population size?

A

Pop. size = the no. of individuals of one species in a particular area

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5
Q

What is a community?

A

Community = all the organisms of dif. species that live in the same habitat

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6
Q

What is the bioshpere?

A

Biosphere = the part of the Earth, and its atmosphere, that’s inhabited by living organisms

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7
Q

What is abundance?

A

Abundance = the no. of individuals of one species in a particular area

Same as pop. size

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8
Q

What is distribution?

A

Distribution = where a species is w/n a particular area

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9
Q

Why does abundance vary?

A
  • Abundance varies b/c of abiotic factors

When conditions are ideal an organism can grow fast and reproduce successfully

E.g a surrounding ideal temp for metabolic reaction = no energy needed to maintain body temp
More energy for growth and reproduction = abundance ↑s

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10
Q

What happens when conditions for organisms aren’t ideal?

A

When conditions aren’t ideal an organism can’t grow fast or reproduce successfully

E.g when surrounding temp is lower/ higher than what is ideal for metabolic reactions = energy is needed to maintain body temp
Less energy for growth and reproduction = abundance ↓

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11
Q

Abundance also varies b/c of biotic factors

A

Abundance also varies b/c of biotic factors

Interspecific competition = competition b/w dif. species

  • Will compete for the same resources
  • Resources available for both are reduced
  • Meaning abundance is limited to resources available
  • b/c energy is used searching for resources rather than growth and reproduction
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12
Q

What is intraspecific competition?

A

Intraspecific competition = competition w/n a species

Abundance ↑s when resources are plentiful (1)

Higher abundance = more competition for the same amount of resources

Resources become limiting = pop. decline (2)

Lower abundance = less competition

Resources aren’t limiting = pop. ↑ again (3)

Carrying Capacity = the max stable pop. size of a species that an ecosystem can support

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13
Q

What is predation?

A

Predation = where an organism kills and eats another organism

  • Prey pop. ↑ = more food for predators = predator pop. grows
  • Predator pop. ↑ = more prey is eaten = prey pop. falls
  • Prey pop. ↓ = less food for predators = predator pop. falls
  • Predator pop. ↓ = less prey is eaten = prey pop. grows
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14
Q

How does distribution vary?

A

Distribution varies b/c of abiotic factors

  • Some plants can only grow on south-facing slopes b/c of a greater light intensity
  • Some plants don’t grow near shoreline b/c the soil is too saline
  • Large trees can’t grow in polar regions b/c of low temps

Distribution also varies b/c of biotic factors

  • The better-adapted species will win the interspecific competition
  • The other one will be out-competed
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15
Q

What is a niche?

A

Niche = the role an organism has w/n its habitat

  • Inc. it’s biotic and abiotic interactions
  • Each species has its own unique niche
  • A niche can only be occupied by one species
  • There’ll always be a slight diff.
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16
Q

Can abundance vary b/c of niches?

A

YES!

  • Species occupying similar niches will compete (interspecific competition)
  • Less of each species will be able to survive
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17
Q

Can distribution vary b/c of niches?

A

YES!

  • Organisms can only exist where the conditions that make up their role exist
  • A lack of certain conditions means a lack of species/ organisms
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18
Q

What are abiotic factors?

A

Abiotic factors = the non-living features of an ecosystem (oh, look a dead body)

E.g temperature and water availability

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19
Q

What are biotic factors?

A

Biotic factors = the living features of an ecosystem

Predators and food

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20
Q

How to investigate abundance?

A

Number of individuals in a sample
Percentage cover

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21
Q

How to conduct sampling?

A
  • Estimates about a whole habitat are based on the samples
    Choose an area to sample
  • Count the no. of individuals of each species - method can change
  • Repeat - take as many samples as possible
  • Use results to estimate total no.
  • When sampling dif. habitats and comparing them, use the same sampling technique
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22
Q

What are the 3 types of sampling?

A

Random
- Divide a field into grids using a measuring tape
- Use a random number generator to select coordinates
- Avoids bias

Non-Random
- Used in habitats where there’s a lot of variety in abiotic factors/ distribution
- Can make sure all the dif. areas are sampled

Systematic
- Non-random sampling
- Samples are taken at a fixed interval along a line
- Can be done where abiotic factors change gradually = environmental gradient

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23
Q

How to use frame quadrats?

A
  • The quadrats are placed on the ground where you are sampling
  • The no. of individuals in each species in each quadrat can be recorded
  • Percentage cover of a plant species can also be measured
  • Count the square if more than half is covered
  • A quick way to investigate pop. rather than counting each individual one
  • Used to quickly investigate species that fit w/n a small quadrat
  • Can also investigate larger species using tape rather than a frame
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24
Q

What is succession?

A

Succession = the process of ecosystem change over time

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25
Q

What is primary succession?

A

Primary succession = land that has been newly formed or exposed

There’s no soil or organic material (it’s bare rock)
E.g volcano eruption or dropped sea level

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26
Q

What is secondary succession?

A

Secondary succession = land that has been cleared of all plants, but soil remains

E.g a forest fire or deforestation

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27
Q

Primary succession

A

The abiotic conditions are hostile so no soil to retain water

Only pioneer species (the first species to colonise an area) can grow b/c they’re specially adapted

The pioneer species changes the abiotic conditions
They die and decompose = dead organic material = soil

Conditions are less hostile = new organisms w/ dif. adaptations can grow

They then die = more organic material = deeper and richer-in-minerals soil = larger plants can grow = more water retained

New species may change it so conditions aren’t good for previous species

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28
Q

Secondary succession

A

Same as primary but soil layer already present
Pioneer species are larger plants

At each stage, dif. plants and animals that are better-adapted move in

  • They out-compete the plants already there
  • They become the dominant species in the ecosystem
  • The ecosystem becomes more complex
  • More species = ↑ biodiversity
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29
Q

What is the final stage of succession?

A
  • A climax community
  • the ecosystem is supporting the largest and most complex community
  • It wont change much b/c its in a steady state
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30
Q

Example of succession

A

Bare rock → Woodland Example

  1. Pioneer species colonise the rocks, E.g lichens grow on and break down rocks, releasing minerals
  2. Lichens die and decompose = a thin soil
  3. Soil thickens as more organic material forms
  4. Other species can grow, E.g. mosses
  5. Larger plants can move in b/c more water as soil deepens, E.g grass
  6. Shrubs, ferns and small trees can grow, outcompeting the other species becoming the dominant species = ↑ diversity
  7. The soil is deep and rich in nutrients = supports large trees = climax community
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31
Q

Organism type and climax communities

A

Dif. organisms = dif. climax communities

Temperate climate = lots of water, mild temp, not much change w/ seasons
Climax community = large trees
Polar climate = not a lot of water, low temp, massive changes w/ season
Climax community = herbs/ shrubs b/c trees can’t grow

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32
Q

Preventing succession

A
  • Artificially stopped succession = community is the climax community but called plagioclimax
  • E.g mowing a grassy field = don’t develop shrubs and trees b/c can’t establish
  • A longer interval b/w, the further succession can progress = ↑ diversity
  • The shorter the interval succession can’t progress = low diversity
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33
Q

What is Phosphorylation?

A

Phosphorylation = adding phosphate to a molecule

E.g ADP is phosphorylated to ATP

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34
Q

What is Photophosphorylation?

A

Photophosphorylation = adding phosphate to a molecule using light

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35
Q

What is Photolysis?

A

Photolysis = the splitting of a molecule using light energy

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36
Q

What is hydrolysis?

A

Hydrolysis = the splitting of a molecule using water

E.g ATP is hydrolysed to ADP

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37
Q

What are redox reactions?

A

Redox reactions = reactions that inv. oxidation and reduction (OIL RIG)

Oxidation always inv. the loss of another molecule as well

38
Q

What is photosynthesis?

A

Photosynthesis = the process where light energy is used to break the strong bonds in H2O

  • The H is stored as glucose
  • Formed when H combines w/ COշ
  • Oշ is formed and released
  • Stored until its released by respiration
39
Q

What is ATP?

A
  • An immediate source of energy in a cell
40
Q

Everything ATP

A
  • During respiration, glucose broken down = energy = ATP
  • ATP carries energy around the cell where it’s needed

Synthesised by the phosphorylation of ADP
- Using energy from an energy-releasing reaction
- ATP synthase catalyses this reaction

It diffuses to the part that needs energy
Broken down via hydrolysis back into ADP + Pi
- Chemical energy is released from the phosphate bond
- ATPase catalyses this
- They’re both recycled so the process starts again

41
Q

Enzymes and Coenzymes

A
  • The rate of photosynthesis is affected by the same things enzyme-controlled reactions are affected by, e.g temp
  • b/c it uses lots of dif. enzymes
  • It also relies on coenzymes
  • Coenzymes = a molecule that helps the function of an enzyme
  • They transfer a chemical group from one molecule to another
  • E.g NADP
42
Q

What is the Light Dependent Reaction?

A
  • Takes place in thylakoid membranes
  • Light energy is converted into chemical energy
  • Light energy adds Pi to ADP to = ATP and reduced NADP (NADPH)
  • ATP transfers energy and NADPH transfers H to - light-independent
  • This process is called phosphorylation
  • HշO is also oxidised to Oշ
  • This process is called photolysis
43
Q

Process of Light-Dependent Reaction

A

STEP 1: Light energy excites electrons in chlorophyll
- Light energy is absorbed by PSII
- This excites electrons
- The electrons move to a higher energy level
- They move down the ETC to PSI

STEP 2: Photolysis of water produces protons, electrons and Oշ
- As electrons leave PSII they must be replaced
- Light energy splits water in photolysis to replace them

STEP 3: Energy from the excited electrons make ATP
- Electrons lose energy as they move down ETC
- Energy is used to transport protons into t- thylakoids
- To have a higher conc. than the stroma
- A proton gradient forms across the membrane
- Protons move down their conc. gradient into stroma via ATP Synthase (enzyme)
- This then makes energy for the combination of ADP and Pi to = ATP
- This process is called Chemiosmosis

STEP 4: The energy also generates NADPH
- Light energy is absorbed by PSI
= This excites electrons even more than before to an even higher energy level
- The electrons are transferred to NADP with H+ from stroma to = NADPH

44
Q

What is the Light-Independent Reaction / Calvin Cycle?

A
  • Takes place in the stroma of chloroplasts
  • ATP and NADPH that are needed are made in the light-dependent stage
  • Also known as Carbon Dioxide Fixation b/c C from COշ is ‘fixed’ into an organic molecule
45
Q

Process of Light-Independent Reaction / Calvin Cycle?

A

STEP 1: COշ is combined w/ RuBP to = GP
- COշ enters the leaf through the stomata
- It diffuses into the stroma of a chloroplast
- It combines w/ RuBP (ribulose biphosphate)
- This reaction is catalysed by RUBISCO
- An unstable 6-C compound is made
- This is broken down into 2x 3-C compounds, GP (glycerate 3-phosphate)

STEP 2: GP is reduced to GALP
- Hydrolysis of ATP makes energy to turn GP into another 3-C Compound, GALP (glyceraldehyde 3-phosphate)
- This also requires H+ ions, which comes from NADPH
- NADPH is recycled to NADP
- 1-C from GALP is converted into other useful organic compounds
- E.g glucose, which requires 6 cycles
- 2x molecules of GALP can make a hexose sugar
- The 5-C leftover continue in the cycle

STEP 3: RuBP is regenerated
- The 5-C leftover of GALP is used to regenerate RuBP
- This uses the rest of the ATP produced by the light-dependent

46
Q

What does the Light-Independent Reaction / Calvin Cycle produce?

A

The Calvin Cycle Products can make other organic substances, such as;

Carbohydrates = simple sugars (e.g glucose) from - 2x GALP, and polysaccharides (e.g starch and cellulose)
- Made by joining 2x hexose sugars
- Glucose is v. important in respiration for energy for biological processes

Lipids = made using glycerol, that’s synthesised from GALP and fatty acids
- Fatty acids are synthesised from GP

  • Amino Acids = some are made from GP
  • Nucleic Acids = sugar in RNA is made using GALP
47
Q

The structure of chloroplasts?

A
  • They’re flattened organelles in plant cells
  • Have a double membrane called chloroplasts envelope
  • Keeps reactants close to their reaction sites
  • Has thylakoids, which have a large SA = light energy can be absorbed
  • Lots of ATP synthases in thylakoid membranes
  • Contain photosynthetic pigments
  • Coloured substances to absorb light energy
  • Found in thylakoid membranes and attached to proteins
  • Protein + pigment = photosystem
48
Q

What do chloroplasts contain that aid photosynthesis?

A

Two photosystems = Photosystem I and Photosystem II

  • Photosystem I absorbs light at 700nm
  • Photosystem II absorbs light at 680nm
  • Stroma contains enzymes, sugars and organic acids required for light independent
  • Also contains oil droplets, which store non-carbohydrate organic material
  • Photosynthesis takes place in chloroplasts
49
Q

The Hill Reaction

A

Can be used to investigate photosynthesis

  • In light dependent, NADP acts as an electron acceptor
  • It accepts electrons and a proton to become NADPH
  • Oxygen is released as a byproduct
    This is called the Hill reaction
  • Can investigate it using a redox indicator dye (DCPIP) to isolate chloroplasts
  • The dye acts as an electron acceptor, and changes colour once oxidised
  • Blue → Clear
  1. Cut a few leaves into pieces→to test→careful w/ sharp objects
    - Make sure to remove any tough stalks
  2. The grind up the pieces in a blender w/ 20cm3 chilled isolation medium→preserves enzyme activity
  3. Filter the liquid into a beaker w/ a funnel lined w/ muslin cloth→ to separate the solution and leaves→be careful to not spill any and slip
  4. Wring the muslin cloth into the beaker→not
    waste any
  5. Transfer to centrifuge tubes and centrifuge at high speed for 10 mins→pellet will gather at the bottom
  6. Remove the liquid from the tubes (supernatant)
  7. Resuspend the pellet in chilled isolation solution (leaf extract)→to act as a buffer
  8. Set up 4 test tubes: A = DCPIP+Leaf extract, B= DCPIP+Buffer, C= no DCPIP+Leaf extract, X= DCPIP+Leaf extract, Y= DCPIP+Supernatant
  • To remember B=Buffer, C=Colour Compare, - X=Xrays in the dark, Y=You-seful/ Y you change colour
  • ABC are controls, X and Y are the tests
  1. Place A, B, C and Y in front of a lamp, and X in the dark
  2. Record how long it takes them to go from blue to green→till Oշ is produced
  • The faster the colour change the faster the rate of the Hill reaction
  • A shouldn’t change, shows chloroplasts (in supernatant) cause the changes (Blue)
  • If it does change then it means in blending the pellet got damaged so some ETC’s entered the leaf extract (leaf extract is the pellet)
50
Q

What are the results of the Hill Reaction?

A

B is to show that the DCPIP won’t just go colourless on its own (Blue)

C is used to compare the other test tubes against to see if DCPIP goes colourless

X is to show that the hill reaction needs light to work (Blue)

Y is the one that should go from blue to green b/c the supernatant contains ETC and so the DCPIP can act as an electron acceptor for it (Green)

51
Q

Biomass and Trophic Levels

A

Energy is transferred through ecosystems

  • It enters an ecosystem from photosynthesis
  • Producers (plants)= convert sunlight energy into a form that can be used by other organisms
  • Store energy as biomass, energy transfer is basically biomass transfer
  • Ecological efficiency = net production of new biomass at each trophic level

Biomass = the mass of living material

Primary Consumers = organisms who eat producers

Secondary Consumers = organisms who eat primary consumers

Tertiary Consumers = organisms who eat secondary consumers

  • Each stage is called a trophic level
52
Q

Energy wasted in biomass transfer?

A

A lot (90%) of energy is wasted in biomass transfer

  • 60% is never taken in
  • Plants can’t use all the energy that reaches their leaves, so it’s reflected or passes through
  • The sunlight might hit parts of a plant that can’t photosynthesise (e.g bark)
  • Some parts of food aren’t eaten so they pass to decomposers
  • Decomposers = organisms that break down dead or undigested material
  • Some parts are indigestible so pass through organisms as waste to decomposers
53
Q

What is net productivity?

A

Net productivity = the volume of energy available for the next trophic level

  • NPP = Gross Primary Productivity - Respiratory Loss
54
Q

What is Net Primary Productivity? (NPP)

A

Net primary productivity = net productivity for producers

55
Q

How to calculate energy transfer efficiency?

A

Calculating energy transfer efficiency = (net / energy received) x 100

56
Q

How to calculate Gross Primary Productivity?

A

Gross primary productivity = NPP - plant respiration

57
Q

How to measure energy transfer b/w trophic levels need the NP of each level?

A
  • Measure the dry mass of the organisms for how much energy it contains
  • Dry out the organisms in an oven at a low temp
  • Then weigh at regular intervals
  • Once constant, the water has been removed so this is its biomass
  • Do this for both organisms and work out the difference
  • May not work though b/c the higher trophic level might have received biomass from other organisms so it isn’t accurate
58
Q

What is climate change?

A

Climate change = long-term changes in global weather patterns

  • Or a significant change in the weather of a region over a period of several decades
  • Inc. natural variations but is mostly changes caused by humans
59
Q

What is global warming?

A

Global warming = rapid ↑ in global temperature over the last century

  • Which causes other types of climate change
60
Q

How to measure climate change? (Temperature records)

A
  • Been measured using thermometers since the 1850s
  • Gives a reliable, short term record of global temp change
61
Q

How to measure climate change? (Dendrochronology)

A
  • Method to figure out how old a tree is using its tree rings
  • Most trees produce one ring per year
  • Ring thickness depends on the climate
  • When warmer the rings will be thicker b/c of better growth conditions
  • Cores from tree trunks can be taken and then each ring can be dated
  • The thickness of each ring then gives us an idea of the climate
62
Q

How to measure climate change? (Pollen in Peat Bogs)

A
  • Shows how temp has changed over thousands of years
  • Pollen is preserved in peat bogs
  • Peat bogs = acidic wetland areas
  • Peat bogs accumulate in layers, so older preserved pollen are deeper down
  • Cores from peat bogs can be taken and pollen grain extracted
  • The pollen grains can then tell us which plant it came from
  • Only fully grown plants produce pollen, so the species were successful at one point
  • Plants in today’s climate living in the past mean there was a similar climate then
  • Plant species vary w/ climate so preserved pollen will vary w/ time
  • A gradual ↑ in pollen of one species that is more successful in warmer climates show a rise in temp
63
Q

What causes climate change? (Anthropogenic Activity)

A

Anthropogenic = human activity

  • Human activity has caused global warming by enhancing the greenhouse effect
  • Greenhouse effect = the effect of greenhouse gases absorbing outgoing energy, so less is lost to space
  • But the greenhouse effect is essential to keep the planet warm
  • Disputed b/c of bias scientists, how good and reliable the data is
64
Q

What causes climate change? (CO2)

A

COշ = global warming

  • Atmospheric COշ has ↑ by over 100 ppm since mid-19th century
  • It was stable for the previous 10 000 years
  • It continues to ↑ b/c of burning fossil fuels and destruction of natural sinks
  • Natural sinks store C as organic compounds
  • COշ is released when trees are burnt, or when decomposers break down the organic compounds and respire them
65
Q

What causes climate change? (CH4)

A

CH4 = global warming

  • Atmospheric CH4 conc. has more than doubled since mid-19th century
  • It was stable for the past 850 years
  • It continues to ↑ b/c more is being released
  • More fossil fuels are being extracted, and there are more cattle
  • Released from natural stores, e.g frozen ground
66
Q

Models for climate change? (Extrapolation)

A
  • Data can be extrapolated to form predictions about the future
  • These can then produce models of how the global climate might change
67
Q

What are the limitations for models predicting climate change?

A
  • Don’t know how much greenhouse gas emissions will change
  • I.e which scenario would be most accurate
  • Don’t know how much each scenario will cause temp to rise by
  • Atmospheric greenhouse gas conc. might change b/c of natural causes
  • There may be attempts to manage the atmospheric conc. or their success
  • There are complex feedback systems inv. so won’t know the exact effects on climate
68
Q

What are the effects of climate change? (Enzyme Activity)

A

An ↑ in temp will affect enzyme activity

  • It will ↑ the rate initially due to more kinetic energy
  • But if the temp goes too high, some bonds will break, ruining the enzyme’s shape
  • Active site will change shape = no enzyme-substrate complexes form
  • The enzymes will become denatured
69
Q

What are the effects of climate change? (Metabolism)

A

Metabolism = chemical reactions that take place in its cells to keep it alive

  • Metabolic reactions are controlled by enzymes
  • A faster enzyme rate = develop and progress through their life cycle faster
  • They’re inv. in photosynthesis, so plants may grow faster and die quicker
  • Cyanobacteria can produce toxins and they photosynthesise
  • They will produce more toxins which are harmful to humans
  • A slow/ stopped enzyme rate = develop and progress through their life cycle slower
  • Above 25°C wheat develop fewer grains so yields will ↓
  • The eggs of cold water fish won’t hatch as they develop at low temps
70
Q

What are the effects of climate change? (Species Distribution)

A

Species’ ideal conditions may be more common
- Subtropical plankton species are being found up north b/c of warmer seas
- European butterflies are being found up north b/c of warmer weather

Species’ ideal conditions may become rare
- Alpine plants grow in cooler conditions and so are moving further up mountains
- Ice caps are melting so polar bears have smaller habitats and ↑ competition

71
Q

What are the effects of climate change? (Rainfall Patterns)

A
  • It can affect development and life cycles
  • Ocotillo is dormant during dry periods, so more dry periods = longer dormancy periods
  • It can affect distribution
  • ↓ rainfall = ↑ deserts, species will have to find new habitats if their original one becomes a desert
72
Q

What are the effects of climate change? (Seasonal Cycles)

A
  • It can affect development and life cycles
  • Red squirrels in Canada are giving birth earlier b/c of an earlier availability of food
  • It can affect distribution
  • Some swallows live in South Africa in winter, and Europe in spring and summer to breed
  • An earlier spring means flowers and insects are earlier than usual
  • When the swallows come to europe, there will be less food available
  • Less swallows will be born which may lead to extinction
73
Q

Investigating the effects of climate change (Seedling growth rate)

A
  1. Plant seedlings in soil trays and measure their height
  2. Place the trays in incubators at dif. temps
  3. Make sure other variables are the same
  4. Then record the change of height
  5. Calculate average growth rate using→average change / incubation period
74
Q

Investigating the effects of climate change (Brine Shrimp Hatch Rate)

A
  1. Plant an equal no. of brine shrimp eggs in water baths of dif. temps
  2. Make sure other variables are the same
  3. Record the no. of hatched brine shrimp
  4. Calculate average hatch rate using→no. of hatched eggs / no. of hours
75
Q

Investigating the effects of climate change (Temperature and Enzyme Catalysed Reactions)

A
  1. Set up boiling tubes of same volume and conc. of hydrogen peroxide
  2. Add the same volume of buffer solution to each→to maintain pH
  3. Place a bung w/ a delivery tube in the boiling tube. Then place an upside down measuring cylinder in a trough of water. The delivery tube should go under and into the measuring cylinder
  4. Then place each set up in dif. water baths which are at dif. temperatures
  5. Using a pipette, add the same volume and conc. of catalase to each boiling tube before quickly reattaching the bung
  6. Record how much Oշ is produced every 10s by recording how much the water in the cylinder moves down
76
Q

How to work out the Initial rate of Reaction?

A

Initial rate of reaction can be calculated by finding the gradient of the tangent at that point

77
Q

Q10

A

Q10 = the temperature coefficient

  • Shows how rate changes w/ a temperature ↑ of 10℃
    = rate at higher temperature
    rate at lower temperature
  • A value of 2 means the rate doubles, a value of 3 means the rate trebles
  • Most enzyme-controlled reactions have a Q10 of ~2
78
Q

Reducing Climate change (Understanding the Carbon Cycle)

A
  • Absorbed by plants during photosynthesis = C compounds in plant tissues
  • Passed onto animals from eating plants and to decomposers from dead organic matter
  • Returned to the atmosphere from respiration
  • C compounds can be turned into fossil fuels
  • Combustion of fossil fuels releases COշ into the atmosphere
  • To reduce conc. of COշ, volume going into the atmosphere needs to ↓
  • Or the volume being taken out of the atmosphere needs to ↑
79
Q

Reducing Climate change (Biofuels)

A
  • Produced from biomass (material that is or was previously living)
  • Often from crops so can be replanted = a sustainable resource
  • They’re burnt to release energy, producing COշ
  • No net ↑ in atmospheric COշ conc.
  • Volume produced = volume taken in during growing
80
Q

Reducing Climate change (Reforestation)

A
  • Planting new trees in existing forests that have shrunk
  • More trees = more COշ removed from atmosphere
  • COշ becomes C compounds and is stored in the plant tissues
  • Less C in atmosphere so less C for global warming
81
Q

Reducing Climate change (Increasing use of Biofuels)

A
  • Farmers will support b/c gov will fund the farming of the crops
  • Drivers will support b/c price of biofuels is lower than oil-based
  • Consumers will oppose b/c less farmland for food so ↑ food costs
  • Conservationists will oppose b/c forests will have to be cleared for space
82
Q

Reducing Climate change (Increasing the use of wind turbines)

A
  • Manufacturers will support b/c their sales will ↑
  • Environmentalists will support b/c electricity produced w/o COշ
  • Local will oppose b/c they’re ugly
  • Bird conservationists will oppose b/c many birds killed by them
83
Q

What is evolution?

A

Evolution = changes in allele frequency in a population over time

84
Q

Process of Natural Selection

A
  1. Individuals w/n a pop. vary b/c of dif. alleles
  2. The dif. alleles are due to gene mutation
  3. This means some individuals are better adapted than others
  4. Individual w/ an allele that ↑ the chance of survival is more likely to survive (intraspecific competition), reproduce and pass on the allele
  5. A greater proportion of the next gen. will inherit the beneficial allele
  6. Meaning they are also more likely to survive and reproduce
85
Q

What is geographical speciation?

A

Geographical Speciation = Allopatric Speciation

  • They will experience dif. conditions
  • Dif. selection pressures = dif. changes
  • b/c of natural selection
  • Allele frequency changes = diff. in the gene pool = changes in phenotypic frequencies
  • Eventually, the dif. pops will become genetically distinct
  • The two pops won’t be able to breed and produce fertile offspring
  • They’ve been reproductively isolated = separate species
86
Q

What is reproductive isolation?

A
  • Seasonal diff. = dif. flowering/ mating/ sexually active seasons
  • Mechanical diff. = dif. genitalia preventing mating
  • Behavioural diff. = courtship rituals that aren’t attractive to others
87
Q

What is sympatric speciation?

A
  • Random mutations occurring w/n a population
  • Lead to reproductive isolation
  • E.g polyploidy = ↑ no. of chromosomes
88
Q

What are genomics?

A
  • Uses DNA technology to determine base sequence of an organism’s genome and functions of its genes
  • Scientists can make comparisons b/w organisms DNA
  • Theory of evolution = all organisms evolved from shared common ancestors
  • The more closely related species the earlier the diversion
  • b/c less time for changes in DNA sequence
89
Q

What are proteomics?

A

The study of proteins

  • The sequence of amino acids is coded by the DNA sequence
  • Related organisms = similar DNA sequences = similar amino acid sequences
  • The more similar proteins = the more recent divergence
90
Q

How is a scientific journal checked?

A

Peer Review = before their work can be published
- Other scientists in that area review the work
- They check the work is valid and supports the conclusions
- Makes sure the experiment was carried out to a high standard

Scientific journal = academic magazines where they publish articles
- Share new ideas, experiments, evidence, theories and conclusions
- Can repeat experiments using same methods to get the same results
- Replicated results means the evidence is reliable

Scientific Conferences = meetings to discuss each others work
- Present their work w/ a lecture or poster presentation
- Other scientists can ask questions and discuss their work
- An easy way for the latest theories to be shared and discussed

A Level Biology (SNAB) (6 decks)

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