24277 + Interview Questions in Biology in Class 12 Page 351 InterviewSolution

17501.	Question : Do you agree that regional and local variations exist within each biome ? Substantiate your answer with suitable example.
Answer» SOLUTION :• Yes, regional and local variations exist within each biome. • Regional and local variations within each biome lead to the formation of a wide variety of habitats. • On planet EARTH, life exists not just in a few favourable habitats but EVEN in extreme and harsh habitats, such as in scorching Rajasthan desert, perpetually rain-soaked Meghalaya forests, deep ocean trenches, torrential streams, permafrost polar regions, high mountain TOPS, boiling thermal springs, and stinking compost pits, to name a few. • Even our intestine is a unique habitat for hundreds of SPECIES of microbes.

Discussion

17502.	Question : Do eukaryotic cells have restriction endonucleases ? Justify your answer.
Answer» Solution :Yes, eukaryotic cells have ENDONUCLEASE. Various techniques of measuring LIKE in Restriction FRAGMENT, lenth polymorphism, presence of USE of restriction endonuclease is seen.

Discussion

17503.	Question : Do eukaryotic cells have restriction endonucleases? Justify your answer.
Answer» Solution :EUKARYOTIC CELLS do not have restriction endonucleases, eukaryotic DNA is METHYLATED by the enzyme methylase. This methylation prevents the ACTION of endonucleases.

Discussion

17504.	Question : Do eukaryotic cells have restriction endonucleases ? Justify your answer .
Answer» Solution :Most restriction endonucleases are prokaryotic in origin. HOWEVER, there are several found in eukaryotic cells, including our own. In eukaryotes they are not referred to as restriction enzymes, just endonucleases. An EXAMPLE of an endonuclease in eukaryotes is Apn 1, isolated from yeast .This enzyme helps toprevent DNAdamage from environmental agents . Another common enzyme family called the toposisomerases PREVENT the supercoiling of DNA at replication forks, by cutting the back bone, relieving the tension and pasting the ends together again -hence the endonuclease activity .In PROKARYOTES, restriction enzymes actually restrictenzymes actually restrict theproliferation of viruses by cleaving their nucleic acids at specific base -pair sequences. These enzymes cut DNA at the exact same sequence no matter which organism the DNA belongs to - that . s why they.re such powerful tools in GENETIC engineering . Eukaryotic endonucleases may not all help in restricting invading nucleic acids and in fact perform many distinct "jobs" .That is probably why they are never referred to as restriction enzymes .

Discussion

17505.	Question : Do coccyx, mammary glands in males, muscles of external ear and opacity of eye due to cataract belong to the same category?
Answer» Solution :No. (i) coccyx and MUSCLES of external ear are VESTIGIAL organs. (ii) MAMMARY GLANDS in males are non-functional due to being SEX influenced trait. (iii) Opacity of eye due to cataract is a degenerative change caused by ageing.

Discussion

17506.	Question : Do biomolecules (DNA, protein) exhibit biological activity in anhydrous conditions ?
Answer» Solution :No, BIOMOLECULES like DNA and PROTEIN cannot EXHIBIT biological activity in anhydrous conditions. HENCE, water is inevitable for life.

Discussion

17507.	Question : Do all the gametes formed from a parent organism have the same genetic composition (identical DNA copies of the parental genome) ? Analyse the situation with the background of gametogenesis and provide or give suitable explanation.
Answer» Solution :The gametes of a parent do not have the same genetic COMPOSITION as they do not have identical copies of DNA. During PACHYTENE and diplotene stages of MEIOSIS - I, the crossing over and chiasma formation take place between homologous chromosomes. The exchange of SEGMENTS of DNA from one chromatid to another (homologous chromosomes) occurs in a random manner, resulting in several new combinations of DNA sequances. Once the meiotic DIVISION is completed, gametes possess DNA with varying degree of variations.

Discussion

17508.	Question : DNA was extracted from E.coli. The proportion of cytosine was found to be 30%, then what will be the amount of adenine?
Answer» 0.6 0.7 0.2 0.4 Answer :C

Discussion

17509.	Question : DNA template strand having the sequences CTGATAGC which will complementary with RNA of which sequences ?
Answer» GUCTUTOCG GACUAUCG GAUTATUG UACTATCU SOLUTION :GACUAUCG

Discussion

17510.	Question :DNA synthesis takes place during
Answer» a]S PHASE B]`G_1` phase C]`G_2` phase d]M phase ANSWER :A

Discussion

17511.	Question :DNA synthesis can be measured by estimating incorporation of radio-labelled
Answer» Uracil Ribose sugar Thymidine ADENINE ANSWER :C

Discussion

17512.	Question : DNA strands are termed antiparallel because of
Answer» H-bonds phospho-diester bonds disulphide (S-S bnds) NONE of the above ANSWER :B

Discussion

17513.	Question : The DNA stands are antiparallel because of __
Answer» H-BONDS PEPTIDE bonds DISULPHIDE bonds Phosphate-diester bonds Answer :A

Discussion

17514.	Question : DNA sequences present in mini-satellites and micro-satellites show high degree of polymorphism due to
Answer» NATURAL selection Sexual RECOMBINATIONS Mutations All the three Answer :C

Discussion

17515.	Question : DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is that:
Answer» Humans and chimpanzees SHARE a RELATIVELY RECENT COMMON ancestor. Humans evolved from chimpanzees. Chimpanzees evolved from humans Humans and chimpanzees are not CLOSELY related. Answer :A

Discussion

17516.	Question : DNA segment cleaved by EcoRI is
Answer» ATTCGATAAGCT GAATTCCTTAAG GCTTAACGAATT GTTCAACAAGTT Answer :B

Discussion

17517.	Question : DNA replication takes place in semi conservative manner was experimentally proved by
Answer» Griffith Messolson and Stahl Hershey and Chase Mc EARTHY, Mecloid and Avery Answer :B

Discussion

17518.	Question : DNA replication starts in the 5^' rarr 3^' direction because :
Answer» DNA polymerase I PERFORMS editing function DNA polymerase I is RESPONSIBLE for polymerization DNA polymerase II can link up only in `5^'rarr3^'` direction DNA polymerase III can POLYMERIZE the nucleotides in the `5^'rarr3^'` ANSWER :D

Discussion

17519.	Question : DNA replication takesplace at ________ phase the cell cycle.
Answer» `G_1` S `G_2` M Solution :(b) : In eukaryotes, the replication of DNA takes place at S-phase of the cell CYCLE. The replicationof DNA takes and celldivision cycle should be coordinated. A failure in cell DIVISION after DNA and only ONE of the STRANDS is copied into RNA.

Discussion

17520.	Question : DNA replication occurs during which part of cell cycle?
Answer» G, PHASE S-phase G, phase DIVIDING phase ANSWER :B

Discussion

17521.	Question :Describe the Semiconservative method of DNA replication.
Answer» Solution :In both the DAUGHTER DNA molecules ONE strand is parental and another is newly synthesized. Hence, DNA replication is called Semi Conservative. It was first shown by Matthew Meselson and Franklin Stahl (1958) in Escherichia coli and subsequently in higher organism. It is popularly known as Meselson and Stahl Experiment. (a) They grew E.coli in NH4Cl medium for many generations. (TMN is heavy isotope of nitrogen) (b) The result was that .N was incorporated into newly synthesized DNA and other nitrogen containing compound as well. (C) This heavy DNA molecule could be distinguished from normal DNA by centrifugation in a caesium chloride (CsCl) density gradient. (d) Then they transferred the E.coli into a medium with normal `""^(15)NH_4Cl` and let them grow.(E.coli divides in 20 minutes) (e) They took samples at definite time INTERVALS as the cells multiplied, and extracted the DNA that remained as double-stranded helices. (f) Various samples were separated independently on CsCl gradients to measure the densities of DNA. (g) The DNA that was extracted from the culture one generation after the transfer from `""^15N` to `""^14N` medium had a hybrid or intermediate density. (h) DNA extracted from the culture after another generation(after 40 min). was composed of equal AMOUNT of this hybrid DNA and light DNA.one generation after the transfer from ..N to "N medium had a hybrid or intermediate density. (h) DNA extracted from the culture after another generation (after 40 min.) was composed of equal amount of this hybrid DNA and of .light .DNA.

Discussion

17522.	Question : DNA replication is called semiconservative.
Answer» SOLUTION :(1) When DNA replication takes place, for each old strand only one new strand is formed. (2) Therefore, new daughter DNA molecule has one old and another new strand. (3) Since 50% of the mother molecule is conserved and 50% is NEWLY formed, the process of DNA replication is CALLED semiconservative.

Discussion

17523.	Question : Why DNA replication is called semiconservative ?
Answer» Solution :The daughter DNA molecules have one parental strand and another new strand. Matthew Meselson and Franklin Stahl (1958) performed the FOLLOWING experiment in E.coli to prove semi-conservative replication They grew E.coli in a MEDIUM containing "NH,CI(is the heavy isotope of nitrogen) as the only nitrogen source for many generations. The result was that "N was incorporated into newly synthesised DNA (as well as other nitrogen containing compounds) This heavy DNA molecule could be distinguished from the normal DNA by centrifugation in a cesium chloride(`CsCl_(2)`) density gradient Then they transferred the cells into a medium with normal "NH,Cl and took samples at various definite time intervals as the cells multiplied, and extracted the DNA that remained as doublestranded HELICES The various samples were separated INDEPENDENTLY on `CsCl_(2)` gradients to measure the densities of DNA Thus, the DNA that was extracted from the culture, one generation after the transfer from "N to "N medium had a hybrid or intermediate density. DNA extracted from the culture after another generation was composed of equal amounts of this hybrid DNA and of .light’ DNA.

Discussion

17524.	Question : Why DNA replication is called semiconservative?
Answer» Solution :In both the daughter DNA MOLECULES one strand is PARENTAL and another is newly synthesized. Hence, DNA replication is called Semi Conservative. It was first shown by Matthew Meselson and Franklin Stahl (1958) in Escherichia coli and subsequently in higher organism. It is popularly known as Meselson and Stahl Experiment. (a) They grew E.coli in NH4Cl medium for many generations. (TMN is heavy isotope of nitrogen) (b) The result was that .N was incorporated into newly synthesized DNA and other nitrogen containing compound as well. (c) This heavy DNA molecule could be DISTINGUISHED from normal DNA by centrifugation in a caesium chloride (CsCl) density gradient. (d) Then they transferred the E.coli into a medium with normal `""^(15)NH_4Cl` and let them grow.(E.coli divides in 20 minutes) (e) They took samples at definite time intervals as the cells multiplied, and extracted the DNA that remained as double-stranded helices. (f) Various samples were separated independently on CsCl gradients to measure the densities of DNA. (G) The DNA that was extracted from the culture one generation after the transfer from `""^15N` to `""^14N` medium had a hybrid or intermediate density. (h) DNA extracted from the culture after another generation(after 40 MIN). was composed of equal amount of this hybrid DNA and light DNA.one generation after the transfer from ..N to "N medium had a hybrid or intermediate density. (h) DNA extracted from the culture after another generation (after 40 min.) was composed of equal amount of this hybrid DNA and of .light .DNA.

Discussion

17525.	Question : DNA replication is called semi-conservative why
Answer» At the end of REPLICATION each RNA POSSESSES ONE PARENTAL chain and the other newly synthesized chain. At the end of replication each DNA molecule is consist of one parent DNA chain and the other newly symthesized DNA chain After replication each DNA molecule is synthesized from parental strand. At the end of DNA is replication only half DNA is synthesized Solution :At the end of replication each DNA molecule is consist of one parent DNA chain and the other newly synthesized DNA chain

Discussion

17526.	Question : DNA replication in bacteria occurs
Answer» during S-phase WITHIN NUCLEOLUS prior to fission just before TRANSCRIPTION Solution :prior to fission

Discussion

17527.	Question : DNA replication in eukaryotic organisms is
Answer» Semi-discontinuous with SINGLE ori Semi-conservation and semi-discontinuous Semi-conservation with single ori Conservation and bidirectional Answer :B

Discussion

17528.	Question : DNA profiling uses repetitive sequences that are highly variable called_____.
Answer» ANSWER :VNTR (VARIABLE NUMBER of tendem REPEAT)

Discussion

17529.	Question : DNA repairingis done by :
Answer» Ligase DNA POLYMERASE I DNA polymerase II BOTH (A) AND (B) ANSWER :C

Discussion

17530.	Question : DNA profiling was first reported by______.
Answer» ANSWER :ALEC Jeffreys

Discussion

17531.	Question : DNA probe is synthesized with the help of(A) Labelled amino acids(B) Labelled nucleotides(C) Labelled ATP(D) Labelled m-RNA Templates
Answer» Labelled amino acids Labelled NUCLEOTIDES Labelled ATP Labelled m-RNA TEMPLATES SOLUTION :Labelled nucleotides

Discussion

17532.	Question : DNA precipitation out of a mixture of biomolecules can be achieved by treatment with
Answer» Isopropanol CHILLED ETHANOL Methanol at ROOM temperature Chilled CHLOROFORM Solution :Chilled ethanol

Discussion

17533.	Question : DNApolymerase that helps in DNA replication is of :
Answer» TWO types Three types Four types Only onetype Answer :D

Discussion

17534.	Question : DNA polymerase links nucleotide by forming which type of bond?
Answer» PHOSPHODIESTER bond hydrogen bond glycosidic bond ester bond Answer :A

Discussion

17535.	Question : DNA packaging in eukaryotes is carried out with the help of histone. The unit of compaction is nucleosome. Which option is correct about nucleosome ?
Answer» Octamer of NUCLEOSOME consists of 2 copies of each H2A, H2B, H3 and H1 In a typical nucleosome 200 bp are found Linker DNA is attached to H4 histone PROTEIN The nucleosome in chromatin are seen as BEADS on string structure when viewed under light microscope Answer :B

Discussion

17536.	Question : DNA or RNA segment tagged with a radioactive molecule is called
Answer» VECTOR PROBE Clone Plasmid ANSWER :B

Discussion

17537.	Question : DNA or RNA segment tagged with a radioactive molecular is called
Answer» VECTOR PROBE Clone PLASMID ANSWER :B

Discussion

17538.	Question : DNA nucleotides are attached by
Answer» HYDROGEN bond Covalent bond Vander WAALS bond Electrovalent bond Answer :A

Discussion

17539.	Question : DNA multiplication is called :
Answer» TRANSLATION Replication Transduction Transcription Answer :B

Discussion

17540.	Question : DNA molecules of plastids are called.
Answer» ANSWER :Plastidone

Discussion

17541.	Question : DNA library prepared by"Teminism" process or cDNA library.
Answer» SOLUTION :(1)cDNA is a complementary DNA which is PRODUCED USING m-ENA in the process of reserve transcription.This process is called terminism.cDNA library is constructed for eukaryotic organisms.(2)Some of the eukaryotic sequences are used for coding while some are not used for coding(non-coding).(3)In eukaryotic cells.Only those MRNA which have transcribed coding sequences are translated into protents.mRNA of different cells,tissue and organs at diffrent times and PHASES in the life cycle of an organism are isolated and converted into cDNA by the process of reverse transcription.For this process,the enzyme reverse transcriptase is used.(4)It also gives the bandings for restriction enzymes which are used.(5)This helps in identifying the exact DNA structure of viruses or plasmids.

Discussion

17542.	Question : DNA molecule looks like a twisted ladder.
Answer» SOLUTION :(1) THEERE are two polynucleotide strands in the DNA molecule which are coiled helically around an imaginary, COMMON, central axis. Hence it shows a twisted appearance. (2) There are hydrogen bonds between purines and pyrimidines of the oposing DNA STRAND. There is double hydrogen bond between A and T or T and A and a triple hydrogen bond between C and G or G and C. (3) Since these bonds appear as the rungs of a ladder, the DNA molecule looks like a twisted ladder.

Discussion

17543.	Question : DNA ligase is also called
Answer» GENETIC SCISSORS BIOTECHNOLOGICAL knive NATURE's scalpel Molecular STITCHES Answer :D

Discussion

17544.	Question : DNA length per turn of helix is :
Answer» `3.8` A `3.4` A `6.8` A 34 A Answer :D

Discussion

17545.	Question : DNA is wrapped around the histone octamer to form
Answer» Nuclein Nucleous NUCLEOSOME NUCLEUS ANSWER :C

Discussion

17546.	Question : DNA is usually intertwind with histone proteins and RNA. But in genetic engineering experiments DNA must be isolated in very pure form . How is this possible ?
Answer» Solution :Histone can be REMOVED by TREATMENT with PROTEASE, RNA with ribonu-clease and other molecules by appropriate TREATMENTS.

Discussion

17547.	Question : DNA is tightly packed structure and is found as units called nucleosomes. Differentiate between euchromatin and hetero-chromatin.
Answer» SOLUTION :Euchromatin-Chromatin region LOOSELY arranged, transcriptionally active/lightly stained. Heterochromatin-Chromatin REGIONS DENSELY packed, transcriptionally inactive/darkly stained.

Discussion

17548.	Question : DNA is parent in
Answer» Chromosomes and dictyosomes Chloroplasts and lysosomes MITOCHONDRIA and chloroplasts Mitochondria and endoplasmic reticulum. Solution :DNA is present both in mitochondria and chloroplast.The DNA molecules are circular,relatively SMALL,double stranded(expect for the DNA of some algae and protonzoans).The MITOCHONDRIAL DNA varies in size starting from `5mum` to `30mum`.Average length of chloroplast DNA is `45mum`.

Discussion

17549.	Question : DNA is tightly packed structure and is found as units called nucleosomes. Explain the concept of nucleosomes.
Answer» Solution :NEGATIVELY CHARGED DNA wrapped AROUND positively charged histone octamer/Nucleosomes are chromatin headed on string/DNA + Histone octamer/labelled diagram of nucleosomes.

Discussion

17550.	Question : How DNA is the better genetic material than RNA. Mention an organism with RNA as genetic material.
Answer» SOLUTION :1) The 2-OH group present at EVERY NUCLEOTIDE in RNA is reactive and makes RNA labile and degradable. But, DNA is less reactive and structurally more stable. 2) The presence of Thymine in PLACE of Uracil in DNA confers its additional stability. 3) RNA being unstable, mutate at a faster rate but DNA provide scope for slow changes (MUTATION) that are required for evolution.

Discussion

Explore topic-wise InterviewSolutions in .

Question : Do you agree that regional and local variations exist within each biome ? Substantiate your answer with suitable example.

Question : Do eukaryotic cells have restriction endonucleases ? Justify your answer.

Question : Do eukaryotic cells have restriction endonucleases? Justify your answer.

Question : Do eukaryotic cells have restriction endonucleases ? Justify your answer .

Question : Do coccyx, mammary glands in males, muscles of external ear and opacity of eye due to cataract belong to the same category?

Question : Do biomolecules (DNA, protein) exhibit biological activity in anhydrous conditions ?

Question : Do all the gametes formed from a parent organism have the same genetic composition (identical DNA copies of the parental genome) ? Analyse the situation with the background of gametogenesis and provide or give suitable explanation.

Question : DNA was extracted from E.coli. The proportion of cytosine was found to be 30%, then what will be the amount of adenine?

Question : DNA template strand having the sequences CTGATAGC which will complementary with RNA of which sequences ?

Question :DNA synthesis takes place during

Question :DNA synthesis can be measured by estimating incorporation of radio-labelled

Question : DNA strands are termed antiparallel because of

Question : The DNA stands are antiparallel because of __

Question : DNA sequences present in mini-satellites and micro-satellites show high degree of polymorphism due to

Question : DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is that:

Question : DNA segment cleaved by EcoRI is

Question : DNA replication takes place in semi conservative manner was experimentally proved by

Question : DNA replication starts in the 5^' rarr 3^' direction because :

Question : DNA replication takesplace at ________ phase the cell cycle.

Question : DNA replication occurs during which part of cell cycle?

Question :Describe the Semiconservative method of DNA replication.

Question : DNA replication is called semiconservative.

Question : Why DNA replication is called semiconservative ?

Question : Why DNA replication is called semiconservative?

Question : DNA replication is called semi-conservative why

Question : DNA replication in bacteria occurs

Question : DNA replication in eukaryotic organisms is

Question : DNA profiling uses repetitive sequences that are highly variable called_____.

Question : DNA repairingis done by :

Question : DNA profiling was first reported by______.

Question : DNA probe is synthesized with the help of(A) Labelled amino acids(B) Labelled nucleotides(C) Labelled ATP(D) Labelled m-RNA Templates

Question : DNA precipitation out of a mixture of biomolecules can be achieved by treatment with

Question : DNApolymerase that helps in DNA replication is of :

Question : DNA polymerase links nucleotide by forming which type of bond?

Question : DNA packaging in eukaryotes is carried out with the help of histone. The unit of compaction is nucleosome. Which option is correct about nucleosome ?

Question : DNA or RNA segment tagged with a radioactive molecule is called

Question : DNA or RNA segment tagged with a radioactive molecular is called

Question : DNA nucleotides are attached by

Question : DNA multiplication is called :

Question : DNA molecules of plastids are called.

Question : DNA library prepared by"Teminism" process or cDNA library.

Question : DNA molecule looks like a twisted ladder.

Question : DNA ligase is also called

Question : DNA length per turn of helix is :

Question : DNA is wrapped around the histone octamer to form

Question : DNA is usually intertwind with histone proteins and RNA. But in genetic engineering experiments DNA must be isolated in very pure form . How is this possible ?

Question : DNA is tightly packed structure and is found as units called nucleosomes. Differentiate between euchromatin and hetero-chromatin.

Question : DNA is parent in

Question : DNA is tightly packed structure and is found as units called nucleosomes. Explain the concept of nucleosomes.

Question : How DNA is the better genetic material than RNA. Mention an organism with RNA as genetic material.