Chapter 7: Photosynthesis

Question 1

Chlorophyll

Answer 1

A green pigment which absorbs red and blue light in order or photosynthesis to take place.

Question 2

Mesophyll

Answer 2

The inner tissue of the leaf which contains chloroplasts.

Question 3

Stomata

Answer 3

Any of the minute pores in the epidermis of the leaf or stem of a plant, forming a slit of variable width that allows movement of gases in and out of the intercellular spaces.

Question 4

Primary acceptor

Answer 4

The molecule to which a high-energy electron from an excited pigment molecule is transferred.
In the thylakoid membrane of a chloroplast or in the membrane of some prokaryotes, a specialized molecule that shares the reaction-center complex with a pair of chlorophyll a molecule and that accepts an electron from them.

Question 5

Accessory pigments

Answer 5

Blue and Red pigments drive photosynthesis.

Question 6

Absorption spectrum

Answer 6

Measures what pigments are most highly absorbed from leaves.

Question 7

Action Spectrum

Answer 7

Measures what pigments drive photosynthesis (very similar to absorption spectrum).

Question 8

Photosystem 1 (PS1)

Answer 8

Re-excites electrons giving them enough energy to reduce NADP+ into NADPH.

Question 9

Photosystem 2 (PS2)

Answer 9

Oxidizes H2O and takes its electrons. This produces O2 and 4H+ ions and supplies 4 electrons to the ETC.

Question 10

Antenna Complex

Answer 10

Light Harvesting Systems: protein-pigment complexes in or on photosynthetic membranes. They receive radiant energy and transfer it to the exaction centres; an array of LHS is referred to as an ‘antenna’.

Question 11

Reaction Centre

Answer 11

Captures the energy of light, They absorb light and use the energy to excite chlorophyll electrons.

Question 12

RUBISCO (Ribulose-1,5-bisphosphate carboxylase oxygenase)

Answer 12

The most abundant enzyme on earth which fixes CO2.

Question 13

What happens in the Thylakoids? (3)

Answer 13

1. Light absorption by chlorophylls and carotenoids
2. Electron Transport
3. ATP synthesis by ATP synthase

Question 14

What happens in the Stroma (space around the thylakoids)? (1)

Answer 14

The Calvin Cycle takes place here.

Question 15

What is exchanged through the Stomata? (2)

Answer 15

Oxygen and Carbon dioxide

Question 16

What are Carotenoids?

Answer 16

Usually red, orange, or yellow pigments, and include the familiar compound carotene, which gives carrots their colour. Carotenoids cannot transfer sunlight energy directly to the photosynthetic pathway, but must pass their absorbed energy to chlorophyll. For this reason, they are called accessory pigments.

Question 17

How are the Action and Absorption Spectrum related?

Answer 17

The pigments which are most highly absorbed are the same as the pigments which drive photosynthesis.

Question 18

Phosphorylation: How ATP is produced in light-dependant reactions

Answer 18

The build up of H+ ions in the thylakoid lumen
is used by an ATP synthase
to convert ADP to ATP

Question 19

What is the basic function of the ETC?

Answer 19

It moves electrons, losing energy, while pumping H+ ions into the thylakoid lumen (generating a pmf).

Question 20

What is the importance of RUBISCO to life on Earth?

Answer 20

The most abundant enzyme on earth and it accounts for about 40% of leaf soluble protein.