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Plant Physiology: II. Plant Nutrition

📆 October 29, 2024

Total Questions: 25

11. ‘Phloem’ in plants is mainly responsible for— [U.P. Lower Sub. (Pre) 2015]

Correct Answer: (a) Transportation of food
Solution:Phloem also called ‘bast’ tissues in plants that carry food produced in the leaves to all other parts of the plant. Phloem is composed of various specialized cells called sieve tubes, companion cells, phloem fibres and phloem parenchyma cells.

12. Which of the living tissues acts as the carrier of organic nutrients in higher plants? [U.P.P.C.S. (Mains) 2012]

Correct Answer: (b) Phloem
Solution:Xylem is composed of dead cells, while phloem is made up of living cells. Phloem transports food from the leaves to the rest of the plant body.

Phloem is a complex tissue in vascular plants that facilitates the transport of sugars, amino acids, and other organic compounds. The movement of these substances through the phloem is known as translocation.

In most cases, the leaves are the source of food (produced through photosynthesis), and other parts of the plant, like roots, shoots, fruits, and seeds, are the destinations or "sinks" where the food is used or stored. Phloem is composed of sieve tubes and companion cells, which are essential for the transport process.

13. Plants receive their nutrients mainly from : [67ᵗʰ B.P.S.C. (Pre) (Re. Exam) 2022]

Correct Answer: (d) soil
Solution:Plants receive their nutrients mainly from the soil. The total essential plant nutrients include seventeen different elements in which carbon, oxygen and hydrogen are absorbed from the air whereas other nutrients including nitrogen are typically obtained from the soil. Mineral nutrients are absorbed by the plants' roots when uptaking water from the soil.

14. Which of the following elements is not essential for plant growth? [Uttarakhand P.C.S. (Pre) 2005]

Correct Answer: (a) Sodium
Solution:Essential elements are classified into two categories:
(i) Macro-elements (Major elements) – These are required by the plant in larger quantities e.g.- Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), Potassium (K), Magnesium (Mg), Calcium (Ca) and Sulphur (S).
(ii) Micro-elements (Minor elements or Trace elements) – These are required by the plant in low quantities. Examples are Boron (B), Zinc (Zn), Manganese (Mn), Copper (Cu), Molybdenum (Mo), Chlorine (Cl), Iron (Fe) and Nickel (Ni).

15. Which of the following is macronutrient in relation to growth of plants? [Chhattisgarh P.C.S. (Pre) 2020]

Correct Answer: (a) Potassium
Solution:Essential elements are classified into two categories:
(i) Macro-elements (Major elements) – These are required by the plant in larger quantities e.g.- Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), Potassium (K), Magnesium (Mg), Calcium (Ca) and Sulphur (S).
(ii) Micro-elements (Minor elements or Trace elements) – These are required by the plant in low quantities. Examples are Boron (B), Zinc (Zn), Manganese (Mn), Copper (Cu), Molybdenum (Mo), Chlorine (Cl), Iron (Fe) and Nickel (Ni).

16. Which of the following elements is NOT a micronutrient in plants? [U.P. B.E.O. (Pre) 2019]

Correct Answer: (d) Magnesium
Solution:(ii) Micro-elements (Minor elements or Trace elements) – These are required by the plant in low quantities. Examples are Boron (B), Zinc (Zn), Manganese (Mn), Copper (Cu), Molybdenum (Mo), Chlorine (Cl), Iron (Fe) and Nickel (Ni).

17. Which one of the following is not an essential nutrient for plants? [I.A.S. (Pre) 1996]

Correct Answer: (c) Sodium
Solution:(ii) Micro-elements (Minor elements or Trace elements) – These are required by the plant in low quantities. Examples are Boron (B), Zinc (Zn), Manganese (Mn), Copper (Cu), Molybdenum (Mo), Chlorine (Cl), Iron (Fe) and Nickel (Ni).

18. Which of the following nutrient is most useful for enhancing oil content in mustard crop? [U.P. R.O./A.R.O. (Pre) 2021]

Correct Answer: (b) Sulphur
Solution:For mustard crop, Sulphur is the most important nutrient due to its role in metabolic processes of plant and oil synthesis in seeds.

Sulfur is a key component of many essential amino acids, like cysteine and methionine, which are building blocks of proteins.

Sulfur is directly involved in the synthesis of oils in mustard seeds.

Sulfur is necessary for the synthesis of chlorophyll, the pigment that enables plants to photosynthesize.

Sulfur plays a role in the activation of various enzymes involved in plant metabolism.

Glucosinolates, which give mustard its characteristic taste and pungency, require sulfur for their synthesis.

Adequate sulfur supply can lead to increased seed yield, oil content, and improved seed quality.

19. Plants accept nitrogen in which form? [U.P. R.O./A.R.O. (Mains) 2021]

Correct Answer: (c) Nitrate
Solution:Nitrogen is one of the most essential nutrients for plant growth. Although nitrogen gas in the atmosphere represents the largest quantity of the nutrient in the environment, it is unavailable to most plants as a direct source. Nitrogen is normally absorbed by plants from soil in the form of nitrate (NO₃⁻) ions, although in acid environments such as boreal forests, where nitrification is less likely to occur, ammonium (NH₄⁺) is more likely to be the dominant source of nitrogen.

20. The plants receive Nitrogen in form of : [U.P. P.C.S. (Pre) 2016]

Correct Answer: (b) Nitrate
Solution:Nitrogen is one of the most essential nutrients for plant growth. Although nitrogen gas in the atmosphere represents the largest quantity of the nutrient in the environment, it is unavailable to most plants as a direct source. Nitrogen is normally absorbed by plants from soil in the form of nitrate (NO₃⁻) ions, although in acid environments such as boreal forests, where nitrification is less likely to occur, ammonium (NH₄⁺) is more likely to be the dominant source of nitrogen.
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