palindromes are groups of letters that form the same words when read both forward and backward, sequences reads 5' - GAATTC - 3' 3' - CTTAAG - 5' the same on the two strands in 5' → 3' direction. This is also true if read in the 3' → 5' direction. Answer : (c)

Purines found both in DNA and RNA are Adenine and guanine Answer : (d)

According to Hugo de Vries, mutations are random and directionless. Devries believed mutation caused speciation and hence called saltation (single step large mutation). Answer : (b)

Expressed Sequence Tags (ESTs) are DNA sequences (genes) that are expressed as mRNA for protein synthesis. These are used in human Genome Project. Answer : (a)

In lac operon i gene → Repressor z gene → β-galactosidase y gene → Permease a gene → Transacetylase Answer : (c)

Deletion of three bases delets a codon and reading frame remains unaltered from that point onwards. No change in reading frame of m-RNA. Answer : (d)

It is now proven that DNA replicates semiconservatively. It was shown first in Escherichia coli. Answer : (b)

The Meselson–Stahl experiment is an experiment by Matthew Meselson and Franklin Stahl in 1958 which supported Watson and Crick's hypothesis that DNA replication was semiconservative. The experiment was done using E.coli. Hence option (a) is not correct match. The Hershey–Chase experiments were a series of experiments conducted in 1952 by Alfred Hershey and Martha Chase that helped to confirm that DNA is genetic material. Bacteriophage was used for the experiment, not TMV. So option (b) is not correct match. Jeffreys had a "eureka moment" in his lab in Leicester after looking at the X-ray film image of a DNA experiment on 10 September 1984, which unexpectedly showed both similarities and differences between the DNA of different members of his technician's family. So option (c) is not correct match. Jacob and Monod discovered that a protein, which they called lac repressor, binds to the gene that produces the required metabolic enzyme and suppresses the gene's transcription and translation when lactose is not present in the environment. So option (d) is correct match. Answer : (d)

In bacteria, more than one gene is arranged together and regulated in units called as operons. Each operon has its specific operator and specific repressor. The lac operon consists of one regulatory gene (the i gene – here the term i does not refer to inducer, rather it is derived from the word inhibitor) and three structural genes (z, y, and a). Enhancer: The binding of these proteins will enhance the transcription of an associated gene. They are not the part of the operon structure. Answer : (a)

Hugo deVries based on his work on evening primrose brought forth the idea of mutations – large difference arising suddenly in a population. He believed that it is mutation which causes evolution. deVries believed mutation caused speciation and hence called it saltation (single step large mutation) Answer : (b)

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Coding strand and mRNA has same nucleotide sequence except, ‘T’ – Thymine is replaced by ‘U’–Uracil in mRNA. Answer : (d)

RNA polymerase binds to promoter and initiates transcription (Initiation). Answer : (b)

A restriction enzyme is a protein isolated from bacteria that cleaves DNA sequences at sequence-specific sites, producing DNA fragments with a known sequence at each end. DNA ligases are used with restriction enzymes to insert DNA fragments, often genes, into plasmids. DNA ligase is not restriction enzymes. Answer : (b)

Adenine forms two hydrogen bonds with Thymine from opposite strand and vice-versa. Answer : (c)

Length of DNA = Number of base pairs * Distance between two consecutive base pairs length of DNA= 6.6 × 109 bp * 0.34 x 10-9m = 2.24 m Answer : (a)

in the first phase itself amino acids are activated in the presence of ATP and linked to their cognate tRNA – a process commonly called as charging of tRNA or aminoacylation of tRNA to be more specific. Answer : (a)

The general structure of a ribonucleotide consists of a phosphate group, a ribose sugar group, and a nucleobase, in which the nucleobase can either be adenine, guanine, cytosine, or uracil. in which the nucleobase can either be adenine, guanine, cytosine, or uracil. Answer : (b)

An oncogene is a gene that has the potential to cause cancer. In tumor cells, these genes are often mutated, or expressed at high levels. Most normal cells will undergo a programmed form of rapid cell death (apoptosis) when critical functions are altered and malfunctioning. Answer : (c)

In his experiments, Muller exposed fruit flies (Drosophila) to x-rays, mated the flies, and observed the number of mutations in the offspring. His discovery indicated the causes of mutation and for that research he later received the Nobel Prize in Physiology or Medicine in 1946 Answer : (b)

The central dogma of molecular biology describes the two-step process, transcription and translation, by which the information in genes flows into proteins: DNA → RNA → protein. Reverse transcription is the transfer of information from RNA to DNA (the reverse of normal transcription) Answer : (d)

Genetic code, the sequence of nucleotides in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) that determines the amino acid sequence of proteins. Answer : (a)

The group of ribosomes bound to an mRNA molecule is called a polyribosome, or polysome A polyribosome or a polysome is an organization of mRNA molecule attached to two or more ribosomes at the same time in order to speed up the translation process of long mRNA transcripts. Answer : (b)

Answer : (a)

UCA=Serine; UUU=Phenylalanine; UCC=Serine GGG=Glycine AGU=Serine Refer question no 1 answer or NCERT page 112 Table 6.1: The Codons for the Various Amino Acids Answer : (b)

Transversion mutation is a specific kind of point mutation, one in which a single purine is substituted for a pyrimidine or vice versa. for example, when a TA or CG pair replaces the wild type AT pair. Answer : (d)

Gene does not produce sugar Answer : (b)

The genetic code is degenerate because there are many instances in which different codons specify the same amino acid. Answer : (d)

base pairs arise in complementary strands of DNA: adenine → thymine (A → T) thymine → adenine (T → A) cytosine → guanine (C → G) guanine → cytosine (G → C) CAT GAC TAG other strand would be GTA CTG ATC Answer : (b)

The central dogma of molecular biology describes the two-step process, transcription and translation, by which the information in genes flows into proteins: DNA → RNA → protein. A reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. The biggest revolution in the central dogma was the discovery of retroviruses, which transcribe RNA into DNA through the use of a special enzyme called reverse transcriptase has resulted in an exception to the central dogma; RNA → DNA → RNA → protein. Answer : (d)