In plant physiology, photosynthesis in green plants takes place in the presence of chlorophyll pigment and which additional essential factor?

Introduction / Context:
Photosynthesis is the fundamental biochemical process by which green plants, algae, and some bacteria convert light energy into chemical energy. It requires specific raw materials and conditions. Many school level statements mention that photosynthesis occurs in the presence of chlorophyll and sunlight. This question asks you to identify the key factor usually paired with chlorophyll in that classical phrase.

Given Data / Assumptions:

• Chlorophyll is the principal green pigment located in chloroplasts.
• Photosynthesis needs light, carbon dioxide, and water as essential inputs.
• The options list water, mineral nutrients, carbon dioxide gas, sunlight, and molecular oxygen.
• We follow the standard wording used in many basic biology texts.

Concept / Approach:
Although water and carbon dioxide are raw materials, the familiar phrase in textbooks is that photosynthesis occurs in the presence of chlorophyll and sunlight. Chlorophyll captures light energy, while sunlight provides the source of that energy. Therefore, when the question is framed specifically as chlorophyll and blank, the most appropriate completion is sunlight, representing light energy rather than a chemical substrate.

Step-by-Step Solution:
Step 1: Recall the overall equation of photosynthesis, which uses carbon dioxide and water to produce glucose and oxygen using light energy. Step 2: Understand that chlorophyll absorbs photons of light, allowing plants to convert light energy to chemical energy. Step 3: Note that many basic biology definitions state that photosynthesis is the process by which green plants manufacture food in the presence of sunlight and chlorophyll. Step 4: Recognize that water and carbon dioxide are substrates, while sunlight is the energy source. Step 5: Check the options and identify sunlight as the factor most logically paired with chlorophyll in the phrase used in the question. Step 6: Conclude that the blank should be filled with sunlight.

Verification / Alternative check:
School textbooks often define photosynthesis with sentences like green plants prepare their own food from carbon dioxide and water in the presence of sunlight and chlorophyll. This wording highlights that chlorophyll on its own is not enough; it must capture light from the sun. Laboratory experiments that grow plants in the dark show that, even with chlorophyll present, photosynthesis does not proceed without light, confirming the essential role of sunlight as an energy source.

Why Other Options Are Wrong:
Water is certainly a raw material for photosynthesis, but the question is about the phrase in the presence of chlorophyll and blank, which is classically completed with sunlight. Mineral nutrients are important for overall plant health but are not the immediate partner in that phrase. Carbon dioxide is another substrate but is not normally paired wording wise with chlorophyll in this sentence. Molecular oxygen is a product of photosynthesis, not a required factor for the process.

Common Pitfalls:
Some learners may overthink and choose water or carbon dioxide because they are raw materials. Others might misread the question and forget the standard school level wording. To avoid confusion, remember that the classic teaching phrase links chlorophyll with sunlight, highlighting the energy aspect rather than the substrates.

Final Answer:
Photosynthesis takes place in the presence of chlorophyll and Sunlight.