NEET Biology Mineral Nutrition MCQs Set 14

Answer: (c) Pb, I, Na

Explanation:
1. Potassium, calcium, magnesium, iron, zinc, manganese, boron and molybdenum are all essential elements.
2. Lead, iodine and sodium are not required by most plants for completing their life cycle.

Teacher's Note:
1. An element is essential only if the plant cannot complete its life cycle without it. Sodium is beneficial only for some plants.

Answer: (c) A balanced nutrient solution

Explanation:
1. In hydroponics the roots are immersed in a nutrient solution that contains all the essential minerals in suitable amounts.
2. Distilled water alone would starve the plant, so option 4 is wrong.

Teacher's Note:
1. Julius von Sachs first grew plants this way in 1860. The method is used to find which minerals are essential.

Answer: (b) Fe, Mg and light

Explanation:
1. Magnesium is the central atom of the chlorophyll molecule.
2. Iron is required for chlorophyll synthesis, and light is needed for the final step of forming chlorophyll.

Teacher's Note:
1. Remember: Mg is part of chlorophyll, Fe is needed to make it. Deficiency of either causes chlorosis.

Answer: (a) Boron

Explanation:
1. Boron deficiency causes brown heart of beet and turnip because of breakdown of internal tissues.
2. Phosphorus, magnesium and molybdenum deficiencies produce different symptoms.

Teacher's Note:
1. Boron is linked with pollen germination, cell elongation and Ca uptake. Its deficiency kills the growing tips.

Answer: (c) Cu

Explanation:
1. Copper deficiency causes die back of shoot tips, as in citrus.
2. Mo deficiency causes whiptail, and Zn deficiency causes little leaf.

Teacher's Note:
1. Cu deficiency is also called reclamation disease in cereals and legumes.

Answer: (a) Whiptail disease of cauliflower

Explanation:
1. Whiptail of cauliflower arises because molybdenum is needed for nitrate reductase, and the leaves become narrow and twisted.
2. Little leaf is due to zinc, reclamation disease is due to copper and brown heart is due to boron.

Teacher's Note:
1. Mo is a component of nitrate reductase and nitrogenase.

Answer: (a) C, H, O, P, N, S

Explanation:
1. Protoplasm is made of carbohydrates, proteins, lipids and nucleic acids.
2. These are built from carbon, hydrogen, oxygen, nitrogen, phosphorus and sulphur.

Teacher's Note:
1. These six elements are also called protoplasmic elements because they build the living matter.

Answer: (c) Mn

Explanation:
1. Magnesium, calcium and phosphorus are needed in amounts above 10 mmole per kg of dry weight.
2. Manganese is needed in very small amounts, so it is a micronutrient.

Teacher's Note:
1. Macronutrients: C, H, O, N, P, K, Ca, Mg, S. Micronutrients: Fe, Mn, Cu, Zn, B, Mo, Cl, Ni.

Answer: (d) Ca

Explanation:
1. Manganese, molybdenum and copper are micronutrients.
2. Calcium is required in large amounts and is a macronutrient.

Teacher's Note:
1. Check the quantity: more than 10 mmole per kg dry weight means macronutrient.

Answer: (d) All of these

Explanation:
1. Cysteine and methionine contain sulphur in their side chains.
2. Cystine is formed by joining two cysteine molecules through a disulphide bond, so it also contains sulphur.

Teacher's Note:
1. Sulphur is also part of coenzyme A and some vitamins such as thiamine and biotin.

Answer: (b) C, H, O

Explanation:
1. Carbon, hydrogen and oxygen make up the bulk of the plant body, including cellulose and other carbohydrates.
2. They come from air and water, not the soil.

Teacher's Note:
1. Framework elements form the main structure of the plant, while the others act in smaller roles.

Answer: (a) Reclamation disease and little leaf

Explanation:
1. Reclamation disease of cereals and legumes is caused by copper deficiency.
2. Little leaf disease is caused by zinc deficiency, which blocks auxin synthesis and so reduces leaf size.

Teacher's Note:
1. Zn is needed for tryptophan and hence IAA synthesis. Without auxin the leaves stay small.

Answer: (a) Zn

Explanation:
1. Zinc is a micronutrient needed in trace amounts.
2. Nitrogen, phosphorus and calcium are macronutrients.

Teacher's Note:
1. Mo is needed in the very least quantity of all essential elements, but it is not among the options here.

Answer: (c) Mg : micronutrient

Explanation:
1. Magnesium is needed in large amounts and is a macronutrient.
2. Cu, Zn and Mn are micronutrients.

Teacher's Note:
1. Mg is part of chlorophyll and activates many enzymes such as RuBisCO and PEP carboxylase.

Answer: (a) N, P, K

Explanation:
1. Crops remove large amounts of nitrogen, phosphorus and potassium from the soil.
2. Their supply decides yield, so fertilisers mainly contain these three elements.

Teacher's Note:
1. NPK fertiliser labels refer to these three elements.

Answer: (b) K

Explanation:
1. Potassium ions are abundant in the cytoplasm and vacuole in free form and help in osmotic regulation.
2. Phosphorus is mostly bound in organic compounds and Fe and B are required in only tiny amounts.

Teacher's Note:
1. K⁺ also helps in opening and closing of stomata.

Answer: (d) Dephosphorylation of ATP

Explanation:
1. Active transport moves ions against the concentration gradient using energy from ATP.
2. ATP gives energy when its terminal phosphate is removed, that is by dephosphorylation.

Teacher's Note:
1. Active transport needs carrier proteins and metabolic energy, and it is selective.

Answer: (b) Mg

Explanation:
1. Chlorophyll has a porphyrin head with a central magnesium atom.
2. On burning, the organic part is lost and magnesium remains.

Teacher's Note:
1. Haemoglobin has Fe at the centre of its porphyrin, while chlorophyll has Mg.

Answer: (b) Zn

Explanation:
1. Khaira disease of rice is caused by zinc deficiency.
2. Zinc is needed for the synthesis of auxin (IAA).

Teacher's Note:
1. Zn deficiency: Khaira in paddy, little leaf in fruit trees and mottled leaf.

Answer: (b) Nitrate (NO₃⁻)

Explanation:
1. Nitrate is the most abundant and stable form of available nitrogen in aerated soil and is taken up by the roots.
2. Plants cannot use N₂ gas directly because they lack nitrogenase.

Teacher's Note:
1. Some nitrogen is also taken up as ammonium ions. Nitrate is later reduced to ammonia inside the plant.

Answer: (b) Carbon

Explanation:
1. Carbon makes up about 45 percent of the dry weight of plants.
2. Iron and manganese are trace elements and nitrogen is only a few percent.

Teacher's Note:
1. Carbon forms the backbone of all organic molecules.

Answer: (b) Mo

Explanation:
1. Molybdenum is a component of nitrate reductase and nitrogenase.
2. These enzymes reduce nitrate and fix atmospheric nitrogen.

Teacher's Note:
1. Mo deficiency causes whiptail in cauliflower.

Answer: (d) Carbon, hydrogen and oxygen

Explanation:
1. Carbohydrates, which form most of the dry matter, contain C, H and O.
2. Minerals taken from the soil are only about 5 percent of the dry weight.

Teacher's Note:
1. Almost 90 to 95 percent of dry weight is made of organic compounds.

Answer: (c) Mn

Explanation:
1. Manganese deficiency causes gray spot disease of oats.
2. Manganese is needed for the photolysis of water and for activity of many enzymes.

Teacher's Note:
1. Mn deficiency also causes chlorosis with green veins and necrotic spots.