Chemiosmotic Hypothesis

Question 1

The chemiosmotic hypothesis has been put forward to explain
the mechanism. Like in respiration, …

Answer 1

Also in photosynthesis, ATP synthesis is
linked to development of a proton gradient across a membrane.

Question 2

This time
these are the membranes of…

Answer 2

thylakoid.

Question 3

There is one difference though, in photosynthesis the proton accumulation is the inside of …. In respiration, protons accumulate in the …. when electrons move through the ETS

Answer 3

the membrane, i.e., in the lumen
intermembrane space of
the mitochondria

Question 4

We need to consider processes that take place during the … to determine the steps that cause a proton gradient to develop .
Step 1:-
(a) Since splitting of the water molecule takes place on the … the protons or hydrogen ions that are produced by
the splitting of water accumulate within the …

Answer 4

activation of electrons and their transport
inner side of the membrane,
lumen of the thylakoids.

Question 5

As electrons move through the photosystems, protons are transported
…This happens because the ..

Answer 5

across the membrane.
primary accepter of
electron which is located towards the outer side of the membrane
transfers its electron not to an electron carrier but to an H carrier.
Hence, this molecule removes a proton from the stroma while
transporting an electron. When this molecule passes on its electron
to the electron carrier on the inner side of the membrane, the proton
is released into the inner side or the lumen side of the membrane.

Question 6

The NADP reductase enzyme is located on the … Along with electrons that come from the acceptor of electrons of …, protons are necessary for the reduction of …
. These protons are also removed from the …

Answer 6

stroma side of the membrane.
PS I.
NADP+
to
NADPH+ H+.
stroma.

Question 7

Hence, within the chloroplast, protons… while in the lumen there is ….

Answer 7

in the stroma decrease in
number.
accumulation of protons.

Question 8

This creates a proton gradient across the … as well as a measurable
… in the lumen.

Answer 8

thylakoid membrane.
decrease in pH.

Question 9

This gradient is important because it is …

Answer 9

the breakdown of this gradient that leads to the
synthesis of ATP

Question 10

The gradient is broken down due to the movement of
protons across the membrane to the stroma through the transmembrane
channel of the …

Answer 10

CF0 of the ATP synthase.

Question 11

The ATP synthase enzyme consists of two parts: one called the .. is embedded in the …
and forms a transmembrane channel that carries out
…
of … across the membrane. The other portion is called …
and
protrudes on the … membrane on the side that faces the …. The break down of the gradient provides enough energy to cause a conformational change in the ..
particle of the ATP
synthase, which makes the …

Answer 11

CF0.
thylakoid membrane.
facilitated diffusion.
protons.
CF1.
outer surface of the thylakoid.
stroma.
CF1.
enzyme synthesise several molecules of energypacked
ATP.

Question 12

Chemiosmosis requires a .1.2.3.4.

Answer 12

1.membrane
2.a proton pump
3.a proton gradient
4.ATP synthase.

Question 13

… is used to pump protons across a membrane, to create a …

Answer 13

Energy.
gradient or a high concentration of protons within the thylakoid lumen.

Question 14

ATP synthase has a channel that allows diffusion of
… this releases enough energy to activate
…. that … the formation of ATP.

Answer 14

protons back across the membrane.
ATP synthase enzyme.
catalyses.

Question 15

Along with the NADPH produced by the movement of electrons, the ATP will be used immediately in the … taking place in the stroma, responsible for …

Answer 15

biosynthetic reaction.
fixing CO2 and synthesis of sugars.