Chapter 11: Photosynthesis

Question 1

What is the main photosynthetic structure in eukaryotic plants?

Answer 1

Leaf

Question 2

Where does photosynthesis take place?

Answer 2

Chloroplasts

Question 3

What are some adaptations of the leaf?

Answer 3

• large SA to absorb as much sunlight as possible
• arrangement of leaves to minimise overlapping and shadowing
• thin so short diffusion distance
• transparent cuticle and epidermis to let light through to mesophyll cells beneath
• long, narrow mesophyll cells packed with chloroplasts that collect sunlight
• numerous stomata for gas exchange
• stomata open and close in response to changes in light intensity
• many air spaces in lower mesophyll layer allow rapid diffusion in gas phase of CO2 and O2
• network of xylem (brings water to leaf cells) and phloem (carries away sugars produced during photosynthesis)

Question 4

List two molecules that are the raw materials of photosynthesis

Answer 4

Carbon dioxide and water

Question 5

List two molecules that are the products of photosynthesis

Answer 5

Oxygen and glucose

Question 6

Main stages of photosynthesis

Answer 6

1: capturing of light energy by chlorophyll
2: light-dependent reaction
3: light-independent reaction

Question 7

Light-dependent reaction

Answer 7

Some light energy absorbed is conserved in chemical bonds. Water splits (photolysis) into protons, electrons and oxygen due to the creation of an electron flow by the effect of light on chlorophyll. The products are reduced to NADP, ATP and oxygen.

Question 8

Light-independent reaction

Answer 8

Protons are used to produce sugars and other organic molecules.

Question 9

Features of chloroplasts

Answer 9

• surrounded by a double membrane
• grana are stacks of thylakoids where the light-dependent stage of photosynthesis takes place.
• thylakoids contain chlorophyll (site of photosynthesis)
• some thylakoids have tubular extensions that join up with thylakoids in adjacent grana= intergranal lamellae
• stroma: fluid-filled matrix where light-independent stage of photosynthesis takes place. Contains structures like starch grains.

Question 10

Where does the light-dependent reaction take place?

Answer 10

Grana

Question 11

Where does the light-independent reaction take place?

Answer 11

Stroma

Question 12

What are the products of the light-dependent reaction?

Answer 12

Protons, electrons and oxygen which are then reduced to NADP, ATP and oxygen

Question 13

What are the products of the light-independent reaction?

Answer 13

Sugars and other organic molecules