Tag: zoology

Quizzes (289) Questions (5869)

Questions Related to zoology

Multiple choice zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

Which of the following is a free living aerobic nitrogen fixing bacterium present in the soil?

  1. Nitrosomonas

  2. Rhizobium

  3. Azotobacter

  4. Pseudomonas
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Azotobacter and Beijerinckia  are aerobic free living saprophytic nitrogen fixing bacteria, while Clostridium is anaerobic free living saprotrophic nitrogen fixing bacterium.

Multiple choice zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

Which one of the following bacteria is not connected with nitrogen fixation?

  1. Azotobacter

  2. Nitrosomonas

  3. Frankia

  4. Rhizobium
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Nitrogen fixation is referred to as conversion of atmospheric nitrogen into ammonia, whereas the Nitrosomonas is a genus of Gram-negative, chemoautotrophic bacteria. This organism oxidizes ammonia into nitrite as a metabolic process. 

 So, the correct option is 'Nitrosomonas'.

Multiple choice zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

Which of the following is a flowering plant with nodules containing filamentous nitrogen-fixing microorganism?

  1. Cicer arietinum

  2. Casuarina equisetifolia

  3. Crotalaria juncea

  4. Cycas revolute
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Answer :
i) All the casuarinas are nitrogen-fixing. 
ii) Casuarinas support an actinorhiza symbiont in their root nodules, as opposes to the rhizobium symbiont found in the root nodules of leguminous trees that fix N2. 

Therefore correct answer is option B.Casuarina equisetifolia.

Multiple choice zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

Nitrifying bacteria convert the________________

  1. Nitrates into nitrites

  2. Ammonium salts into nitrates

  3. Ammonium salts into amino acids

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Nitrifying bacteria are chemoautotrophic or chemolithotrophs depending on the genera (Nitrosomonas, Nitrosococcus, Nitrobacter, Nitrococcus) bacteria that grow by consuming inorganic nitrogen compounds. Many species of nitrifying bacteria have complex internal membrane systems that are the location for key enzymes in nitrification: ammonia monooxygenase, which oxidizes ammonia to hydroxylamine, and nitrite oxidoreductase, which oxidizes nitrite to nitrate. Nitrifying bacteria are a narrow species in the environment and are found in the lowest numbers, where considerable amounts of ammonia are present (areas with extensive protein decomposition, and sewage treatment plants). Nitrifying bacteria thrive in lakes and rivers streams with high inputs and outputs of sewage and wastewater and freshwater because of the low ammonia content.

Multiple choice zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

Nitrifying bacteria _________________.

  1. Oxidize.2riimonia to nitrates

  2. Convert free nitrogen to nitrogen compounds

  3. Convert proteins into ammonia

  4. Reduce nitrates to free nitrogen
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Nitrifying bacteria oxidize ammonia to nitrites and then to nitrates in a two-step process. Nitrosomonas converts ammonia to nitrite, and Nitrobacter converts nitrite to nitrate. This is part of the nitrogen cycle.

Multiple choice zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

Nitrifying bacteria are able to 

  1. Convert atmospheric nitrogen into soluble forms

  2. Convert ammonia to nitrate

  3. Ammonia to nitrogen

  4. Nitrate to nitrogen
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Nitrification is an important process in nitrogen cycle in nature, which is brought about by nitrifying bacteria. In warm moist soils having a temperature of $30-35^0$C and neutral pH, ammonia gets oxidized to nitrite ($NO _2^-$) and then nitrate ($NO _3^-$) by the process of nitrification. 

Nitrifying bacteria like Nitrosomonas convert ammonia to nitrite and another bacterium, called as Nitrobacter converts nitrite to nitrate.

Multiple choice zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

The common nitrogen-fixer in paddy field is _______________.

  1. Azospirillum

  2. Oscillatoria

  3. Frankia

  4. Rhizobium
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The common Nitrogen fixer in the paddy field is Azospirillum. This is a soil and root bacteria. It is a nitrogen-fixing bacteria when added to the soil it multiplies and supplies 30-40Kg nitrogen per hectare per season. It also produces Indole acetic acid which helps in growth.


Hence the correct option is A.