Chapter 6: Cell Energy: Photosynthesis and Respiration
Section 1: Photosynthesis: Capturing and Converting Energy
Photosynthesis

In the process of photosynthesis, plants convert the energy of
_________________________________ into the energy in the chemical bonds
of _______________________________________________________________

Put more simply, plants use the energy of sunlight to produce carbohydrates
in a process called __________________________________________

An understanding of photosynthesis was developed from studies of
________________________________________

Dutch physician ______________________________________________
devised an experiment to determine how plant growth actually works
o Found the _________________________ of a pot of dry soil and a
small seedling
o Planted the seedling in the pot of soil
o Watered regularly for __________________________
o Gained about _______________
o Mass of soil was ____________________________________
o Concluded that most of the mass must come from
______________________ because that is all he added to the pot

Although Van Helmont did not realize it, ______________________________
in the air made a major contribution to the mass of his tree

It is the ___________________________ in carbon dioxide that is used to
make carbohydrates in photosynthesis

Almost 100 years after Van Helmont’s experiment, ______________________
___________________________ performed an experiment that would give
another insight into the process of photosynthesis
o Took a candle, placed a glass jar over it, and watched as the flame
__________________________________________
o Something in the air was necessary to keep a candle burning
o When that substance was used up, the candle went out


_________________________
Priestley then placed a ___________________________________ under the jar
and allowed a few days to pass, the candle could be relighted and would
remain lighted for awhile

The mint had produced the substance required for burning
o ______________________

Later, Dutch scientist _____________________________________________
showed that this only occurred when the plant was exposed to _____________
Requirements for Photosynthesis

These experiments reveal that in the presence of light, plants transform
___________________________________________ and __________________
into __________________________________ and release
____________________

Usually produces the sugar ____________________________

______________________________  ______________________________
Sunlight

Nearly all organisms on Earth depend on the ________________ for energy

____________________________________ – organisms that are able to use a
source of energy, such as sunlight, to produce food directly from simple
inorganic substances in the environment

____________________________________– organisms that obtain energy
from the foods they eat

The sun bathes the Earth in a steady stream of light
o We see colorless “________________________” light but it is actually
a mixture of different wavelengths of light
o _____________________________________________
Pigments

Process of photosynthesis begins when light is absorbed by
_____________________________ in the plant cell
o Colored substances that __________________________ or
________________________ light
o Principal pigment in green plants is _____________________________

Absorbs ______________ and _________________ light but
does not absorb light in the middle region of the spectrum very
well

These wavelengths are ____________________________
Energy-Storing Compounds

In a green plant, the energy of sunlight is transferred to
______________________________, raising them to a higher energy level
o The electrons belong to the pigment _____________________________
o High-energy electrons are trapped in chemical bonds

Two ways in which energy of sunlight is trapped in chemical
bonds

First way ____________________________ is trapped in chemical bonds
o Simpler of the two
o A pair of high-energy electrons are passed directly to an
______________________________________

A molecule that can accept a pair of electrons and later transfer
them along with most of their energy to another compound

Plants use the electron carrier __________________________

When NADP+ accepts a pair of high-energy electrons, it
is converted to _____________________
o ONE WAY IN WHICH SOME OF THE
ENERGY OF SUNLIGHT CAN BE
TRAPPED IN CHEMICAL FORM

Second way _____________________________ is trapped in chemical bonds
o Involves ____________________________________________________

Consists of adenine, a 5-carbon sugar called ribose, and three
phosphate groups

During photosynthesis, green plants produce ATP, which is an
energy-storing compound used by ________________________
___________________