Plants: Photosynthesis, Nutrition and Biotechnology
Plants: Photosynthesis, Nutrition and Biotechnology
Plants make their own food by photosynthesis, take in water and minerals through roots, and are controlled by plant hormones. Biotechnology uses living cells and DNA to make useful products, such as Bt cotton and insulin from bacteria. NTPC asks the raw materials and products of photosynthesis, plant hormones, transpiration, and examples of biotechnology.
1. Photosynthesis
6CO₂ + 6H₂O + light energy gives C₆H₁₂O₆ + 6O₂ (in chloroplasts, with chlorophyll)
| Item | Fact |
|---|---|
| Raw materials | Carbon dioxide and water |
| Products | Glucose and oxygen |
| Source of released oxygen | Water (splitting of water molecules) |
| Pigment | Chlorophyll, green; contains magnesium |
| Light reaction | In grana; makes ATP and NADPH, splits water |
| Dark reaction (Calvin cycle) | In stroma; fixes carbon dioxide into sugar |
| Starch test | Iodine turns starch blue-black |
| Stomata | Pores in leaves for gas exchange; guard cells open and close them |
2. Plant Nutrition and Hormones
| Item | Fact |
|---|---|
| Transpiration | Loss of water vapour through stomata; pulls water up the xylem |
| Root nodules of legumes | Rhizobium bacteria fix atmospheric nitrogen |
| Insectivorous plants | Pitcher plant, Venus flytrap; get nitrogen from insects |
| Parasitic plant | Cuscuta (dodder) |
| Saprophytes | Mushrooms; feed on dead matter |
| Auxin | Growth of shoot tips; bending towards light (phototropism) |
| Gibberellin | Stem elongation; used to grow bigger grapes |
| Cytokinin | Cell division |
| Abscisic acid | Stress hormone; closes stomata, causes dormancy |
| Ethylene | Gaseous hormone; ripens fruits |
3. Biotechnology
| Item | Fact |
|---|---|
| Bt cotton | Contains a gene from Bacillus thuringiensis; resists bollworm; the main GM crop grown commercially in India |
| Golden rice | Rich in vitamin A (beta-carotene) |
| Recombinant insulin | Made by inserting the human insulin gene into bacteria |
| Dolly the sheep | First mammal cloned from an adult cell (1996) |
| DNA fingerprinting | Identifies people by DNA patterns; developed by Alec Jeffreys; in India linked with Lalji Singh |
| Restriction enzymes | Molecular scissors that cut DNA |
| Green Revolution in India | M.S. Swaminathan; high-yielding wheat and rice |
| Genetic engineering | Changing an organism's DNA to add useful traits |
✗ The oxygen released in photosynthesis comes from carbon dioxide | ✓ It comes from water molecules split in the light reaction
✗ Auxin ripens fruits | ✓ Ethylene ripens fruits; auxin controls shoot growth and bending towards light
हिंदी नोट: प्रकाश संश्लेषण में कार्बन डाइऑक्साइड और जल से ग्लूकोज़ और ऑक्सीजन बनते हैं; निकली ऑक्सीजन जल से आती है। एथिलीन फल पकाने वाला गैसीय हार्मोन है। बीटी कपास में बैसिलस थुरिंजिएंसिस का जीन होता है, जो इसे बॉलवर्म से बचाता है।
Exam Pointer: No NTPC shift was verified for these patterns in this run; they are tagged syllabus-based. Photosynthesis, plant hormone and biotechnology questions are standard General Science items.
Pariksha Pattern: Every Way NTPC Asks This Topic
Pattern 1: Photosynthesis
[Pattern: syllabus-based, PYQ-style]
EXAM LEVEL
Q. Which metal is present in chlorophyll?
Magnesium.
Answer: Magnesium
EXAMATLAS LEVEL
Q. Name the raw materials and products of photosynthesis. From which substance does the released oxygen come, and in which part of the chloroplast is carbon dioxide fixed?
Carbon dioxide and water are the raw materials; glucose and oxygen are the products. The oxygen comes from water. Carbon dioxide is fixed in the stroma during the Calvin cycle.
Answer: CO₂ and water, glucose and O₂; water; stroma
Pattern 2: Plant hormones
[Pattern: syllabus-based, PYQ-style]
EXAM LEVEL
Q. Which plant hormone is a gas and helps fruits ripen?
Ethylene.
Answer: Ethylene
EXAMATLAS LEVEL
Q. Match the hormone with its effect: auxin, gibberellin, abscisic acid, cytokinin.
Auxin makes shoots grow and bend towards light, gibberellin lengthens stems, abscisic acid closes stomata under stress, and cytokinin promotes cell division.
Answer: Phototropism; stem elongation; stomata closing; cell division
Pattern 3: Transpiration and modes of plant nutrition
[Pattern: syllabus-based, PYQ-style]
EXAM LEVEL
Q. What is the loss of water vapour from the aerial parts of a plant called?
Transpiration, mostly through the stomata.
Answer: Transpiration
EXAMATLAS LEVEL
Q. Which bacteria in pea root nodules fix nitrogen, and why do pitcher plants trap insects though they are green?
Rhizobium fixes nitrogen in legume root nodules. Pitcher plants grow in soil poor in nitrogen, so they get nitrogen by digesting insects while still making food by photosynthesis.
Answer: Rhizobium; to get nitrogen
Pattern 4: Biotechnology applications
[Pattern: syllabus-based, PYQ-style]
EXAM LEVEL
Q. Bt cotton gets its pest resistance from a gene of which bacterium?
Bacillus thuringiensis.
Answer: Bacillus thuringiensis
EXAMATLAS LEVEL
Q. Which was the first mammal cloned from an adult cell, which rice is engineered to supply vitamin A, and what are restriction enzymes called?
Dolly the sheep (1996). Golden rice carries beta-carotene, which the body turns into vitamin A. Restriction enzymes are called molecular scissors.
Answer: Dolly; Golden rice; molecular scissors
60-Second Revision
- Photosynthesis: CO₂ + water to glucose + O₂; O₂ from water; chlorophyll has Mg.
- Auxin phototropism; gibberellin elongation; ethylene ripening; abscisic acid stress.
- Rhizobium fixes nitrogen; transpiration through stomata.
- Bt cotton, Golden rice, recombinant insulin, Dolly 1996, DNA fingerprinting.
Next Step: Biology done. Revise the disease and vitamin tables with the ExamAtlas RRB NTPC 2026 mock tests; biology gives the most science questions in NTPC.