PHOTOSYNTHESIS

Photosynthesis is the process that uses light energy to produce food energy. The name comes from "_______________" which means light, and "_______________" which means put together. Photosynthesis then is a process that uses light to put together food.

The process requires _____________, ______________, ____________, and ____________.

The equation for the chemical reaction is:

___________ + ___________ ------------> ___________ + ___________ + ___________

LIGHT & CHLOROPHYLL

Light travels in waves. The various colors of the spectrum are measured in wavelengths. The colors (_________, _________, _________, _________, _________, _________, _________) are absorbed by some pigments and reflected by others. Green plants appear green because chlorophyll in the leaves reflects the green wavelength and absorbs the other wavelengths.

The pigment _______________ is found inside the chloroplasts of the cells, contained in stacks of membranes called _______________. The electrons of the chlorophyll molecules are sensitive to the frequencies of visible light. When light hits the chlorophyll it excites or energizes the electrons.

THE PROCESS OF PHOTOSYNTHESIS

The process of photosynthesis is broken down into two major parts or phases.

The first phase is called the _______________because they depend on the presence of light energy and occur only in the light. The second phase is called the _______________ which do not depend directly on light and can occur day or night.

THE LIGHT REACTIONS:

The light reactions begin as light shines on _______________ molecules. The light energizes the electrons so much that some of them escape their orbit around their nucleus. These escaped electrons are captured by other molecules. The electrons are passed from one molecule to another in a series of reactions called the _____________. This movement of electrons from molecule to molecule can be compared to the flow of electrons through a wire that we call electricity. The energy from the flow of electrons through the electron transport chain is used to provide enough energy to change a molecule of _______________ (adenosine diphosphate) into a molecule of _______________ (adenosine triphosphate). This is accomplished by adding a third _________ group to the ADP.

The chlorophyll molecules would rapidly run out of electrons if this continued. However, the chlorophyll replaces its electrons by taking electrons away from molecules of _______________. Since water molecules are held together by sharing electrons between the oxygen and hydrogen, the molecules rapidly break apart. The oxygen atoms are released into the air and provide oxygen for us to breathe. The hydrogen atoms are captured by a hydrogen acceptor compound called _______________ (nicotinamide adenine dinucleotide phosphate). The new compound formed will be called NADPH₂.

In summary, the 3 main products of the light reactions were _______________, _______________, and _______________.

THE DARK REACTIONS

The dark reactions (often called the _______________ cycle because they were discovered by Dr. Calvin) are called "dark" because they do not rely directly on light for their energy. Therefore, the dark reactions can occur in the dark. The name is a little misleading because the dark reactions can also occur in the light. The energy source for the dark reactions is the _______________ that was formed during the light reactions. Whenever energy is required in the dark reactions, the third phosphate is removed from the ATP, leaving a molecule of _______________, and transferring the phosphate and the energy to the dark reactions.

The dark reactions begin as carbon dioxide, CO₂, from the atmosphere diffuses into the leaf and combines with a chemical called _______________ (often called RDP or RuDP). RDP is a 5-carbon chemical that is manufactured by the leaves. The combining of CO₂ and RDP forms a 6-carbon compound that is so unstable that it immediately breaks apart into two molecules of a compound called _______________ (phosphoglyceric acid). Each molecule of PGA contains 3 carbon atoms.

The two PGA molecules then combine with the hydrogen from the NADPH₂ that was captured and stored during the light reactions. The new compound thus formed is called _______________ or phosphoglyceraldehyde. Some of these molecules of PGAL are then combined together by a condensation reaction to form the 6-carbon sugar called glucose and water. Other molecules of PGAL are converted into RDP to replace the RDP used up in the early stages of the dark reactions.

In review, the dark reactions use ________ ________ from the air, ___________ manufactured by the leaf, ____________ from the light reactions, and ___________ from the light reactions to manufacture glucose and more RDP.