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Microbiology

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Which of the following proteins is present in 'prokaryotes'?

  1. H1 protein

  2. H2 protein

  3. HU protein

  4. H3 protein

  5. H4 protein


Correct Option: C
Explanation:

HU is the most abundant protein in prokaryotes. 

Which of the following is NOT a characteristic of a prokaryotic genome?

  1. Single circular chromosome is present.

  2. Extrachromosomal plasmids are not commonly seen.

  3. Transcription and translation occurs simultaneously.

  4. Nucleoid is formed by DNA supercoiling.

  5. Small amounts of repetitive DNA present.


Correct Option: B
Explanation:

This is a characteristic of eukaryotes.

Iron uptake is problematic owing to the insolubility of the Fe 3 + ion (usually in the form of hydroxides). Microbes overcome this difficulty by secreting special high-affinity, iron-binding molecules termed as __________.

  1. siderophores

  2. permeases

  3. methionine

  4. vitamins

  5. phosphoenolpyruvate


Correct Option: A
Explanation:

This is true. Microbes have built up specialized transport systems called siderophores. After the molecule is transported in, it gives up the iron ion which is then reduced to the ferrous form (Fe 2+). These siderophores are recycled.

“Amongst the eukaryotes, fungi and plants are found to have plasmids, but not animals. ”Which of the following are true for the eukaryotic plasmids?

  1. In case of filamentous fungi, plasmids are frequently found in isolates of natural populations.

  2. One strain of fungi always contain a single type of plasmid only.

  3. Plasmids are inherited paternally in crosses.

  4. Circular plasmids are absent in Neurospora sp.

  5. Circular plasmids have two open reading frames (ORF).


Correct Option: A
Explanation:

This is true for filamentous fungi. Here the plasmids are frequently found in isolates of natural populations.

Whenever bacteria are inoculated into a fresh culture medium, they show characteristic growth curve having four distinct phases. Indicate the phase wherein all the nutrients in the culture medium are used up and the inhibitory end products of metabolism get accumulated.

  1. Lag phase

  2. Log phase

  3. Stationary phase

  4. Death phase

  5. Intermediary phase


Correct Option: C
Explanation:

During the stationary phase, the nutrients in the culture medium are used up and the inhibitory end products of metabolism get accumulated.

Which molecule enhances the coupling of anabolic and catabolic reactions in a microbial metabolism?

  1. Flavin mononucleotide(FMN)

  2. Ribozyme

  3. ATP

  4. Ligase

  5. Isomerase


Correct Option: C
Explanation:

When complex molecules get split (catabolism), some energy is liberated and stored in ATP. The remaining energy is given off as heat. When simple molecules combine together (anabolism), ATP provides the required energy.

Which of the following statements is true?

  1. Propionibacterium can use lactic acid produced by other bacteria.

  2. Pseudomonas is oxidase negative.

  3. Escherichia is oxidase positive.

  4. Salmonella can be readily distinguished from E. coli by the production of lactic acid.

  5. All bacteria have cytochrome C.


Correct Option: A
Explanation:

This is true. Propionibacteria can transform lactic acid to pyruvic acid in preparing for the Kreb’s cycle.

Frankia is a genus of the bacterial group termed as actinomycetes. Which of the following is NOT true for this particular genus?

  1. These are filamentous bacteria.

  2. They are noted for the production of airborne pores.

  3. The common soil dwelling streptomyces belong to this group.

  4. They develop nitrogen fixing root nodules.

  5. Frankia species are very fast growing in culture.


Correct Option: E
Explanation:

The species grows very slowly in culture.

Who demonstrated the mutational effects of UV radiation?

  1. Hermann Muller

  2. Edgar Altenburg

  3. Charlotte Auerbach and J. M. Robson

  4. Lewis Stadler

  5. Bruce Ames


Correct Option: B
Explanation:

Edgar Altenburg demonstrated the mutational effect of UV radiation in 1928.

Biological nitrogen fixation (BNF), discovered by Beijerinck in 1901, is performed by a specialised group of organisms (prokaryotes). These prokaryotes use the enzyme nitrogenase to catalyze the process of transformation of atmospheric nitrogen (N2) to ammonia (NH3). Which of the following organisms can bring about biological nitrogen fixation?

  1. Cyanobacteria

  2. Azotobacter

  3. Azospirillium

  4. Rhizobium

  5. All of the above


Correct Option: E
Explanation:

All of the mentioned organisms can bring about biological nitrogen fixation.

RNA directed DNA polymerase is the other name for

  1. RNA polymerase

  2. reverse transcriptase

  3. ribozymes

  4. DNA polymerase

  5. integrase


Correct Option: B
Explanation:

Reverse transcriptase, also referred to as RNA-directed DNA polymerase, is an enzyme encoded from the genetic material of retroviruses. It catalyzes the transcription of retrovirus RNA (ribonucleic acid) into DNA (deoxyribonucleic acid). This catalyzed transcription is the reverse process of normal cellular transcription of DNA into RNA, that is why it is called the reverse transcriptase.

Which of the following viruses does not possess capsid?

  1. Rous Sarcoma virus

  2. Reo virus

  3. Polio virus

  4. Potato spindle virus

  5. Phage virus


Correct Option: D
Explanation:

Potato spindle virus has no capsid.

Which of the following plasmids is used to reduce the expression of an endogenous gene?

  1. Cloning plasmids

  2. Expression plasmids

  3. Gene knockdown plasmids

  4. Reporter plasmids

  5. Viral plasmids


Correct Option: C
Explanation:

These plasmids are used for reducing the expression of endogenous genes. This is often attained through the expression of an shRNA while targeting the mRNA of the gene of interest. These plasmids possess promoters that can influence the expression of short RNAs.

Which of the following are used as intercalating agents in chemical mutation?

  1. Acridine orange, proflavin and ethidium bromide

  2. Nitrosoguanidine, methyl methanesulfonate and ethyl methanesulfonate

  3. NAAAF

  4. Peroxides

  5. Aminopurine


Correct Option: A
Explanation:

Acridine orange, proflavin and ethidium bromide are flat, multiple ring molecules which react with DNA bases and insert between them. This insertion creates a stretching in the DNA duplex and the DNA polymerase is fooled into inserting an extra base opposite an intercalated molecule. The result is that intercalating agents cause frameshifts.

Which of the following is a retrovirus?

  1. HIB

  2. HIV

  3. Influenza virus

  4. Rabbis virus

  5. Phage virus


Correct Option: B
Explanation:

A retrovirus is an RNA virus, which replicates inside a host cell by the process of reverse transcription. Initially it employs its own reverse transcriptase enzyme to produce DNA from its RNA genome. This is the opposite of the normal pattern and hence, it is called retro or backwards. This new DNA is in turn included into the host's genome by an integrase enzyme.

In case of ribosomes ‘S’ denotes ___________

  1. Slubility

  2. Svedberg subunit

  3. Sdimentation coefficient

  4. Both 2 and 3

  5. None of the above


Correct Option: D
Explanation:

‘S ‘ denotes both Svedberg subunit and Sedimentation coefficient.

By which process you can measure the size of a virus?

  1. Filtration

  2. Silicoid centrifugation

  3. Electron microscopy

  4. X-ray

  5. Diffraction technique


Correct Option: C
Explanation:

EM or electron microscopy is the process by which the size of a virus can be measured accurately.

If an mRNA can be made from the DNA chain having nucleotide sequence 5’TCCAAGTTA3’, the sequence that will be generated in the newly formed mRNA will be ________.

  1. 5’AGGTTCAAT3’

  2. 5’AGGUUGAAU5’

  3. 5’AGGUUCAAT5’

  4. 5’AGTUUCAAU3’

  5. None of the above


Correct Option: E
Explanation:

The correct sequence will be 3’AGGUUCAAU5’

Which of the following features is NOT true for a retrovirus?

  1. The membrane of a retrovirus contains glycoproteins, which are capable of binding to a receptor protein on a host cell.

  2. Inside the cell there are two strands of DNA that have three enzymes, protease, reverse transcriptase and integrase.

  3. Inside the cells, reverse transcriptase makes a complementary strand of DNA from the retrovirus RNA and the RNA is degraded.

  4. Inside the nucleus, the DNA is incorporated into the host cell DNA with the aid of integrase.

  5. Ribosomal units are employed to transcribe the viral mRNA into amino acid sequences that can be transformed into proteins in the RER.


Correct Option: B
Explanation:

This statement is wrong. The correct statement is - Inside the cell there are two strands of RNA that have three enzymes, protease, reverse transcriptase and integrase.

Which mutation causes a change in all the amino acids downstream?

  1. Transition

  2. Frameshift mutation

  3. Transversion

  4. Chromosome mutation

  5. Point mutation


Correct Option: B
Explanation:

This type of mutation causes a change in all the amino acids downstream.

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