energy for biological processes

Question 1

how do organisms transfer energy

Answer 1

they make use of energy in the bonds of organic molecules

Question 2

where do these bonds come from

Answer 2

bonds are formed during photosynthesis

Question 3

define respiration

Answer 3

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

Question 4

what reaction creates most biomass on earth

Answer 4

photosynthesis

Question 5

how is photosynthesis and respiration related

Answer 5

the raw materials for respiration are produced in photosynthesis

Question 6

define bond energy

Answer 6

the same quantity of energy is involved whether a particular bond is broken or formed

Question 7

describe the energy distribution in respiration

Answer 7

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

Question 8

how are organic molecules more easily broken apart than inorganic molecules

Answer 8

contain large number of C-H

forming a non-polar molecule which is easy to break apart

Question 9

how is ATP essential in both reactions

Answer 9

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)

Question 10

define an electron transport chain (ETC)

Answer 10

made up of a series of electron carriers, each with progressively lower energy levels

Question 11

where do excited electrons come from

Answer 11

electrons present in pigments absorb light energy (from the Sun)

high energy electrons are released when chemical bonds break in respiratory substrate molecules

Question 12

how do protons move back

Answer 12

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)

Question 13

define photosynthesis

Answer 13

process by which light energy is used to build organic molecules

Question 14

define an autotroph

Answer 14

organisms that use inorganic molecules to synthesis organic molecules

Question 15

define a heterotroph

Answer 15

organisms that obtain organic molecules by eating other organisms

Question 16

describe chlorophyll

Answer 16

pigment molecule
which absorb specific wavelengths of light and reflect others

Question 17

what does chlorophyll-a reflect and absorb

Answer 17

absorbs red and blue light
reflects green light

Question 18

what do accessory pigments form

Answer 18

antennae complex

absorbs light energy of different wavelengths and transfer it to the reaction centre (RC)

Question 19

how is the absorption of light energy maximised?

Answer 19

the RC surrounded by the antennae complex

Question 20

summarise the 2 stages of photosynthesis

Answer 20

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.

Question 21

define chemiosmosis

Answer 21

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

Question 22

what are the carriers that make up the electron transport chain called

Answer 22

cytochromes

contain Fe ion

Question 23

how is the proton gradient maintained when they are pumped by the energy from the ETC

Answer 23

the membrane is impermeable to protons

Question 24

give two adaptations of chloroplasts which maximise the process of photosynthesis

Answer 24

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)