Test: Transcription, Genetic Code & Types of RNA

• In some eukaryotes, genes consist of coding nucleotide sequences, which are separated from each other by blocks of non-coding sequences. The coding sequences here are called exons and non-coding sequences are introns.
• The primary transcript from a typical eukaryotic gene contains introns as well as exons. The introns are removed from this primary transcript by a process called RNA splicing. 

Fig: RNA Splicing 

Hence, the correct option is D.
NCERT Reference: Page no. 111 of topic “6.5.3 Types of RNA and the process of Transcription” of chapter 6.

• Transcription is when RNA is made from DNA.
• During transcription, RNA polymerase makes a copy of a gene from the DNA to mRNA as needed. During transcription, the DNA site at which RNA polymerase binds is called the promoter.
• Transcription begins with binding of sigma factor proteins to the RNA polymerase holoenzyme, thus, allowing it to bind to promoter DNA. 
• RNA polymerase creates a transcription bubble, which separates the two strands of the DNA helix and initiates the transcription. 

Transcription in progress: RNA polymerase slides along the DNA and makes an RNA copy (Genes are the only parts of DNA that get copied into RNA):

Hence, the correct option is C.
NCERT Reference: Page no. 108 of topic “6.5 TRANSCRIPTION” of chapter 6.

• The genetic code by which DNA stores the genetic information consists of "codons" of three nucleotides. These codon translates to form protein sequences.
• A codon is defined by the initial nucleotide from which translation starts known as start codon.

Fig: Initiation Codon

Hence, the correct option is D.
NCERT Reference: Page no. 111 of topic “6.6 GENETIC CODE” of chapter 6.

The genetic code is degenerate: Some amino acids are encoded by more than one codon, in as much as there are 64 possible base triplets and only 20 amino acids. In fact, 61 of the 64 possible triplets specify particular amino acids and 3 triplets (called stop codons) designate the termination of translation.

Thus, for most amino acids, there is more than one codeword.

Fig: Codons synthesizing amino acids

Hence, the correct option is C.
NCERT Reference: Page no. 112 of topic “6.6 GENETIC CODE” of chapter 6.

GGG code is present only 1 time and the amino acid produced by GGG is glycine.

Hence, the correct option is B.
NCERT Reference: Page no. 112 of topic “6.6 GENETIC CODE” of chapter 6.

Transcription is the first step of gene expression. In this process, a particular segment of DNA is copied into mRNA. Thus. it controls gene expression.

• tRNA has an anticodon loop that has bases complementary to the code, it also has an amino acid acceptor end by which it binds to amino acids.
• The site lies at the 3' end opposite the anticodon in tRNAs are specific for each amino acid.

Fig: tRNA binding site 
Hence, the correct option is C.
NCERT Reference: Page no. 114 of topic “6.6.2 tRNA– the Adapter Molecule” of chapter 6.

• A part of one chain of DNA molecule known as the sense strand which codes a polypeptide is called cistron.
• Each cistron consists of many codons, and a codon comprises three consecutive nitrogenous bases.

Fig: DNA transcription unit

Hence, the correct option is D.
NCERT Reference: Page no. 109 of topic “6.5 TRANSCRIPTION” of chapter 6.

A transposable element (TE or transposon) is a DNA sequence that can jump to different locations within a genome also known as "jumping genes", sometimes creating or reversing mutations and altering the cell's genetic identity and genome size.

Fig: Transposons 

Hence, the correct option is D.

Three base triplets form a codon that codes for an amino acid. Thus AUG codes for methionine and GUG codes for Valine. AUG and GUG are both initiating codons for translation.

Hence, the correct option is B.
NCERT Reference: Page no. 112 of topic “6.6 GENETIC CODE” of chapter 6.