Respiration and Photosynthesis long anwers

Question 1

Describe pathway 1 photosynthesis

Answer 1

Light is absorbed in the chlorophyll.
Light energy is transferes to electron
Electrons pass through the chlorophyll where they become energised.
These high energy electron pass from the electron acceptor to a series of electron acceptors releasing energy.
The energy released by the electrons are used to form ADP and a phosphate to form ATP.
The electrons return back to the orginal chlorophyll molecule.

Question 2

Describe pathway 2

Answer 2

Light is absorbed by chlorophyll.
Light energy is transfered to electron.
Water is split by light (photolysis) into protons, electron and oxygen.
The electrons pass through the chlorophyll to a sceries of electron acceptors where energy is released. To use ADP and phosphate to make ATP.
These high energy electrons do not return to the chlorophyll.
2 electrons then combine with NADP+ to form NADP-. This then combines with protons to form NADPH.

Question 3

describe the dark stage of photosynthesis and what they are used for

Answer 3

ATP - supplies energy for the dark stage reactions to form glucose.
NADPH - transfers protons and electrons to dark stage to help for glucose
Oxygen- can be used for internal respiration and atomsphere

Question 4

Describe the dark stage reactions

Answer 4

Reactions are controlled by enzymes. Takes place in stroma.
CO2 enters the chloroplast.
NADPH transfers protons and energised electrons for dark stage reactions.
Protons and electrons convert CO2 to glucose.
ATP supplies the energy for glucose.

Question 5

Describe stage 1 Gycolysis

Answer 5

Gycolysis occours in the cytosol
Anaerobic process
Splitting of glucose itno two cabon 3 molecules called pyruvaic acid/pyruvate
Only a small amount of energy is relased here. Electrons and protons are released to turn NAD+ into NADH

Question 6

Describe stage 2 of respirtion

Answer 6

Kerbs cycle occours in the mitochondria
Pyruvic acid is completely broken down to form Acetyl co enzyme A which is a two carbon molecule. Oxygen enters, bonds with a carbon and leaves as CO2
High energy electrons and protons are released . Energy is relesed to turn ADP and Phosphate into ATP

Question 7

Describe the electron transport chain

Answer 7

NADH released high enegy electrons and protons and become NAD- and return to stage 1 to be resused. The protons go towards the proton pool and the high energy electrons go through a series of reactions, releasing a large amount of energy. The low energy electrons then combine with oxygen, which is the final electron acceptor , and bond with protons to form Water. Water is a waste product

Question 8

Explain the transpiration stream

Answer 8

• The water molecules evaporate from the xylem out through the stomata into the air
• water molecules stick together due to the hydrogen bonds, forming a continous coloum. Cohesion is the stong attraction of the water molecules with eachother due to hydrogen bonding. Adhesion is the atraction of the water molecules with the walls of the xylem.
  Due to the cohesion, the next water molecule is pulled upwars along by the one in front of it in the xylem tissue.
  When the water column in the xylem is streched it is said to be under tension.