U3A2: 5A photosynthesis and chloroplasts

Question 1

photosynthesis

Answer 1

biological process where photoautotrophs capture light energy from the sun and convert it into chemical energy.

Question 2

photosynthesis word equation

Answer 2

carbon dioxide + water —> glucose + oxygen + water

Question 3

photosynthesis chemical equation

Answer 3

6CO₂ + 12H₂O —> C₆H₁₂O₆ + 6O₂ + 6H₂O

Question 4

mesophyll cells

Answer 4

the main photosynthesising cells in leaves

Question 5

chloroplasts

Answer 5

inside mesophyll cells. organelle at the site of both stages of photosynthesis.

Question 6

chlorophyll

Answer 6

pigment responsible for initiating photosynthesis by capturing and being energised by light energy.

Question 7

stomata

Answer 7

tiny pores on the surface of leaves which open to allow carbon dioxide in the atmosphere to diffuse into the leaf, or close to prevent water loss in dry conditions.

Question 8

location of the light-dependant stage

Answer 8

on thylakoid membranes

Question 9

inputs of the light-dependant stage

Answer 9

12 water, 12 NADP, 18 ADP+Pi

Question 10

outputs of the light-independant stage

Answer 10

6 oxygen, 12 NADPH, 18 ATP

Question 11

process of the light-dependant stage

Answer 11

• light energy excites elections in thylakoid chlorophyll. elections move along membrane proteins, powering the pumping of H into the thylakoid lumen.
• water donates electrons to replace electrons that leave, causing photolysis of water.
• oxygen is released from chloroplast out of stomata.
• H ions from water are used to generate coenzyme NADPH
• movement of H down its concentration gradient generates coenzyme ATP

Question 12

location of the light-independant stage

Answer 12

stroma of chloroplasts

Question 13

inputs of the light-independant stage

Answer 13

6 carbon dioxide, 12 NADPH, 18 ATP

Question 14

outputs of the light-independant stage

Answer 14

glucose, 6 water, 12 NADP, 18 ADP+Pi

Question 15

process of the light-independant stage

Answer 15

• carbon dioxide molecules combine with a 5-carbon molecule, then splitting into two 3-carbon molecules.
• NADPH donates its hydrogen ions and electrons. ATP molecules break into ADP+Pi to release energy and facilitate further change to carbon molecules.
• specific 3-carbon molecule is made and leaves the cycle, contributing to formation of glucose. overall 6 carbon dioxide molecules must enter the cycle to produce glucose.
• some oxygen molecules leftover from the initial breaking of carbon dioxide with hydrogen ions from NADPH to create water.

Question 16

summarise light-dependant and light-independant stages

Answer 16

dependant: light energy splits water molecules to produce ATP, NADPH and oxygen

independant: carbon dioxide is converted into organic molecules using ATP and NADPH, and more water is produced.