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The correct option is (a) PROMOTER

To ELABORATE: The promoter region which is present towards the 5’ end of the coding strand is the start SITE for transcription to occur. These are regions on the DNA where the RNA polymerase enzyme will bind. This leads to the process of transcription.

The correct ANSWER is (a) True

The best EXPLANATION: Genes are the functional units of a living organism. They are the information carriers that are present on the DNA. But a gene cannot be entirely defined BASED on its DNA SEQUENCE alone. The DNA sequence coding for either the tRNA or the rRNA also defines the gene.

The correct option is (c) Organiser

The BEST I can explain: The transcription unit of a DNA molecule consists of a promoter region, the STRUCTURAL gene and a TERMINATOR. A transcription unit consists of a sequential ARRANGEMENT of nucleotides which are used to CODE for the RNA molecule during the process of transcription.

The correct answer is (b) False

Explanation: If both the strands of DNA are copied into the RNA acting as a template strand, then coding of these RNA MOLECULES into protein will become complex during the process of translation. Translation is the second STAGE during the central dogma of DNA. So, only a single strand of DNA is copied into the RNA for the synthesis of protein.

Correct choice is (a) True

To elaborate: In DNA, the double hydrogen base pairing is seen between Adenine and THYMINE. Likewise, the TRIPLE hydrogen base pairing is seen between Guanine and Cytosine. But Uracil is present in the PLACE of Thymine in the single stranded structure of RNA. So, Adenosine forms a base pair with Uracil INSTEAD of Thymine.

The CORRECT OPTION is (b) TRANSCRIPTION

To elaborate: The process of copying a single strand of DNA into a strand of RNA is called as transcription. The process of transcription is the first STAGE in the central dogma of DNA.

Correct answer is (d) The S PHASE

For explanation: The PROCESS of replication will take place during the S phase of the E. Coli BACTERIUM’s cell cycle. During this time, the replication of the DNA and the cell cycle should be highly coordinated.

Correct answer is (b) 5’ → 3’

The explanation is: The direction for DNA DEPENDENT DNA polymerases to catalyse the polymerisation reaction is the 5’ → 3’ direction. But, in this direction of polarity, a discontinuity can be observed. These DISCONTINUOUS strands of DNA can then be linked together with the help of DNA ligases. But, in the direction of 3’ → 5’ in the DNA, the replication process can be seen to be continuous.

Right CHOICE is (d) Replication fork

For explanation: In the CASE of large sized DNA molecules, the double strands of these molecules cannot be ENTIRELY separated. This is because, an extremely high amount of energy SUPPLY is required. So, in such cases, the PROCESS of replication fork takes place. It is a process in which a small opening is made in the portion of the DNA helix for replication to occur.

The correct CHOICE is (a) Mutation

Explanation: If any abnormal changes have to occur during the PROCESS of replication, mutations in the cells will ARISE. These changes occur if the DNA polymerase is not fast enough and also if the CATALYSIS process is not done with high rate of accuracy.

Right answer is (c) 18 minutes

The best I can explain: The E. Coli has a total of 4.6 × 10^6 base PAIR. It completes its process of replication within 18 minutes. This means that the average RATE of polymerisation of E. Coli DNA is 2000 base pairs per second.

Correct option is (d) DNA polymerase

Best explanation: In most of the living CELLS of organisms like E. Coli, for the process of replication to occur, certain ENZYMES are USED. The main enzyme which is used is a DNA DEPENDENT enzyme which is the DNA polymerase.

Correct choice is (C) Vicia faba

Explanation: Taylor and his colleagues conducted an experiment on Vicia fabain 1958. They used RADIOACTIVE thymidine to DETECT the distribution of newly synthesised DNA in the chromosomes of the cells. They PROVED that the DNA which is present inside the chromosomes replicate semi conservatively.

The correct option is (d) Escherichia COLI

For explanation I would say: It was PROVED by WATSON and Crick that the DNA replicates semi-conservatively. This was first observed in Escherichia coli. Later, the same concept was observed in PLANTS and human CELLS too.

The correct choice is (b) ^15N

The explanation: Mathew Meselson and Franklin Stahl grew Escherichia coli in a medium CONTAINING ^15NH4Cl as the only source of NITROGEN for many YEARS together. The isotope of nitrogen in this compound is ^15N. It is SAID to be the heavy isotope of nitrogen.

Right choice is (C) PRESENCE of both PARENTAL and newly synthesised strands in DNA

Explanation: The term semiconservative DNA replication means that the DNA molecule has both a parental and newly synthesised strand by the PROCESS of replication. During replication, the template strand of the DNA (the separated strand from the double helical structure) will help in the synthesis of complementary strands.

The correct choice is (a) True

To elaborate: The double helical structure of the DNA MOLECULE possesses two strands. It is SEPARATED during the PROCESS of replication. The separate strands will act as templates for the synthesis of complementary strands. So, when the process of replication COMES to an end, every DNA molecule has a parental and newly synthesised strand.

Correct OPTION is (a) DNA

Easiest explanation: DNA is a stable genetic molecule in comparison to the RNA. So, the carriage of the genetic INFORMATION will be carried out by the DNA. The transmission of the genetic MATERIAL will be done by RNA as it is COMPARATIVELY less stable.

Right option is (b) RNA

For explanation I would say: The STORAGE of the genetic INFORMATION takes place in the DNA. It CARRIES all the necessary information needed for heredity. The stability of the DNA is more too, this helps in carrying information. During the central dogma, DNA in transcripted to RNA after which RNA will be responsible for the transmission of the genetic MATERIAL.

The correct choice is (a) FASTER rate

For explanation: Mutations can be seen in both DNA and RNA. But RNA mutates at a much faster pace in comparison to the DNA. This is due to the lack of stability that is seen in RNA. Likewise, the viruses which contain RNA as their genetic material also MUTATE at a faster rate. Their life span will stand SHORT on the contrary.

Right answer is (d) DNA is a BETTER genetic MATERIAL than RNA

For EXPLANATION I would SAY: DNA is comparatively less reactive than RNA. The 2’-OH group which is present at the nucleotide of the RNA is the reactive group. This makes the RNA highly reactive in comparison to the DNA. RNA is also catalytic and liable. It cannot be easily degraded. Due to these reasons, the conclusion is that that DNA is the better genetic material than the RNA.

The correct answer is (d) They will combine with each other under appropriate conditions

For EXPLANATION I would SAY: From the GRIFFITH’s experiment RELATED to the transforming principle, we could understand that the GENETIC material still possessed some stability. Likewise, the genetic material DNA which is present in this case also has the capability to join the 2 complementary strands despite it being heated up under appropriate conditions.

Right option is (a) True

To explain I would say: Heat killed the bacterium but, it didn’t DESTROY all of its GENETIC material characteristics. This was proved by GRIFFITH in his EXPERIMENTS concerning about the transformation principles. From this it can be inferred that the stability of the genetic material (either DNA or RNA) cannot be entirely killed. The stability of the genetic can be seen.

The correct choice is (b) False

For EXPLANATION: The genetic material of an organism should be STABLE and not change during the course of an organism or PERSON’s lifetime. If any changes are to occur, then variations and problems will arise. It is also clearly inferred from the “transforming principle” of Griffith from his EXPERIMENTS revolving around the R and S strains of the bacterium that stability PERSISTS.

The correct ANSWER is (c) It is not stable under alkaline conditions

To ELABORATE: The hydrogen atom which is attached to the hydroxyl group on the 2’- C atom of the RNA can be easily deprotonated. The PRESENCE of larger grooves in RNA is also a REASON for it not being stable under alkaline conditions. But under the same condition, the DNA molecule will be stable for it has smaller grooves which cannot be easily attacked or penetrated.

Right option is (b) GENERATION of its replica

For explanation: Proteins form polypeptide CHAINS by the peptide BOND formation between amino ACIDS. Their different folding statures RESULTS in the formation of non-covalent bonds as well as the different forms of proteins. Despite these capabilities, proteins lack the ability to generate their replica.

The correct choice is (d) RADIOACTIVITY cannot be DETECTED in the supernatant

Explanation: As a RESULT of the process of centrifugation, a radioactive bacterium will be produced. The VIRUS attached to the bacterium will leave during the process of blending. It will leave after injecting the radioactive material INSIDE the bacterium. So, radioactivity will not be detected in the supernatant.

The correct choice is (b) Should be able to express itself in the form of “Bohr’s characters”

For explanation I would say: A genetic material must be both chemically and STRUCTURALLY stable. It must be able to replicate. It should PROVIDE scope for the evolutionary changes. But it should ALSO be able to express itself in the form of “Mendelian characters” and not “Bohr’s characters”. These Mendelian characters REFER to the three laws that were proposed by Gregor Mendel.

Correct option is (d) Conjugation

Explanation: Infection is the FIRST stage where the viral particle attaches itself to the bacterial coat and starts to inject its genetic material inside of it. Blending is the second stage where the viral coats were removed from the bacterium by the act of “blending”. Centrifugation is the third stage where the viral particles are CENTRIFUGED from the bacterium by SPINNING.

Correct answer is (C) A medium containing radioactive phosphorous (P)

For explanation: ALFRED Hershey and Martha Chase wanted to figure out whether it was the protein from the bacteriophage that was entering into the bacteria or if it was the DNA. So, they cultured the bacteriophage in a medium containing radioactive phosphorous. In this medium they observed that the radioactive DNA was PRESENT in the virus but not the radioactive protein. This is because, protein doesn’t CONTAIN phosphorous but on the CONTRARY, the DNA does.

The correct choice is (a) True

The explanation: The bacteriophage comes and attaches itself onto the top of the bacterial cell WALL. After ATTACHMENT, the virus makes contact with the bacterial cell wall and TRIES to inject its genetic material (DNA or RNA) into the bacteria. The bacteria will consider the VIRAL genetic material to be as its own and will not do anything.

The correct option is (d) Alfred Hershey and Martha Chase

Easiest EXPLANATION: Alfred Hershey and Martha Chase in the year of 1952 proved that DNA was the genetic material through experiments. They worked with bacteriophages. Oswald Avery and Maclyn McCarty helping in the determination of the biochemical natures from GRIFFITH’s experiment with regards to the “TRANSFORMING PRINCIPLE”.

Correct CHOICE is (b) Bacteriophage

The explanation is: The viruses that AFFECT bacteria are known as bacteriophage. They have the CAPABILITY to both enter the bacterium and reproduce inside them. Alfred HERSHEY and Martha Chase worked with these kinds of viruses.

Right option is (c) Protein

The explanation: PRIOR to the works done by Oswald AVERY, Colin MacLeod and Maclyn McCarty, the genetic material was thought to be as the protein. NUCLEOIDS are the irregular shaped structures in the prokaryotic cell. They contain nearly all of the genetic material of the prokaryotes. Nucleons are present inside the nucleus of an atom, alongside with the PROTONS. CHROMOSOME carries the genetic information of the genes.

Right option is (a) Alive

The explanation is: The mouse fed with the S-strain from the STAPHYLOCOCCUS pneumoniae, happens to NATURALLY die. This is on an ACCOUNT that the S-strains are virulent. Under such conditions, the mouse will not be ABLE to survive. But, when the heat killed S-strains from Staphylococcus pneumoniae are injected into the mouse, it will live.

Right option is (a) DNase

To explain I would say: The presence of protease (protein DIGESTING enzymes) and RNase (RNA digesting enzymes) in the presence of the virulent or avirulent strains will not affect the PROCESS of transformation. But on the contrary, when the DNase is present, the process of transformation will not occur. This PROVES that the transformation process cannot occur as long as the DNase enzyme is present. The role of nuclease is to cleave the phosphodiester bonds between the nucleotides of nucleic ACIDS.

Correct answer is (c) PURIFIED bio-chemicals from heat killed S-strain

To elaborate: S-strains are the virulent ones which have the ability to KILL a mouse when injected into it. But, when the heat killed S-strain is injected into the mouse along with the R-strain, the mouse happens to die DUE to transformation. The purified bio-chemicals (protein, DNA and RNA) from the heat killed S-strain, transforms the R-strain into the S-strain (virulent).

The correct answer is (b) Shiny COLONIES (S) and ROUGH colonies (R)

The best I can explain: In 1928, Frederick Griffith cultured the pneumococcus BACTERIUM. He observed that those bacteria were producing different colonies. These colonies were NAMED as the S and R colonies. The S colonies are the Shiny colonies because they had the mucous(polysaccharide) COAT. The R colonies are the Rough colonies because they did not possess the mucous coat.

The correct answer is (d) MICE -> Heat killed S strain + live R strain -> Alive

The explanation: When the heat killed S-strain of the bacterium is given along with the R strain to the mice, a PROCESS of transformation occurs. The heat killed S strain (avirulent) was able to TRANSFORM the R strain (avirulent) to BECOME a virulent strain. During this process of transformation, the heat killed S strained bacterium, transforms the R strain to produce the mucous(polysaccharide) and become virulent.

Right option is (a) False

Easy explanation: The S strain produced by the BACTERIUM is SAID to be the virulent strain. The mice infected with the S strain will die DUE to its virulent NATURE. Whereas, the ONE infected with the R strain doesn’t die due to its avirulent.

Mice -> S strain -> Death

Mice -> R strain -> Alive

Right ANSWER is (d) Streptococcus pneumoniae

To EXPLAIN: Streptococcus PYOGENES CAUSES TONSILLITIS and rheumatic fever. Staphylococcus aureus causes abscesses. Streptococcus pneumoniae causes pneumonia. Staphylococcus saprophyticus causes urinary tract infections.

Right answer is (a) 0.34 NM

The explanation: The double STRANDED helical structure of the DNA, takes a turn after every 10 BASE pairs which is noted to be as 3.4 nm. This is CALLED as a pitch (DISTANCE). 0.34 nm is considered to be the distance between 2 base pairs.

The correct answer is (d) Non-Histone chromosomal proteins

To explain: NHC or Non-Histone Chromosomal proteins are the collection of proteins that ACT in a EUKARYOTIC nucleus. They are responsible for the PROCESSES of DNA replication, RNA synthesis, RNA processes and also nuclear processes.