Question

When a plant grows, the atoms used come from carbon dioxide in the air and water. Plants are able to accomplish this through the process of photosynthesis, cellular respiration and biosynthesis of macromolecules.

Where does the energy come from that allow plants to synthesize the necessary biological macromolecules that allow it to grow? Hint: It is NOT from sunlight. Explain your answer.

Answer 1

ANSWER :-) Yes, its not the sunlight.There are series of steps in it. It can be said that LIGHT DEPENDENT REACTIONS are involved.

So, The basic requirement of all organisms, including humans is energy which is needed to fuel the metabolic reactions of growth, development, and reproduction. But organisms can't use this light energy directly for their metabolic needs. Instead, it must first be converted into chemical energy through the process of photosynthesis.

So, before this one must know about photosynthesis.

What is photosynthesis?

Photosynthesis involves the process of  converting light energy to chemical energy in the form of sugars. In a process driven by light energy, glucose molecules (or other sugars) are constructed from water and carbon dioxide, and oxygen is released as a byproduct. The glucose molecules provide organisms with two crucial resources: energy and fixed—organic—carbon.

• Energy. The glucose molecules serve as fuel for cells: their chemical energy can be harvested through processes like cellular respiration and fermentation, which generate adenosine triphosphate—{ATP} which is a small, energy-carrying molecule.

• Fixed carbon. Carbon from carbon dioxide—inorganic carbon—can be incorporated into organic molecules; this process is called carbon fixation, and the carbon in organic molecules is also known as fixed carbon.

• Photosynthesis may be summarised by the word equation:

  carbon dioxide + water

  glucose + oxygen

  The conversion of usable sunlight energy into chemical energy is associated with the action of the green pigment chlorophyll which is a complex molecule.

• Basically, the Photosynthesis in the leaves of plants involves many steps, but it can be divided into two stages i.e the light-dependent reactions and the Calvin cycle.

• Light-dependent reactions:-) a light-dependent series of reactions which occur in the grana, and require the direct energy of light to make energy-carrier molecules that are used in the second process: it takes place in the thylakoid membrane which require a continuous supply of light energy. Chlorophylls absorb this light energy, which is converted into chemical energy through the formation of two compounds,ATP and NADPH . In this process, water molecules are also converted to oxygen gas—the oxygen we breathe!

• Calvin cycle :-) This is also called the light-independent reactions that takes place in the stroma and does not directly require light. Instead, the Calvin cycle uses ATP and NADPH from the light dependent reactions to fix the carbon dioxide and produce three carbon sugar glyceraldehyde-3-phosphate, or G3P, molecules—which join up to form glucose.

• Overall, the light-dependent reactions capture light energy and store it temporarily in the chemical forms of ATP and NADPH. Here ATP is broken down to release the energy ,and NADPH donates its electrons to convert carbon dioxide molecules into sugars. At last, the energy that started out as a light winds up trapped in the bonds of the sugars.

• Summary of stages of photosynthesis