Q50. Which statement accurately describes photosynthesis in green plants?
[RRB NTPC (Graduate), CBT-I — 25 March 2026]
(A) It occurs mainly in mitochondria
(B) It changes light energy into chemical energy
(C) It breaks down glucose to release energy
(D) It occurs mainly at night
Answer: (B) It changes light energy into chemical energy
Explanation: Photosynthesis captures solar energy through chlorophyll and stores it in chemical bonds of carbohydrates. Chloroplasts, not mitochondria, are its principal sites in green plant cells. Glucose breakdown belongs to cellular respiration, whereas photosynthesis mainly synthesises energy-rich organic substances.
Q49. The primary food substance formed by a plant during photosynthesis belongs to which category?
[RRB NTPC (Graduate), CBT-I — 24 March 2026]
(A) Minerals
(B) Proteins
(C) Vitamins
(D) Carbohydrates
Answer: (D) Carbohydrates
Explanation: Green plants combine carbon dioxide and water using light energy to synthesise carbohydrates. Simple sugars may subsequently be converted into starch for storage. Proteins and many other compounds can be manufactured later using these carbon skeletons and additional mineral nutrients.
Q48. Which structures together allow a leaf to take in carbon dioxide and convert sunlight into chemical energy?
[DSSSB MTS — 3 May 2026, Shift 3]
(A) Cuticle and stem
(B) Petals and sepals
(C) Veins and root hairs
(D) Stomata and chloroplasts
Answer: (D) Stomata and chloroplasts
Explanation: Stomata are microscopic pores that allow carbon dioxide to diffuse into a leaf. Chloroplasts contain chlorophyll and perform photosynthesis. Root hairs and veins aid absorption or transport, but neither replaces the gas-exchange function of stomata or the light-capturing machinery.
Q47. Where does photosynthesis chiefly occur in a typical green plant?
[DSSSB MTS — 3 May 2026, Shift 3]
(A) Only in stem tissues
(B) In chloroplasts of leaf cells
(C) Inside the roots
(D) Only in flowers
Answer: (B) In chloroplasts of leaf cells
Explanation: Leaf cells contain many chloroplasts, organelles carrying photosynthetic pigments and enzymes. Their chlorophyll absorbs light that supports carbohydrate synthesis. Green stems can also photosynthesise, but leaves are the main food-producing organs in most ordinary green plants.
Q46. Which adaptation allows many desert plants to photosynthesise while reducing daytime water loss?
[RRB Technician Grade III — 6 March 2026]
(A) Photosynthesis is restricted to darkness
(B) Carbon dioxide is taken in at night and carbohydrates are synthesised in daylight
(C) Light is collected at night and stored as starch
(D) Oxygen is absorbed at night while carbon dioxide is released by day
Answer: (B) Carbon dioxide is taken in at night and carbohydrates are synthesised in daylight
Explanation: Many desert succulents use CAM photosynthesis. Their stomata open at night, allowing carbon dioxide uptake with relatively little water loss. The carbon is temporarily stored in organic acids and later used during daytime carbohydrate synthesis, when the stomata can remain shut.
Q45. Which description best fits autotrophic nutrition?
[RRB Group D — 29 December 2025, Shift 2]
(A) Digesting dead matter outside the body
(B) Feeding only on other living organisms
(C) Making organic food from carbon dioxide and water using sunlight
(D) Taking ready-made organic food from a host
Answer: (C) Making organic food from carbon dioxide and water using sunlight
Explanation: Autotrophs synthesise their own organic food from simpler inorganic materials. In green plants, light and chlorophyll enable this conversion of carbon dioxide and water into carbohydrates. The other descriptions concern saprotrophic, holozoic or parasitic forms of nutrition.
Q44. Food produced by photosynthesis but not immediately used is commonly stored in plants as what?
[RRB Group D — 21 December 2025, Shift 3]
(A) Glucose only
(B) Protein
(C) Starch
(D) Cellulose only
Answer: (C) Starch
Explanation: Plants may convert surplus soluble sugars formed through photosynthesis into insoluble starch. Starch serves as an energy reserve and can later be broken down when required. Iodine solution turning blue-black is a standard school experiment demonstrating starch in a leaf.
Q43. Which process is NOT a direct part of photosynthesis in green plants?
[RRB Group D — 19 December 2025, Shift 3]
(A) Reducing carbon dioxide to carbohydrates
(B) Converting light into chemical energy
(C) Absorbing light with chlorophyll
(D) Breaking down carbohydrates to release energy
Answer: (D) Breaking down carbohydrates to release energy
Explanation: Photosynthesis stores incoming light energy in manufactured carbohydrates, while cellular respiration releases usable energy by breaking down those organic compounds. Although both processes occur in plants, glucose breakdown for energy belongs to respiration, not the photosynthetic food-making process.
Q42. Green plants occupy which basic ecological role in an ecosystem?
[CGPSC Preliminary Examination — 9 February 2025]
(A) Primary producers
(B) Primary consumers
(C) Secondary consumers
(D) Decomposers
Answer: (A) Primary producers
Explanation: Most green plants are primary producers because they create organic food using sunlight, water and carbon dioxide. Herbivores obtain this stored energy by eating plants, while other consumers depend on it indirectly. Decomposers recycle materials from dead organisms instead of producing food photosynthetically.
Q41. Which organism can use both autotrophic and heterotrophic modes of nutrition?
[RRB NTPC (Graduate), CBT-I — 13 June 2025]
(A) Amoeba
(B) Euglena
(C) Plasmodium
(D) Paramecium
Answer: (B) Euglena
Explanation: Euglena is capable of photosynthesis in adequate light because it has chloroplasts. Under certain conditions it can also obtain organic nutrients from its surroundings. This nutritional flexibility is called mixotrophy and contrasts with the predominantly heterotrophic feeding of Amoeba and Paramecium.