In basic biology, what are the two main products of photosynthesis that are released or stored by green plants?

Introduction / Context:
Photosynthesis is the key process by which green plants, algae, and some bacteria convert light energy into chemical energy. Understanding its main products is essential in biology and environmental science, because these products support life on Earth and affect the composition of the atmosphere.

Given Data / Assumptions:
- Photosynthesis uses carbon dioxide and water as reactants.
- The process takes place in chloroplasts using chlorophyll and other pigments.
- The question asks about the main products produced by photosynthesis.

Concept / Approach:
The simplified overall equation for photosynthesis can be written as: carbon dioxide plus water, using light energy, produce sugar and oxygen. Sugars represent stored chemical energy and provide carbon skeletons for building other organic molecules. Oxygen gas is released as a by product into the atmosphere and is vital for aerobic respiration in many organisms. Therefore, the two main products to focus on are sugar (often represented as glucose) and oxygen.

Step-by-Step Solution:
Step 1: Recall the basic photosynthesis equation: carbon dioxide + water, using light, produce sugar and oxygen. Step 2: Identify sugar as the primary organic product, which can be converted into starch, cellulose, and other molecules. Step 3: Recognize oxygen gas as a by product that diffuses out of the leaf into the surrounding air. Step 4: Note that carbon dioxide is a reactant, not a product, in this process. Step 5: Conclude that both oxygen and sugar are the main products of photosynthesis.

Verification / Alternative check:
Textbook diagrams of photosynthesis always show arrows from the atmosphere delivering carbon dioxide into the leaf and arrows from the leaf releasing oxygen gas. Inside the plant, arrows show sugars being transported to other parts of the plant. This consistent representation reinforces that the main products are oxygen and sugar.

Why Other Options Are Wrong:
Option A: Oxygen is indeed a product, but this option ignores sugar, which is equally important and central to the process.
Option B: Sugar is also a main product, but focusing only on sugar overlooks the critical release of oxygen into the atmosphere.
Option D: Carbon dioxide is not a product but a reactant that plants take in from the air; it is consumed during photosynthesis rather than produced.

Common Pitfalls:
Students sometimes reverse reactants and products, thinking that plants produce carbon dioxide and take in oxygen during photosynthesis. In reality, carbon dioxide is taken in and oxygen is released. Another confusion is mixing up respiration and photosynthesis. Respiration uses oxygen and produces carbon dioxide, while photosynthesis uses carbon dioxide and produces oxygen.

Final Answer:
The correct answer is both oxygen gas and sugar molecules produced together because photosynthesis produces sugars that store energy and carbon, and releases oxygen as a by product into the atmosphere.