Photosynthesis- Light reactions

Question 1

Biochemical energy in animals comes from the ??? (in mitochondria) of organic fuel from food

Answer 1

oxidation

Question 2

Photosynthesis provides carbohydrate building blocks in the form of:
* ???
* coal deposits
* crude oil
* gas deposits

Answer 2

biomass

Question 3

Photosynthesis liberates ??? and produces carbohydrates which are used by animals in the oxidative processes of respiration

Answer 3

oxygen

Question 4

TRUE or FALSE: Almost all energy flow and all fixed carbon in the biosphere, originated from photosynthesis. Almost all oxygen in the atmosphere is generated by photosynthesis

Answer 4

TRUE

Question 5

2H2O + hu + CO2 → (CH2O)n + O2 is the basic equation for ???

Answer 5

photosynthesis

Question 6

Use of the stable isotope ??? proved that the oxygen involved in
photosynthesis is derived from water

Answer 6

18O

Question 7

Photosynthetic bacteria eg. purple sulphur bacteria can use alternative electron donors such as ???

Answer 7

H2S

Question 8

Pigments absorb light energy and convert it to ???, ATP and O2

Answer 8

NADPH

Question 9

??? and ATP from photosynthesis are used to reduce CO2 to form (CH2O)n

Answer 9

NADPH

Question 10

in a leaf cell, photosynthesis occurs in the ???. More specifically, the thylakoids found in this structure

Answer 10

chloroplast

Question 11

“Light reactions” = electron transport/proton gradient which takes place in the ??? membranes. The pigments absorb light and solar energy is converted to ATP and NADPH

Answer 11

thylakoid

Question 12

Photosynthesis Step 1: light converts H2O to a good electron DONOR or ACCEPTOR?

Answer 12

DONOR

Question 13

Photosynthesis Step 2: electrons run through the transport chain on thylakoid membrane and the electron carriers pump H+ into thylakoid lumen as electrons flow to ??? which is an e- acceptor in the stroma

Answer 13

NADP+

Question 14

Photosynthesis step 3: energy from flow of electrons is stored as ???

Answer 14

electrochemical potential

Question 15

Photosynthesis Step 4: ATP synthase uses ??? to synthesise ATP

Answer 15

electrochemical gradient

Question 16

What is the main photoreceptor in chloroplasts?

Answer 16

Chlorophyll is the main photoreceptor in chloroplasts

Question 17

Chlorophyll have delocalised electrons that are easily excited by photons of VISIBLE or NONVISIBLE light.

Answer 17

VISIBLE

Question 18

Chlorophyll absorbs light in the
blue, green or red regions of visible light?

Answer 18

Blue and Red

Question 19

Secondary light absorbing pigments are called ???

Answer 19

carotenoids

Question 20

The two most important carotenoids are:
* β-Carotene (red-orange)
* ??? (yellow)

Answer 20

Lutein

Question 21

The carotenoid pigments, β-Carotene and Lutein, absorb light at wavelengths not absorbed by ???, thus serve as supplementary light receptors to expand the range of wavelengths absorbed

Answer 21

chlorophyll

Question 22

TRUE or FALSE: Carotenoids also function as anti-oxidants

Answer 22

TRUE

Question 23

light-absorbing pigments are
arranged in arrays called
photosystems embedded in the
thylakoid ???

Answer 23

thylakoid membrane

Question 24

Absorption of light (photon) by
antenna chlorophyll leads to excitation of the ???

Answer 24

reaction centre

Question 25

Specialized chlorophyll molecules associated with the photochemical reaction centre can transduce light into ???

Answer 25

chemical energy

Question 26

Excitation and Electron Transfer Step 1: light excites an ??? molecule (chlorophyll or accessory pigment), raising an electron to a higher energy level

Answer 26

antenna molecule

Question 27

Excitation and Electron Transfer Step 2: excited antenna molecule passes energy to a neighbouring chlorophyll molecule, exciting it. this is called ???

Answer 27

excitation transfer

Question 27

Excitation and Electron Transfer Step 3: excitation transfer energy is transferred to a chlorophyll of the ??? special pair, exciting it

Answer 27

reaction centre

Question 28

Excitation and Electron Transfer Step 4: the excited reaction centre chlorophyll passes an electron to an electron ACCEPTOR or DONOR?

Answer 28

ACCEPTOR

Question 29

Excitation and Electron Transfer Step 5: the electron hole in the reaction centre is filled with an electron from an electron ACCEPTOR or DONOR?

Answer 29

DONOR

Question 30

TRUE or FALSE: Excitation and Electron Transfer = the absorption of a photon causes the separation of charge in the reaction centre

Answer 30

TRUE

Question 31

Photosystem I and II have multiple antenna pigment molecules and a pair of reaction centre ??? + contain a series of electron transfer molecules

Answer 31

chlorophylls

Question 32

TRUE or FALSE: PSII and PSI are linked by the cytochrome b6f complex

Answer 32

TRUE

Question 33

Cytochrome b6f Complex: e- transfer from PSII through plastoquinone (PQ) to Cyt b6f and then to ???

Answer 33

PSI

Question 34

how many protons (H+) are released by cyt b6f into lumen to contribute to proton gradient (to drive ATP synthase to generate ATP)

Answer 34

4 H+

Question 35

P680/P700 are the ??? PS which receives light energy

Answer 35

reaction centre

Question 36

Cooperation between PSII and PSI creates an e- flow from ??? to NADP+ in a Z-like scheme between the two PS

Answer 36

water

Question 37

ferredoxin drives a cyclic transfer of electrons by controlling whether NADP+ is reduced to ???. ferredoxin takes the electrons, when limited state of ATP, cycles electrons back through to start of cycle at Cyt b6f

Answer 37

NADPH

Question 38

Plastocyanin: mobile electron carrier that shuttles electrons from ??? to PSI

Answer 38

cytochrome b6f