Photosynthesis: Autotrophy & Energy — NEET Biology
📚 Practice ConceptAll animals including human beings depend on plants for their food. Have you ever wondered from where plants get their food? Green plants, in fact, have to make or rather synthesise the food they need and all other organisms depend on them for their needs. The green plants make or rather synthesise the food they need through photosynthesis and are therefore called autotrophs. You have already learnt that the autotrophic nutrition is found only in plants and all other organisms that depend on the green plants for food are heterotrophs. Green plants carry out 'photosynthesis', a physico-chemical process by which they use light energy to drive the synthesis of organic compounds. Ultimately, all living forms on earth depend on sunlight for energy. The use of energy from sunlight by plants doing photosynthesis is the basis of life on earth. Photosynthesis is important due to two reasons: it is the primary source of all food on earth. It is also responsible for the release of oxygen into the atmosphere by green plants. Have you ever thought what would happen if there were no oxygen to breath? This chapter focusses on the structure of the photosynthetic machinery and the various reactions that transform light energy into chemical energy.
Which of the following statements comprehensively explains the fundamental basis of dependence of all heterotrophic life forms on green plants? S1: Green plants synthesize food required by heterotrophs through photosynthesis, forming the base of most food chains. S2: Green plants release oxygen into the atmosphere, which is vital for aerobic respiration in heterotrophs. S3: Green plants contribute to water retention in the soil, which indirectly supports habitats for heterotrophs. S4: Green plants provide direct shelter and nesting sites for many animal species, influencing biodiversity. S5: Green plants are the primary producers that convert light energy into chemical energy, making it available to the entire biotic world.
View solution & NCERT explanation
Correct answer: A — S1, S2 and S5 are correct
The question asks for statements that comprehensively explain the fundamental dependence of heterotrophs on green plants, as established by photosynthesis. S1: This statement is correct. "All animals including human beings depend on plants for their food." Green plants, as autotrophs, produce organic food that forms the basis of all food chains. S2: This statement is correct. "It is also responsible for the release of oxygen into the atmosphere by green plants." Oxygen is crucial for aerobic respiration in heterotrophs. S3: This statement is partially correct in a broader ecological context but the question asks for 'fundamental basis' related to photosynthesis. Water retention is an ecological service, but not a direct fundamental dependence derived from photosynthesis. S4: This statement is also partially correct. Shelter is an ecological role, but again, not a direct fundamental dependence stemming from the core process of photosynthesis (food and oxygen production). S5: This statement is correct. "Ultimately, all living forms on earth depend on sunlight for energy. The use of energy from sunlight by plants doing photosynthesis is the basis of life on earth." This encapsulates the energetic dependence. While S3 and S4 describe valid ecological dependencies, S1, S2, and S5 directly address the fundamental energy and gaseous exchange dependencies rooted in the photosynthetic process itself, which is the anchor concept. The question specifically asks for the 'fundamental basis' which primarily refers to food and oxygen and the initial energy conversion. Therefore, S1, S2 and S5 are correct as the most fundamental explanations.
What does NCERT say about All animals including human?
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Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
176/180MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.