Biology AQA Unit 4

  • Created by: Rachel
  • Created on: 12-12-12 14:40
Ecology
The study of the inter-relationships between organisms and their enviroment
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Population
A group of interbreeding organisms of one species in a habitat
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Community
All the populations of different organisms living and intercating in a particular place at the same time
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Habitat
The place where a community of organisms lives
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Ecological Niche
How an organisms fits into its enviroment, including all the biotic and abiotic factors that affect it
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Why use a transect instead of random quadrats?
When some form of transition is taking place in the communities of plants and animals
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Equation for the mark-release-recapture technique
(total number of indv in sample 1 x total number of indv in sample 2) / marked individuals recaptured
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Equation for population growth
(births + immigration) - (deaths + emigration)
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Percentage population growth rate equation
(population change during the period/population at the start of the period) x 100
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Factors affecting birth rate
Economic Conditions, Cultural/Religious Backgrounds, Social pressures and conditions, Birth Control, Political Factors
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Birth Rate Equation
(number of births per year/total population in same year) x 1000
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Factors Affecting Death Rate
Age Profile, Life Expectancy at birth, Food Supply, Safe Drinking Water And Sanitation, Medical Care, War and Natural Disasters
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Death Rate Equation
(number of deaths per year/total population in the same year) x 1000
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Hydrolysis Of ATP Equation
ATP + H2O --> ADP + Pi + Energy
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Oxidation
Loss of electrons, loss of hydrogen, gain of oxygen
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Reduction
Gain of electrons, gain of hydrogen, loss of oxygen
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Equation For The Photolysis Of Water
2H2O --> 4H+ + 4e- + O2
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Where does the light dependent reaction take place?
In the thylakoids of chloroplasts
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How are the chloroplasts adapted to carry out the light dependent reaction?
Thylakoid membranes have a large S/A for attachment of chlorophyll, electron carriers and enzymes. 2. A network of grana proteins hold the chlorophyll in a precise manner for max light absorption.
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Where does the light independent reaction take place and how is it adapted?
The stroma, contains all needed enzymes, fluid surrounds grana so products of LD reaction readily diffuse, got DNA and ribosomes so can easily make proteins
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How is phosphorylated glucose formed?
Glucose is made more reactive by adding two phosphate molecules in the first stage of glycolysis. The Pi have come from the hydrolysis of ATP.
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What is the overall yield from glycolysis?
2 x ATP, 2 x Reduced NAD, 2 x pyruvate
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Equation For The Link Reaction
pyruvate + NAD + CoA --> acetyl CoA + Reduced NAD + CO2
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For each molecule of pyruvate, what does the link reaction/Krebs Cycle produce?
Reduced coenzymes (NAD/FAD), 1 x ATP, 3 x CO2
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Where is the electron transport chain found?
In the mitochondria, attached to the inner folded membrane (cristae) are the enzymes and other proteins
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Why would muscle cells have more mitochondria than some other cells?
Vital for respiration, more densely packed cristae mean larger S/A for attachement of enzymes/other proteins for e- transport chain
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What happens in the electron transport chain?
Reduced NAD/FAD donate e- to first molecule, series of oxidation/reduction reactions, e- lose energy as go down, some used to form ATP, some lost as heat
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What role does the mitochondrial membrane play in the electron transport chain?
The protons from the H are actively transported into the membrane and accumlate, before diffusing back into the matrix through special protein channels
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Anaerobic Equation For Plants
pyruvate + reduced NAD --> ethanol + Carbon Dioxide + NAD
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Anaerobic Equation For Animals
pyruvate + reduced NAD --> lactate + NAD
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Food Chain
A feeding relationship in which producers are eaten by primary consumers
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Why is most of the suns energy not converted to organic matter?
Over 90% reflected into space by clouds/dusts, absorbed by atmosphere, not all wavelengths can be absorbed, light may not fall on chlorophyll, limiting factors
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Net Production
= gross production - respiratory losses
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Why is such a low % of energy transferred at each stage?
1. Some not eaten/digested 2. Lost in excretory materials 3. Losses as heat (high in mammals)
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Energy Transfer Equation
(energy available after transfer/energy available before transfer) x 100
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Biomass
The total mass of plants and/or animals in a particular place
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Measurement For Energy Flow
kJ m-2 year -1
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Additional energy for an agricultural ecosytem compared to a natural one
Food (workers) and Fossil Fuels (machinery)
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Biological Control
Using organisms that are predators/parasites of a pest organism to control it
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Advantages Of Biological Control
Specific, no need for reapplication, pest won't become resistant
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Disadvantages Of Biological Control
Act slowly, could become a pest itself
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Ammonification
Production of ammonia from ammonium containing compounds eg urea - decomposers feed on the compounds, releasing ammonia to form ammonium ions in soil
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Nitrification
Oxidation reaction, ammonoim ions --> Nitrite ions --> Nitrate ions, needs air spaces
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Nitrogen Fixation
Nitrogen Gas --> Nitrogen Containing Compounds, either free-living or mutualistic bacteria
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Denitrification
Anaerobic denitrifying bacteria, convert soil nitrates into gas nitrogen, less for plants
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Negative Effects Of Nitrogen Containing Fertilisers
Reduced Species Diversity (favour certain species), leaching, eutrophication
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Features Of A Pioneer Species
Rapid germination of seeds, ability to fix nitrogen from air, tolerance to extreme conditions, produce lots of seedds (wind-dispersed to reach isolated places)
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Common features of succession
Abiotic less hostile, more/varied habitats, increased biodiversity, more complex food webs, increased biomass
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Gene Pool
All the alleles of all the genes of all the individuals in a population at any one time
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Allelic Frequency
The number of times an allele occurs within the gene pool
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5 Conditions Of Hardy Weinberg
1. No mutations 2. Large Population 3. No selection 4. Random mating 5. Isolated Population
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What does Hardy Weinberg Predict?
That the proportion of dominant/recessive alleles of any gene in a population will remain the same from 1 generation to the next assuming his 5 conditions are met
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Directional Selection
Favouring individuals that vary in one direction from the mean of the population
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Stabilising Selection
Favours average individuals
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Speciation
Evolution of a new species from existing species (always describe using frequency of alleles, gene pools)
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Geographical Isolation
When a physical barrier prevents 2 populations from interbreeding
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Other cards in this set

Card 2

Front

Population

Back

A group of interbreeding organisms of one species in a habitat

Card 3

Front

Community

Back

Preview of the front of card 3

Card 4

Front

Habitat

Back

Preview of the front of card 4

Card 5

Front

Ecological Niche

Back

Preview of the front of card 5
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Comments

george power

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Great help!

Ajay

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Great for last minute revision. Thanks!

Cameron

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Thank you alot this really helped me understand what I didnt know so I could revise it :)

Aryeh Wolfson-West

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This is mad thanks!

:) PurpleJaguar (: - Team GR

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These are so good 

Thanks! :)

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