Tag: the living world

Questions Related to the living world

Thermococcus, Methanococcus and Methanobacterium exemplify 

botany the living world archaebacteria the three domains of life classification of microbes

  1. Bacteria that contain a cytoskeleton and ribosomes

  2. Archaebacteria that contain protein homologous to eukaryotic core histones

  3. Archaebacteria that lack any histones resembling those found in eukaryotes but whose DNA is negatively supercoiled

  4. Bacteria whose DNA is relaxed or positively supercoiled but which have a cytoskeleton as well as mitochondria

Show answer
Correct Option: B
Explanation:

Thermococcus, Methanococcus and Methanobacterium are archaea whose histones are shorter than eukaryotic histones and are assembled in tetramers.

So the correct answer is' Archaebacteria that contain protein homologous to eukaryotic core histones'

Which of the following statements is incorrect regarding the structure of a typical bacterial cell?

botany the living world archaebacteria the three domains of life classification of microbes

  1. Cells possess naked circular DNA which is folded to form nucleoid.

  2. Cells are surrounded by a peptidoglycan cell wall and a mucilaginous sheath.

  3. Cells possess well developed membrane bound cell organelles.

  4. Ribosomes in these cells are 70S in nature.

Show answer
Correct Option: C
Explanation:

The bacterial cell is a prokaryotic type of cell which lacks membrane-bound cell organelles.

So, the correct option is 'Cells possess well-developed membrane-bound cell organelles.'

Read the following statements regarding methanogens and select the correct option.
(i) They are included in the group Archaebacteria.
(ii) They are responsible for the production of biogas in gobar gas plants.
(iii) They live in hot sulphur springs.
(iv) They are strictly anaerobic. 

botany the living world archaebacteria the three domains of life classification of microbes

  1. Statements (i) and (ii) are correct.

  2. Statements (i), (ii) and (iv) are correct.

  3. Statements (ii), (iii) and (iv) are correct.

  4. All statements are correct.

Show answer
Correct Option: A
Explanation:

Archaebacteria differ from other bacteria in having a different cell wall structure and this feature is responsible for their survival in extreme conditions. Methanogens are present in the gut of several ruminant animals such as cows and buffaloes and they are responsible for the production of methane (biogas) from the dung of these animals. Methanogens are obligate anaerobes.

So the correct option is "Statement(i) and (ii) are correct".

Choose the correct answers from the alternatives given.
Which of the following is mismatched?

botany the living world archaebacteria the three domains of life classification of microbes

  1. Diatomssilica shell, boxlike, golden brown

  2. Euglenoidsflagella, pellicle, eye spot

  3. Parameciumcilia, calcium carbonate shell, gullet

  4. Foraminiferantest, pseudopod, digestive vacuole

Show answer
Correct Option: C
Explanation:

Paramecium consists cilia on the cell wall which is made up of the pellicle, paramecium does not contain calcium carbonate shell and the food in the paramecium passes through the cell mouth into the gullet.

So, the correct option is 'Paramecium cilia, calcium carbonate shell, gullet.'

Which of the following bacteria is present in the rumen of cattle ?

botany the living world archaebacteria the three domains of life classification of microbes

  1. Azotobacfer

  2. Rhizoblum

  3. Methanobacterium

  4. Azospirilium

Show answer
Correct Option: C
Explanation:

Methanobacterium is found in the rumen (a part of the stomach) of cattle. A lot of cellulosic material is also available in the rumen. In rumen, these bacteria help in the breakdown of cellulose and play an important role in nutrition of cattle.

Select the correct combination of the statements (i - iv) regarding the characteristics of certain organisms.
(i) Methanogens are archaebacterial which produces methane in marshy areas.
(ii) Nostoc is a filamentous blue-green alga which fixed atmospheric nitrogen.
(iii) Chemosynthetic autotrophic bacteria synthesize cellulose from glucose.
(iv) Mycoplasma lacks a cell wall and can survive without oxygen.

botany the living world archaebacteria the three domains of life classification of microbes

  1. (ii) and (iii)

  2. (i), (ii) and (iii)

  3. (ii), (iii) and (iv)

  4. (i), (ii) and (iv)

Show answer
Correct Option: D
Explanation:

Methanogens produce methane gas, nostoc fixes atmospheric nitrogen, mycoplasma lacks a cell wall and can survive without oxygen.

So, the correct option is '(i), (ii) and (iv)'.

Organisms living in salty areas are called as

botany the living world archaebacteria the three domains of life classification of microbes

  1. Methanogens

  2. Halophiles

  3. Heliophytes

  4. Thermoacidophiles

Show answer
Correct Option: B
Explanation:

Halophiles can be found in a concentration of salt five times greater than the salt concentration of the ocean.

So, the correct option is 'halophiles'.

Certain bacteria are able to thrive under extreme environmental conditions such as absence of oxygen, high salt concentration, high temperature or highly acidic environment. What are these bacteria called?

botany the living world archaebacteria the three domains of life classification of microbes

  1. Probacteria

  2. Neobacteria

  3. Hardy bacteria

  4. Archaebacteria

Show answer
Correct Option: D
Explanation:
Archaebacteria are the oldest organisms living on the Earth. They are unicellular prokaryotes and belong to the kingdom, Archaea. They were first discovered in 1977 and classified as bacteria. Most archaebacteria appear like bacteria, when observed under the microscope. However, they are quite different from bacteria and eukaryotic organisms. Archaebacteria are found in very harsh conditions such as in the volcanic vents or at the bottom of the sea. They can easily survive in such extreme environment as sea vents releasing sulfide-rich gases, hot springs, or boiling mud around volcanoes.
So the correct option is 'archaebacteria'.

These bacteria grow anaerobically on cellulosic material, produce large amount of methane along with $CO _2$ and $H _2$ and are collectively called as methanogens. Examples of such bacteria are:

botany the living world archaebacteria the three domains of life classification of microbes

  1. Melhanobacterium

  2. Mathanobrevibacter

  3. Methanococcus

  4. All of these

Show answer
Correct Option: D
Explanation:

Methanogens are microorganisms that produce methane as a metabolic byproduct in anoxic condition. They include Methanobacterium, Methanobrevibacter and Methanococcus. 

Methanogens can be found 

botany the living world archaebacteria the three domains of life classification of microbes

  1. In swamps

  2. In a cow's stomach

  3. In marshes

  4. All of the above

  5. None of the above

Show answer
Correct Option: D
Explanation:

Methanogens are the primitive bacteria belonging to archaea which are able to produce methane. These organisms can utilise the carbon dioxide and hydrogen gas to form methane. These organisms are found in marshy areas where they produce the marsh gas, in swamps and in the stomach of certain animals. These organisms are responsible for methane production in the stomach of cattle which causes belching.

Thus, the correct answer is option D.