biol 1103 light sep reac.

What is the energy of a photon first used to do in photosynthesis?

split a water molecule energize an electron produce ATP synthesize glucose B

Plants produce oxygen when they photosynthesize. Where does the oxygen come from?

splitting water molecules ATP synthesis the electron transport chain chlorophyll A

wavelength:

the distance between consecutive points of a wave

chlorophyll b

the form of chlorophyll that absorbs blue and red-orange light

chlorophyll a

the form of chlorophyll that absorbs violet-blue and red light

photon

:a distinct quantity or "packet" of light energy

photosystem

:a group of proteins, chlorophyll, and other pigments that are used in the light-dependent reactions of photosynthesis to absorb light energy and convert it into chemical energy

Which molecule absorbs the energy of a photon in photosynthesis?

ATP glucose chlorophyll water C

Section Summary

In the first part of photosynthesis, the light-dependent reaction, pigment molecules absorb energy from sunlight. The most common and abundant pigment is chlorophyll a. A photon strikes photosystem II to initiate photosynthesis. Energy travels through the electron transport chain, which pumps hydrogen ions into the thylakoid space. This forms an electrochemical gradient. The ions flow through ATP synthase from the thylakoid space into the stroma in a process called chemiosmosis to form molecules of ATP, which are used for the formation of sugar molecules in the second stage of photosynthesis. Photosystem I absorbs a second photon, which results in the formation of an NADPH molecule, another energy carrier for the Calvin cycle reactions.

Describe the pathway of energy in light-dependent reactions.

The energy is present initially as light. A photon of light hits chlorophyll, causing an electron to be energized. The free electron travels through the electron transport chain, and the energy of the electron is used to pump hydrogen ions into the thylakoid space, transferring the energy into the electrochemical gradient. The energy of the electrochemical gradient is used to power ATP synthase, and the energy is transferred into a bond in the ATP molecule. In addition, energy from another photon can be used to create a high-energy bond in the molecule NADPH.

Which color(s) of light does chlorophyll a reflect?

red and blue green red blue B

electromagnetic spectrum

the range of all possible frequencies of radiation

absorption spectrum

the specific pattern of absorption for a substance that absorbs electromagnetic radiation