Mineral Nutrition

Question1
Which micronutrient is required for splitting of water molecule during
photosynthesis?

[NEET 2023]
Options:

A.
Molybdenum

B.
Magnesium

C.
Copper

D.
Manganese

Answer: D

Solution:

Solution:

Manganese plays a major role in the splitting of water to liberate oxygen during photosynthesis.
Copper is essential for the overall metabolism in plants.
Molybdenum is included in nitrogen metabolism.
Magnesium activates several enzymes involved in photosynthesis and respiration.

-------------------------------------------------------------------------------------------------

Question2
Match List I with List II:

List I List II
A. Iron I. Synthesis of auxin
B. Zinc II. Component of nitrate reductase
C. Boron III. Activator of catalase
D. Molybdenum IV. Cell elongation and differentiation

Choos the correct answer from the options given below:

[NEET 2023]
Options:

A.

A-II, B-III, C-IV, D-I

B.

A-III, B-I, C-IV, D-II

C.

A-II, B-IV, C-I, D-III

D.
A-III, B-II, C-I, D-IV

Answer: B

Solution:

Solution:

Iron activates catalase enzyme.

-------------------------------------------------------------------------------------------------

Question3
Which of the following mineral ion is not remobilized in plants?

[NEET 2023 mpr]

Options:

A.
Potassium

B.
Calcium

C.
Nitrogen

D.
Phosphorus

Answer: B

Solution:

Mineral remobilization is a process in which nutrients are transported from older tissues (like mature leaves) to newer
ones (like young leaves or developing seeds). Most mineral ions like potassium, nitrogen, and phosphorus are
remobilized in plants. However, calcium, once incorporated into plant tissue, generally remains immobile. Therefore,
calcium is considered a mineral ion that is not remobilized in plants.

-------------------------------------------------------------------------------------------------

Question4
Match Column I with Column II.

Column - I Column - II
(A) Nitrococcus (I) Denitrification
(B) Rhizobium (II) Conversion of ammonia to nitrite
(C) Thiobacillus (III) Conversion of nitrite to nitrate
(D) Nitrobacter (IV) Conversion of atmospheric nitrogen to ammonia

[NEET 2023 mpr]

Options:

A.
(A)-(III), (B)-(I), (C)-(IV), (D)-(II)

B.
(A)-(IV), (B)-(III), (C)-(II), (D)-(I)

C.

(A)-(II), (B)-(IV), (C)-(I), (D)-(III)

D.
(A)-(I), (B)-(II), (C)-(III), (D)-(IV)

Answer: C

Solution:

Explanation :

(A) Nitrococcus - (II) Conversion of ammonia to nitrite: Nitrococcus is a type of bacteria involved in the nitrification
process, specifically, it converts ammonia into nitrite.

(B) Rhizobium - (IV) Conversion of atmospheric nitrogen to ammonia: Rhizobium is a type of bacteria found in soil that
fix nitrogen after becoming established inside root nodules of legumes. They convert atmospheric nitrogen into
ammonia, a process known as nitrogen fixation.

(C) Thiobacillus - (I) Denitrification: Thiobacillus is involved in denitrification, the process of reducing nitrates and
nitrites to nitrogen gas and returning it to the atmosphere.

(D) Nitrobacter - (III) Conversion of nitrite to nitrate: Nitrobacter is a genus of bacteria that play an important role in
the nitrogen cycle, where they convert nitrite to nitrate.

-------------------------------------------------------------------------------------------------
Question5

Choose the correct answer from the options given below :

A. (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)

B. (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)

C. (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)

D. (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)

Answer: C

Solution:

(a) Porins-Types of proteins which forms pores of large size in the outer membranes of plastids such as chloroplast,
mitochondria and membranes in bacteria.
(b) Leg-Haemoglobin-Pink pigment in root nodules of leguminous plants, as soybean, that is essential for N2 − fixation. It
acts as O2-scavenger
+
(c) H -accumulation → lumen of thylakoid.
(d) Respiration-Amphibolic pathway → a biochemical pathway that includes both anabolic and catabolic processes.

-------------------------------------------------------------------------------------------------

Question6
Which of the following protects nitrogenase inside the root nodule of a
leguminous plant?
[NEET Re-2022]
Options:

A. Glutamate dehydrogenase

B. Catalase

C. leg haemoglobin

D. Transaminase

Answer: C
Solution:

The enzyme Nitrogenase is highly sensitive to the molecular oxygen square It acquires anaerobic condition. The nodules
have adaptations that ensure that the enzyme is protected from oxygen. To protect these enzymes, the nodule contains
an oxygen scavenger called leghaemoglobin.

-------------------------------------------------------------------------------------------------

Question7
Which of the following pair represents free living nitrogen fixing
aerobic bacteria?
[NEET Re-2022]
Options:

A. Pseudomonas and Thiobacillus

B. Rhizobium and Beijernickia

C. Azotobacter and Beijernickia

D. Anabaena and Rhodospirillum

Answer: C

Solution:

Solution:

Atmospheric N2 cannot be utilized by living organisms. Few prokaryotes can reduce nitrogen (N2) into ammonia-
Biological Nitrogen Fixation.
N2 fixing bacteria can be free living or symbiotic.

Azotobacter, Beijernickia - Free living N2 fixers.

-------------------------------------------------------------------------------------------------

Question8
Which one of the following produces nitrogen fixing nodules on the
roots of Alnus?
[NEET-2022]
Options:

A. Rhizobium

B. Frankia

C. Rhodospirillum

D. Beijerinckia

Answer: B

Solution:
The microbe, Frankia, produces nitrogen fixing nodules on the roots of non-leguminous plants (e.g.Alnus)

-------------------------------------------------------------------------------------------------

Question9
Match Column-I with Column-II.

Choose the correct answer from options given below.

A. (a)-(ii) (b)-(iv) (c)-(i) (d)-(iii)

B. (a)-(i) (b)-(ii) (c)-(iii) (d)-(iv)

C. (a)-(iii) (b)-(i) (c)-(iv) (d)-(ii)

D. (a)-(iv) (b)-(iii) (c)-(ii) (d)-(i)

Answer: A

Solution:

Solution:
• Nitrogen fixation is conversion of atmospheric N 2 to N H 3 (ammonia). It is carried out by N 2 fixers such as Rhizobium.
• N H 3 is converted to N O2−(nitrite) by nitrifying bacteria such as Nitrococcus.
• Then N O2−is converted to N O3−(nitrate) by nitrfying bacteria called Nitrobacter.
• Thiobacillus carries out denitrification, a process where N O2− ∕ N O3− is converted to N 2.

-------------------------------------------------------------------------------------------------

Question10
Match the following concerning essential elements and their functions
in plants
[2020]
Options:

A. (a)

B. (b)

C. (c)

D. (d)

Answer: B

Solution:

Solution:
(b) Iron is essential for the formation of chlorophyll. Zinc is needed for synthesis of auxin. Boron plays a role in pollen
grain germination. Manganese is involved in the splitting of water to liberate O2, during photosynthesis.
Iron (Fe) deficiency is a plant disorder also known as “lime-induced chlorosis”. Zinc deficiency occurs when plant growth
is limited because the plant cannot take up sufficient quantities of this essential micronutrient from its growing medium.
boron deficiency are expressed at growing tips of the root or shoot, and generally include stunting and distortion of the
growing tip that can lead to tip death, brittle foliage, and yellowing of lower leaf tips. Manganese deficiency causes
yellowing of leaves and undergoes interveinal chlorosis.

-------------------------------------------------------------------------------------------------
Question11
The product(s) of reaction catalyzed by nitrogenase in root nodules of
leguminous plants is/are
[2020]
Options:

A. Nitrate alone

B. Ammonia and oxygen

C. Ammonia and hydrogen

D. Ammonia alone

Answer: C

Solution:

Solution:
(c) Ammonia and Hydrogen.
N 2 + 8e− + 8H + + 16AT P → 2N H 3 + H 2 +16ADP + 16Pi
The steps involved in the process of nitrogen fixation are as follows:
The steps involved in the process of nitrogen fixation are as follows:

Rhizobia multiply and colonise the surroundings of roots and get attached to epidermal and root hair cells.
The root-hairs curl and the bacteria invade the root-hair.
An infection thread is produced carrying the bacteria into the cortex of the root, where they initiate the nodule
formation in the cortex of the root.
Then the bacteria are released from the thread into the cells which leads to the differentiation of specialised
nitrogen fixing cells.
The nodule thus formed, establishes a direct vascular connection with the host for exchange of nutrients.
The nodule contains all the necessary biochemical components, such as the enzyme nitrogenase and
leghaemoglobin.
The enzyme nitrogenase is a Mo-Fe protein and catalyses the conversion of atmospheric nitrogen to ammonia, the
first stable product of nitrogen fixation.

-------------------------------------------------------------------------------------------------

Question12
In which of the following forms is iron absorbed by plants?
[2018]

Options:
A. Ferric

B. Ferrous

C. Both ferric and ferrous

D. Free element

Answer: A

Solution:

Solution:
(a) Iron is absorbed by plants in the form of ferric ions.
2+ 3+
Plants uptake iron in its oxidized forms, F e (ferrous form) or F e (ferric form). Another mechanism involves the
+
release of protons (H ) and reductants by the plant roots, to lower pH levels in root zone. Iron is considered a micro-
nutrient because only small amounts are required to aid in normal plant growth. Plants can suffer iron deficiency with
symptoms of chlorosis and stunted growth, but plants can also take in too much iron, especially under certain growing
conditions.

-------------------------------------------------------------------------------------------------

Question13
Which of the following elements is responsible for maintaining turgor in
cells?
[2018]

Options:

A. Magnesium

B. Sodium

C. Calcium

D. Potassium

Answer: D

Solution:

Solution:
(d) Plants require potassium ions (K+) for protein synthesis and for the opening and closing of stomata, which is
regulated by proton pumps to make surrounding guard cells either turgid or flaccid.

-------------------------------------------------------------------------------------------------

Question14
Which is essential for the growth of root tip?
NEET II 2016

Options:
A. Z n

B. F e

C. Ca

D. M n

Answer: C

Solution:

Solution:
(c) : Calcium (Ca) is necessary for the proper growth and functioning of root tips and meristems.

-------------------------------------------------------------------------------------------------

Question15
In which of the following all three are macronutrients?
NEET I 2016

Options:

A. Molybdenum, magnesium, manganese

B. Nitrogen, nickel, phosphorus

C. Boron, zinc, manganese

D. Iron, copper, molybdenum

E. None of the above

Answer: E

Solution:

Solution:
None of the options is correct. Macronutrients are essential elements which are present in easily detectable quantities, 1-
10 mg per gram of dry weight. The macronutrients include carbon, hydrogen, oxygen, nitrogen, phosphorous, sulphur,
potassium, calcium and magnesium. Micronutrients or trace elements, are needed in very small amounts (equal or less
than 0.1 mg/gm of dry matter). These include iron, manganese, copper, molybdenum, zinc, boron, chlorine and nickel.

-------------------------------------------------------------------------------------------------

Question16
The oxygen evolved during photosynthesis, comes from water molecules.
Which one of the following pairs of elements is involved in this
reaction?
NEET 2015
Options:

A. Magnesium and Molybdenum

C. Manganese and Chlorine

D. Manganese and Potassium

Answer: C

Solution:

(c) : Oxygen is evolved during photosynthesis by the process of photolysis of water taking place in the membranes of
grana thylakoids. The phenomenon of breaking up of water into hydrogen and oxygen in the illuminated chloroplasts is
called photolysis or photocatalytic splitting of water. Light energy, an oxygen evolving complex (OEC) and electron
carrier Y z are required for this process. Oxygen evolving complex is attached to the inner surface of thylakoid membrane
2+ 3+ 4+ −
and the enzyme has four Mn ions. Light energised changes in Mn (M n , M n , M n ) remove electrons from OH
component of water forming oxygen. Liberation of O2 also requires two other ions, Ca2+ and Cl −

-------------------------------------------------------------------------------------------------

Question17
During biological nitrogen fixation, inactivation of nitrogenase by
oxygen poisoning is prevented by
NEET 2015

Options:

A. carotene

B. cytochrome

C. leghaemoglobin

D. xanthophyll

Answer: C

Solution:

Solution:
(c) : Leghaemoglobin is a pinkish pigment present in the root nodules of leguminous plants. It acts as oxygen scavenger
and prevents the inactivation of nitrogenase enzyme by oxygen poisoning.

-------------------------------------------------------------------------------------------------

Question18
Minerals known to be required in large amounts for plant growth
include
2015 cancelled
Options:

A. potassium, phosphorus, selenium, boron

B. magnesium, sulphur, iron, zinc

C. phosphorus, potassium, sulphur, calcium

D. calcium, magnesium, manganese, copper

Answer: C

Solution:

Solution:
(c) : Macroelements (macronutrients) are those essential elements which are present in easily detectable quantities, i.e.,
1 − 10mg per gram of dry matter. Macroelements are usually involved in the synthesis of organic molecules and
development of osmotic potential. They are nine in number −C, H , O, N , P, K , S, M g and Ca

-------------------------------------------------------------------------------------------------

Question19
Deficiency symptoms of nitrogen and potassium are visible first in
2014

Options:

A. senescent leaves

B. young leaves

C. roots

D. buds

Answer: A

Solution:

Solution:
(a) : Deficiency symptoms appear first in young leaves and young tissues in case of elements which are relatively
immobile inside the plant e.g., Ca, S For mobile elements like N and K , deficiency symptoms first appear in old and
senescent leaves as the elements are mobilised from senescing regions for supply to young tissues.

-------------------------------------------------------------------------------------------------

Question20
The deficiencies of micronutrients, not only affects growth of plants but
also vital functions such as photosynthetic and mitochondrial electron
flow. Among the list given below, which group of three elements shall
affect most, both photosynthetic and mitochondrial electron transport?
2005
 ©

Options:

A. Co, N i, M o

B. Ca, K , N a

C. M n, Co, Ca

D. Cu, M n, F e

Answer: D

Solution:

Solution:
(d) : Iron is mainly available in the ferrous form and it is absorbed in the ferric form, also. It is a part of catalases,
peroxidases, cytochromes etc. and plays a role in electron transport system in photosynthesis. Manganese is absorbed
by the plants when it is in the bivalent form. Manganese participates in the photolysis of water in pigment system II
during photosynthesis and thus it helps in the electron transport from water to chlorophyll. Copper is absorbed on the
clay particles as divalent cations, from where it can be absorbed by the plants by exchange mechanism. It is constituent
of plastocyanin which takes part in electron transport during photosynthetic phosphorylation.

-------------------------------------------------------------------------------------------------

Question21
The first stable product of fixation of atmospheric nitrogen in
leguminous plants is
2013

Options:
−
A. N O3

B. glutamate
−
C. N O2

D. ammonia

Answer: D

Solution:

Solution:
(d) : The enzyme nitrogenase is a Mo- Fe protein and catalyses the conversion of atmospheric nitrogen to ammonia, the
first stable product of nitrogen fixation. Nitrogen fixation is the conversion of inert atmospheric nitrogen or dinitrogen
(N 2) into utilisable compounds of nitrogen like nitrate, ammonia, amino acids etc. There are two methods of nitrogen
fixation abiological and biological. Biological nitrogen fixation is performed by both free living and symbiotic forms.
Symbiotic nitrogen fixing organisms hand over a part of their nitrogen to the host in return for shelter and food. The
nodule of leguminous plants contains all the necessary biochemical components, such as the enzyme nitrogenase and
leghaemoglobin, for nitrogen fixation.

-------------------------------------------------------------------------------------------------
Question22
Specialized cells for fixing atmospheric nitrogen in Nostoc are
KN 2013

Options:

A. heterocysts

B. hormogonia

C. nodules

D. akinetes

Answer: A

Solution:

Solution:
(a) : Certain species of cyanobacteria (Nostoc) possess some special cells called heterocysts which occur in terminal,
basal and intercalary positions. Heterocysts are yellowish in colour and contents are homogenous. Heterocysts are now
known as sites of nitrogen fixation. Atmospheric nitrogen is made available in the form of ammonia by cyanobacteria.

-------------------------------------------------------------------------------------------------

Question23
Which of the following elements is a constituent of biotin?
KN 2013
Options:

A. Magnesium

B. Calcium

C. Phosphorus

D. Sulphur

Answer: D

Solution:

Solution:
(d) : Sulphur is present in two vitamins of B complex, thiamine and biotin. Biotin is important to hair. It is normally found
in protein foods, such as eggs, lettuce, sprouts etc.

-------------------------------------------------------------------------------------------------

Question24
Which two distinct microbial processes are responsible for the release
of fixed nitrogen as dinitrogen gas (N 2) to the atmosphere?
KN 2013

Options:

A. Aerobic nitrate oxidation and nitrite reduction

B. Decomposition of organic nitrogen and conversion of dinitrogen to ammonium compounds

C. Enteric fermentation in cattle and nitrogen fixation by Rhizobium in root nodules of legumes

D. Anaerobic ammonium oxidation and denitrification

Answer: D

Solution:

Solution:
(d) : Denitrification is a chemical process in which nitrates in the soil are reduced to molecular nitrogen (N 2) which is
released into the atmosphere. It is done by denitrifying bacteria like Pseudomonas denitrificans. Anaerobic oxidation of
ammonium (N H 4) also releases nitrogen in the atmosphere.

-------------------------------------------------------------------------------------------------

Question25
Best defined function of manganese in green plants is
2012

Options:

A. photolysis of water

B. Calvin cycle

C. nitrogen fixation

D. water absorption.

Answer: A

Solution:

Solution:
2+
(a) : Manganese (Mn ) is used for photolysis of water to produce oxygen and electrons during light reaction of
photosynthesis. It is the phenomenon of breaking up of water into hydrogen and oxygen in the illuminated chloroplast. It
acts as an essential cofactor.

-------------------------------------------------------------------------------------------------

Question26
Which one of the following is correctly matched?
2012
 ©

Options:

A. Passive transport of nutrients - ATP

B. Apoplast - Plasmodesmata

C. Potassium - Readily immobilisation

D. Bakane of rice seedlings −F . Skoog

Answer: C

Solution:

Solution:
(c) : Immobilization or fixation of a nutrient means that the nutrient becomes unavailable for plant. The process of
converting exchangeable or water soluble potassium to its non exchange or water insoluble form is known as potassium
immobilisation. Potassium is present in relatively large quantities in soil (averaging about 1.9 % ). Depending on the
circumstances, soil potassium may be not easily available, slowly available or readily available. The first category
accounts for 90 to 98 % of the total soil potassium, which is only slightly soluble, the second category constitutes 2-10 %
of total mineral soil and third category makes up for about 1%

-------------------------------------------------------------------------------------------------

Question27
For its action, nitrogenase requires
Mains 2012

Options:

A. high input of energy

B. light
2+
C. M n

D. super oxygen radicals

Answer: A

Solution:

Solution:
(a) : Nitrogenase enzyme is present in prokaryotic nitrogen fixers. The enzyme nitrogenase requires a high input of
energy to carry out biological nitrogen fixation. This can be illustrated by the following equation.
Nitrogenase
− +
N 2 + 8e + 8H + 16 ATP ──────── 2 NH3 + H2 + 16 ADP + 16Pi

-------------------------------------------------------------------------------------------------

Question28
Which one of the following elements in plants is not remobilised?
2011

Options:

A. Phosphorus

B. Calcium

C. Potassium

D. Sulphur

Answer: B

Solution:

Solution:
Calcium is the element in plants which is not mobilised.
This is because it is a structural component and hence needs to be localised.
Phosphorus, Sulphur and Potassium are not structural elements and hence can be remobilised based on their need.
Thus the element in plants is not remobilised is calcium.

-------------------------------------------------------------------------------------------------

Question29
Nitrifying bacteria
2011

Options:

A. oxidize ammonia to nitrates

B. convert free nitrogen to nitrogen compounds

C. convert proteins into ammonia

D. reduce nitrates to free nitrogen

Answer: A

Solution:

Solution:
(a) : Nitrifying bacteria involves the oxidation of ammonia to nitrates through nitrites called nitrification. Nitrite bacteria
(Nitrosomonas and Nitrococcus) convert ammonia to nitrites whereas, nitrate bacteria (Nitrobacter and Nitrocystis)
convert nitrite to soluble nitrates.

-------------------------------------------------------------------------------------------------

Question30
The function of leghaemoglobin in the root nodules of legumes is
2011
 ©

Options:

A. inhibition of nitrogenase activity

B. oxygen removal

C. nodule differentiation

D. expression of nif gene

Answer: B

Solution:

Solution:
(b) : The root nodule of legume contains enzyme nitrogenase and leghaemoglobin. Nitrogenase catalyses the conversion
of atmospheric nitrogen to ammonia. It is highly sensitive to the molecular oxygen and requires anaerobic conditions.
The nodules have adaptations that ensure that the enzyme is protected from oxygen. To protect these enzymes, the
nodule contains an oxygen scavenger called leghaemoglobin.

-------------------------------------------------------------------------------------------------

Question31
Which one of the following helps in absorption of phosphorus from soil
by plants?
2011

Options:

A. Glomus

B. Rhizobium

C. Frankia

D. Anabaena

Answer: A

Solution:

Solution:
(a) : Some fungi form symbiotic associations with plants (mycorrhiza). Many members of the genus Glomus form
mycorrhiza. The fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant. Plants
having such associations show other benefits also, such as resistance to root borne pathogens, tolerance to salinity and
drought, and an overall increase in plant growth and development.

-------------------------------------------------------------------------------------------------

Question32
Which one of the following is not an essential mineral element for
plants while the remaining three are?
Mains 2011

Options:

A. Iron

B. Manganese

C. Cadmium

D. Phosphorus

Answer: C

Solution:

Solution:
(c) : C, H, O, N, P, K, S, M g, C a, F e, B, M n, C u, Zn, Mo, Cl, Ni are essential elements, which has a specific structural or
physiological role and without which plant cannot complete their life cycle.

-------------------------------------------------------------------------------------------------

Question33
An element playing important role in nitrogen fixation is
2010

Options:

A. molybdenum

B. copper

C. manganese

D. zinc.

Answer: A

Solution:

Solution:
(a) : Molybdenum is a micronutrient which is required in very minute amount by the plants. It is responsible for
nodulation in legumes. It is part of nitrate reductase enzyme which helps in nitrogen fixation.

-------------------------------------------------------------------------------------------------

Question34
Which one of the following is not a micronutrient?
2010
 ©

Options:

A. Molybdenum

B. Magnesium

C. Zinc

D. Boron

Answer: B

Solution:

Solution:
Macronutrients are essential elements which are present in easily detectable quantities, 1-10 mg per gram of dry weight.
The macronutrients include carbon, hydrogen, oxygen, nitrogen, phosphorous, sulphur, potassium, calcium and
magnesium. Micronutrients or trace elements, are needed in very small amounts (equal or less than 0.1 mg/gm of dry
matter). These include iron, manganese, copper, molybdenum, zinc, boron, chlorine and nickel.

-------------------------------------------------------------------------------------------------

Question35
Leguminous plants are able to fix atmospheric nitrogen through the
process of symbiotic nitrogen fixation. Which one of the following
statements is not correct during this process of nitrogen fixation?
Mains 2010

Options:

A. Leghaemoglobin scavenges oxygen and is pinkish in colour.

B. Nodules act as sites for nitrogen fixation.

C. The enzyme nitrogenase catalyses the conversion of atmospheric N 2 to N H 3.

D. Nitrogenase is insensitive to oxygen.

Answer: D

-------------------------------------------------------------------------------------------------
Question36
Study the cycle shown below and select the option which gives correct
words for all the four blanks mathrm A, mathrm B, mathrm C and
mathrm D
Mains 2010
Options:

A. (a)

B. (b)

C. (c)

D. (d)

Answer: B

Solution:

(b) : A - Denitrification
B - Ammonification
C - Plants
D-Animals

-------------------------------------------------------------------------------------------------

Question37
Manganese is required in
2009

Options:

A. plant cell wall formation

B. photolysis of water during photosynthesis

C. chlorophyll synthesis

D. nucleic acid synthesis

Answer: B

Solution:

2+
(b) : Manganese (Mn ) is used for photolysis of water to produce oxygen and electrons during light reaction of
photosynthesis. It is the phenomenon of breaking up of water into hydrogen and oxygen in the illuminated chloroplast. It
acts as an essential cofactor.

-------------------------------------------------------------------------------------------------

Question38
Which one of the following elements is not an essential micronutrient
for plant growth?
2007
 ©

Options:

A. Z n

B. Cu

C. Ca

D. M n

Answer: C

Solution:

Solution:
(c) : Calcium is an essential macronutrient for plant growth. Macronutrients are essential elements which are required by
plants in quantity more than 1mg/g dry matter. It is used as a calcium pectinate for the formation of middle lamella in
cell wall for lipid metabolism, for cell division and cell enlargement, helps in translocation of carbohydrates and also
activates enzyme activity in plants. All other like Zn, Cu and Mn are micronutrients of plants.

-------------------------------------------------------------------------------------------------

Question39
A plant requires magnesium for
2007

Options:

A. protein synthesis

B. chlorophyll synthesis

C. cell wall development

D. holding cells together

Answer: B

Solution:

Solution:
(b) : Magnesium is an important constituent of chlorophyll, found in all green plants and essential for photosynthesis. The
chlorophyll molecule has a tetrapyrolic or porphyrin head and a phytol tail. Mg atom is present in the centre of porphyrin
head. It is like tennis racket.

-------------------------------------------------------------------------------------------------

Question40
Sulphur is an important nutrient for optimum growth and productivity
in
2006
 ©

Options:

A. oilseed crops

B. pulse crops

C. cereals

D. fibre crops

Answer: A

Solution:

Solution:
(a) : Sulphur is present in all the cells of the body in association with proteins made of sulphur containing amino acids,
viz., cystine, cysteine and methionine. Members of Cruciferae and animal proteins are rich sources of sulphur; other
vegetable proteins (e.g., pulses) have only little sulphur. Plants absorb sulphur from soil in the form of sulphate ions
(SO4−−). It is a constituent of ferredoxin and some of the lipids present in chloroplasts. Pungent floroue and odour of
mustard, cabbage, turnip etc. of Family Brassicaceae is due to the presence of sulphur containing oils. Application of
40kg ∕ ha to oilsed based cropping system is found to increase the yield, oil and protein content of the seeds.

-------------------------------------------------------------------------------------------------

Question41
If by radiation all nitrogenase enzyme are inactivated, then there will be
no
2004

Options:

A. fixation of nitrogen in legumes

B. fixation of atmospheric nitrogen

C. conversion from nitrate to nitrite in legumes

D. conversion from ammonium to nitrate in soil.

Answer: A

Solution:

Solution:
(a) : The process by which N 2 is reduced to N H 4+ is called nitrogen fixation. Nitrogenase enzyme catalyzes this
reduction. It is only carried out by prokaryotic microorganisms. Principal N 2 -fixers include certain free living
cyanobacteria in symbiotic associations with fungi in lichens or with ferns, mosses, and liverworts, and by bacteria or
other microbes associated symbiotically with roots, especially those of legumes. About 15 percent of the nearly 20,000
species in the Fabaceae (Leguminosae) family have been examined for N 2 fixation, and approximately 90 percent of
these have root nodules in which fixation occurs. So without active nitrogenase enzyme there will be no N 2 fixation in
legumes.

-------------------------------------------------------------------------------------------------
Question42
Gray spots of oat are caused by deficiency of
2003

Options:

A. Cu

B. Z n

C. M n

D. F e

Answer: C

Solution:

Solution:
(c) : Gray spot diseases of oat is caused due to deficiency of manganese. Its symptoms include greyish - brown elongated
specks and streaks, empty panicles, interveinal chlorosis on stem and leaves. The symptoms that occur only on leaves
are irregular, greyish brown lesions which coalesce and bring about collapse of leaf. This is called grey speck symptom.

-------------------------------------------------------------------------------------------------

Question43
Boron in green plants assists in
2003

Options:

A. activation of enzymes

B. acting as enzyme co-factor

C. photosynthesis

D. sugar transport.

Answer: D

Solution:

Solution:
(d) : Boron occurs in the soil as a part of silicates, boric acid, calcium borate and magnesium borate. It is available to the
plants as boric acid and borates of calcium and magnesium. It plays a role in carbohydrate metabolism and translocation
of sugar is facilitated through the cell membrane through the agency of borate ion as it forms complexes with the
carbohydrates.

-------------------------------------------------------------------------------------------------

Question44
Choose the correct match. Bladderwort, sundew, Venus flytrap
2002

Options:

A. Nepenthes, Dionea, Drosera

B. Nepenthes, Utricularia, Vanda

C. Utricularia, Drosera, Dionea

D. Dionea, Trapa, Vanda.

Answer: C

Solution:

Solution:
(c) : Bladderwort or Utricularia is a rootless free floating insectivorous plant. Its stem is green and bears green lobed or
dissected leaves. Some lobes of the leaves become modified into bladder like structures for catching insects. Sundew or
Drosera is another insectivorous plant which has leaves that are green and bear many glandular hairs or tentacles having
shining droplets to attract the insects and later trap them. Venus flytrap or Dionea is also an insectivorous plant in which
the leaf is modified into two jaw like structures. Each jaw has long sensitive hairs on its upper surface and also has many
digestive enzymes. These jaws interlock to trap the insect that enters in it. Thus Utricularia, Drosera and Dionea are all
insectivorous plants.

-------------------------------------------------------------------------------------------------

Question45
Roots of which plant contains a red pigment which have affinity for
oxygen?
2001

Options:

A. Carrot

B. Soybean

C. Mustard

D. Radish

Answer: B

Solution:

Solution:
(b) : Leghaemoglobin is a red respiratory pigment found in the root nodules of leguminous plant if Rhizobium is present.
Soybean is a legume plant so it contains leghaemoglobin in its root nodules.

-------------------------------------------------------------------------------------------------
Question46
Which aquatic fern performs nitrogen fixation?
2001

Options:

A. Azolla

B. Nostoc

C. Salvia

D. Salvinia

Answer: A

Solution:

Solution:
(a) : Azolla is an aquatic fern which is inoculated in the rice field to increase the yield. Azolla contains Nostoc and
Anabaena (BGA) in its leaf cavities which perform nitrogen fixation.

-------------------------------------------------------------------------------------------------

Question47
M g is a component of
2000

Options:

A. chlorophyll

B. cytochrome

C. haemoglobin

D. haemocyanin.

Answer: A

Solution:

Solution:
(a) : Magnesium is an important constituent of chlorophyll, found in all green plants and essential for photosynthesis. The
chlorophyll molecule has a tetrapyrolic or porphyrin head and a phytol tail. Mg atom is present in the centre of porphyrin
head. It is like tennis racket.

-------------------------------------------------------------------------------------------------

Question48
Plants take zinc in the form of
2000

Options:

A. Z nSO4

B. Z n++

C. Z nO

D. Z n

Answer: B

Solution:

Solution:
(b) : Zinc is available to the plants for absorption in the divalent form. The availability of soil decreases when the pH of
soil shifts towards alkaline side. Zinc may form zinc phosphate in the soil which is insoluble and in that case, it is not
available to the plants. It is essential for synthesis of tryptophan amino acid, which forms IAA (Indole Acetic Acid) its
deficiency causes chlorosis of older leaves.

-------------------------------------------------------------------------------------------------

Question49
When the plants are grown in magnesium deficient but urea rich soil,
the symptoms expressed are
2000

Options:

A. yellowish leaves

B. colourless petiole

C. dark green leaves

D. shoot apex die.

Answer: A

Solution:

Solution:
(a) : Magnesium is important constituent of chlorophyll, thus it is found in all green plants and is essential for
photosynthesis. It also helps in binding of ribosomal particles where protein synthesis occurs. It is also part of many
enzymes of respiration. The deficiency symptoms of magnesium includes interveinal chlorosis in leaves and yellowing of
leaves starting from basal to younger ones.

-------------------------------------------------------------------------------------------------

Question50
Which of the following is not caused by deficiency of mineral nutrition?
1997

Options:

A. Etiolation

B. Shortening of internode

C. Necrosis

D. Chlorosis

Answer: A

Solution:

Solution:
(a) : When the plants are kept in dark, they become pale yellow in colour and also become abnormally long with
considerable internodal elongation, it is called etiolation. It is because 'flavonoids', which are inhibitors of GA are not
formed in dark and hence in absence of flavonoids, GA show their full effect, i.e., elongation (etiolation). Chlorosis
involves non-development or loss of chlorophyll. It occurs due to deficiency of nitrogen and sulphur. Necrosis involves
death of tissues. It occurs due to deficiency of copper. Stunted growth occurs due to deficiency of potassium.

-------------------------------------------------------------------------------------------------

Question51
Which one of the following elements is almost non-essential for plants?
1996

Options:

A. Zn

B. Na

C. Ca

D. Mo

Answer: B

Solution:

Solution:
(b) : The 16 elements necessary for plants called essential elements, are as : C, H , O, N , P, S, K , M g,
Ca, F e, Cu, B, Z n, M n, M o and Cl Zn is essential for the synthesis of tryptophan amino acid.
Ca is the part of middle lamella, it stabilizes the structure of chromosomes. Mo is responsible for nodulation in legumes. It
is a part of nitrate reductase enzyme which helps in nitrogen fixation. Na is a non-essential element. It seems to be
involved in membrane permeability but its essentiality has not been proved.

-------------------------------------------------------------------------------------------------

Question52
Which of the following elements plays an important role in biological
nitrogen fixation?
1995

Options:

A. Copper

B. Molybdenum

C. Zinc

D. Manganese

Answer: B

Solution:

Solution:
(b) : Molybdenum is a micronutrient which is required in very minute amount by the plants. It is responsible for
nodulation in legumes. It is part of nitrate reductase enzyme which helps in nitrogen fixation.

-------------------------------------------------------------------------------------------------

Question53
Which one is an essential mineral, not constituent of any enzyme but
stimulates the activity of many enzymes?
1989

Options:

A. Z n

B. M n

C. K

D. M g

Answer: C

Solution:

(c) : Potassium is an essential mineral. It is not a constituent of any enzyme but accelerates the rate of activity of many
enzymes. Potassuim is rich in actively dividing cells of buds, young leaves root tips. It is needed for proper growth and
development. It regulates movement of stomata. A high amount of potassium is required in the process of protein
synthesis.

-------------------------------------------------------------------------------------------------
Question54
Phosphorous and nitrogen ions generally get depeleted in soil because
they usually occur as
1989
Options:

A. neutral ions

B. negatively charged ions

C. positively charged ions

D. both positively and negatively charged but disproportionate mixture.

Answer: B

Solution:

(b) : Phosphorus and nitrogen ions generally get depleted in soil because they usually occur as negatively charged ions.
Both the elements are essential for plants and acts as macromolecules which are required in large quantities.

-------------------------------------------------------------------------------------------------