NEET Biology Genetic Code And RNA Multiple Choice Question And Answers

by

Biology MCQs with Answers for NEET Genetic Code And RNA

Question 1. A sequence of three base codes along the DNA molecule is called

  1. Genetic code
  2. Gene pool
  3. Genetic drift
  4. Genome

Answer: 1. Genetic code

The relationship between the sequence of bases in DNA or RNA and the sequence of amino acids in a polypeptide chain is called genetic code. It is a sequence of three base codes

Question 2. Who was the first one to suggest that genetic codes are a triplet?

  1. George Gamow
  2. Crick
  3. Ochoa
  4. Nirenberg

Answer: 1. George Gamow

“molecular basis of inheritance “

Question 3. The genetic code is a triplet code. Three adjacent bases which specify an amino acid are called as

  1. Recon
  2. Muton
  3. Intron
  4. Codon

Answer: 4. Codon

Three bases in the genetic code that specify an amino acid are called codons.

Read And Learn More: NEET Biology Multiple Choice Question And Answers

Question 4. Consider the following statements.

  1. Six codons do not code for any amino acid.
  2. Codon is read in mRNA in a continuous fashion.
  3. Three codons function as stop codons.
  4. The initiator codon AUG codes for methionine.

Choose the option containing an incorrect statement.

  1. 1, 2 and 4
  2. 1, 2 and 3
  3. 2, 3 and 4
  4. Only 2
  5. Only 1

Answer: 3. 2, 3 and 4

All statements are correct except The incorrect statement can be corrected as 61 codons code for amino acids and 3 codons do not code for any amino acids, hence they function as stop codons.

Question 5. Genetic code is

  1. The sequence of nitrogenous bases on hnRNA
  2. The sequence of nitrogenous bases on tRNA
  3. The sequence of nitrogenous bases on rRNA
  4. The sequence of nitrogenous bases on DNA

Answer: 4. Sequence of nitrogenous bases on DNA

“molecular biology mcq “

Genetic code comprises the sequence of nitrogenous bases (A, G, T, C, U) on DNA. These bases are arranged in a different manner to form a triplet codon.

Biology MCQ For NEET With Answers

NEET Biology Genetic Code And RNA Multiple Choice Question And Answers

Question 6. Genetic code determines

  1. Structure of proteins
  2. Structure of amino acids
  3. The sequence of amino acids
  4. Metabolic pathways

Answer: 3. Sequence of amino acids

Genetic code is the set of rules by which genetic information in DNA is translated into proteins within the cell.

This information is present in the form of a series of triplets of nitrogenous bases in DNA, from which a complementary sequence of codons in messenger RNA is transcribed.

The sequence of these codons, in turn, determines the sequence of amino acids during protein synthesis.

Question 7. The genetic code was explained by

  1. Nirenberg
  2. Matthaei
  3. Both 1 and 2
  4. Khorana

Answer: 3. Both 1 and 2

Nirenberg and his post-doctoral fellow Heinrich Matthaei explained the genetic code for the first time. Thus, option (c) is correct

Question 8. The initiation codon in eukaryotes is

  1. GAU
  2. AGU
  3. AUG
  4. UAG

Answer: 3. AUG

AUG codes for methionine and acts as an initiation codon in eukaryotes during translation. Thus, it has dual functions.

Question 9. Genetic code is

  1. Degenerate, overlapping, ambiguous
  2. Degenerate, non-overlapping, unambiguous
  3. Universal, overlapping, ambiguous
  4. Degenerate, non-overlapping, ambiguous

Answer: 2. Degenerate, non-overlapping, unambiguous

Salient features of the genetic code are as follows

The codon is a triplet, i.e. 61 codons code for amino acids, and 3 codons function as stop codons. One codon codes for only one particular amino acid, hence the code is unambiguous, non-overlapping, and specific. Some amino acids are coded by more than one codon, hence the codons are degenerated. There are no punctuations in the triplet codon. The code is nearly universal. For example, from bacteria to humans, UUU codes for phenylalanine (phe). Some exceptions to this rule are found in mitochondria and protozoan’s codons.

Biology MCQ For NEET With Answers

Question 10. Genetic code consists of

  1. Adenine and guanine
  2. Cytosine and uracil
  3. Cytosine and guanine
  4. All of the above

Answer: 4. All of the above

Genetic code is the relationship between the amino acid sequence in a polypeptide chain and the base sequence of mRNA. I include adenine, guanine, cytosine, uracil, and thymine.

“molecular biology mcq “

Question 11. Which of the following is a non-sense codon?

  1. AUG
  2. USA
  3. UAG
  4. AGG

Answer: 3. UAG

A codon for which no normal tRNA molecule exists is called a non-sense codon.

It causes termination of translation. There are three non-sense codons, viz. amber (UAG), ochre (UAA), and opal (UGA).

Question 12. Which one of the following has dual functions?

  1. AUG
  2. AUC
  3. ACU
  4. ACA

Answer: 1. AUG

AUG codes for methionine and acts as an initiation codon in eukaryotes during translation. Thus, it has dual functions.

Question 13. Which of the following amino acids has a single codon?

  1. Tyrosine
  2. Tryptophan
  3. Serine
  4. Cysteine

Answer: 2. Tryptophan

Only tryptophan (UGG) and methionine (AUG) are specified by single codons.

Cysteine and tyrosine are coded by two codons, while serine is coded by 6 codons

Biology MCQ For NEET With Answers

Question 14. Which triplet codon does not have a tRNA associated with it?

  1. UAA
  2. UUA
  3. UUU
  4. AUU
  5. GUU

Answer: 1. UAA

UAA is the termination codon and thus, no tRNA and no amino acid is associated with it

Question 15. The triplet UUU codes for

  1. Leucine Odisha
  2. Methionine
  3. Phenylalanine
  4. Glycine

Answer: 3. Phenylalanine

It is the first genetic code discovered by Nirenberg. It codes for phenylalanine

Question 16. Which sequence of codons specifies leucine-threonine-proline?

  1. CUC-GCU-CCC
  2. AAA-ACC-CCC
  3. UUG-AGC-UAG
  4. CUA-ACA-CCU

Answer: 4. CUA-ACA-CCU

It is the first genetic code discovered by Nirenberg. It codes for phenylalanine

Question 17. From bacteria to men, a nearly universal code for phenylalanine is

  1. UUU
  2. UUA
  3. UUG
  4. CUU

Answer: 1. UUU

It is the first genetic code discovered by Nirenberg. It codes for phenylalanine.

“molecular biology mcq “

Question 18. Match the names of triplet codons listed under Column 1 with the amino acids given under Column 2. Choose the correct option from the codes given below.

NEET Biology Genetic Code And RNA MCQs Question 18 Match the following coloumn

Answer: 2. 1-5, 2-4, 3-3, 4-2.

Question 19. Which of the following groups of codons code for amino acid serine?

  1. CUU, CUC, CUA and CUG
  2. UAU, UAC, UGU, and UGC
  3. UCU, UCC, UCA and UCG
  4. UGU, UGC, UGA and UAG
  5. GUU, GUC, GCU, and GCC

Answer: 3. UCU, UCC, UCA and UCG

The codons UCU, UCC, UCA, UCG, AGU, and AGC, are all codes for the amino acid serine.

Question 20. The number of codons that code different amino acids is

16
31
61
64

Answer: 3. 61

There are 64 triplet codons which code for only 20 amino acids. Out of 64, three codons are non-sense codons as they do not specify any amino acid. Thus, only 61 codons code for amino acids.

NEET Biology Mcq

Question 21. The starting codon is universal means HP

  1. It is the same universally for all organisms
  2. Two or more codons
  3. Any variable code is called starting which can start protein synthesis
  4. All codons originated from the same starting codon

Answer: 1. It is the same universally for all organisms

Starting codon is universal means it is the same universally for all organisms.

Question 22. Which of the following statements is correct regarding genetic code?

  1. It is the initiation codon which also codes for phenylalanine
  2. There are 64 triplet codons and only 20 amino acids
  3. Three random nitrogen bases specify the placement of one amino acid
  4. UAA is the non-sense codon which also codes for methionine

Answer: 2. Three random nitrogen bases specify the placement of one amino acid

“molecular biology mcq “

The statement in option 2 is correct regarding genetic code. There are 64 triplet codons which code for only 20 amino acids.

This is due to the degeneracy of code as some amino acids are influenced by more than one codon. Only tryptophan and methionine are specified by a single codon.

Rest statements are not correct regarding genetic code and can be corrected as UUU is not the initiation codon, three
random nitrogen bases specify one codon and UAA does not code for any amino acid.

Question 23. Given below are different codons and amino acids coded by them.

  1. ACG – Threonine
  2. GAG – Glycine
  3. UAU – Tyrosine
  4. CGU – Leucine

Choose the option containing incorrectly matched pairs.

  1. 1 and 3
  2. 2 and 4
  3. 3 and 4
  4. 2 and 3

Answer: 2. 2 and 4

2 and 4 are incorrectly matched pairs and can be corrected as GAG codes for glutamic acid and CGU codes for arginine. The rest others are correctly matched pairs.

Question 24. Which one of the following pairs of codons are correctly matched with their function or the signal for the particular amino acid?

  1. GUU, GCU–Alanine
  2. UAG, UGA–Stop
  3. AUG, ACG–Start-Methionine
  4. UUA, UCA–Leucine

Answer: 2. UAG, UGA–Stop

Option 2 is correctly matched pairs. UAG and UGA are stop codons. They do not code for any amino acid.

“molecular biology mcq “

Rest options are not correctly matched pairs and can be corrected as GUU codes for valine and GCU codes for alanine. AUG is a start codon that codes for methionine but ACG codes for threonine.

UUA codes for leucine but UCA codes for serine.

NEET Biology Mcq

Question 25. Which one of the following statements is not correct?

  1. Cysteine is coded by UGU and UGC codons
  2. Tyrosine is coded by UAU and UAC codons
  3. UAA codon codes for lysine
  4. UGG codon codes for tryptophan

Answer: 3. UAA codon codes for lysine

The statement in option 3 is not correct and can be corrected as UAA is a stop codon. It does not specify any amino acid and thus, is called a non-sense codon. Rest statements are correct

Question 26. Match the codons in Column 1 with Column 2 their respective amino acids and choose the correct answer.

NEET Biology Genetic Code And RNA MCQs Question 26 Match the following coloumn

Answer: 1. A–3, B–4, C–1, D–5, E–2

Question 27. According to the wobble hypothesis,

  1. The process of polypeptide chain elongation has been established
  2. The first base is unstable
  3. The second base is the most unstable
  4. The third base is the most unstable

Answer: 4. Third base is the most unstable

“molecular biology mcq “

The Wobble hypothesis discovered by Francis Crick states that the rules of base pairing are relaxed at the third position, i.e. it is most unstable. Thus, a base can pair with more than one complementary bases

Question 28. Which of the following codon anticodon combinations shows the wobble phenomenon?

  1. UUU/AAA
  2. GCA/CGA
  3. AAU/UUA
  4. CCA/GGU

Answer: 2. GCA/CGA

According to the wobble hypothesis, in codon-anticodon pairing, the third base may not be complementary. Thus, the wobble hypothesis applies to option 2, which shows A is being paired with A only.

Question 29. Genetic code is universal, it means

  1. It is the same for all living organisms
  2. It is the same for a specific protein
  3. It is the same for triplet codon
  4. None of the above

Answer: 1. It is the same for all living organisms

The code is nearly universal which means it is the same for all living organisms. For example, from bacteria to humans, UUU codes for phenylalanine (Phe).

Question 30. Consider the following statements.

  1. Genetic code is unambiguous.
  2. One codon codes for more than one amino acid.

Choose the correct option.

  1. Statement 1 is correct, but 2 is incorrect
  2. Statement 1 is incorrect, but 2 is correct
  3. Both statements 1 and 2 are correct
  4. Both statements 1 and 2 are incorrect

Answer: 1. Statement 1 is correct, but 2 is incorrect

“molecular biology mcq “

Question 31. Because most amino acids are represented by more than one codon, the genetic code is

  1. Overlapping
  2. Wobbling
  3. Degenerate
  4. Generate

Answer: 3. Degenerate

All amino acids are specified by more than one codon (except tryptophan and methionine).

Hence, they are degenerate.

Since there are 64 possible combinations of the four different nucleotides in sets of three, there is a redundancy in the system, which means that most amino acids can be coded by more than one triplet.

Question 32. Out of the total 64 codons, 61 code for 20 amino acids, this suggests

  1. Degeneracy Of Codons
  2. Overlapping Of Codons
  3. Redundancy Of Codons
  4. Both 1 and 3

Answer: 3. Redundancy Of Codons

All amino acids are specified by more than one codon (except tryptophan and methionine). Hence, they are degenerate.

Since there are 64 possible combinations of the four different nucleotides in sets of three, there is a redundancy in the system, which means that most amino acids can be coded by more than one triplet.

Question 33. The terminator codons are

  1. UAA, UAG, UGA
  2. AUG, UAG, UGA
  3. UAC, AUG, UAG
  4. DCC, UAA, CAC
  5. AUG, ACG, GAG

Answer: 1. UAA, UAG, UGA

UAA (ochre), UAG (amber), and UGA (opal) are the three codons, which bring about the termination of the polypeptide chain and thus, are called terminator codons.

Question 34. If there are 999 bases in an RNA that codes for a protein with 333 amino acids and the base at position 901 is deleted such that the length of the RNA becomes 998 bases, how many codons will be altered?

  1. 1
  2. 11
  3. 33
  4. 333

Answer: 3. 33

999 bases in RNA code for a protein with 333 amino acids. If the base at the 901 position is deleted, the first 900 bases will be normal, while the bases after the 901th position will be altered that is 99 bases will be altered.

3 bases = 1 codon. So, 99 bases = 33 codons will be altered 901 position

“rna polymerase diagram “

Question 35. Given below are the codons and their common names.

  1. UAA – Ochre
  2. UAG – Opal
  3. UGA –Amber

Choose the option containing incorrectly matched pairs.

  1. Only 1
  2. Only 3
  3. 2 and 3
  4. 1, 2 and 3

Answer: 3. 2 and 3

2 and 3 are incorrectly matched pairs and can be corrected as UAG is called amber and UGA is called opal. The rest other is a correctly matched pair.

Question 36. Which form of RNA has a structure resembling clover leaf?

  1. rRNA
  2. hnRNA
  3. mRNA
  4. tRNA

Answer: 4. tRNA

The two-dimensional structure of tRNA looks like a clover leaf, hence its structure is referred to as a cloverleaf structure. It was given by Holley in 1965.

Question 37. DHU arm is also called

  1. Dihydrouracil arm
  2. Dihydroxyuracil arm
  3. Dehydroxyuracil arm
  4. Dihydroperoxyuracil arm

Answer: 1. Dihydrouracil arm

DHU arm is the base pair segment of the cloverleaf structure of transfer RNA. It has a loop containing 5,6-dihydrouracil attached to it.

Question 38. Which site of the tRNA molecule binds to a mRNA molecule?

  1. Codon
  2. Anticodon
  3. 5′ end of tRNA
  4. 3′ end of tRNA

Answer: 2. Anticodon

A tRNA molecule is held tightly at the A- and P-sites only if its anticodon forms base pairs with a complementary codon (allowing for wobble) on the mRNA molecule that is bound to the ribosome.

“which one of the following is not applicable to rna “

Question 39. tRNA contains

  1. 5 unpaired bases
  2. 7 unpaired bases
  3. 3 unpaired bases
  4. 4 unpaired bases

Answer: 3. 3 unpaired bases

Each tRNA contains a set of three unpaired nucleotide bases called an anticodon. The anticodon of a given tRNA can bind to one or a few specific mRNA codons.

Question 40. Anticodon occurs in

  1. tRNA
  2. mRNA
  3. rRNA
  4. DNA

Answer: 1. tRNA

Codons are present on mRNA and anticodon on tRNA.

Question 41. Consider the following statements.

  • The D-arm of tRNA is a highly variable region.
  • T ψ C arm of tRNA contains thymidine, pseudouridine, and cytidine.

Choose the correct option.

  1. Statement 1 is correct, but 2 is incorrect
  2. Statement 1 is incorrect, but 2 is correct
  3. Both statements 1 and 2 are correct
  4. Both statements 1 and 2 are incorrect

Answer: 3. Both statements 1 and 2 are correct

Question 42. How many types of anticodons are present on tRNAs for stop codons?

  1. One
  2. Two
  3. Three
  4. None of these

Answer: 4. None of these

There are no anticodons on tRNA to read stop codons on mRNA (UAA, UAG, UGA). This implies there is no tRNA for the stop codon. Thus, option (4) is correct

Question 43. What is true about tRNA?

  1. It binds with an amino acid at its 3-end
  2. It has five double-stranded regions
  3. It has a codon at one end which recognizes the anticodon on messenger RNA
  4. It looks like a clover leaf in the three-dimensional structure

Answer: 1. It binds with an amino acid at its 3-end

Option (a) is true about tRNA. Anticodon is the sequence of three nucleotides in a transfer RNA molecule that pairs with a complementary sequence of three nucleotides (codon) on a molecule of messenger RNA.

tRNA has CCA nucleotides at the 3′ end that are meant for attaching to a specific amino acid (AA-binding site). Rest options are not true about tRNA. tRNA has four double-stranded regions.

It has an anticodon that recognizes a codon on mRNA. It looks L-shaped in a 3-D structure

Question 44. Identify A, B, C, and D in the image given below.

NEET Biology Genetic Code And RNA MCQs Variable arms and amino acid arms

  1. A–Variable arm, B–Amino acid arm, C–T-loop, D–Anticodon arm
  2. A–Amino acid arm, B–T-loop, C–Variable arm, D–Anticodon arm,
  3. A–Amino acid arm, B–Variable arm, C–Codon, D–D-loop
  4. A–Amino acid arm, B–T-loop, C–Anticodon loop, D–Anticodon

Answer: 3. A–Amino acid arm, B–Variable arm, C–Codon, D–D-loop

Question 45. The similarity between the hairpin model and the clover leaf model of tRNA is that

  1. Both models show three arms
  2. Both models show the presence of a variable arm or lump
  3. Both models show CCA nucleotide at 3′ acceptor end
  4. None of the above

Answer: 3. Both models show CCA nucleotide at 3′ acceptor end

“which of the following is an initiation codon “

The hairpin model of tRNA structure was given by Hoagland and Cloverleaf was proposed by Holley. Both models show CCA nucleotide at 3′ acceptor end.

Question 46. An anticodon is the sequence of the nitrogenous bases on

  1. The complementary strand of DNA, which codes for one amino acid
  2. The complementary strand of mRNA, which codes for one amino acid
  3. Trna molecules, where the amino acid is attached
  4. tRNA molecule, which recognizes the appropriate sequence of a base on the mRNA

Answer: 4. tRNA molecule, which recognizes the appropriate sequence of the base on the mRNA

Each tRNA contains a set of three unpaired nucleotide bases called an anticodon. The anticodon of a given tRNA can bind to one or a few specific mRNA codons.

Question 47. The tRNA carrying the first amino acid in eukaryotes is denoted as

  1. N-formyl methionine- tRNA
  2. Val-tRNA
  3. Met-tRNA
  4. Amino acyl-tRNA

Answer: 3. Met-tRNA

In eukaryotes, the initiating amino acid is methionine rather than N-formylmethionine. However, as in prokaryotes, a special tRNA participates in initiation.

This aminoacyl-tRNA is called Met-tRNAi or Met-tRNAf (the subscript ‘i’ stands for initiation and ‘f ’ indicates that it can be formulated in vitro).

Leave a Comment