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On The Wild Side - Topic 5, A-Level Biology
Terms in this set (45)
What are Abiotic Factors that Affect Abundance?
1. Non-living or physical and chemical factors.
2. Solar energy input.
5. Oxygen concentration.
6. Edaphic factors.
What are Biotic Factors that Affect Abundance?
1. 'living' factors.
5. Anthropogenic factors.
What is a Niche?
The role of a species within its habitat. It includes biotic and abiotic factors.
How Can Abundance be Explained by the Niche Concept?
Two species occupying similar niches will compete, so fewer individuals of both species will be able to survive in the area.
How Can Distribution be Explained by the Niche Concept?
Organisms can only exist inhabitants where all the conditions that make up their role exist.
What are the 2 Types of Succession?
1. Primary succession - happens on newly formed or exposed land.
2. Secondary succession - happens on land that has been cleared of all the plants but where soil remains.
Describe Primary Succession
Pioneer species begin to colonise. The abiotic conditions are hostile. As specialised plants colonise, they change the abiotic conditions, adding nutrients to the soil. This means a wider variety of plants can colonise etc...
Describe Secondary Succession
Happens like primary succession, but there is already a soil layer so succession starts at a later stage, e.g. shrubs.
What is a Climax Community?
The final stage of succession. When the ecosystem is supporting the largest and most complex community of plants and animals it can.
Describe the Overall Reaction for Photosynthesis
Energy from light is used to break apart the strong bonds in H₂O molecules. Hydrogen from the breakdown of H₂0 is stored in glucose (a fuel), which is formed when hydrogen is combined with CO₂. O₂ is released into the atmosphere.
What are the Light Dependent Reactions in Photosynthesis?
Use energy from light and hydrogen from photolysis of water to produce reduced NADP, ATP and oxygen (waste).
What Does OIL RIG Stand For?
Oxidation is loss, reduction is gain.
Where Does Photosynthesis Take Place?
In the chloroplasts.
What are the 2 Photosystems in Chloroplasts?
1. PSI - absorbs 700nm wavelength.
2. PSII - absorbs wavelength 680nm.
What is the Light Energy Absorbed by the Photosystems in the Light-Dependent Reaction For?
1. Making ATP from NAD and inorganic phosphate - photophosphorylation.
2. Making reduced NADP from NADP.
3. Splitting water into protons (H+ ions0, electrons and oxygen - photolysis.
What are the 7 Stages in the Light-Dependent Reaction, Once Light has been Absorbed by the Photosystems?
1. Energy from light raises 2 electrons to an excited state.
2. Electrons leave excited chlorophyll and pass along electron carrier molecules in the thylakoid membrane that form the ETC.
3. Electrons from PSII chlorophyll pass from one carrier to the next, loosing energy. The energy is used in the synthesis of ATP - photophosphorylation.
4. Electrons from PSII replace those lost from PSI.
5. Electrons from PSII must be replaced so flow of electrons along ETC can continue.
6. In the thylakoid space, enzymes catalyse the splitting of water (photolysis), producing oxygen, hydrogen and electrons. This raises hydrogen ion conc. in thylakoid space.
7. One electrons from PSI chlorophyll have passed along ETC they combine with co-enzyme NADP and H ions from water, forming reduced NADP.
What are the 4 Main Steps in the Light-Dependent Reaction?
1. Light energy excites electrons in chlorophyll.
2. Photolysis of water produces protons (H+ ions), electrons and O₂.
3. Energy from excited electrons makes ATP.
4. Reduced NADP is generated.
Where Does the Light-Independent Reaction Take Place?
Within the stroma of the chloroplasts, using the reduced NADP and ATP from the light-dependent reactions.
What are the 5 Stages of the Calvin Cycle?
1. CO₂ combines with RuBP (5C), catalysed by RuBISCO.
2. 6C compound formed = unstable, breaks down into 2 x 3C molecules (GP).
3. 3C compound reduced into GALP (H used comes from LD reaction). ATP from LD is also used.
4. 2/12 GALPs involved in creation of 6C sugar - hexose.
5. 10/12 GALPs involved in recreation of RuBP. The 10 GALPs rearrange to form 6 x 5C compounds which are phosphorylated using ATP to form RuBP.
How are the Products of the Calvin Cycle used by Plants, Animals and Other Organisms in Respiration & Synthesis of New Biological Molecules?
GALP and GP are used to make:
3. Amino acids.
4. Nucleic acids.
The simple sugars produced can be passed along the food chain.
How is the Structure of Chloroplasts Important in Photosynthesis?
1. Thylakoid membrane - proteins, chlorophyll & electron carriers are embedded in the membrane.
2. DNA loop.
3. Stroma - contains enzymes for LI reaction.
4. Starch grain - stores products of photosynthesis.
6. Inner membrane - contains transport molecules and decides what enters and leaves.
7. Outer membrane - freely permeable to CO₂ and H₂O.
8. Thylakoid space - contains enzymes for photolysis.
What is Net Productivity?
= gross primary productivity - respiratory loss.
It is the amount of energy available for the next trophic level.
What is Net Primary Productivity?
When you are just talking about producers.
NPP = GPP - plant respiration.
How Can the Efficiency of Biomass and Energy Transfers be Calculated?
1. Calculate energy difference between each level.
2. Multiple results by size of population.
3. Difference in energy between trophic levels = energy transferred.
What is Gross Primary Productivity?
The rate at which energy is incorporated into organic molecules by an ecosystem.
What is Dendrochronology?
Figuring how old a tree is from the tree rings. The thickness depends on the climate - warmer = thicker ring. By looking at the rings, scientists can see how climate has changed over the years.
How Can Pollen in Peat Bogs Show Climate Change?
Pollen grains are preserved in the peat. When they are taken by scientists, the plant species they came from is identified. The samples show the plants that were successful at that time. In each layer they find similar species, showing the climate was similar. So, an increase in pollen from a plant species more successful in warmer climates shows there was a rise in temperature.
How Does Climate Change Alter Rainfall Patterns and Seasonal Cycles?
1. Rainfall patterns - will be altered so some areas get more/less rain. This will affect development and life cycles of some organisms.
2. Seasonal Changes - seasons will change which organisms aren't adapted to.
How Does Climate Change Affect the Rate of Enzyme Activity?
Increases because theres more kinetic energy so molecules move faster. This makes enzymes more likely to collide with substrate molecules. If the temperature gets too high the reaction stops - active site changes shape.
What Does Increased Enzyme Activity Due to Climate Change mean for Organisms?
May speed up the rate of growth, so life cycle will be faster. May be too high and so rate of growth will decrease.
What is Evolution?
When the frequency of an allele in a population changes over time. This is due to gene mutations. Alleles that increase the chance of survival are more likely to survive, reproduce and pass on their genes.
What is Speciation?
Speciation happens when populations of the same species become reproductively isolated, reducing gene flow. This means that natural selection acts on each population separately - so new species develop.
What Changes Can Affect a Species Breeding Together?
1. Season changes.
2. Mechanical/physical changes.
3. Behavioural changes.
What is Genomics?
A branch of science using DNA technology ro determine the base sequence of an organisms genome and the function of its genes. This allows scientists to make comparisons between organisms DNA.
What is Proteomics?
The study of proteins and the sequence of amino acids in a protein coded for by the DNA sequence in a gene.
What are the Main 3 Ways that the Scientific Community Shares and Discuss's its work?
1. Scientific journals - academic magazines where scientists can publish their ideas, theories etc. It allows other scientists to repeat them, increase validity.
2. Peer review - other scientist read and check the work is valid and supports the conclusion.
3. Conferences - meetings where work can be shared and discussed.
What is Allopatric Speciation?
Occurs where populations are geographically isolated from one another, preventing the groups from mating with each other, and so populations become reproductively isolated.
What is Sympatric Speciation?
Where two populations become reproductively isolated in the same environment without any geographical barrier, due to other isolating mechanisms.
Why is Climate Change Controversial?
1. Scientists cannot prove the theories.
2. There is incomplete knowledge of how the climate systems of our planet work.
What are the Ethical Arguments about Global Warming?
1. We all have the right to choose if we use fossil fuels.
2. We have a duty to allow others to improve their standard of living.
3. We have a duty to preserve the environment for the next generation.
What is Upsetting the Balance in the Carbon Cycle?
1. Combustion of fossil fuels.
How can Biofuels Help with Climate Change?
They are a sustainable resource. There is no net increase in atmospheric CO₂ because what is released when burnt equals what was taken in during growth.
How can Reforestation Help with Climate Change?
More trees being planted = more CO₂ is removed from atmosphere by photosynthesis.
What are the Controversial Views about Biofuels?
1. Farmers will support, as governments will fund the farming of crops.
2. Drives will support as fuel is cheaper.
3. Consumers may oppose - the use of farmland could cause food shortages.
4. Conservationists may oppose - forests have been cleared to grow biofuels.
What are the Controversial Views about Wind Turbines?
1. Companies that make them would support.
2. Environmentalists will support - produce electricity without increasing CO₂ concentration.
3. Local communities think it ruins landscape.
4. Bird conservationists oppose- birds are killed flying into them.
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