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CBSE Questions for Class 11 Medical Biology Mineral Nutrition Quiz 7 - MCQExams.com
CBSE
Class 11 Medical Biology
Mineral Nutrition
Quiz 7
In the root nodules of legumes, leghaemoglobin is important because it
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0%
Transports oxygen to the root nodule.
0%
Acts as an oxygen scavenger.
0%
Provides energy to the nitrogen fixing bacterium.
0%
Acts as a catalyst in transamination.
Explanation
The root nodule bacterium is microaerobic in the sense that it requires oxygen but the high concentration of oxygen is detrimental to nitrogen-fixing enzyme system. Here leghaemoglobin proves beneficial, it absorbs or binds oxygen so that there is no free oxygen left in the nodule and then carries micro-amounts of oxygen to the nodule bacteroids. Thus the correct answer is option B.
Ammonium sulphate is a
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0%
Pesticide
0%
Weedicide
0%
Fertilizer
0%
Tonic chemical
Explanation
Ammonium sulfate is a fertilizer as it increases the fertility of soil and plants can use it for their functions.
It cannot kill pests or weeds and hence is not a pesticide or a weedicide.
Tonic chemicals are medicines given to feel vigour. Ammonium sulfate has no such function.
So the correct answer is 'Fertilizer'.
Brown heart disease is due to the deficiency of
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Boron.
0%
Iron.
0%
Molybdenum.
0%
Phosphorus.
Explanation
Boron regulates pentose phosphate pathway, increases sugar translocation in plants. Due to deficiency of boron growth of roots stops and the disease ' brown heart' is caused in sugarbeet. Thus option A is the correct answer.
Bidirectional translocation of minerals take place in the
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Xylem tissues
0%
Phloem tissues
0%
Parenchyma cells
0%
Cambium
Explanation
Transport takes place through xylem and phloem.
Parenchyma and cambium are not involved in transport of materials.
Xylem only has unidirectional transport.
Phloem has bidirectional translocation of food and minerals.
So, the correct answer is ' Phloem tissues'.
All heterotrophs require environment which can provide
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0%
Nitrates in solution
0%
Organic compounds
0%
Ammonium salts
0%
Vitamin A
Explanation
Heterotrophs cannot prepare their own food from inorganic compounds.
They need organic compounds for nutrition and energy.
Hence Nitrates, Ammonium salts and Vitamins are not enough for heterotrophs.
So the correct answer is ' Organic compounds'.
Select the correct statement regarding "
A trace element is an element which".
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Is a radio active and can be traced by Geiger counter.
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Is required in very minute amounts.
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Draws other element out of protoplasm.
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Was one of the first to be discovered in protoplasm.
Explanation
Trace elements are the ones which are required in. Very less amount and are present in less amounts as compared to other elements of major use.
Usually, they have very specific functions and do not contribute structurally.
Macronutrients were discovered first in the cytoplasm.
Radioactive elements are usually not present in the plant bodies.
So the correct answer is 'Is required in very minute amounts'.
A trace element essential for plant growth and a radioactive isotope which is used in cancer therapy is
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Calcium
0%
Iron
0%
Cobalt
0%
Sodium
Explanation
Calcium, Iron and Sodium are not trace elements but macronutrients and required in large quantities.
Cobalt is a trace element but essential for plant growth because it helps in cell division and nitrogen fixation.
It is also used in cancer therapy.
So the correct answer is 'Cobalt'.
Active transport from outside to inside of molecules across a membrane requires
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Cyclic AMP
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ATP
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Phloroglucinol
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Acetyle chloine
Explanation
The active transport of substances require energy and hence they use up ATP which is the energy currency of the cell.
Acetly choline and Cyclic AMP are involved in cell signalled.
Phloroglucinol is a stain used to observe lignin.
So the correct answer is 'ATP'.
Carefully read the following reactions carried out by nitrogen fixing bacteria. Identify the statement about these equations which is true:
2
N
H
3
+
3
O
2
⟶
2
N
O
−
2
+
2
H
+
+
2
H
2
O
.
.
.
.
.
(
A
)
2
N
O
−
2
+
O
2
⟶
2
N
O
−
3
.
.
.
.
.
.
(
B
)
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Step
(
A
)
is carried out by
Nitrosomonas
or
Nitrococcus
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Step
(
B
)
is carried out by
Nitrobacter
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Both the steps
(
A
)
and
(
B
)
can be called nitrification
0%
All of the above
Explanation
The reactions given are the step of nitrification. This is the first step of nitrogen fixation in the nitrogen cycle. The first reaction is the conversion of ammonia to nitrite. This reaction is carried out by the
Nitrosomonas
and
Nitrococcus
. The second reaction is the conversion of the nitrite to nitrate. This reaction is carried out by
Nitrobacter
.
Thus, the correct answer is option D.
The enzyme nitrogenase is extremely sensitive to
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Oxygen.
0%
Nitrogen.
0%
Hydrogen.
0%
Helium.
Explanation
Nitrogenase of bacteria is highly sensitive to oxygen and are thus nitrogen fixing bacteria are called microaerobic. Enzyme nitrogenase is oxygen labile. Oxygen will make the enzyme irreversibly inactive. So, the nitrogen-fixing bacteria needs to protect the nitrogenase enzyme from oxygen. Leghaemoglobin pigment present in the root nodules scavenges free oxygen so that nitrogenase can carry out its activity of nitrogen fixation unhindered.
Thus, the correct answer is option A.
Which of the following microorganims can fix nitrogen in non-leguminous plants?
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Rhodospirillum
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Azotobacter
0%
Frankia
0%
Rhizobium
Explanation
Plants cannot directly use atmospheric nitrogen. Plants absorb nitrogen from the soil in the form of nitrates, nitrites and ammonium ions.
Symbiotic nitrogen fixation is a process in which plant harbor nitrogen-fixing bacteria within their tissues. Microorganisms that fix nitrogen include
Azotobacter
,
Rhizobia,
Frankia
. While the leguminous plants enter into a symbiotic association with rhizobia to fix nitrogen,
Frankia
is used by the non-leguminous plants in their symbiotic association.
Thus, the correct answer is option C.
Which of the following is responsible for biological nitrogen-fixation?
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Nif gene
0%
Nitrogenase
0%
Yeast alanin tRNA synthetase
0%
RNA synthetase
Explanation
The nitrogen fixation enzymes are encoded by nif genes that are present in both free-living and symbiotic nitrogen-fixing bacteria.
Primary nitrogen fixation enzyme is nitrogenase complex.
Yeast alanine tRNA synthetase binds alanine to respective tRNA.
RNA synthetase enzyme catalyzes RNA synthesis in RNA viruses.
So, the correct answer is option A.
Hydroponics is otherwise called
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0%
Soil-less agriculture
0%
Tank farming
0%
Chemical gardening
0%
All the above
Rhizobium
is found in
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Maize root.
0%
Gram root.
0%
Branch of a plant.
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Sugarcane root.
Explanation
Rhizobium
is the bacterium which fixes nitrogen in symbiotic association with roots of leguminous plants. Gram is one of the examples of the dicot legume plant. Initially, the bacteria grow in soil near the roots of higher plants where they fail to fix the nitrogen. These bacteria when coming in contact with leguminous plants, interact chemically and enter into roots through root hairs, and fix nitrogen with the help of the enzyme nitrogenase.
Thus, the correct answer is option B.
Hydroponics is
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Soilless farming.
0%
To grow plants in water.
0%
To grow aquatic plants.
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To grow floating hydrophytes.
Explanation
Correct Answer: A
Explanation:
Hydroponics is the technique of culturing the plant in a solution of nutrients.
It is also known as soilless culture.
It helps in the growth of healthy plants without using traditional methods.
Nitrogen fixation is performed by
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Green algae and fungi
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Ferns and cycads
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Legumes and cereals
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Blue-green algae and bacteria
Explanation
The atmospheric nitrogen is not available to plants. There are some nitrogen-fixing bacteria which converts atmospheric nitrogen into ammonia which is readily available to plants.
Azotobacter
is a free-living nitrogen-fixing bacteria.
Rhizobium
in association with the leguminous plants carries out the process of nitrogen fixation. Blue-Green algae like
Anabaena
and
Nostoc
are free-living nitrogen-fixing bacteria. However, they are symbiotic bacteria as well.
Thus, the correct answer is Blue-green algae and bacteria.'
In
Aulosira, Tolypothrix
and
Nostoc
, ............ are the sites for nitrogen fixation.
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Vesicles
0%
Arbuscles
0%
Akinetes
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Heterocysts
Explanation
Heterocyst is transparent thick walled empty cell which is present in intermittent position in filaments of blue green algae. They are the site of nitrogen fixation.
Aulosira, Tolypothrix and Nostoc
are the blue green algae wherein heterocyst serves as site for nitrogen fixation. Correct answer is D.
Bacterium associated with legume roots is
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Rhizobium
0%
Nostoc
0%
Spirogyra
0%
Clostridium
Explanation
Legumes are in symbiotic association with nitrogen-fixing bacteria like
Rhizobium
. They fix nitrogen with the help of bacteria that live in their roots. These bacteria invade root hairs of leguminous plants and forms root nodules in which they fix nitrogen. A red pigment present in the root nodules of leguminous plants is known as leghaemoglobin.
Thus, the correct answer is '
Rhizobium
.'
A completely free living organism which takes part in nitrogen fixation is
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Anabaena
0%
Bacillus
0%
Azotobacter
0%
Rhizobium
Explanation
The atmospheric nitrogen is not available to plants. There are some nitrogen fixing bacteria which converts atmospheric nitrogen into ammonia which is readily available to plants.
Azotobacter
are free-living nitrogen fixing bacteria.
Anabaena
is a free-living nitrogen fixing bacteria. However, it also forms symbiotic association with plants like mosquito fern. Hence, they are symbiotic bacteria as well.
Thus, the correct answer is '
Azotobacter
.'
A non-legume, symbiotic nitrogen fixing bacterium is
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0%
Rhizobium
0%
Azotobacter
0%
Frankia
0%
Clostridium
Explanation
Atmospheric nitrogen is not available for plants. However, nitrogen-fixing bacteria convert atmospheric nitrogen into ammonia and make it available to plants.
Azotobacter
is a free-living nitrogen-fixing bacterium.
Rhizobium
is a symbiotic nitrogen-fixing bacterium. It fixes atmospheric nitrogen with symbiotic association with legume plants.
Frankia
is a non-legume symbiotic nitrogen-fixing bacterium.
Clostridium
is free-living anaerobic nitrogen-fixing bacterium.
Thus, the correct answer is '
Frankia
.'
Nitrogen fixation can be represented as
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N
2
→
N
H
3
0%
N
2
→
N
O
3
0%
N
2
→
Amino acid
0%
Both A and B
Explanation
Nitrogen fixation is a process by which atmospheric nitrogen is converted into ammonia and other compounds like nitrate. These nitrogenous compounds are then made available for plants. Bacteria involved in the process of nitrogen fixation are called as nitrogen fixing bacteria. Examples include
Rhizobium
,
Azotobacter
.
Thus, the correct answer is 'Both A and B.'
Which one is most abundantly found in plants?
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Nitrogen
0%
Carbon
0%
Iron
0%
Manganese
Explanation
Carbon is the most abundant element present in plants. Plant obtains carbon from carbon dioxide through the process of photosynthesis. It is the main constituent of the cell wall. The other framework elements are hydrogen and oxygen. Thus, the correct answer is option B.
A free living nitrogen fixing cyanobacterium which can also form symbiotic association with the aquatic fern
Azolla
is
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Tolypothrix
0%
Chlorella
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Nostoc
0%
Anabaena
Explanation
Chlorella is a special type of micro algae that is known for its detoxifying & immune benefits. Nostoc is found in various environments that forms colonies composed of filaments of cells in a gelatinous sheath. Any sample of
Azolla
examined under a microscope will have filaments of Anabaena living within ovoid cavities inside the leaves which fixes nitrogen. It is a free living N
2
fixing cyanobacterium which forms symbiotic association with the aquatic fern
Azolla
.
So, the answer is D.
Which one of the following statements about nitrogenase is correct ?
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It is sensitive to
C
O
2
and therefore present is isolated nodules.
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It requires
O
2
and therefore functional during the day.
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It is sensitive to
O
2
and therefore is functional anaerobic environments.
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It is sensitive to light and therefore functions only in dark.
Explanation
Rhizobium fixes nitrogen with the help of nitrogenase enzyme that converts nitrogen to ammonium. Leghaemoglobin pigment present in the root nodules scavenges free oxygen so that nitrogenase can carry out its activity of nitrogen fixation unhindered. Enzyme nitrogenase is oxygen labile. Oxygen will make the enzyme irreversibly inactive. So, the nitrogen-fixing bacteria needs to protect the nitrogenase enzyme from oxygen. Thus, the correct answer is option C.
Match the columns and find the correct combination.
(a)
N
(i)
Copper texture of leaf
(b)
Mg
(ii)
Premature leaf fall
(c)
Bo
(iii)
Interveinal chlorosis
(d)
P
(iv)
Mottled chlorosis and necrosis
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a-iv, b-i, c-ii, d-iii
0%
a-i, b-ii, c-iii, d-iv
0%
a-iv, b-iii, c-i, d-ii
0%
a-iv, b-ii, c-i, d-iii
Root nodules are not formed in non-leguminous plants because they grow in
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Nitrogen deficient soils
0%
Soils having bacteria for converting nitrogen into usable form
0%
Soils rich in nitrogen
0%
All the above
Explanation
Roots nodules are not formed in non-leguminous plants because they grow in soils having bacteria for converting nitrogen into a usable form. So, they do not need bacteria stored in the nodules to obtain nitrogen content like legumes.
So, the correct option is 'Soils having bacteria for converting nitrogen into a usable form'.
Tracer elements are those that are
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0%
Required in small amount by the plant
0%
Radioactive and can be used to investigate a process in the plant
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First to be traced in the plant
0%
Present in traces in the soil solution
Explanation
Tracer elements are those elements which are required in very small quantities i.e., less than 0.1 gm/mg of dry weight of plant. They are also called micronutrients or trace elements.
Hence, option A is the correct answer.
Micronutrients mainly function as
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Osmotic constituents of cell sap
0%
Components of important biochemicals
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Cofactors of enzymes
0%
Constituents of chlorophyll
Explanation
Micronutrients are those that are needed in minor quantities for growth and development. They are mostly co-factors and are necessary for the function of enzymes in the plant. Iron, cobalt, chromium, copper, iodine, manganese, selenium, zinc and molybdenum are some of the micronutrients.
Thus, the correct answer is option (C).
Buds that produced lateral branches develop at
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Internodes
0%
Apical meristems
0%
Auxillary meristems
0%
Nodes
Essential macronutrients are
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Manufactured during photosynthesis
0%
Produced by growth hormones
0%
Absorbed from soil
0%
Produced by enzymes
Explanation
Essential macronutrient are those essential elements which are generally present in the large amount in the plant tissues i.e., in excess of 10 mmole per Kg of dry matter, e.g. carbon, nitrogen, hydrogen, potassium, phosphorus, sulphur and magnesium etc. They are absorbed from the soil by the roots.
So, the correct answer is 'Absorbed from soil'
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