Lab Exam 2: Lab 5 Flashcards
What is one of the most important processes carried out by photosynthetic autotrophs?
The conversion of light energy into useful biological energy (ATP) and “reducing power” that drives the conversion of carbon dioxide and water into sugar
What is the first step of photosynthesis?
The absorption of visible light photons by chlorophyll
What gives plants its green color?
Chlorophyll
What is the relationship between energy associated with a photon and its wavelength?
Inversely related; the greater the energy of a photon, the smaller the wavelength
What does the photon energy absorbed by chlorophyll permit?
It permits the removal of electrons from water (producing oxygen and protons), and the shuttling of the electrons and protons in ways that drive the generation of ATP and reduce carbon dioxide
What is an absorption spectrum?
The pattern of absorption by a substance
Does changing the concentration of the pigment substantially alter the position (wavelength) of the peaks?
No, because the substance, regardless of how concentrated it is, will absorb more light at a specific wavelength
Does changing the concentration of the pigment substantially alter the height (absorbance) of the peaks?
Yes, the less concentrated a solution, the less amount of light it absorbs and vice versa
What appears to be the relationship between the concentration of pigment and the height of the peaks?
Directly related; as concentration increases, so does absorbance which means the height of the peaks will increase too
Is position or height on a absorbance spectrum more useful in identifying a substance?
Position, because every substance has a wavelength of maximum absorbance
What would be the consequences to photosynthesis be if the chlorophyll molecule were transparent to light?
Plants undergo photosynthesis to receive energy, and thus if they were transparent, they would no longer be able to sustain themselves; they would also not be able to produce oxygen for animals
What would the absorption spectrum of a colorless, transparent substance look like?
It would be horizontal line at the x-axis (absorption = 0)
Chlorophyll is green; how does this relate to its absorption spectrum?
Chlorophyll does not absorb much light at green wavelengths, therefore it reflects the color of the light it does not absorb which explains why it appears green to the human eye
How much photosynthesis would a plant carry out if it were illuminated by green light alone?
It would carry out very little photosynthesis because it does not absorb that much green light
Does chlorophyll absorb more blue light or red light?
Blue light
