9. Photosynthesis

Question 1

Def. of photosynthesis

Answer 1

The way in which plants make their food using light energy

Question 2

Photosynthesis equation

Answer 2

6CO2 + 6H2O —–Light+Chlorophyl—> C6H12O6 +6O2

Question 3

Role of photosynthesis

Answer 3

Source of O2 for living things
Makes food for plants
Makes food for animals

Question 4

Where photosynthesis takes place

Answer 4

Chloroplast

Question 5

Name stage 1

Answer 5

Light dependent stage

Question 6

Where does stage 1 happen

Answer 6

Granium of the chloroplast

Question 7

Products of stage 1

Answer 7

ATP, NADPH, O2

Question 8

Fate of products from stage 1

Answer 8

ATP- used in dark stage to provide energy to reduce H+, e- and CO2 to form glucose

NADPH- Provides H+ and e- to reduce CO2

O2- released as gas (wasted) or used in respiration

Question 9

Photolysis

• means
• what
• where
• how

Answer 9

• means: photo=light, lysis= burst
• what: water splitting in light dependent stage
• where: In the chloroplast of the leaf
• how: energy from the sun

Question 10

What is the reaction centre chlorophyll

Answer 10

Is the molecule that specifically absorbs the light energy

Question 11

Sources of things needed for photosynthesis

CO2, H2O, Light

Answer 11

CO2- air, respiration, burning fossil fuels
H2O- absorbed through roots from soil
Light- Sunshine

Question 12

What is chlorophyll

Answer 12

Green pigment in leaf used to absorb light energy

Question 13

Name stage 2

Answer 13

Light independent stage / dark stage/ Calvin cycle

Question 14

Where does stage 2 happen

Answer 14

Stroma of chloroplast

Question 15

Products of second stage

Answer 15

Glucose (C6 H12 O6)
ADP
NADP

Question 16

Fate of products from stage 2

Answer 16

Glucose (C6 H12 O6)- glucose used as food/ used in respiration/ stored as starch
ADP- will go back to stage 1 to be phosphorylated
NADP- will go back to stage 1 to gain H+ and e-

Question 17

Describe process in stage 1

Start

Answer 17

Light energy absorbed by chlorophyll in chloroplast.
Electrons become energised and leave chlorophyll in pairs.
Picked up by 2 pathways.
Pathway 1
Pathway 2

Question 18

Describe Pathway 1 in stage 1

Name and what happens

Answer 18

Pathway 1: Cyclic photo phosphorylation
Electrons picked up by electron acceptor which passes them into a carrier system, C1-C2-C3, releases energy at each stage which is used to make ATP

Question 19

Describe pathway 2 (stage 1)

Name and what happens

Answer 19

Pathway 2: Non cyclic photo phosphorylation
The 2 electrons join with the NADP+ to make NADP-
A water molecule splits to make H+, e-, O2
The H+ joins with the NADP- to form NADPH
The electron passes into a carrier system releasing energy to form ATP and returns to the chlorophyll (reaction centre)

Question 20

Describe Stage 2

Answer 20

NADPH releases electron(e-) and hydrogen molecule (H+)
An ATP from stage 1 is carried over and loses a phosphate and releases energy (ATP=ADP+ P)
The e- and H+ reduces the CO2 with energy from the ATP and forms glucose