Chapter 8

Question 1

Photosynthesis

Answer 1

The conversion of light energy to chemical energy that is stores in sugars or other organic compounds.

Question 2

Two stages of photosynthesis

Answer 2

1. Light reactions in thylakoids: convert solar energy to chemical energy of ATP and NADPH, releases O2.
2. Calvin cycle in stroma: fixation of CO2 and reduction of the fixed carbon into carbohydrate.

Question 3

Photo phosphorylation

Answer 3

The process of generating ATP from ADP and phosphate by means of chemiosmosis using a proton motive force generated across the thylakoid membrane during light reactions.

Question 4

Light energy is originally converted to what

Answer 4

NADPH and ATP

Question 5

Carbon fixation

Answer 5

The initial incorporation of carbon from CO2 into an organic compound by an autotrophic organism.

Question 6

Photons

Answer 6

Discreet particles of light

Question 7

Substances that absorb visible light

Answer 7

Pigments

Question 8

Chlorophyll absorbs what

Answer 8

All by green light

Question 9

3 kinda of pigments in chlorophyll

Answer 9

1. Chlorophyll a- key light capturing pigment (blue green)
2. Chlorophyll b- this and accessory pigments called carotenoids (broaden spectrum of colour that can be used for photosynthesis)(orange yellow)

Question 10

Structure of chlorophyll

Answer 10

Phophyrin ring: light absorbing lead with magnesium in Center

CH3 in chlorophyll a, CHO in b

Hydrocarbon tail: interacts with hydrophobic region so fproteins inside thylakoids membranes.

Question 11

Photo system

Answer 11

A light capturing unit located in the thylakoid membrane of the chloroplast or in the membrane of some prokaryotes consisting of a reaction Center complex surrounded by numerous light harvesting complexes. Two types of photosystems (1 and 2.)

Question 12

Reaction Center complex

Answer 12

A complex of proteins associated with a special pair of chlorophyll a molecules and primary e-acceptor. This complex trigger the light reactions of photosynthesis. Excited by light energy the park of chlorophyll donates an electron to the primary electron acceptor which passes to an electron in an ETC.

Question 13

Light harvesting complex

Answer 13

A complex of proteins and pigment molecules (a,b, carotenoids) that Capture light energy and transfer it to the reaction Center pigments in a photosystem.

Question 14

As soon as the chlorophyll electron is excited to higher state the….

Answer 14

Primary e- acceptor captures it; redox reaction.

Question 15

PS2

Answer 15

Light capturing unit in thylakoid membrane (membrane of pro.). Acts first!!

Absorbs red part of spectrum

Question 16

Linear electron flow

Answer 16

A route of electron flow during light reactions that involve both photosymstwms and produces ATP, NADPH and O2.

Question 17

Thylakoid membrane pumps protons from — to —

Answer 17

Stroma then into thylakoid

Question 18

APT is synthesized as hydrogen ions diffuse from

Answer 18

The thylakoid space back to the stroma through ATP synthase

Question 19

Carbs produced by Calvin cycle are

Answer 19

Not glucose but G3P.

Question 20

For net synthesis of one molecule of G3P Calvin cycle must take place how many time?

Answer 20

3 times, fixing 3 molecules of CO2.

Question 21

Phase 1 of Calvin cycle

Answer 21

Carbon fixation- incorporates each CO2, one at a time, by attaching it to a 5- carbon sugar (RUBP). The enzyme used to catalyze this is rubisco. Creates two molecules of 3-Phophoglycerbte from each CO2 fixed.

Question 22

Phase 2 of Calvin cycle

Answer 22

Reduction- each molecule of 3- phophoglycerbte receives an additional phosphate from ATP, becoming 1,3 Biphosphoglycerate. A par of e- donated from NADPH reduces 1,3 bi… which also loses a phosphate group becoming G3P. G3P is a sugar (same as formed in glycolysis)

Question 23

Phase 3 of Calvin cycle

Answer 23

Regeneration of the CO2 acceptor (RUBP)-carbon skeletons of 5 G3P are rearranged into 3 molecules of RUBP. Uses 3 ATP to do so. RUBP is now ready to receive CO2 again.

Question 24

Net synthesis of 1 G3P molecule

Answer 24

9 ATP used

6 molecules of NADPH used

Question 25

C 3 plants

Answer 25

A plant that uses the Calvin cycle for the initial steps that incorporates CO2 into organic material, for,in a three-carbon compound as the first stable intermediate. (Produce less sugar)

Close stomata on hot days
Rice

Question 26

Photorespiration

Answer 26

A metabolic pathway that consumes O2 and ATP, releases CO2 and decreases photosynthetic output. Occurs on hot days

Question 27

C4 plants

Answer 27

Calvin cycle is proceeded by light reactions that incorporate a 4- carbon compound. The end product supplies CO2 for the Calvin cycle.
Partially close stomata on hot days
Sugarcane

Question 28

CAM plants

Answer 28

A plant that uses crassulacean acid metabolism. Carbon dioxide enters the stomata during the night is converted to organic acids, which release CO2 for the Calvin cycle during the day.

Cactus