Nitrogen Cycle

Q.

An example of symbiotic bacteria is

1. Erwinia amylovora

2. Rhizobium leguminosarum

3. Xanthomonas campestris

4. Agrobacterium tumefaciens

Q.

Which is the first stable product of nitrogen fixation?

Q. Look at figure and find the position of xylem in the vascular bundle.

Q.

What are the different types of nitrogen fixation?

Q. Choose the statements that correctly differentiate between phosphorus and carbon cycle.
I. Phosphorus is released into the atmosphere due to respiratory activities while carbon is not
II. Carbon is released into the atmosphere due to respiratory activities while phosphorus is not
III. Phosphorus cycle is sedimentary while carbon cycle is gaseous
IV. Lithosphere is the reservoir for phosphorus cycle while atmosphere is the reservoir for carbon cycle

1. I, III and IV
2. II, III and IV
3. II and III
4. I and IV

Q.

Why is biological nitrogen fixation important in ecology?

Q.

All animals and human beings are directly or indirectly depend on plants for __________.

1. Food.

2. Oxygen

3. Both food and Oxygen

4. Petroleum product

Q. Study the cycle shown below and select the option which gives correct words for all the four blanks A, B, C and D.

1. $\begin{array}{cccc}\text{A}& \text{B}& \text{C}& \text{D}\\ \text{Nitrification}& \text{Ammonification}& \text{Animals}& \text{Plants}\end{array}$
2. $\begin{array}{cccc}\text{A}& \text{B}& \text{C}& \text{D}\\ \text{Denitrification}& \text{Ammonification}& \text{Plants}& \text{Animals}\end{array}$
3. $\begin{array}{cccc}\text{A}& \text{B}& \text{C}& \text{D}\\ \text{Denitrification}& \text{Nitrification}& \text{Plants}& \text{Animals}\end{array}$
4. $\begin{array}{cccc}\text{A}& \text{B}& \text{C}& \text{D}\\ \text{Nitrification}& \text{Denitrification}& \text{Animals}& \text{Plants}\end{array}$

Q.

The organism which is autotrophic but does not have the pigment is

1. Nostoc

2. Wolffia

3. Yeast

4. Nitrosomonas

Q.

What are artificial and natural methods of nitrogen fixation?

Q. Choose the correct option with respect to UAA, UAG, and UGA codons.

1. These play significant role in active amino acid formation.
2. These are recognised by protein release factors rather than tRNAs.
3. These are called opal, ochre and amber respectively.
4. These code for glycine, valine and phenylalanine respectively.

Q. Nitrite reductase enzyme is used to convert

1. nitrate into nitrite ion
2. nitrogen of atmosphere into ammonia
3. ammonia into nitrates
4. nitrite to ammonia

Q.

What are chemoautotrophic nitrifying bacteria?

Q. This gymnosperm has coral-like roots that form a symbiotic association with organisms that aid in nitrogen fixation. Identify the gymnosperm.

1. Sequoia
2. Cedrus
3. Pinus
4. Cycas

Q. Match the following

	Column A		Column B
p	Bacillus thuringiensis	1	Bio fertiliser
q	Rhizobium	2	Agrochemical
r	Urea	3	Biopesticide

1. p - 1, q - 3, r - 2
   
2. p - 3, q - 1, r - 2
   
3. p - 2, q - 1, r - 3
   
4. p - 3, q - 2, r - 1
   

Q. The plumule and radicle are enclosed in sheath which are called

1. aleurone layer, scutellum
2. aleurone layer, coleorhiza
3. coleoptile, coleorhiza
4. aleurone layer, coleoptile

Q. Describe the internal structure of a dorsiventral leaf with the help of labelled diagrams.

Q. Assertion: Manganese is an activator of enzyme nitrite reductase. Reason: Manganese deficient cells prefer ammonia over nitrate.

1. Both the reason and assertion are false
2. Both assertion and reason are true and the reason is the correct explanation for the assertion.
3. Both the reason and assertion are true but the assertion is not the correct explanation for reason.
4. Assertion is true but reason is false.

Q. "Large scale cultivation of Spirulina is highly advantageous for human population." Explain giving two reasons. [2]

Q. Creatinine is not produced by

1. Children
2. Fasting persons
3. Healthy males
4. Pregnant women

Q. Match the columns and choose the correct answer.

	I		II
(p)	Thiobacillus	(i)	Nitrogen fixation
(q)	Nitrosomonas	(ii)	Ammonification
(r)	Azotobacter	(iii)	Nitrification
(s)	Pseudomonas	(iv)	Denitrification

1. p-iv, q-iii, r-i, s-ii
2. p-iii, q-v, r-i, s-ii
3. p-iv, q-ii, r-i, s-iii
4. p-ii, q-i, r-iii, s-iv

Q.

The function of leghaemoglobin in the root nodules of legumes is:

1. Expression of nif gene

2. Inhibition of nitrogenase activity

3. Nodule differentiation

4. Oxygen removal

Q. Decomposers like fungi and bacteria are

(i) autotrophs
(ii) heterotrophs
(iii) saprotrophs
(iv) chemo-autotrophs

1. (i) and (iii)
2. (i) and (iv)
3. (ii) and (iii)
4. (ii) and (iv)

Q. What are various steps involved in biological nitrogen fixation in plants?

Q.

Ability to convert atmospheric nitrogen into nitrate/ammonium ions is called----------------

Q. Roots of Cycas are specialised with extensive branching, called coralloid roots, which help in:

1. Fixation of $C{O}_2$
2. Fixation and absorption of nitrogen
3. Respiration
4. Absorption of minerals

Q. Which of the following is not an aerobic nitrogen fixing free living bacteria?

1. Azospirillum
2. Azotobacter
3. Beijerinickia
4. Chromatium

Q.

In the nitrogen cycle, which group of bacteria convert nitrates and nitrites back to atmospheric gas?

1. Denitrifying bacteria

2. Nitrifying bacteria

3. Nitrogen-fixing bacteria

4. All of the above

Q. What is the role of pseudomonas in nitrogen cycle?

1. Transfers nitrogen
2. Fixes elemental nitrogen
3. Produces elemental nitrogen
4. Changes ammonium nitrogen to nitrate state

Q.

State one advantage of growing a leguminous crop between two cereal crops.