BIOENERGETICS (BIOLOGY UNIT 2)

MDCAT, NUMS, AKU

Bioenergetics

The study of energy relationships and energy conversions in biological systems. Living organisms require a constant supply of energy to grow, reproduce, and carry out life processes. This energy primarily comes from the sun and is harnessed 1% only through the process of photosynthesis in plants while 99% is reflected back.

Photosynthesis Basics

The process by which plants convert light energy (from the sun) into chemical energy stored in sugar and other organic molecules. The presence of photosynthesis on Earth led to the accumulation of oxygen in the atmosphere, which allowed for the evolution of cellular respiration. Respiration releases a significant amount of energy, part of which is used to form ATP molecules, linking catabolic and anabolic processes.

Photosynthesis

Can be defined as “the process in which energy poor inorganic oxidized compounds of carbon (CO2) and hydrogen (Mainly H2O) are reduced to energy rich carbohydrates (i.e. glucose) using the light energy that is absorbed and converted into chemical energy by chlorophyll and some other photosynthetic pigments.”

Reaction of Photosynthesis

6CO2 + 12H20 (Light, Chlorophyll)—> C6H12O6 + 6O2 + 6H2O

CO2 —> Glucose = Reduction
12H2O —> Oxygen = Oxidation

Reactants and Products of Photosynthesis

Reactants: CO2, H2O, Light

Products: Glucose, Oxygen

(No net yield of H2O bc it is used as reactant and product)

Relationship between Photosynthesis and Respiration

Photosynthesis uses the products of respiration, and respiration uses the products of photosynthesis. Photosynthesis occurs only in the daytime whereas respiration occurs day and night.