Tag: evs

Questions Related to evs

Favourable condition for nitrogenase activity in heterocyst of BGA is due to

evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

  1. Loss of PS-II

  2. Loss of PS-I

  3. Presence of thick wall

  4. More than one option is correct

Show answer
Correct Option: A
Explanation:

Heterocysts are specialized nitrogen-fixing cells formed during nitrogen starvation by some blue-green algae. They fix nitrogen from di-nitrogen in the air using the enzyme nitrogenase and nitrogenase is inactivated by oxygen, so the heterocyst must create a micro-anaerobic environment and that's why heterocysts degrade photo-system II, which produces oxygen.

So, the correct option is 'Loss of PS-II'.

Leghaemoglobin is required in the process of

evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

  1. Nitrification

  2. Reductive amination

  3. Ammonification

  4. Diazotrophy

Show answer
Correct Option: D

In root nodules of legumes, leghaemoglobin is important because it:-

evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

  1. Acts as a catalyst in transamination

  2. Transports oxygen to the root nodule

  3. Provide energy to the nitrogen fixing bacteria

  4. Acts as an oxygen scavenger

Show answer
Correct Option: B
Explanation:

  • Leghaemoglobin (also leghemoglobin or legoglobin) is an oxygen carrier and hemoprotein found in the nitrogen-fixing root nodules of leguminous plants. 
  • Leghaemoglobin buffers the concentration of free oxygen in the cytoplasm of infected plant cells to ensure the proper function of root nodules.

So, the correct answer is "transports oxygen to the root nodule".

Which one of the following can be used as a biofertilizer?

evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

  1. Plasmodium

  2. Rhizobium

  3. Chenopodium

  4. Agrobacterium

Show answer
Correct Option: B
Explanation:

Microorganisms which, when applied to seed, plant surfaces, or soil, colonizes the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant. Rhizobium can be used as biofertilizer. Rhizobium are found in the soil and after infection, produce nodules in the legume where they fix nitrogen gas (N2) from the atmosphere turning it into a more readily usable form of nitrogen.


So, the correct option is 'Rhizobium'.

Bio-fertiliser which makes available phosphorus is?

evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

  1. Azolla

  2. Aulosira

  3. Mycorrhiza

  4. Chromatium

Show answer
Correct Option: C
Explanation:

Mycorrhizal fungi, which form a symbiosis with the roots of nearly all vascular plants, play a key role in solving the phosphate shortage problem for plants. Mycorrhizal fungi can effectively increase phosphate uptake by converting insoluble phosphates to soluble, available forms.

So, the correct option is 'Mycorrhiza'.

Which of the following is incorrect about leg-haemoglobin?

evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

  1. It acts as $O _2$ scavenger

  2. It imports pink or red colour to the nodules

  3. It combines unit $O _2$ and protects nitrogenase

  4. It is a Mo-Fe protein

Show answer
Correct Option: D
Explanation:

Leg-haemoglobin is an oxygen carrier. It is found in root nodules of leguminous plants. It is red in colour and is a hemoprotein. It provides or helps in providing oxygen to symbiotic bacterial cells. 

It is Mo-Fe protein.

Leghaemoglobin in symbiotic nodules helps :

evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

  1. To provide energy to the growing symbionts

  2. In nitrogen reallocation between symbionts and plants

  3. By scavenging Oxygen

  4. To stabilize redox potential of host cells

Show answer
Correct Option: C
Explanation:

Leghaemoglobin helps to mantain internal oxygen in symbiotic nodules, because this protein has ten times more affinity for oxygen as compared to blood pigment haemoglobin.Therefore they acts as oxygen scavenger.

So, the correct answer as 'by scavenging oxygen'

The $N _{2}$ fixing bacterium associated with root nodules of legumes is known as

evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

  1. Azotobacter

  2. Nitrobacter

  3. Lactobacillus

  4. Rhizobium

Show answer
Correct Option: D
Explanation:

Rhizobium is microaerophilic rod shaped gram negative bacteria found in association with legume plants in root nodules. These bacteria fix atmospheric nitrogen into ammonium ions, which can be readily assimilated by plants.

The pigment useful in nitrogen fixation is

evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

  1. Nitrogenase

  2. Haemoglobin

  3. Myoglobin

  4. Leghaemoglobin

Show answer
Correct Option: D
Explanation:

Plants cannot consume atmospheric nitrogen directly, because in atmosphere nitrogen occurs in stable diatomic form. The atmospheric nitrogen needs to be converted into plant usable forms like nitrate, nitrite and ammonium ion. This process is called as nitrogen fixation. 

Rhizobium is a microaerobic bacteria, which occurs in root nodules of legume plants in symbiotic association. Rhizobium bacteria nodule is pink coloured due to presence of a bacterial pigment called as leghaemoglobin. This pigment binds excess oxygen present in nodules. Free oxygen is harmful for the nitrogenase enzyme of Rhizobium. Rhizobium bacteria reduces atmospheric nitrogen into ammonium ions using reducing power obtained from host plant.

Leguminous plants have their roots modified into

evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

  1. Fibrous roots.

  2. Stilt roots.

  3. Nodulated roots.

  4. Prop roots.

Show answer
Correct Option: C
Explanation:

Nodules develop in the roots of leguminuos plants like pulses and grams. These nodules have a very specific function. They inhabit rhizobium bacteria. it is a type of nitrogen fixing bacteria, It absorbs free nitrogen from the atmosphere and converts it into nitrites and nitrates and fixes it in the soil. From soil, plants absorb nitrogen fixed by the bacteria. So, nitrogen requirement of leuminuous plants is fulfilled.

So, option C "Nodulated roots" is the correct answer.