unit 3 AOS2 biology

What is photosynthesis

The process in plants where light energy is converted to chemical energy

What does the xylem do

Transport water around the cell. One way

What does the phloem do

Transport sugars and ions around the cell. Two way

What is a photoautoroph

An organism capable of undertaking photosynthesis

Where does the light dependant stage occur

In the grana and thylakoids of the chloroplast

What are the inputs of the light dependant stage

Light, H20, NADP+ , ADP + Pi

What are the outputs of the light dependant stage

O2 gas, NADPH, ATP

Give a summary of the light dependant stage

. Light energy enters electrons in chlorophyll within the thylakoid, causing them to move along the protein and power the pumping of H+ ions.

. Water molecules split(photolysis) to replace lost electrons. Releasing oxygen and H+ ions.

. Oxygen released as gas or used in cellular respiration.

. H+ ions help generate NADPH and ATP

. Coenzymes then move onto light independent stage.

Give a short description about the light dependant stage

The splitting of water molecules into H+ ions and oxygen gas

Give a brief description of the light independent stage

Series of biochemical reactions that occur in the stroma of the chloroplast. H+ ions combine with carbon dioxide to form glucose

What are in inputs for the light independent stage( Calvin cycle)

CO2, ATP and NADPH

What are the outputs for the light independent stage( Calvin cycle)

NADP+, ADP + Pi, glucose

Give a summary of the light independent stage

• CO2 collected from
  stomata enters cyclic reaction

• Carbon from CO2 undergoes reactions powered by ATP and NADPH to produce a series of carbon based molecules

• Specific carbon molecule reached that contributes to the formation of glucose.

Where is chlorophyll found

In the grana and thylakoids

What is the chemical equation of photosynthesis

Sunlight

12H20+6CO2———>C6H12O6+6O2+6 H2O

What is the point of photosynthesis

To create sugar

What is the Grana

A stack of thylakoids

What is a thylakoid

Flattened membrane bound sac containing chlorophyll

What is the stroma

The fluid between the grana

What is a C4 plant and where are they found

A plant that has an adaption to photosynthesis to reduce photorespiration occurring. Found tropical enviroments

What does the adaption in C4 plants do

Separate the light independant stage from the mesophyll cells by completing the light independant stage in the bundle sheath cells instead. This is called spatial seperation.

Give a summary of the process of photosynthesis in C4 plants

• CO2 binds with PEP at a PEP carboxylase enzyme to make a 4 carbon molecule called malic acid.

• Malic acid travels through plasmodesmata in bundle sheath cell

• Malic acid is broken into CO2 and pryuvate

• CO2 moves to chroloplasts and enters calvin cycle

• Pryuvate is recycled back into PEP to be joined with CO2.

What is a CAM plant and where is it found

A plant that has an adaption to prevent water loss by opening the stomata at night. Found in dry arid locations

What does the adaption in CAM plants do

By opening their stomata at night they reduce water loss, while still enabling CO2 to enter the leaf. The CO2 is stored in vacuoles to be used during the day for the light independent stage. This is called temporal seperation.

Give a summary of the process of photosynthesis in CAM plants

• Plants opens stomata at night to take in CO2

• CO2 is combined with PEP by PEP carboxylase to make malic acid and is stored in the large vacuole.

• Malic acid is broken down to provide the calvin cycle with CO2

What is RuBisCO

A critical enzyme used in the light independent stage of photosynthesis. It facilitates carbon fixation by converting CO2 into organic molecules(glucose)

What happens when RuBisCO heats up

• Its shape changes making oxygen fit better into the active site allowing photorespiration to occur.

• This does not make sugar so the plant has less energy for growth.