Photosynthesis & Cellular Respiration
Directions: Read the article and fill in the chart below with things that are unique to each process
and things they have in common
Photosynthesis and cellular respiration are two biochemical reactions, which have a crucial role to play when it comes to life on the
planet Earth. While photosynthesis is a process where plants absorb energy directly from the Sun to prepare their own food, cellular
respiration refers to the process where the energy that is stored in plants in the form of glucose is used by organisms for their own
survival. The basic rule that energy cannot be created or destroyed, but can only be transferred from one form to another applies to
both of these biochemical reactions.
Photosynthesis and Cellular Respiration
While plants and animals both use a form of respiration, photosynthesis is only restricted to green plants and few other organisms.
This - however, doesn't mean that the latter is only useful for plants and other organisms that are directly involved. Both these
processes are important for all the life forms on the planet - either directly or indirectly, as they are related to each other. In order to
understand how photosynthesis is related to cellular respiration, one has to understand the basics of each of them.
Photosynthesis:
Photosynthesis is a process where the production of sugar (glucose) is carried out using sunlight (which acts as the energy source),
carbon dioxide and water. Simply put, photosynthesis is a chemical process by which plants, algae as well as some species of bacteria
produce their own food using sunlight, carbon dioxide and water. The chemical equation for photosynthesis is 6CO2 + 6H2O + Light
energy → C6H12O6 + 6O2; where carbon dioxide (CO2), water (H2O) and sunlight are reactants and glucose (C6H12O6) and
oxygen (O2) are the products of photosynthesis.
Cellular Respiration:
In the process of cellular respiration, the biochemical energy derived from nutrients is converted to adenosine triphosphate (ATP),
which is necessary for these organisms to carry out various life functions. Simply put, cellular respiration is a metabolic process where
the chemical bonds of glucose derived from food are converted to energy that is used by many organisms - including us humans, for
various life processes. The chemical equation for cellular respiration is C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy released (2830
kJ mol-1); where glucose (C6H12O6) and oxygen (O2) are reactants, and carbon dioxide (CO2), water (H2O) and Energy are
products.
How are Photosynthesis and Cellular Respiration Related?
In the information of each of these two processes, you must have noticed that the products of one process are reactants of another and vice versa. Glucose and oxygen - which happen to be the products of photosynthesis, are required to carry out cellular respiration,
while carbon dioxide - a product of cellular respiration, is required to carry out the process of photosynthesis. This very fact forms the
basis of the relationship between cellular respiration and photosynthesis. In other words, the plants and other life forms that use
photosynthesis are dependent on organisms that use cellular respiration and produce carbon dioxide, and all these organisms are, in
turn, dependent on the glucose that they get from plants for their energy requirements. The photosynthesis-cellular respiration
relationship explains why the two are necessary for the presence of life on the planet. To summarize the entire relationship; the energy
from the Sun is used to produce glucose during photosynthesis, and the same glucose is eventually used to produce usable energy in
the process of cellular respiration.
Photosynthesis
BOTH
Cellular Respiration