Energy and the Environment Flashcards
Properties of ATP
- Allows energy release in small amounts
- Energy released in single-step reaction
- Soluble in water
- Quickly broken down and resynthesised
Functions of ATP
- Active transport
- Synthesis reactions
- Muscle contraction
- Cell division
- Light independent reaction
- First stage of glycolysis
Process of oxidative phosphorylation
1) Coenzymes release hydrogen to electron carrier.
2) Each H splits giving e- and H+
3) e- pass down carriers at decreasing energy levels. Energy is released as they’re transferred, which is used to transport H+ into the inter-membrane space.
4) H+ gradient establishes, causing H+ to diffuse back into the matrix via ATP synthase.
5) This movement releases energy, used to form ATP.
6) e- combines w/ H+ and oxygen to form water at the end of the chain.
Limitations of a simple respirometer
- Temperature or atmospheric pressure changes can affect gaseous volume, this affects pressure in the apparatus, so the measured distance is based on factors other than O2 level.
- Chemicals used might alter gas composition.
- Volume change calculated using tube diameter may be inaccurate
Process of Non-cyclic phosphorylation
1) Light energy is absorbed by chlorophyll in PSII exciting e- to a higher energy level, giving chlorophyll a + charge.
2) e- pass along cytochromes in ETC, decreasing in energy level at each, releasing energy used to move H+ into the thylakoids. H+ gradient establishes causing H+ to diffuse back into the stroma via ATP synthase. Energy released phosphorylates ADP
3) e- is transferred to chlorophyll in PSI.
4) Light energy is absorbed by chlorophyll in PSI, exciting e- to a higher energy level.
5) e- and H+ are accepted by NADP (used in LIR)
Where is the ETC during photosynthesis in plants?
Thylakoids in grana
Cytochrome
Type of electron carrier associated with phosphorylation during photosynthesis
Cyclic Phosphorylation
1) Light energy is absorbed by chlorophyll in PSI exciting e- to a higher energy level.
2) High energy e- acceptor is reduced.
3) e- release energy as they pass down a series of electron carriers (like cytochromes) at decreasing energy levels. Energy transport H+ into the thylakoid. H+ gradient is established and H+ diffuse into the stroma via ATP synthase. Energy transferred by the movement of H+ is used to form ATP.
4) E- eventually return to chlorophyll in PSI
Photorespiration
Competing reaction to photosynthesis, where RuBP fixes O2, resulting in production of glycolate which is broken down to release CO2, but no ATP is generated.
Carotenoids
- Yellow, orange or brown pigments that strongly absorb blue-violet light. Pass light to chlorophyll.
- Protect chlorophylls from XS light and oxidation.
- Usually masked by green chlorophylls
Action spectrum
Graph showing effectiveness of different wavelengths of light in stimulating photosynthesis
Absorption spectrum
Graph of relative amounts of light absorbed at different wavelengths for a pigment.
C4 plants
Enhance ability of certain plants to fix CO2 under conditions that cause most plants to lose organic material from photo respiration
Ectotrophic mycorrhizae
Group of mycorrhizae which form a sheath around the root and penetrate air spaces between cortex cells. Forms an extensive intercellular net. Found in forest trees and their fruiting bodies (mushrooms) can be seen near trees.
Endotrophic mycorrhizae
Group which form intercellular network and extend into soil, but penetrate root hair cells.
Apoplast pathway
Movement of water through cellulose cell walls of adjacent cells and intracellular spaces between (not endodermis). Casparian passage forces ions and water to pass through the symplast pathway.
Symplast pathway
Movement of water by osmosis through inter-connecting cytoplasm of adjacent cells. Water travels through the plasmodesmata, think strands of protoplasm linking throughout cytoplasm of adjacent cells.
Water adhesion
Attraction between water molecules and xylem wall
Ecosystem
Natural unit consisting of biotic factors, their interactions with each other and the abiotic factors of the habitat
Community
In a particular habitat and based upon dynamic feeding relationships between the different species.
Population
Group of organisms of the same species occupying the same habitat at the same time.
Species
Organisms w/ similar characteristics which can interbreed to produce fertile offspring. Have similar DNA and share the same ecological niche.
Niche
Particular role of an organism in an ecosystem governed by its adaptation to the food supply, the habitat it occupies and abiotic factors that are present.
Producers
Autotrophic. Plants convert light energy into chemical energy by photosynthesis. They produce organic compounds and are the basis of every food chain.
Consumers
Heterotrophic, break down large insoluble organic compounds into smaller soluble molecules which provide energy for growth. Primary are herbivores, secondary + tertiary are carnivores.
Saprobionts
Bacteria and fungi which break down dead organisms. Are essential for recycling nutrients in the environment.
Detritivores
Feed on detritus, break down decaying matter into smaller pieces, increasing SA for decomposition by microbes. Aids recycling of nutrients in the ecosystem.
How does light affect biotic factors of an ecosystem?
Light availability affects number and diversity of plant species and consequently the number and type of consumers in an ecosystem.
How does pH affect biotic factors of an ecosystem?
In acidic and alkaline soils, the growth of specific plant species are favoured, determining the fauna of an ecosystem. Enzymes have narrow pH ranges and deviation from the optimum can lead to denaturation.
How does termperature affect biotic factors of an ecosystem?
Enables enzymatic reactions, affects flora & fauna as shown by lack of species diversity in very hot/cold habitats. In aquatic habitats an increase in temperature reduces amount of dissolved O2 available to living organisms.
Examples of abiotic factors
Temperature, pH, light, oxygen, carbon dioxide, humidity, salinity, pollution etc
Pyramid of biomass
Total mass of organisms at each trophic level in a food chain. Measured as dry mass per unit area or volume.
Pyramids of energy
Each bar represents the amount of energy per unit area or volume that flows through that trophic level in a given time period.
Why is energy transfer of light so inefficient?
- Light misses chloroplasts/chlorophyll/photosynthetic tissue
- Some light which hits chlorophyll is reflected/not absorbed
- Only certain wavelengths of light used in photosynthesis
