Q1. Inorganic nutrients are present in the soil in the form of
Molecules
Atoms
Compounds
Electrically charged ions
Solution
Inorganic nutrients are present in the soil in the form of electrically charged ions. For example, K+ is present in inorganic compounds such as potassium sulphate, potassium nitrate etc. in clay soil.
Q2. Lime is
added to the soil which is too
Sandy
Salty
Alkaline
Acidic
Solution
Lime is
alkaline in nature. It is added to soil which is too acidic. It improves the
pH of the soil. Lime is added to the soil types which are deficient in calcium
and magnesium as in case of sandy soil.
Q3. Which one
of the following is a micronutrient in plants?
Magnesium
Zinc
Potassium
Calcium
Solution
Zinc is a
micronutrient and is required everywhere in the plant. It participates in
chlorophyll formation and helps in the production of the growth hormone auxin. Magnesium, potassium and calcium are
macronutrients which are required in large quantities by the plant.
Q4. Plants can be grown in
Soil with essential nutrients
Water with essential nutrients
Either water or soil with essential nutrients
Water or soil without essential nutrients
Solution
Plants can be grown in either water or soil with essential nutrients. The technique of growing plants by placing their roots in water with essential nutrients is called hydroponics.
Q5. Manganese in toxic concentrations leads to the deficiency of
Phosphorus
Iron
Potassium
Sulphur
Solution
Manganese in toxic concentrations leads to the deficiency of calcium,
iron and magnesium as it competes with iron and magnesium for nutrient
uptake.
Q6. Which one
of the following is not an essential mineral element for plants while the
remaining three are?
Iron
Manganese
Cadmium
Phosphorus
Solution
Cadmium
is not an essential element for plants, while iron, manganese and phosphorus
are essential elements for plants. Iron and manganese are micronutrients
required in minute quantities, whereas phosphorus is a macronutrient required
in large quantities by plants.
Q7. Deficiency
of which of the following can cause yellowing of intravenous regions of
leaves?
Calcium
Potassium
Copper
Phosphorus
Solution
Interveinal
chlorosis (i.e. yellowing of intravenous regions of leaves) occurs due to the
deficiency of potassium.
Q8. The
function of leghaemoglobin in the root nodules of legumes is
Inhibition
of nitrogenase activity
Oxygen removal
Nodule differentiation
Expression
of the nif gene
Solution
Leghaemoglobin
is a red-coloured pigment found in the root nodules of leguminous plants. It
combines with oxygen and thus helps in oxygen removal from root nodules.
Q9. During
nitrification, which bacteria convert ammonia to nitrate?
Nitrobacter
Pseudomonas
Nitrosomonas
Mycobacterium
Solution
Nitrosomonas convert ammonia to nitrate during the
process of nitrification in biological nitrogen fixation. It is performed in
two steps - nitrite formation and nitrate formation.
Q10. Elements which
make up 99% of all elements found in the living system are
C, H, O
C, H, O,
N
C, H, O,
N, P
C, H, O,
P
Solution
Carbon,
hydrogen, oxygen and nitrogen are the structural elements of cells. They are
the components of biomolecules so they make up to
99% of all elements found in the living system.
Q11. Which one
of the following elements in plants is not remobilised?
Phosphorus
Calcium
Potassium
Sulphur
Solution
Calcium
is an immobile element. It cannot be remobilised in plants, so its deficiency
symptoms first appear in younger tissues rather than older ones. Phosphorus,
potassium and sulphur are mobile elements. They can be remobilised in plants,
so their deficiency symptoms first appear in older tissues.
Q12. The number of essential elements required for normal growth of plants is
10
16
20
25
Solution
There are 16 essential elements required for the normal growth of plants. These essential elements are divided into two groups - micronutrients and macronutrients depending on their concentrations in dry matter.
Q13. Micronutrients
are
Mn, Ni,
Zn
O, Cu, B
Mg, Mn, Mo
Ca, S, Fe
Solution
Manganese,
nickel and zinc are micronutrients required in minute quantities by plants.
Their quantity is equal to or less than 10 mmol kg−1
of dry matter.
Q14. Name the element which plays an important role in biological nitrogen fixation.
Molybdenum
Manganese
Copper
Zinc
Solution
Molybdenum activates the enzymes involved in nitrogen metabolism and hence plays an important role in nitrogen fixation.
Q15. Bacteria
which reduce nitrates in the soil to nitrogen are
Nitrosomonas
Pseudomonas
Rhizobium
Clostridium
Solution
Pseudomonas reduce the nitrates to atmospheric nitrogen
by the process of denitrification.
Q16. Which one of the following statements can best explain the term critical concentration of an essential element?
Essential element concentration below which plant growth is retarded.
Essential element concentration below which plant growth becomes stunted.
Essential element concentration below which the plant remains in the vegetative phase.
None of the above.
Solution
Critical concentration is the concentration of an essential element below which plant growth is retarded. The element is called deficient when present below the critical concentration.
Q17. Denitrification is carried out by
Pseudomonas
Nitrobacter
Nitrosomonas
Nitrococcus
Solution
Pseudomonas reduces the nitrates into gaseous compounds of nitrogen and thus carries out the function of denitrification.
Q18. The
macronutrients which are an essential component of all organic compounds and
yet not obtained by plants from soil are
Nitrogen
Carbon
Phosphorus
Magnesium
Solution
Carbon is
obtained from air and is not obtained from the soil, so it is considered a non-mineral
element.
Nitrogen
is both a mineral and non-mineral element as it can be obtained from air or
soil.
Phosphorus
and magnesium are present in soil, so they are considered mineral elements.
Q19. Conversion
of ammonia into nitrates through Nitrosomonas
is called
Nitrogen
fixation
Nitrification
Denitrification
Ammonification
Solution
Nitrosomonas convert ammonia into nitrates by a process
called nitrification. It is performed in two steps - nitrite formation and
nitrate formation.
Q20. The most
abundant element present in plants is
Nitrogen
Manganese
Iron
Carbon
Solution
Carbon,
hydrogen, oxygen and nitrogen form the composition of plant body. The most
abundant element present in plants is oxygen. Next to oxygen is carbon. Iron
and manganese are found in trace quantities.
Q21. Insectivorous plants are usually adapted to
Water-rich soil
Soil deficient in sugars
Soil rich in trace elements
Soil deficient in nitrogenous compounds
Solution
Insectivorous plants are usually adapted to soil deficient in nitrogenous compounds. They trap and digest the insects to absorb mineral nutrition, particularly nitrogen.
Q22. Which one
of the following is a wrong statement?
Anabaena and Nostoc
are capable of fixing nitrogen in the free-living state also.
Root nodule-forming
nitrogen fixers live as aerobes under free-living conditions.
Phosphorus
is a constituent of cell membranes, certain nucleic acids and cell proteins.
Nitrosomonas and Nitrobacter
are chemoautotrophs.
Solution
Root nodule-forming
nitrogen fixers show symbiotic relationship with the host plant. They are not
free living.
Q23. Which of
the following is not an essential element?
Iron
Manganese
Zinc
Iodine
Solution
Iodine is
not an essential element as its deficiency does not make it impossible for a
plant to complete the vegetative or reproductive stage of its life cycle.
Iron, manganese and zinc are essential elements which cannot be replaced by
another element.
Q24. Which one of the following is not an essential element for plants?
Aluminium
Copper
Iron
Zinc
Solution
Aluminium is not an essential element as its deficiency does not make it impossible for a plant to complete the vegetative or reproductive stage of its life cycle. Copper, iron and zinc are essential elements.
Q25. Which is essential for root hair growth?
Zn
Ca
Mo
S
Solution
Calcium is essential for the development of root hair as well as the root and stem apices.
Q26. Molybdenum is the essential constituent of
Nitrogenase
Respiratory chain
Growth regulators
Chlorophyll
Solution
Molybdenum is the essential constituent of nitrogenase enzyme. Nitrogenase is a Mo-Fe protein and catalyses the conversion of atmospheric nitrogen into ammonia.
Q27. The middle lamella mainly contains
Ca
Mg
Na
K
Solution
Calcium is required for the synthesis of pectin in the middle lamella of the cell wall.
Q28. The major portion of the dry weight of plants comprises
Calcium, magnesium and sulphur
Carbon, nitrogen and hydrogen
Carbon, hydrogen and oxygen
Nitrogen, phosphorus and potassium
Solution
Carbon, hydrogen and oxygen are present in plant tissues in concentrations of at least one milligram per gram of dry matter. Thus, they constitute the major portion of the dry weight of plants.
Q29. The deficiency of which element affects the process of photosynthesis
Calcium
Magnesium
Chlorine
Sulphur
Solution
The deficiency of chlorine affects the process of photosynthesis as it
plays an important role in PS II during photosynthesis.
Q30. Which one
of the following microbes forms a symbiotic association with plants and helps
them in their nutrition.
Azotobacter
Aspergillus
Glomus
Trichoderma
Solution
Glomus is a fungus which forms a symbiotic
association with the roots of plants (mycorrhiza) and helps them to absorb
their nutrition.
Q31. In cabbages, ‘Whiptail’ is a characteristic deficiency disease. It is caused by the deficiency of
Chlorine
Magnesium
Molybdenum
Boron
Solution
In cabbages, ‘Whiptail’ is caused by the deficiency of molybdenum
which is characterised by the distortion of young leaves, a long mid-rib and
poorly developed ragged blades.
Q32. Which one of the following elements is not an essential micronutrient for plant growth?
Zn
Cu
Ca
Mn
Solution
Calcium is not an essential micronutrient, but it is an essential macronutrient required in large quantities by the plant. It is essential for the synthesis of pectin in the middle lamella of the cell wall and is required for the development of stem and root apices.
Q33. The element which regulates stomatal movement is
Potassium
Sodium
Sulphur
Phosphorus
Solution
Potassium regulates stomatal movement. It helps in the opening and closing of stomata. Influx of potassium ions opens the stomata, while efflux of potassium ions closes the stomata.
Q34. Name the
elements which occur in a nucleic acid molecule.
C, H, O,
N, S
C, O, N,
S
C, O, P,
S
C, H, O,
N, P
H, O, P
Solution
Nucleic
acid comprises the elements C, H, O, N and P. Nucleic acids are linear
polymers of nucleotides consisting of a nitrogenous base (purine or
pyrimidine), pentose sugar and phosphate group.
Q35. About 98% of the mass of every living organism is composed of just six elements including carbon, hydrogen, nitrogen, oxygen,
Sulphur and magnesium
Magnesium and sodium
Calcium and phosphorus
Phosphorus and sulphur
Solution
Six elements which make about 98% mass of every living organism are carbon, hydrogen, nitrogen, oxygen, phosphorus and sulphur. These are also called the building elements of living organisms.
Q36. Nitrogenase enzyme converts
Atmospheric nitrogen into ammonia
Ammonia into nitrate and nitrite
Nitrate into nitrite
Nitrate and nitrite into nitrogen
Solution
Nitrogenase enzyme catalyses the conversion of atmospheric nitrogen into ammonia.
Q37. The function of leghaemoglobin (a red pigment) in root nodules of leguminous plant is
To regulate O2 supply in cells
To regulate CO2 supply in cells
To regulate production of phenolic compounds
To regulate the Mo supply in cells
Solution
Leghaemoglobin is a red pigment which gives a pinkish appearance to the nodules of leguminous plants. It combines with oxygen and regulates O2 supply in cells.
Q38. For its action, nitrogenase requires
High input of energy
Light
Mn2+
Super oxygen radicals
Solution
The nitrogenase enzyme requires a high input of energy in the form of ATP. ATP is used to transfer hydrogen atoms to dinitrogen during biological nitrogen fixation.
Q39. Which of the following is a macronutrient?
Mo
Ca
Zn
Mn
Solution
Calcium is a macronutrient which is found abundantly in most of the soil types and plants. It is important for the synthesis of pectin in the middle lamella of the cell wall. Mo, Zn and Mn are micronutrients which are required in minute quantities by plants.
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