Light and Photosynthesis Flashcards
What is photosynthesis?
The process used by plants to produce all their own organic substances using only light energy and simple inorganic substances.
What does photosynthesis involve?
The conversion of light energy into chemical energy.
Where does photosynthesis occur?
In the plant’s chloroplasts.
What does photosynthesis consist of?
Light-dependent and light-independent reactions.
What organic compounds are produced in the light independent reactions?
Glucose and amino acids (and some others)
What organic compounds are produced from light-dependent reactions?
“Intermediate compounds” that are used in light-dependent reactions
When are intermediate compounds used up?
In the dark.
What is a spectrum?
A range of wavelengths of electromagnetic radiation.
What is the spectrum of light?
The range of wavelengths from 400nm-700nm.
Which wavelength has the lowest energy?
Red, at 700-750nm.
Which wavelength has the highest energy?
Purple, at 350-400nm.
In photosynthesis, what is efficiency?
The percentage of light of a wavelength that is used in photosynthesis.
What is the action spectrum?
A graph that profiles the relative effectiveness of different wavelengths of radiation in driving a particular process.
According to the action spectrum graph, what colors of light are used the most efficiently?
Violet and blue (400-425)
According to the action spectrum graph, what color of light is used least efficiently?
Green and yellow (525-625)
What colors of light are mediocre at efficiency in photosynthesis?
Orange and red (625-700).
What is the main photosynthetic pigment?
Chlorophyll
What kinds of light are reflected rather than absorbed?
Green and yellow
What are pigments?
Substances that absorb light of different wavelengths such as chlorophyll a and b.
What does chlorophyll a do in light reactions?
Directly participates and absorbs violet-blue light and red light.
What do accessory pigments chlorophyll b, carotene, and xanthophylls do?
They broaden the amount of good light colors that can be absorbed and use for photosynthesis.
What is the main difference between the graphs of absorption and action?
Absorption shows little green-yellow light absorbed by chloroplasts.
Action shows some green-yellow light absorbed BECAUSE of carotene and xanthophylls.
Where are pigments found?
In photosystems two and one, within proteins found in the thylakoid membrane.
