In plant nutrition, plants are often described as photoautotrophs. What does it mean when we say that plants are photoautotrophic?

Introduction / Context:
The term photoautotroph is used in biology to describe organisms like green plants, algae and some bacteria that produce their own food using light. Understanding this word helps you understand how energy flows through ecosystems and how plants support life on Earth. This question asks you to interpret the term correctly and connect it to the process of photosynthesis.

Given Data / Assumptions:

• The organisms in question are plants, which contain chlorophyll.
• The key word is photoautotroph, which combines photo and autotroph.
• We assume that the learner knows in a basic way how photosynthesis works.

Concept / Approach:
The word autotroph means self feeding and refers to organisms that can make their own organic food from inorganic raw materials. The prefix photo means light. A photoautotroph is therefore an organism that uses light energy to convert inorganic substances such as carbon dioxide and water into organic molecules like glucose. Plants use chlorophyll to capture light energy, which drives the chemical reactions of photosynthesis. They do not need to feed on other organisms for energy, unlike heterotrophs, which include animals and many fungi.

Step-by-Step Solution:
Step 1: Break down the word photoautotroph into photo and autotroph. Step 2: Recall that photo refers to light, as in photography or photosynthesis. Step 3: Recall that autotroph refers to an organism that produces its own food from simple inorganic substances. Step 4: Combine the meanings to understand that photoautotrophs use light energy to manufacture food. Step 5: Match this combined meaning with the option that describes plants making organic molecules from carbon dioxide and water using light.

Verification / Alternative check:
A standard biology textbook explains that plants are autotrophic because they synthesise carbohydrates from carbon dioxide and water, and they are photoautotrophic because they use sunlight as the energy source. This is described in the context of photosynthesis, particularly in chloroplasts. The correct option mirrors this explanation exactly, while the other options either describe heterotrophic behaviour or conditions that do not fit plant physiology.

Why Other Options Are Wrong:
Option A describes organisms that digest other organisms and is closer to heterotrophic nutrition, not photoautotrophy. Option C suggests survival only in complete darkness and use of chemical energy from minerals, which is closer to chemoautotrophy, not photoautotrophy. Option D states that plants depend entirely on animals for sugars and fats, which directly contradicts the idea that they make their own food. Option E speaks of storing light energy as heat without forming chemical compounds, which is not how photosynthesis works.

Common Pitfalls:
Students sometimes confuse photoautotrophs with chemoautotrophs or heterotrophs because of the similar sounding terms. A simple way to avoid this is to remember that photo always signals light and auto always signals self. So a photoautotroph makes its own food using light. Heterotrophs, by contrast, must obtain ready made organic molecules by eating other organisms or decaying matter.

Final Answer:
When we say that plants are photoautotrophs, we mean that they use light energy to make organic food molecules from inorganic substances such as carbon dioxide and water.