★ Light dependent reaction.

In the light dependent reactions, chlorophyll converts sunlight energy into chemical energy (ATP and NADPH)

2 H2O + 2 NADP+ + 3 ADP + 3 Pi + light → 2 NADPH + 2 H+ + 3 ATP + O2

Light is then captured by pigments in chlorophyll.
Various pigments:
Chlorophyll - absorbs violet, blue and red light. (reflects green)
Carotenoids - absorb blue and green light. (reflect yellow, orange, or red)

Phycocyanins - absorb green and yellow light. (reflect blue or purple)
Xanthophyll - type of carotenoid that reflects yellow light.

★ Light-independent reactions. (The calvin cycle)

In the light-independent reaction, the ATP and NADPH produced by the light-dependent reaction provides the energy to make glucose and other organic molecules from inorganic carbon dioxide and water .

6CO2 + 18ATP + 12NADPH2 → C6H12O6 (glucose) + 12 NADP+ + 18 ADP + 18 Pi + 6 H2O

★ ATP: Adenosine Triphosphate
★ NADPH: Nicotinamide adenine dinucleotide phosphate

A video to let you know more about The Calvin Cycle.

Source from: http://www.biologycorner.com/bio4/notes/photosynthesis.html

★ What would happen if there were no photosynthesis?

If there was no photosynthesis ,there would be no oxygen produced by the trees which would cause the world to eventually be left with carbon dioxide as all the oxygen will be used up in the end which would lead to and increase in the degee of global warning and all living things will eventually die.
Food cycle would also be disrupted as all living things directly/indirectly depends on plants for food as plants are the starters of food chains as they produce glucose through photosynthesis.

Photosynthesis & Respiration.

★ What is the relationship between photosynthesis & respiration?

Our initial theory: Both happens in plants and keeps the plant alive. When living things respire, we take in oxygen and gives out carbon dioxide, the plant will photosynthesis and take in the carbon dioxide and give out oxygen.

A better theory:
-Photosynthesis and respiration are reversible chemical reactions, meaning that the products of one process are the exact reactants for the opposite process.
Respiration: 6O2 + C6H12O6 --->6CO2 +6H2O
Photosynthesis: 6CO2 +6H2O--->C6H12O6 +6O2
-ATP molecules are made in photosynthesis and used in respiration.