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
What causes inefficiency in energy transfer between trophic levels?
- Most energy is transferred to environment as heat released from respiration
- Not all of organism consumed or indigestible parts present which aren’t absorbed
- Loss via excretory products
Energy transfer equals
(energy available after the transfer/energy available before the energy transfer) X 100
Gross Primary Productivity (GPP)
Gross photosynthesis is the total amount of light energy converted to chemical energy in photosynthesis.
Net Primary Productivity (NPP)
Net photosynthesis is the amount of energy from photosynthesis which remains available to the primary consumers. (GPP - respiratory loss)
What causes the size of a population to vary?
- Effect of abiotic factors
- Interactions between organisms
- Inter- and intra-specific competition
- Predation
Density dependent factors in stability of a population
Higher proportion of population is affected when density of population is high. Due to increased competition, increased predation or parasitism.
Density independent factors in stability of a population
Same proportion of population is affected whatever the population size e.g. climate
Rhizobium
Type of nitrogen fixing bacteria which can form mutualistic relationships of leguminous plants
Ammonification
Production of NH3 from decaying organisms or waste products by saprobionts. Returned to soil as NH4+
Denitrification
Conversion of nitrates into gaseous nitrogen by denitrifying bacteria. Reduces soil fertility
Nitrification
Oxidation of NH3 and NH4+ into nitrates and nitrites by nitrifying bacteria. Increases soil fertility.
Biodiesel
Biodiesel is produced by extracting oil from crops like soybean, oil seed rape and palm oil, and converting it to biodiesel. 1st gen biofuel
Bioethanol
Produced from sugar beet, sugar cane and corn. Sugars are fermented to ethanol by yeast. 1st gen biofuel.
Lignocellulosic biofuels
Produced through breakdown of carbohydrates in the cell walls of plants, which can be fermented by yeast and other microorganisms. This type of plant material makes up about half of the world’s biomass and represents non-edible part of a plant. Microbes that naturally produce cellulase are used to breakdown this material to sugars which can then be fermented to produce ethanol.
Algae as a biofuel
Photosynthesise to produce biomass including oils which can be converted to biodiesel. Potentially could produce 100 times more oil per acre than any terrestrial plant, also don’t compete for land.
How are biofuels made from algae
Can be produced by processing the biomass to produce sugars that are then fermented. If the sugars released from the biomass are fermented by other types of microorganisms, other fuel products instead of ethanol can be produced.
Lincoln index assumptions
- Organisms mix randomly within population
- Sufficient time between capture and recapture to allow random mixing.
- Only populations who are restricted to area
- Organisms disperse evenly in area of population.
- Changes in population size as a result of immigration, emigration, births and deaths are negligible.
- Marking does not endanger organisms.
- Marking cant be rubbed, licked off between captures.
Biodiversity
Refers to variety of organisms occupying a particular habitat. Can relate to a range of habitats, or a small local habitat to the Earth
Species richness
A measure of the number of different species in a community.
Chi squared test
Enables significance of differences between observed and expected values to be established.
It is a measure of the degree of deviation between an observed and expected result.
Succession
The gradual change in the plant and animal communities at a site, starting from pioneer species and eventually leading to a climax community
Advantages of organic fertilizers
- Cheap
- Not easily lost by leaching
- Improves soil
Advantages of inorganic fertilizers
Exact composition is known
Disadvantages of organic fertilizers
- Variable (usually low) nutrient content
- Slow release of nutrients
- May contain plant or animal pathogens that cause disease
Disadvantages of inorganic fertilizers
- Expensive and energy consuming to manufacture
- Most components are soluble –rapid leaching into rivers causing eutrophication
- Applied in concentrated form can cause osmotic damage to plants
Eutrophication
Enrichment of an aquatic ecosystem by nutrients. Usually occurs over a long period of time but can be increased by use of fertilizers.
Effects of organic effluent
- Suspended soils
- Nitrate and phosphate compounds
- Toxins
- Microorganisms
Organic effluent effect - suspended soils
- Reduce penetration of light
- Aquatic plants can’t photosynthesise and so die
- BOD due to increased activity of respiring aerobic saprophytic bacteria
Organic effluent effect - nitrate and phosphate compounds
- Nitrogen compounds are broken down into NH4+, NO3- and NO2- during the nitrogen cycle. Phosphates are released by saprophytic bacteria. Eutrophication may lead to algal blooms and BOD
- Some algae produce toxins which cause fish death.
- High nitrate concentration can damage human health
Biochemical Oxygen Demand
Method of assessing water quality by measuring bacterial activity.
The amount of dissolved oxygen needed by aerobic decomposers to break down organic materials.
Pesticide
Chemical substances used by humans to control pests.
Pest
Any unwanted organism that interferes, either directly or indirectly, with human activity
Ideal pesticide
- Selective
- Non-persistent
- Non-mobile
- Cost effective
Bioaccumulation
When a toxin builds up in the food chain
Auxin as a herbicide
Selective, cheap and very effective.
Cause twisted growth and reduction in growth. Potentially affects normal expression of genes and production of enzymes.
When finding a control agent for biological control of a pest, what characteristics are important?
- Specific
- Not change its prey and become a pest itself
- Not introduce diseases
- Whether its life cycle allows it to develop into a population large enough to act as economic control.
Advantages of biological control
- Specific, so highly effective against particular pest
- Natural i.e. does not pollute
- Once introduced, control organism reproduces itself
- Pests don’t become resistant
- Cheaper than repeated applications of chemicals
Disadvantages of biological control
- Control agents can sometimes become pests
- Once released, hard to control
- Testing/for correct organism can be expensive
- Pest resurgence may require reintroduction
Three main methods of pest control
- Chemical
- Cultural
- Biological
What background information is required for successful integrated management
- Crop growth characteristics
- Type, number and life cycles of the pest species
- Pest pop. dynamics & relationship to crop damage
- Pest-host plant relationships
- Pest-predator relationships and effect on pest pop.
- Insecticide effect on crops, pests & non-target species
What causes the stability of an ecosystem to increase as succession occurs?
- More interactions between species, so more complex food webs; if numbers of one species change there will be less effect on other species
Why are climax communities rarely reached in the UK?
Grazing by domestic animals;
ploughing and planting of new crops;
use of herbicides
Monoculture
Same crop grown in large areas
Effects of monoculture on diversity
- Reduced diversity due to fewer niches/habitats/food
- Reduced soil fertility as same nutrients removed
- Increased risk of crop failure, crop specific pathogens
- Hedgerows removed
- Soil erosion from ploughing
How do fertilisers lead to a reduction in diversity in a lake ecosytem?
- Nitrates/Phosphates/ causes increase in plant growth and then algal bloom
- Algae block out light;
- Plants unable to photosynthesise and die
- Increase in bacteria/saprobionts
- Bacteria/saprobionts use up oxygen in respiration
- Less oxygen available/BOD increases
Indicator species
Species used to monitor dissolved oxygen content of an aquatic ecosystem.
How can an indicator species be used to measure water pollution in a lake?
- Take samples, Identify whether species associated with more/less oxygen are present
Why should pesticides be only used when natural methods are ineffective?
- Not cost effective to apply when not required
- Pesticides kill predators of pests
- They kill other non-target species either directly or through killing food source
- Pesticides stored in fatty tissue and bioaccumulate leading to death of species higher up in the food chain.
Biological control example
- Whiteflies damage greenhouse crop plants by eating and laying eggs on crops. Parasitic wasp lays egg in each larval scale. This eats away at the body of its host before emerging.
Biodegradable
Can be broken down by microorganisms
Closer to a hedgerow, the transpiration rate of plant crops decreases, explain why?
Wind speed decreases, so water vapour in air remains, so water potential gradient is lower
