BSC2011L - Photosynthesis Lab Practical

Describe photosynthesis

The process in which plants convert light energy into CO2 and water into carbohydrates (glucose, etc.)

Where does photosynthesis occur in plant cells

Chloroplast

Chemical equation for photosynthesis

CO2 + H2O --> C6H12O6 + O2

Describe the two stages of photosynthesis and the products that arise from them.

Light "photo" reaction:

- solar energy to chemical energy

- chloroplasts absorbs light

- energy helps split H20, electron binds to NADP+

- products: ATP, NADPH, O2

Calvin cycle "synthesis":

- CO2 --> organic carbon

- CO2 absorbed from air

- NADPH gives up electron

- ATP provides energy

- Products: NADP+, C6H12O6, ADP+P

What properties of light (amplitude and wavelength) determine its intensity and color

Wavelength --> color

amplitude (wave height)--> intensity

What does it mean when an object absorbs light?

color is not shown

What does it mean when an object reflects light?

color is shown

What does it mean when an object transmits light?

is produces it

Which colors of light have higher rates of higher/lower rates of photosynthesis?

higher with red and blue

lower with green

Which intensities of light have higher/lower rates of photosynthesis?

low to high intensities, increased rate of photosyethesis

How does a spectrophotometer work?

This machine directs beams of light of different wavelengths through a solution of the pigment and measures the fraction of the light transmitted at each wavelength. A graph plotting a pigment's light absorption versus wavelength is called an absorption spectrum.

What was the purpose of the experimental, control and blank cuvettes?

- blank cuvette to calibrate the spectrophotometer

- control to have a baseline for comparison

- experimental is for testing the variable (intensity or color)

How does the spectrophotometer allow us to measure relative rates of photosynthesis?

measures the absorbance (amount of light absorbed) from the experimental

use slope of absorbance over time to find the rate of photosynthesis

What was the function of the DCPIP?

- is an artifical electron accetor

- helps detect the reducing agent produced by chloroplast

- blue when oxidized and colorless when reduced