topic 5 Flashcards
ecosystem definition
a community and its interactions with the non-living parts of its habitat
community definition
multiple populations living and interacting in the same area
population definition
all of the individuals of one species living in a habitat
habitat definition
the place with a distinct set of conditions where an organism lives
niche definition
role of species within its habitat/environment
what happens when two species have the exact same ecological niche within the habitat?
theres competition. (this is because they have same food source, same time of feeding, same shelter site and so on)
what is abiotic factor and example?
- non living or physical and chemical factors
- light intensity, wavelength, turbidity of water, humidity, soil/ water pH, salinity, soil composition, O2 and CO2 conc
how does light intensity affect a community
- needed by plants for photosynthesis.
- more light = increase in rate of photosynthesis and so increase in plant growth rate.
how does temperature affect a community
- affects rate of photoysnthesis
how does wind intensity and direction affect a community
- wind speed affects transpiration rate, which affects rate of photosynthesis as it ensures water and mineral ions are transported to the leaves
what is topography
- the arrangement of the physical features of a particular area or surface
- eg: altitude which affects climate, slope, which direction the land faces and drainage
what are edaphic factors
- factors connected with the soil, include soil pH and mineral ion conc
soil textures and what they could mean
- sandy soils = well drained. they dry out easily in droughts, but theyre well aerated and rarely waterlogged in wet weather
- clay gets easily waterlogged, but retains water well which is an advantage in drought
biotic factors and examples
- the living factors that influence populations within community
- eg: predation, food availability, inter and intraspecific competiton, parasitism, disease
interspecific competition
when individuals of different species compete for resources
intraspecific competition
individuals of the same species compete for resources
how availability of food affects a community
- more food means organisms have higher change of surviving and reproducing so their pop can increase
how do new predators affect a community
- in balanced ecosystem, predators catch enough prey to survive but not so many to wipe out the prey population. if new predator is introduced to ecosystem, it may become unbalanced
how new pathogens affect community
- the populations living therte will have no ummunity or resistance to it and population may decline or be wiped out.
mutualism
- relationship where both partners benefit
density dependant
- effects are related to the size of population relative to area available.
- larger population density means a greater competition for food, space and so on.
anthropogenic factors
- those arising from human activity that can be euther abiotic or biotic
abundance
the number of individuals of a particular species living in a habitat
distribution
where a species lives
why would abundance vary bc 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 ↑
- 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 ↓
why would abundance vary bc of biotic factors
- interspecific competition: the abundance increases when the resources are plentiful but
- when they become limiting, there is a population decline.
- the lower abundance = less competition which means that resources are no longer limiting, and the pop increases again.
what does dynamic ecosystem mean
- theyre constantly changing
succession meaning
- process of ecosystem change overtime
what is primary succession
- land that has been newly formed or exposed
examples of primary succession
- volcano eruption or dropped sea level
aspects of primary succession
- abiotic conditions are hostile, so no soil to retain water
- only pioneer species can grow as theyre specially adapted
- they change the abiotic conditions
- they die and decompose = dead organic material = soil
- conditions r less hostile so new organisms w diff adaptations can grow
pioneer species and example
- first organisms to colonise bare rock.
- lichens and algae
succession from bare rock
- Pioneer species colonise the rocks, E.g lichens grow on and break down rocks, releasing minerals
- Lichens die and decompose = a thin soil
- Soil thickens as more organic material forms
- Other species can grow, E.g. mosses
- Larger plants can move in b/c more water as soil deepens, E.g grass
- Shrubs, ferns and small trees can grow, outcompeting the other species becoming the dominant species = ↑ diversity
- The soil is deep and rich in nutrients = supports large trees = climax community
what is secondary succession
- same as primary but the soil layer is already present
- the pioneer species are larger plants
- each stage, diff plants and animals that r better adapted move in, outcompeting plants that are already there
- they become the dominant species in the ecosystem and it becomes more complex
final stage of succession
- it is usually stable, a climax community
- The ecosystem is supporting the largest and most complex community of plants and animals that it can
- It won’t change much more b/c it’s in a steady state
deflected succession
- community that remains stable only because human activity prevents succession from running its course.
phosphorylation
adding phosphate to molecule
photophosphorylation
adding phosphate to molecule using light
photolysis
- splitting of molecule using light
what is energy required for
- building new molecules from products of digestion during anabolic reactions
- moving substances across cell membranes in active transport or to move substances within cells
- muscle contraction
- conduction of nerve impulses
hydrolysis
splitting of molecule using water
atp full form
adenosine triphosphate
structure of atp
- a nucleic acid
- phosphorylated nucleotide
ribose grp that is connected to adenine on one side and three phosphate grps on the other side
what is the light dependent reaction of photosynthesis
- using energy from light and hydrogen from photolysis of water
- to produce reduced NADP, ATP and waste product oxygen
formation of ATP
- phosphorylation of ADP
ADP + Pi -> ATP
non cyclic photophosphorylation steps
- light energy hits photosystem 2 in thylakoid membrane
- two electrons gain energy, and are said to be excited to a higher energy level
- the excited electrons leave photosystem and pass to first protein in electron transport chain
- as excited electrons leave photosystem 2, they are replaced by electrons from photolysis of water
- electrons pass down chain of electron carriers (electron transport chain)
- energy is released as electrons pass down etc, allowing chemiosmosis to occur:
- H+ ions are actively pumped from low conc in stroma to high conc in thylakoid space, generating conc gradient accross thylakoid membrane
- H+ ions diffuse back across the thylakoid membrane into stroma via ATP synthase enzymes embedded in membrane
- the movement of H+ ions causes ATP synthase enzyme to catalyse production of ATP.
- at the end of the electron transpot chain, the electrons from photosystem 2 are passed to photosystem 1.
- light energy also hits ps1 exciting another pair of electrons which leave the photosystem and pass along the etc
- these electrons combine with hydrogen ions from photolysis of water and coenzyme NADP to form reduced NADP
- the reduced NADP and ATP then pass to light independent reactions
cyclic photophosphorylation steps
- light hits ps1
- electrons become excited to higher energy level and leave ps
- excited electrons pass along electron transport chain, releasing energy as they do so
- energy released as electrons pass down etc provides energy to drive process of chemiosmosis
- H+ ions are actively pumped from a low concentration in the stroma to a high concentration in the thylakoid space, generating a concentration gradient across the thylakoid membrane
- H+ ions diffuse back across the thylakoid membrane into the stroma via ATP synthase enzymes embedded in the membrane
- The movement of H+ ions cause the ATP synthase enzyme to catalyse the production of ATP
- At the end of the electron transport chain the electrons rejoin photosystem I in a complete cycle; hence the term cyclic photophosphorylation
- The ATP produced enters the light-independent reaction
what is the light independent reactions of photosynthesis
- calvin cycle
- its to produce complex organic molecules like starch for storage, sucrose for transport, cellulose for making cell walls
steps of light independent reaction
- Carbon dioxide is combined with ribulose bisphosphate (RuBP), a 5-carbon (5C) compound; this yields two molecules of glycerate 3-phosphate (GP), a 3-carbon (3C) compound
- GP is reduced to glyceraldehyde 3-phosphate (GALP), another 3C compound, in a reaction involving reduced NADP and ATP
- RuBP is regenerated from GALP in reactions that use ATP
carbon fixation steps
- Carbon dioxide combines with a 5C sugar known as RuBP in a reaction catalysed by the enzyme rubisco
- The resulting 6-carbon (6C) compound is unstable and splits in two
- This results in two molecules of a 3C compound known as glycerate 3-phosphate (GP)
- The carbon dioxide has been ‘fixed’, meaning that it has been removed from the external environment and become part of a molecule inside the plant cell
reduction step of light independent stage of photosynthesis
- Energy from ATP and hydrogen from reduced NADP, both produced during the light-dependent reactions, are used to reduce the two molecules of GP to two 3C molecule known as GALP
- Some of the carbons in GALP go towards the production of useful organic molecules such as glucose, while the rest remain in the Calvin cycle to allow the regeneration of RuBP
- Two molecules of GALP contain six carbon atoms, five of which are needed to regenerate RuBP; this means that for every turn through the Calvin cycle only one sixth of a molecule of glucose is produced
- Glucose is a 6-carbon molecule, so six turns of the Calvin cycle are required to produce one molecule of glucose
regeneration step of light independent stage of photosynthesis
- Five sixths of the GALP molecules are used to regenerate RuBP
- This process requires ATP
what is glycerate-3-phosphate (GP) used to produce
- Amino acids which can be used in protein synthesis for building polypeptides
- Fatty acids which form the tails of lipid molecules such as triglycerides and phospholipids
what is GALP used to produce
- Hexose sugars e.g. glucose
- Hexose sugars can be converted into other hexose sugars e.g. glucose can be converted to sucrose for transport in the phloem
- Hexose sugars can be joined to make polysaccharides such as starch and cellulose
- Glycerol can be used for building lipid molecules such as triglycerides and phospholipids
- Nucleic acids form the basis of DNA and RNA
chloroplast membrane structure
- double membrane known as chloroplast envelope
- phospholipid bilayer
what does the stroma contain
- its a cytoplasm like fluid
- contains enzymes, sugars, ribosomes and chloroplast DNA
- if it has been photosynthesising, there may be starch grains or lipid droplets
- also contains a seperate system of membranes (the fluid filled sacs known as thylakoids, each surrounded by a thylakoid membrane)
chloroplast envelope function
- double membranw that encloses chloroplast, keeping all components for photosynthesis close together
- transport proteins in inner membrane control flow of molecules between stroma and cytoplasm
stroma structure and function
- gel like fluid containing enzymes tht catalyse reactions of photosynthesis
dna in the chloroplast function
- contains genes that code for some of the proteins used in photosynthesis
ribosomes in chloroplast function
- enable translation of proteins coded by chloroplast dna
thylakoid membrane function
- the space between the two membranes of this double membrane is known as thylakoid space
- the conditions can differ from the stroma, such as establishing a proton gradient
- space has a v small volume so proton gradient can develop very quickly
grana function
- creats large surface area, maximising number of photosystems and allowing max light absorption
- grana also provides more membrane area for proteins like electron carriers and ATP synthase enzymes which enable production of ATP
photosystems function
- ps1 and ps2, both contain diff combinations of photosynthetic pigments like chlorophyll a, b and carotene
- they absorb light of diff wavelength, maximising light absorption
what are producers
- organisms that convert light energy into chemical energy stored in biological molecules by photosynthesis
what is primary productivity
- rate at which producers convert light energy into chemical energy
what is gross primary productivity (GPP)
the rate at which chemical energy is converted into carbohydrates during photosynthesis
what is net primary productivity
- GPP minus plant respiratory losses
- rate at which energy is stored in plant biomass
why is NPP important
- it represnets the energy tht is available to organisms at higher trophic levels in ecosystem such as primary consumers and decomposers
NPP equation
NPP = GPP - R
- R is respiration
how much energy is released from glucose to creat ATP for plant during respiration
90%
NPP unit using area
J m^-2 yr^-1
NPP unit using volume
J m^–3 yr^-1
biomass
mass of living material
energy efficiency equation
Energy efficiency = (net productivity divided by energy received) x 100
- as a percentage
