Refresher - Photosynthesis and Respiration

The Two Most Important Energy-Producing Processes

Both photosynthesis and respiration are responsible for producing and delivering both the energy and gases that all living organisms need for life.

Photosynthesis
Nearly every living organism on earth depends on the oxygen, food, and energy that are produced by photosynthesis in plants.The only known exceptions are organisms living around deep sea vents on the ocean floor.

Photosynthesis is our ultimate source of food and energy.Photosynthesis is responsible for converting the energy in sunlight into chemical forms (ATP and glucose) that we use for food and energy.

How Photosynthesis works:
Photosynthesis converts the carbon dioxide (CO2) that plants produce into oxygen (O2) that animals breathe.

It takes place in two steps.

  • Step 1. In the light phase: Solar energy is converted into and stored as energy in the form of ATP (adenosine triphosphate).
  • Step 2. CO2 and energy from ATP are used to form glucose - a sugar. The net effect of photosynthesis is:
    C CO2, and H2O + energy from the sun O2 + C

 

Source: Wikimedia Links to an external site. By: Daniel Mayer Links to an external site.. License: Creative Commons Attribution Sharealike 3.0 unported Links to an external site..
During photosynthesis plants use energy from the sun to manufacture food. Solar energy transforms carbon dioxide and water into glucose and oxygen.This is the source of the O2 we breathe, and thus, a significant factor in the concerns about deforestation.

 

 

Where Photosynthesis takes place

Photosynthesis occurs in chloroplasts, tiny organelles found in leaves. Chloroplasts are often described as little carbohydrate factories powered by solar energy. These tiny factories produce the food that plants and practically every other living thing on earth rely on for survival.

Leaf - Source: Wikimedia Links to an external site.. Photo courtesy of PDPhoto.org Links to an external site.. License: Public Domain.


Plagiomnium - Source: Wikimedia Links to an external site.. By: Kristian Peters Links to an external site.. License: Creative Commons Attribution Sharealike 3.0 Links to an external site..
Underside of leaf - Source: http://remf.dartmouth.edu/images/botanicalLeafSEM/source/16.html Links to an external site.. By: Photohound Links to an external site.. License: Creative Commons Zero (Non-US)

 

Cellular Respiration makes Energy Available for Use

Cellular Respiration happens in all living organisms. In plants, it follows photosynthesis. Respiration serves the same purpose in all organisms --It converts the energy in sugar (glucose) into a form every organism can use for energy (ATP).


Source: Wikimedia Links to an external site.. By: Bogjgalindo Links to an external site.. License: Creative Commons Attribution Sharealike 3.0 unported Links to an external site..
During humans respiration, we inhale (take in) oxygen and exhale (release) carbon dioxide. Cellular respiration is not entirely different.During respiration, cells use the glucose from photosynthesis and oxygen to release stored energy

 

Mirror Images: photosynthesis and respiration

The equations for photosynthesis and respiration are opposites

 

 

Energy is stored as ATP
the Primary Energy Source for all Organisms

Plants are the prime source of energy for all living organisms. This energy is stored in every plant cell as glucose a molecule called ATP - and used by consumers, like the insects, deer, and cows that eat plants.

Plants and some deep sea bacteria are the only organisms on earth that are capable of producing their own food and deriving energy from it.


Plants and bacteria produce energy and store it as ATP. (adenosine triphosphate. Energy (as ATP) is passed up the food chain from producer to consumer to carnivore.

 

A Comparison between Photosynthesis and Respiration 

Photosynthesis and Cell Respiration

The Process

Photosynthesis

Respiration

Which organisms use this metabolic pathway?

Plants

 Plants, Animals, & Bacteria (all living organisms)

Short explanation of the process

Carbon dioxide, energy from the sun and some minerals are used to manufacture food

Food (carbohydrates)  is turned into energy that the organism can actually use: ATP

When does the process take place in plants?

Before respiration

After photosynthesis

Where does the process occur?

In chloroplasts, (tiny organelles in leaves)

In all plant, animal, and bacterial cells

What happens to the energy?

Solar energy is used for the synthesis of glucose, which is used or stored as ATP

Energy in glucose is converted to a form of energy the cell can use: ATP. (This done by breaking chemical bonds in glucose molecules.)

What is consumed during the process?

carbon dioxide, water and energy from sunlight

oxygen

What is released during the process?

Oxygen

carbon dioxide and energy

Chemical reactions

6CO2 + 6H2O + solar energy→ C6H12O6 + 6O2

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP energy