Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Photosynthesis is the physiological process by which green plants synthesize complex organic food substances (glucose) from simple inorganic raw materials like and in the presence of sunlight and chlorophyll.
The raw materials required are Carbon dioxide (), which enters through the stomata, and Water (), which is absorbed from the soil by roots.
The process occurs in the chloroplasts, which are specialized organelles containing the green pigment called chlorophyll that traps solar energy.
The end products of photosynthesis are Glucose (), Water (), and Oxygen (). Oxygen is released into the atmosphere as a byproduct.
The solar energy is converted into chemical energy and stored in the bonds of the glucose molecule.
Plants convert excess glucose into starch for long-term storage in different parts of the plant like roots, stems, or leaves.
Factors affecting the rate of photosynthesis include light intensity, concentration of , temperature, and the availability of water.
📐Formulae
💡Examples
Problem 1:
A leaf is plucked from a plant kept in the dark for 48 hours and tested with Iodine solution. What will be the observation and why?
Solution:
The leaf will turn brown (the color of iodine) and will not turn blue-black.
Explanation:
Keeping the plant in the dark for 48 hours results in 'destarching.' Since there was no sunlight, no photosynthesis occurred to produce new glucose. The existing starch was consumed by the plant for survival. Therefore, the absence of starch results in a negative iodine test.
Problem 2:
In an experiment, a plant is provided with containing a heavy isotope of oxygen (). Does the released gas contain this isotope?
Solution:
No, the released does not contain the isotope from .
Explanation:
Scientific studies show that the Oxygen () released during photosynthesis comes from the splitting of Water () molecules (photolysis), not from the Carbon dioxide () molecules.