AP Inter 2nd Year Botany Important Questions Chapter 2 Mineral Nutrition

Students get through AP Inter 2nd Year Botany Important Questions 2nd Lesson Mineral Nutrition which are most likely to be asked in the exam.

AP Inter 2nd Year Botany Important Questions 2nd Lesson Mineral Nutrition

Very Short Answer Questions

Question 1.
Define hydroponics.
Answer:
Hydroponics: The technique of growing plants in a specified nutrient solution is known as hydroponics.

Question 2.
How do you categorize a particular essential element as a macro or micronutrient?
Answer:

1. We can categorize an element as macro or micro, based on the quantitative requirement.
2. The elements which are required in large amounts are called macronutrients.
3. The elements which are required in small amounts are called micronutrients.

Question 3.
Give two examples of essential elements that act as activators for enzymes.
Answer:
Magnesium, Manganese, Potassium, Iron, Calcium.

Question 4.
Name the essential mineral elements that play an important role in the photolysis of water.
Answer:
Calcium

Question 5.
Out of 17 essential elements which elements are called non-mineral essential elements?
Answer:
Carbon, Hydrogen

Question 6.
Name two amino acids in which sulphur is present. [TS MAR-19]
Answer:
Cysteine, Methionine

Question 7.
When is an essential element said to be deficient?
Answer:
An essential element is said to be deficient when it is present below the critical concentration.

Question 8.
Name two elements whose symptoms of deficiency first appear in younger leaves.
Answer:
Nitrogen, Potassium

Question 9.
Explain the role of the pink colour pigment in the root nodule of legume plants. What is it called? [AP,TS M-15]
Answer:

1. The pink-coloured pigment in the root nodules of legume plants is called “Leg-haemoglobin”.
2. Its role is to protect the dinitrogenase enzyme, which is highly sensitive to oxygen.

Question 10.
Excess Mn in soil leads to a deficiency of Ca, Mg and Fe. Justify.
Answer:

1. Manganese competes with iron(Fe) and magnesium(Mg) for uptake.
2. Mn also inhibits ‘calcium(Ca) translocation’ in the shoot apex.
3. herefore excess of Mn in soils, leads to deficiencies of Fe, Mg and Ca.

Question 11.
What acts as a reservoir of essential elements for plants? By what process is it formed?
Answer:

1. Soil acts as a reservoir of essential elements for plants.
2. It is formed by ‘weathering and breakdown of rocks.

Question 12.
Which element is regarded as the 17th essential element? Name a disease caused by its deficiency.
Answer:

1. Nickel is regarded as the 17th essential element.
2. Its deficiency causes “mouse ear” disease in Pecan.

Question 13.
Nitrogen fixation is shown by prokaryotes only. Why not by eukaryotes?
Answer:

1. In prokaryotes, nitrogenase contains Mo-Fe protein which is capable of nitrogen reduction.
2. But it is absent in Eukaryotes. So nitrogen fixation is not shown in eukaryotes.

Question 14.
Give an example for each of the aerobic and anaerobic nitrogen-fixing prokaryotes.
Answer:

1. Aerobic nitrogen-fixing prokaryotes, Ex: Azotobacter, Blue-green algae & Beijemikia.
2. Anaerobic nitrogen-fixing prokaryotes. Ex: Bacillus and Rhodospirillum.

Question 15.
Non -legume plants also form root nodules. Justify.
Answer:

1. Microbe Frankia, a nitrogen fixer, produces nitrogen-fixing root nodules on the roots of non-leguminous plants.
2. Ex: Alnus is non-leguminous plant.

Question 16.
Name the essential elements present in the nitrogenase enzyme. What type of essential elements are they?
Answer:

1. Nitrogenase enzyme contains the essential elements Mo and Fe.
2. They are micronutrients.

Question 17.
Write the balanced equation of nitrogen fixation. |TS MAR-161
Answer:
N₂ + 8H⁺ + 8e^– + 16 ATP → 2NH₃ +H₂ + 16ADP + 16Pi

Question 18.
How many ATPs of energy is required to fix one molecule of atmospheric nitrogen by biological mode? What is the source of that energy?
Answer:

1. To fix one molecule of nitrogen, 8ATPs for each molecule of NH₃ are required.
2. The energy is obtained from ‘the respiration of the host cell’.

Question 19.
Why are amides transported through Xylem?
Answer:

1. Amides contain more nitrogen than aminoacids.
2. So they are transported stably through the xylem.

Question 20.
Name any two essential elements and the deficiency diseases caused by them.
Answer:

1. The essential elements are N and K.
2. Deficiency of N and K in plants causes a disease called “Chlorosis”.

Short Answer Questions

Question 1.
All elements that are present in a plant need not be essential for its survival. Justify.
Answer:
1) More than 60 mineral elements present in the soil enter plants through roots. Among those some are essential and some others are non-essential.

2) Some important essential elements are Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, Sulphur, Iron, Manganese, Zinc, Copper, Boron, Chlorine, Nickel and Molybdenum

3) Criteria for essentiality:

1. The element must be ‘absolutely necessary’ for supporting ‘normal growth and reproduction’.
2. The requirement of the element must be ‘specific’ and not replaceable by another element.
3. The element must be ‘directly involved’ in the ‘metabolism’ of the plant.

4) Some elements like Iodine, Cobalt and Sodium are useful as food supplements but are not essential.

5) Some elements like Lithium, radium, mercury stimulate growth but are not essential.

Question 2.
Name at least five different deficiency symptoms in plants. Describe them and correlate them with the concerned mineral deficiency.
Answer:
1) Chlorosis: It is the loss of chlorophyll which leads to yellowing in leaves.
It is due to deficiency of N, K, Mg, S, Fe, Mn, Zn & Mo.

2) Necrosis: It is the death of tissues in leaves.
It is due to deficiency of Ca, Mg, K.

3) Inhibiting cell division: It is the stopping of’Normal cell division’.
It is due to deficiency of N, K ,S, Mo .

4) Stunted plant growth: It is the reduced or low level growth of plants.
It is due to deficiency of Magnesium, Potassium, Copper, Sulphur.

5) Premature fall of leaves & buds: Deficiency of Phosphorus, Molybdenum causes premature falling of leaves and buds in plants.

6) Delay of flowering: Deficiency of N, S, Mo causes delay of flowering in plants.

Question 3.
Explain the steps involved in the formation of root nodule. [AP MAR-17,19] [TS MAY-17] [TS MAR-16] [TS 20]
Answer:
Steps involved in the formation of root nodule:

1. The roots of host Legume release sugars and amino acids.
2. These sugars attract Rhizobia.
3. They multiply, colonise and get attached to the epidermis of root hair cells.
4. The root hairs curl and bacteria spread into the cortex of the root.
5. Then an infection thread is produced.
6. It carries the bacteria into the cortex.
7. The bacteria initiate nodule formation in the cortex of the root.
8. Then the bacteria present in the cortical cells, stimulate the host cells to divide.
9. This leads to the differentiation of specialised nitrogen-fixing cells, which form root nodules.
10. The nodule thus formed establishes a direct vascular connection with the host, for exchange of nutrients.
    

Question 4.
Some angiospermic plants have adapted to absorb molecular nitrogen from the atmosphere. Explain, citing two examples.
Answer:
1. Plants cannot use atmospheric nitrogen directly. But some angiospermic plants can fix nitrogen with the help of nitrogen-fixing bacteria present in the root nodules.

2. Rhizobium bacteria contains a pink pigment called ’leg-haemoglobin’. It absorbs atmospheric nitrogen and converts into nitrites and supply them to the plant. In return, it gets food and shelter from the plant.

3. This type of relation between ’roots of legume plants and Rhizobium bacteria’ is called Symbiosis.

4. Ex 1 :Legume plants (like alfalfa, sweet pea) contain Rhizobium bacteria in their nodular roots.

5. Ex 2: Alnus plants contain Frankia. Frankia is a genus of’free living nitrogen fixing bacteria’ in non-leguminous plants. It converts atmospheric nitrogen into ammonia via nitrogenase enzyme.

Question 5.
Write in brief how plants synthesize amino acids. [TS MAR-17] [AP MAR-16] [AP MAY-17]
Answer:
Amino acids in plants are synthesized in tw o ways:
1. Reductive animation: In this process, ammonia reacts with a-ketoglutaric acid and forms an amino acid called glutamic acid.

2. Transamination: In this process, transfer of an amino group from an amino acid to the keto group of a keto acid takes place. Glutamic acid is the main amino acid from which the transfer of NH₂ takes place. Thus another amino acid is formed by transamination in the presence of Transaminase.

Question 6.
What will happen if healthy plant is supplied with excess essential elements? Explain.
Answer:

1. Excess of an element may inhibit uptake of another element.
2. Any mineral ion concentration, in tissues, that reduces the dry weight of tissues by about 10 percent is considered toxic.
3. The Manganese (Mn) toxicity shows ‘appearance of brown spots’ surrounded by chlorotic veins.
4. Mn, in excess, competes with iron and Mg for uptake and with Magnesium for binding with enzymes.
5. Mn also inhibits calcium translocation in the shoot apex. ,
6. So excess of essential Mn to healthy plants leads to deficiencies of iron, magnesium and calcium.

Question 7.
Explain in brief how plants absorb essential elements.
Answer:

1. Absorption of essential elements happens in two phases, a) apoplast b) symplast
2. a) Apoplast: Rapid uptake of ions occurs into the outer space or free space of cells.
   The movement of ions into the apoplast along the concentration gradient is a ‘passive process’.
3. b) Symplast: Uptake ions are taken slowly into the inner space .
   The movement of ions to and from the symplast against the concentration gradient requires metabolic energy. It is an ‘active process’.
4. The movement of ions is called ‘flux’; the inward movement into the cells is called ‘in flux’ and the outward movement is called ‘efflux’.

Question 8.
‘Nitrogen is fixed into the soil, not only by biological processes’. Elaborate
Answer:
1) Apart from biological nitrogen fixation, nitrogen is fixed by physical processes also.

2) Lightning & thunders, forest fires, industrial combustions, power generating stations are sources of atmospheric nitrogen oxides.

3) During lightening and thunders, dinitrogen is dissolved in rain water and reaches soil as nitrous and nitric acids.

4) These acids react with alkali radicals of soil and form nitrates. The soluble nitrates are directly absorbed by plants.

5) The chemical reactions are as follows
N₂ + O₂ → 2NO
2NO + O₂ → 2NO₂
2NO₂ + H₂O → HNO₂+ HNO₃
HNO₃+ Calcium + Potassium salts → Calcium and Potassium nitrates.
Thus nitrogen fixation is not only always a biological process but is also sometimes a physical process. .

Long Answer Questions

Question 1.
Explain the nitrogen cycle, giving relevant examples. [AP MAR-20]
Answer:
Nitrogen Cycle: The cyclic movement of nitrogen from the atmosphere to the soil and from the soil back into the atmosphere through plants, animals and micro organism is called as Nitrogen cycle. It includes five steps.

1. Nitrogen fixation
2. Nitrogen assimilation
3. Ammonification
4. Nitrification
5. Denitrification

1) Nitrogen fixation: Conversion of molecular nitrogen into ammonia or nitrites or nitrates is known as Nitrogen fixation.
a) Biological nitrogen fixation: Conversion of molecular ntirogen into ammonia by prokaryotes is called biological nitrogen fixation.

Ex: Free-living nitrogen fixing anaerobic microbes – Rhodospirillum.

b) Physical nitrogen fixation: In nature, lightening and ultraviolet radiation provide energy to convert nitrogen into nitrogen oxides. Industrial combustion, forest fires, automobile exhausts and power generating stations are also sources of nitrogen oxides.
N₂+ O₂ → 2NO; 2NO + O₂ → 2NO₂

2) Nitrogen assimilation: The nitrates and ammonia absorbed by plants are converted into amino acid, proteins, enzymes, nucleic acids and hormones in the plant body.
These organic constituents are eaten by animals.

3) Ammonification: Decomposition of organic nitrogen of dead plants and animals into ammonia is called Ammonification. This is done by ammonifying bacteria.

4) Nitrification: The conversion of Ammonia into Nitrites and Nitrates is called Nitrification.
It occurs in two steps.
Step 1: Ammonia is oxidised to nitrite by bacteria called Nitrosomonas and Nitrococcus.
2NH₃ + 3O₂ → 2NO₂^– + 2H⁺ + 2H₂O
Step 2: The nitrite is further oxidised to nitrate by bacteria called Nitrobacter.
2NO₂ + O₂ → 2NO₃^–
The nitrates are absorbed by plants and are transported to leaves.
They are reduced to form ammonia and finally converted into Amino acids.

5. Denitrification: A small quantity of nitrates and ammonia is converted into free nitrogen by harmful bacteria called pseudomonas and Thiobacillus. This process is called denitrification.

Question 2.
Trace the events starting from the coming in contact of Rhizobium with a leguminous root tilll nodule formation. Add a note on the importance of leg haemoglobin.
Answer:
Steps involved in the formation of root nodule:

1. The roots of host Legume release sugars and amino acids.
2. These sugars attract Rhizobia.
3. They multiply, colonise and get attached to the epidermis of root hair cells.
4. The root hairs curl and bacteria spread into the cortex of the root.
5. Then an infection thread is produced.
6. It carries the bacteria into the cortex.
7. The bacteria initiate nodule formation in the cortex of the root.
8. Then the bacteria present in the cortical cells, stimulate the host cells to divide.
9. This leads to the differentiation of specialised nitrogen-fixing cells, which form root nodule.
10. The nodule thus formed establishes a direct vascular connection with the host, for the exchange of nutrients.

Importance of leg-haemoglobin:

1. It facilitates oxygen supply to the nitrogen-fixing bacteria.
2. It protects enzyme nitrogenase from being inactivated by oxygen.

Exercise

Question 1.
Who should be credited for the initiation of hydroponics?
Answer:
Julius Von Sachs

Question 2.
Are all the essential elements required by plants mineral elements? Explain.
Answer:
Yes. Whenever the supply of a particular element is hindered, the plant shows the deficiency symptom.

Question 3.
Which essential clement is needed to activate the enzymes required for CO₂ fixation?
Answer:
Magnesium and Manganese.

Question 4.
Name a cation and an anion that maintain osmotic balance in cells.
Answer:
Potassium and Chlorine.

Question 5.
Which element is required for the formation of a mitotic spindle?
Answer:
Calcium.

Question 6.
What is the role of sulphur in plant life?
Answer:
Sulphur is absorbed from the soil by the root system of a plant in the form of SO₄ ions. Sulphur is required for the synthesis of amino acids namely Cysteine and Methionine. It is a constituent of several co-enzymes like Co-A, and vitamins like biotin, and thiamine.

Question 7.
Which microelement is required in more quantity than the other micronutrients?
Answer:
Iron

Question 8.
Which element is necessary for the synthesis of the chief photosynthetic pigment without being its structural component?
Answer:
Iron.

Question 9.
Which micronutrient necessary for photolysis of water is absorbed by plants in an-ionic form?
Answer:
Chlorine.

Question 10.
Which enzyme is activated by the 17*h essential element?
Answer:
Nickel is the 17th essential element which acts as an activator for “Urease”.

Question 11.
When is an element considered to be toxic?
Answer:
Any mineral ion concentration in tissues that reduces the dry weight of tissues by about 10 percent is considered toxic.

Question 12.
Which element when supplied in excess leads to the appearance of brown spots surrounded by chlorotic veins?
Answer:
Manganese.

Question 13.
Name an anaerobic, free-living, photo-heterotrophic nitrogen-fixing bacterium.
Answer:
Rhodospirillum

Question 14.
Which microorganism produces nitrogen-fixing nodules in Alnus?
A; Frankia

Question 15.
When the cross-section of root nodules of ground nut plants are observed under a microscope, they appear pinkish. Why?
Answer:
Due to the presence of Leg-haemoglobin.

Question 16.
Apart from the cortical cells, which other cells are stimulated to divide by the bacteroids inside the root nodules?
Answer:
Pericycle cells.

Question 17.
What is the ratio of electrons and protons required for the fixation of atmospheric molecular nitrogen through biological mode?
Answer:
8 Protons and 8 electrons i.e., 1:1 ratio.

Question 18.
What acts as an oxygen scavenger in the legume-root nodule combination?
Answer:
Leg-haemoglobin

Question 19.
In what way does aspargine differ from aspartic acid? ‘
Answer:

1. Aspargine is an amide.
2. It is found in plants as a structural part of the protein.
3. It is formed by the addition of another amino group to aspartic acid.

Question 20.
Through which tissue the amino acids are transported inside the plant body?
Answer:
Through xylem vessels, amino acids are transported.

Question 21.
Plants like the Pitcher and Venus fly trap have special nutritional adaptations. Name the essential element and its source for which they show such adaptations.
Answer:
a) Nitrogen (N₂)
b) Nitrogen is absorbed from the body of insects.

Question 22.
Excess Mn in soils leads to a deficiency of Ca, Mg and Fe. Justify.
Answer:
Sometimes, excess of an element may inhibit the uptake of another element. For eg: Manganese
competes with Iron and Magnesium for uptake. Manganese also inhibits calcium translocation in the shoot apex. So an excess of Manganese induces a deficiency of Fe, Mg and Ca.

Question 23.
What acts as a reservoir of essential elements for plants? By what process is it formed?
Answer:
Soil acts as a reservoir of essential elements for plants. Soil is formed due to weathering and breakdown of rocks.

Question 24.
Nitrogen fixation is shown by prokaryotes only. Why not by eukaryotes?
Answer:
The enzyme Nitrogenase is required for the reduction of Nitrogen. It is present only in prokaryotes,
but not in Eukaryotes.

Multiple Choice Questions

Question 1.
Ammonia is oxidized to nitrites by the bacterial
1) Nitrosomonas
2) Nitrobacter
3) Nitrosococcus
4) Pseudomonas
Answer:
1) Nitrosomonas

Question 2.
By using some techniques, minerals arc able to detect the mineral at a very low concentration of
1) 10^-12 gm /ml
2) 10^-15 gm / ml
3) 10^-10 gm /ml
4) 10^-8 gm / ml
Answer:
4) 10^-8 gm / ml

Question 3.
Chlorophyll is formed in the presence of
1) Cu and Fe
2) Mo and Cl
3) Mg and Mo
4) Fe and Mg
Answer:

Question 4.
Deficiency of which element causes Yellowing of leaf
1) Fe
2) Cl
3) P
4) B
Answer:
4) B

Question 5.
Enzyme required for nitrogen fixation is
1) Transaminase
2) Nitroreductase
3) Nitrogenase
4) Transferase
Answer:
3) Nitrogenase

Question 6.
Filamentous cyanobacteria which fix atmospheric N₂ is
1) Rhizobium
2) Frankia
3) Nostoc
4) ulothrix
Answer:
3) Nostoc

Question 7.
Highly toxic form of Nitrogen is
1) NH₄⁺
2) NH₃
3) NO₃^–
4) Urea
Answer:
1) NH₄⁺

Question 8.
The number of essential elements is equal to
1) 60
2) 30
3) 17
4) 9
Answer:
3) 17

Question 9.
…………. element facilitates translocation of sugars in plants
1) Zn
2) K
3) B
4) Mo
Answer:
3) B

Question 10.
Nitrogen fixation is facilitated by
1) Cu
2) B
3) Zn
4) Mo
Answer:
4) Mo

Question 11.
In the absence of essential mineral elements, leaves of many plant turn yellow due to
1) Plasmolysis
2) Chlorosis
3) Necrosis
4) Etiolation
Answer:
2) Chlorosis

Question 12.
………. a micronutrient in plants
1) Magnesium
2) Zinc
3) Potassium
4) Calcium
Answer:
2) Zinc

Question 13.
An element playing an important role in cell division is
1) Calcium
2) Copper
3) Manganese
4) Zinc
Answer:
1) Calcium

Question 14.
Zn, Mn, Fc, Cu arc
1) Trace elements
2) Non-essential elements
3) Macronutrients
4) Tracer elements
Answer:
1) Trace elements

Question 15.
…………. element is required for the germination of pollen grains
1) Boron
2) Calcium
3) Chlorine
4) Potassium
Answer:
1) Boron

Question 16.
………….. element is a constituent of eell membrane
1) Nitrogen
2) Carbon
3) Phosporus
4) Magnesium
Answer:
3) Phosporus

Question 17.
Microelements which act as enzyme activators are
1) Iron, Magnesium, Copper
2) Iron, Potassium, Molybdenum
3) Iron, Zinc, Copper
4) Potassium, Magnesium, Manganese
Answer:
3) Iron, Zinc, Copper

Question 18.
The number of carbon atoms present in the substrate during the formation of Clutamie acid is
1) 2
2) 3
3) 4
4) 6
Answer:
2) 3

Question 19.
…………. is a Macronutricnt
1) Mg
2) Mo
3) Mn
4) Zn
Answer:
1) Mg

Question 20.
Number of elements present in plants is estimated by
1) Solution culture experiments
2) Plant ash analysis
3) Sand culture experiments
4) Bell jar experiments
Answer:
2) Plant ash analysis

Question 21.
Copper is present in
1) Plasmalemma
2) Plastoquinone
3) Cytochrome ‘c’ oxidase
4) Ferredoxin
Answer:
3) Cytochrome ‘c’ oxidase

Question 22.
The movement of ions from soil to plants require energy and is termed as
1) Flux
2) Influx
3) Efflux
4) Inhibition
Answer:
1) Flux

Question 23.
Which one of the following elements is not an essential micronutrient for plant growth?
1) Zn
2) Cl
3) Ca
4) Mn
Answer:
3) Ca

Question 24.
Chlorosis in leaf occurs due to the deficiency of
1) Chloride
2) Magnesium
3) Phosphate
4) Molybdenum
Answer:
2) Magnesium

Question 25.
Hydroponics require
1) purified water
2) impure water
3) mineral nutrient salt
4) both (1) and (3)
Answer:
4) both (1) and (3)

Question 26.
Hydroponic is a successfully employed technique for the commercial production of vegetables like
1) tomato
2) seedless cucumber
3) lettuce
4) all
Answer:
4) all

Question 27.
C, H, O are mainly obtained from
1) Soil and H₂O
2) Soil only
3) H₂O and CO₂
4) CO₂ only
Answer:
3) H₂O and CO₂

Question 28.
Some beneficial element required by higher plants are
1) Na, Si, Co, Se
2) Na, Si, Os, I
3) Na, Co, Ir, At
4) Na, Si, W, Ag
Answer:
1) Na, Si, Co, Se

Question 29.
N, K, and Mg arc
1) Actively mobile elements
2) Macro mineral elements
3) Transport from older to younger leaves
4) All the above
Answer:
4) All the above

Question 30.
A pair of mineral elements present in chlorophyll is
1) Fe and Mn
2) Mg and Fe
3) Mg and N
4) C, H, O, Mg and N
Answer:
2) Mg and Fe

Question 31.
Zn2+ is an activator of
1) Carbonic anhydrose
2) Alcoholic dehydrogenase
3) Carboxylases
4) All
Answer:
4) All

Question 32.
The elements which occur in nucleic acid macromolecule are
1) C, H, O, N, S
2) C, O, N, S
3) C, O, P, S
4) C, H, O, N, P
Answer:
4) C, H, O, N, P

Question 33.
An element playing important role in nitrogen fixation is
1) Molybdenum
2) Copper
3) Manganese
4) Zinc
Answer:
1) Molybdenum

Question 34.
The element which involves in splitting of water molecule, inhibit uptake of Fe, Mg and translocation Ca in shoot apex is
1) Cl
2) Ca
3) Mn
4) Fe
Answer:
3) Mn

Question 35.
The enzyme which involves in the first step of nitrogen cycle is
1) Nitrate reductase
2) Nitrogenase
3) Cellulose
4) Carboxylase
Answer:
2) Nitrogenase

Question 36.
The most available form of nitrogen for plants is
1) NH₃
2) NO₂–
3) NO₃–
4) N₂
Answer:
1) NH₃

Question 37.
The most important step of Nitrogen cycle for recycling minerals is called
1) Nitrogen fixation
2) Ammonification
3) Nitrogen assimilation
4) Nitrification
Answer:
4) Nitrification

Question 38.
The steps of Nitrogen cycle which are chemically similar show reduction
1) Nitrification and Ammonification
2) N₂ fixation and Nitrificatgiori
3) N₂ fixation and Denitrification
4) Ammonification and Nitrogen assimilation
Answer:
3) N₂ fixation and Denitrification

Question 39.
Zinc is activator of ………… proteolytic ezyme
1) Alcoholic dehydrogenase
2) Pepsi
3) Carbonic hydrase
4) Carboxy peptidase
Answer:
4) Carboxy peptidase

Question 40.
Pick out the correct microorganism involved in the following oxidations
1) Organic nitrogen to Ammonia →Nitrosomonas
2) Nitrate to Nitrogen → Nitrobacter
3) Ammonia to Nitrite → Nitrococcus
4) Nitrite to Nitrate → Pseudomonas
Answer:
3) Ammonia to Nitrite → Nitrococcus

Question 41.
The number of H⁺, e^– & ATP required for the formation of 2NH₃ + H₂ is
1) 6H⁺, 8e^–, 8 ATP
2) 8H⁺, 8e^–, 16 ATP
3) 8H⁺, 6e^–, 16 ATP
4) 8H⁺, 8e^–, 16 ATP
Answer:
2) 8H⁺, 8e^–, 16 ATP

Question 42.
The role of leg- haemoglobin is
1) to provide reducing power to N₂
2) to protect nitrogenase from oxygen
3) to attract the Rhizobia by root hair
4) for the multiplication of Bacteria
Answer:
2) to protect nitrogenase from oxygen

Question 43.
In soyabean nodules, the fixed nitrogen is translocated in the form of
1) Amino acids
2) Amides
3) Ureides
4) NH₃
Answer:
3) Ureides

Question 44.
The enzyme nitrogenase is a protein associated with
1) Fe alone
2) Fe & Mg
3) Mo & Fe
4) Fe & N₂
Answer:
3) Mo & Fe

Question 45.
Nitrifying bacteria
1) Liberates ammonia
2) Changes ammonia into ionic form
3) Oxidises ammonia to nitrate
4) Oxidises ammonia to nitrite
Answer:
3) Oxidises ammonia to nitrate

Question 46.
The enzyme responsible for the reduction of molecular nitrogen to the level of ammonia id leguminous root nodule is
1) Hydrogenase
2) Carboxylase
3) Nitrogenase
4) Nitrite reductase
Answer:
4) Nitrite reductase

Question 47.
Which one of the following is an amide involved in nitrogen assimilation by plants
1) Glycine
2) Serine
3) Alanine
4) Aspargine
Answer:
4) Aspargine

Question 48.
N₂ + 8H⁺ + 8e^– + 16 ATP → 2NH₃ +H₂ + 16ADP + 16Pi
This equation refers to
1) Ammonification
2) Nitrification
3) Nitrogen fixation
4) Denitrification
Answer:
3) Nitrogen fixation

Question 49.
Reducing power required for reduction of dinitrogen into ammonia
1) 8e^–, 8H⁺
2) 6 e^–, 6H⁺
3) 4 e^–, 4H⁺
4) 2 e^–, 2H⁺
Answer:
3) 4 e^–, 4H⁺

Question 50.
In cyanobacteria, dinitrogenase is protected in :
1) Hormogonia
2) Endospores
3) Akinetes
4) Heterocysts
Answer:
4) Heterocysts

Question 51.
Which is essential for the growth of root tip?
1) Zn
2) Fe
3) Ca
4) Mn
Answer:
3) Ca