Online Test — Mineral Nutrition
15 Questions • 15 min • Chapter MCQ
15:00
Question 1 of 15
Which gases/elements come from air and water, not the soil?
Nitrogen, phosphorus, potassium
Carbon, hydrogen, oxygen
Iron, zinc, copper
Calcium, magnesium, sulphur
Explanation: C, H and O come from air and water; minerals come from the soil.
Question 2 of 15
An essential element is one that:
Can be replaced by another element
Is needed to complete the life cycle and has a specific role
Is never used in metabolism
Is only decorative
Explanation: Essential elements are required to complete the life cycle and have specific irreplaceable roles.
Question 3 of 15
Nutrients needed in large amounts are:
Micronutrients
Macronutrients
Vitamins
Trace elements
Explanation: Macronutrients (N, P, K, etc.) are needed in large amounts.
Question 4 of 15
Which of these is a micronutrient?
Nitrogen
Potassium
Zinc
Calcium
Explanation: Zinc is a micronutrient (trace element).
Question 5 of 15
The soil-less culture method used to identify essential elements is:
Hydroponics
Grafting
Layering
Budding
Explanation: Hydroponics grows plants in a defined nutrient solution.
Question 6 of 15
Nitrogen is a component of all the following EXCEPT:
Proteins
Nucleic acids
Chlorophyll
Cellulose
Explanation: Cellulose is a carbohydrate (no nitrogen); proteins, nucleic acids and chlorophyll contain nitrogen.
Question 7 of 15
The central atom of the chlorophyll molecule is:
Iron
Magnesium
Calcium
Zinc
Explanation: Magnesium sits at the centre of chlorophyll.
Question 8 of 15
General yellowing of leaves due to lack of chlorophyll is:
Necrosis
Chlorosis
Etiolation
Wilting
Explanation: Chlorosis is loss of green colour from reduced chlorophyll.
Question 9 of 15
Deficiency symptoms of mobile elements (N, P, K) appear first in:
Older leaves
Younger leaves
Roots only
Flowers only
Explanation: Mobile elements are moved from old to young leaves, so symptoms show first in older leaves.
Question 10 of 15
Calcium is mainly needed for the:
Cell wall and cell division
Chlorophyll molecule
Stomatal opening
Triple bond of N₂
Explanation: Calcium is part of the cell wall (middle lamella) and is needed for cell division.
Question 11 of 15
Plants cannot use atmospheric N₂ directly because it is:
Too rare
Very unreactive (strong triple bond)
Poisonous
A solid
Explanation: The strong N≡N triple bond makes N₂ unreactive; it must be fixed first.
Question 12 of 15
The enzyme that carries out biological nitrogen fixation is:
Amylase
Nitrogenase
Pepsin
Catalase
Explanation: Nitrogenase fixes nitrogen in nitrogen-fixing microbes.
Question 13 of 15
Rhizobium fixes nitrogen in the root nodules of:
Cereals
Legumes
Grasses
Conifers
Explanation: Rhizobium lives symbiotically in legume root nodules.
Question 14 of 15
Which is a free-living nitrogen fixer?
Rhizobium
Azotobacter
Amoeba
Yeast
Explanation: Azotobacter is a free-living soil nitrogen fixer.
Question 15 of 15
Growing legumes to enrich soil nitrogen is the basis of:
Crop rotation
Hydroponics
Transpiration
Pruning
Explanation: Legumes restore soil nitrogen, which is why crop rotation includes them.