energy for biological processes Flashcards
how do organisms transfer energy
they make use of energy in the bonds of organic molecules
where do these bonds come from
bonds are formed during photosynthesis
define respiration
process which organic molecules are broken down into inorganic molecules
the energy stored i hte bonds of the organic molecules are used to synthesise ATP
what reaction creates most biomass on earth
photosynthesis
how is photosynthesis and respiration related
the raw materials for respiration are produced in photosynthesis
define bond energy
the same quantity of energy is involved whether a particular bond is broken or formed
describe the energy distribution in respiration
the total energy required to break the bonds in an organic molecule is less than the total energy released; excess energy released by the formation of bonds is used to synthesis ATP
how are organic molecules more easily broken apart than inorganic molecules
contain large number of C-H
forming a non-polar molecule which is easy to break apart
how is ATP essential in both reactions
light energy is used to form chemical bonds in ATP, which break to release energy for forming organic molecules
(photosynthesis)
organic molecules break down and the energy released is used to synthesise ATP
ATP is used to supply the energy to break bonds in the metabolic reactions of the cell
(respiration)
define an electron transport chain (ETC)
made up of a series of electron carriers, each with progressively lower energy levels
where do excited electrons come from
electrons present in pigments absorb light energy (from the Sun)
high energy electrons are released when chemical bonds break in respiratory substrate molecules
how do protons move back
through hydrophilic membrane channels linked to ATP synthase
flow of protons through the channel provides the energy used to synthesis ATP (with ADP and P)
define photosynthesis
process by which light energy is used to build organic molecules
define an autotroph
organisms that use inorganic molecules to synthesis organic molecules
define a heterotroph
organisms that obtain organic molecules by eating other organisms
describe chlorophyll
pigment molecule
which absorb specific wavelengths of light and reflect others
what does chlorophyll-a reflect and absorb
absorbs red and blue light
reflects green light
what do accessory pigments form
antennae complex
absorbs light energy of different wavelengths and transfer it to the reaction centre (RC)
how is the absorption of light energy maximised?
the RC surrounded by the antennae complex
summarise the 2 stages of photosynthesis
light-dependent stage – light energy absorbed and used to form ATP. hydrogen from water is used to reduce NADP.
light-independent stage – r.NADP and CO2 is used to build organic molecules. ATP supplies the required energy.
define chemiosmosis
diffusion of protons down a concentration gradient through a p.p. membrane
movement of protons releases energy for the conversion of ADP + P to ATP
what are the carriers that make up the electron transport chain called
cytochromes
contain Fe ion
how is the proton gradient maintained when they are pumped by the energy from the ETC
the membrane is impermeable to protons
give two adaptations of chloroplasts which maximise the process of photosynthesis
network of long membranes gives high SA to maximise absorption of light energy
thylakoids stacked to form grana which are joined by lamellae
(many thylakoids)
