Chapter 7

Question 1

What is Photosynthesis?

Answer 1

The conversion of light energy to chemical energy in the form of sugar and other organic molecules, a reduction of CO2 and a oxidation of H2O. Opposite of cellular respiration.

Question 2

What two parts does photosynthesis have?

Answer 2

The light reactions (collect light energy, oxidize H20, store energy as ATP and NADPH) and the Carbon Fixation/Calvin Cycle (uses ATP and NADPH to reduce CO2)

Question 3

Where do the light reactions happen?

Answer 3

In the thylakoid lumen membrane

Question 4

What is Chlorophyll?

Answer 4

It’s always bound to proteins and only present in the Thylakoid membrane, it has a hydrophobic tail. It is what captures the light/has pigments.

Question 5

What is the function of Chlorophyll?

Answer 5

The photon excites the electron and that is what makes photosynthesis happen.

Question 6

What happens in the Light Reactions?

Answer 6

Electrons are taken away from water to produce oxygen, electrons are excited using light and then they go through a series of reactions to create NADPH

Question 7

What happens in the Photosystems?

Answer 7

The energy of light is captured by protein complexes called reaction centres, they absorb light and use the energy to excite chlorophyll electrons. The excited electrons are then passed to other carriers.

Question 8

What does Photosystem 2 do?

Answer 8

Starts things off by oxidizing H2O and taking its electrons, producing O2 and 2H+; supplies 4 electrons to the ETC

Question 9

What does the Light Harvesting System do?

Answer 9

The light harvesting system helps the reaction centre by absorbing lots and lots of energy.

Question 10

What does Photosystem 1 do?

Answer 10

Re-excites the electron and then it is used to make NADPH which can be used to convert CO2 into carbohydrates.

Question 11

What is Photophosphorylation?

Answer 11

Chemiosmosis in the thylakoid lumen.

Question 12

What is the initial electron donor and final electron acceptor in the light reactions?

Answer 12

Water and NADP+

Question 13

Where do the “Dark” reactions occur?

Answer 13

In the stoma of the chloroplast

Question 14

What are the input for the Dark reactions?

Answer 14

The ATP and NADPH produced by the light reactions.

Question 15

Where does gas exchange occur?

Answer 15

Between the atmosphere and inside the leaf.

Question 16

What happens during the Carbon Fixation Reactions?

Answer 16

CO2 from the atmosphere is reduced and energized using NADPH and ATP to give simple carbohydrates. Input of CO2, ATP, NADPH and an output of Triose Phosphate.

Question 17

What is Rubisco?

Answer 17

The most abundant enzyme on earth; accounts for about 40% of leaf soluble protein; fixes CO2 by lining it with the organic products to make sugars.

Question 18

How many Trios Phosphate make a glucose?

Answer 18

2 G3Ps can synthesize glucose.

Question 19

What are the three major steps in the Calvin Cycle?

Answer 19

Carboxylation (CO2 taken in), Reduction (putting energy in the first organic product), Regeneration (regenerate the initial starting product)

Question 20

What are Autotrophs?

Answer 20

Photosynthetic organisms.

Question 21

What are Photoautotrophs?

Answer 21

Photosynthetic organisms that use light as their energy source and CO2 as their carbon source. Known as Earth’s primary producers and source of organic molecules for heterotrophs.

Question 22

What is Phototrophy?

Answer 22

Organism that obtains energy from light.

Question 23

True or False: Photons contain a fixed amount of energy.

Answer 23

True, they must be absorbed for this energy to be used. A photon can only excite an electron when the energy of the photon matches the amount of energy required to raise the electron from the ground state to an excited state.

Question 24

What are the three possibilities after absorbing a photon?

Answer 24

1. The excited electron from the pigment molecule returns to its ground state, releasing the energy through fluoresence
2. The energy of the excited electron (but not the electron) is transferred to a neighbouring pigment molecule through inductive resonance
3. Excited electron is transferred from the pigment molecule to a nearby electron-accepting molecule called a primary acceptor

Question 25

What does photosynthesis depend on?

Answer 25

The absorption of light by chloroplylls and carotenoids.

Question 26

What is the Antenna Complex?

Answer 26

A large collection of pigment-proteins that surround a central reaction centre.

Question 27

What is the Cyclic Electron Transport?

Answer 27

An electron transport pathway associated with photosynthesis 1 that produced ATP without the synthesis of NADPH.