DNA & RNA MCQ Quiz - Objective Question with Answer for DNA & RNA - Download Free PDF

The correct answer is Nucleotides.

Key Points

• DNA was first recognized and identified by the Swiss biologist, Johannes Friedrich Miescher in 1869 during his research on white blood cells.
• DNA: DNA is a double helical long polymer of deoxyribonucleotides. The length of DNA is usually defined as a number of nucleotides (or a pair of nucleotides referred to as base pairs) present in it. This also is the characteristic of an organism.
• DNA contains a sugar-phosphate backbone, and the nucleotide bases (guanine, cytosine, adenine, and thymine).

​

• The coding segment of DNA is called the exon. A segment of DNA within a gene that encodes a sequence ultimately translated into a protein product.
• So, DNA is a polymer of nucleotide bases.

The correct answer is one.

• A single chromosome contains only one DNA (deoxyribonucleic acid) molecule and so many genes.
• Humans have 23 pairs of chromosomes.
  • 22 pairs of autosomes chromosomes and one pair of sex chromosomes, X and Y.

Important Points

• In the cell nucleus, the DNA molecule is packaged into thread-like structures called chromosomes.
  • A chromosome (microscopic structure) is made up of DNA tightly coiled many times around proteins called histones that support its structure.
  • A chromosome has two arm - p arm (short arm) and q arm (long arm), joined in the location of the centromere.

Key Points

• The information in DNA (double helix structure) is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).
  • DNA has two base pairs, A-T and G-C, attached to a sugar-phosphate backbone.

The correct answer is Uracil

Explanation:

• RNA (Ribonucleic Acid) is a nucleic acid present in all living cells. It is primarily involved in the synthesis of proteins and carries genetic information in some viruses.
• The structure of RNA is similar to DNA but has some differences, including the presence of ribose sugar instead of deoxyribose and the use of uracil instead of thymine.
• In RNA, the nitrogenous bases are adenine A, uracil U, cytosine C, and guanine G.
• In RNA, adenine pairs with uracil through hydrogen bonding.
• This pairing is crucial for the proper transcription and translation processes during protein synthesis.

Other Options:

• Guanine: Guanine pairs with cytosine in RNA, not adenine. This pairing is also essential for the stability and structure of RNA strands.
• Thymine: Thymine is not present in RNA. It is replaced by uracil. Thymine pairs with adenine in DNA, but in RNA, adenine pairs with uracil.

The correct answer is Nucleotides.

Key Points

• DNA was first recognized and identified by the Swiss biologist, Johannes Friedrich Miescher in 1869 during his research on white blood cells.
• DNA: DNA is a double helical long polymer of deoxyribonucleotides. The length of DNA is usually defined as a number of nucleotides (or a pair of nucleotides referred to as base pairs) present in it. This also is the characteristic of an organism.
• DNA contains a sugar-phosphate backbone, and the nucleotide bases (guanine, cytosine, adenine, and thymine).

​

• The coding segment of DNA is called the exon. A segment of DNA within a gene that encodes a sequence ultimately translated into a protein product.
• So, DNA is a polymer of nucleotide bases.

The Correct answer is ribonucleic acid.

Key Points

• Ribonucleic Acid (RNA) is a crucial molecule involved in various biological roles, including coding, decoding, regulation, and expression of genes.
• RNA is made up of a long chain of nucleotides, each consisting of a nitrogenous base, a ribose sugar, and a phosphate group.
• There are several types of RNA, including messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA), each with distinct functions in the cell.
• mRNA carries the genetic information copied from DNA in the form of a series of three-base code "words," each specifying a particular amino acid.
• tRNA is the key to decoding the mRNA sequence into a protein. It functions at specific sites in the ribosome during translation.
• rRNA is a component of ribosomes, which are the protein synthesis machinery in the cell.
• RNA is single-stranded, unlike DNA, which is double-stranded. This single-stranded nature allows RNA to fold into complex three-dimensional shapes.

 Additional Information

• Red blood corpuscles
  • Red blood corpuscles (RBCs), also known as erythrocytes, are cells that carry oxygen from the lungs to the rest of the body and bring carbon dioxide back to the lungs for exhalation.
  • RBCs contain a protein called hemoglobin, which binds oxygen. Their unique biconcave shape increases the cell's surface area and facilitates the exchange of oxygen and carbon dioxide.
• Ribosomes
  • Ribosomes are the molecular machines in the cell that synthesize proteins. They read the sequence of the mRNA and translate it into the amino acid sequence of a protein.
  • Ribosomes can be found floating freely in the cytoplasm or attached to the endoplasmic reticulum, forming rough ER.

The correct answer is one.

• A single chromosome contains only one DNA (deoxyribonucleic acid) molecule and so many genes.
• Humans have 23 pairs of chromosomes.
  • 22 pairs of autosomes chromosomes and one pair of sex chromosomes, X and Y.

Important Points

• In the cell nucleus, the DNA molecule is packaged into thread-like structures called chromosomes.
  • A chromosome (microscopic structure) is made up of DNA tightly coiled many times around proteins called histones that support its structure.
  • A chromosome has two arm - p arm (short arm) and q arm (long arm), joined in the location of the centromere.

Key Points

• The information in DNA (double helix structure) is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).
  • DNA has two base pairs, A-T and G-C, attached to a sugar-phosphate backbone.

The correct answer is Nucleotides.

Key Points

• DNA was first recognized and identified by the Swiss biologist, Johannes Friedrich Miescher in 1869 during his research on white blood cells.
• DNA: DNA is a double helical long polymer of deoxyribonucleotides. The length of DNA is usually defined as a number of nucleotides (or a pair of nucleotides referred to as base pairs) present in it. This also is the characteristic of an organism.
• DNA contains a sugar-phosphate backbone, and the nucleotide bases (guanine, cytosine, adenine, and thymine).

​

• The coding segment of DNA is called the exon. A segment of DNA within a gene that encodes a sequence ultimately translated into a protein product.
• So, DNA is a polymer of nucleotide bases.

The correct answer is Uracil.

Key Points

• In DNA, Adenine, Guanine, Thymine, and Cytosine are present.
• In RNA Adenine, Guanine, Cytosine, and Uracil are present.
• Uracil
  • It is one of the four nucleobases in nucleic acid RNA.
  • In DNA, Uracil nucleobases are replaced by thymine.
  • Its formula is C₄H₄N₂O_2.

_{Additional Information}

•  Guanine
  • It is one of the four main nucleobases found in the nucleic acids DNA and RNA.
  • It is used to make one of the building blocks of DNA and RNA.
• Adenine
  • It is also one of the four main nucleobases found in the nucleic acids DNA and RNA.
  • It is part of many substances in the body that give energy to cells.
• Cytosine
  • It is pyrimidine and one of the nitrogenous bases found in RNA and DNA acid for making genetic code.
  • It Plays an essential role in forming base pairs by bonding with guanine.

• The two strands of the DNA are held together by hydrogen bonds formed between the complementary nitrogenous bases (adenine, guanine, cytosine, and thymine) of the two strands.
• Adenine and thymine are held by 2 hydrogen bonds whereas cytosine and guanine are held by 3 hydrogen bonds.

The correct answer is The bases found in DNA come in only three varieties: adenine, cytosine and guanine.

Key Points

• DNA​
  • DNA stands for Deoxyribonucleic Acid.
  • There are four types of nitrogen bases;
    • i.e. Adenine (A), Thymine (T), Guanine (G), and Cytosine (C). Hence, Option 1 is incorrect.
• DNA is the molecule that is the hereditary material in all living cells because it contains the genetic code which are instructions needed for an organism to grow, develop, survive and reproduce. Hence, option 3 is correct.
  • So, ​DNA is called the blueprint of life.
• DNA is made up of a polymer chain comprised of smaller monomers called nucleotides.
• Each nucleotide has three-part i.e. a sugar group, a phosphate group, and a nitrogen base. Hence, option 4 is correct.
• A gene consists of enough DNA to code for one protein, and a genome is simply the sum total of an organism's DNA. DNA is long and skinny, capable of contorting it into chromosomes. Hence, Option 2 is correct.

​

The correct answer is James Watson and Francis Crick.

Key Points

•  The DNA double helix structure was discovered by James Watson and Francis Crick in 1953.
• Their groundbreaking discovery was based on data and insights from several other scientists, including Rosalind Franklin and Maurice Wilkins, who had conducted X-ray crystallography studies of DNA.
• Watson and Crick's model of the DNA double helix, along with the complementary base pairing they proposed, laid the foundation for our current understanding of the structure of DNA and its role in genetics.
• Nobel Prize in Physiology or Medicine in 1962 was awarded to James Watson and Francis Crick.

• DNA does not contain Uracil.
• DNA has Thymine in place of Uracil.
• DNA or Deoxyribonucleic Acid is a double stranded structure that contains the genetic information of an organism.
• In place of Thymine, Uracil is present in RNA.

• The term ‘Genetics’ was coined by William Bateson in the year 1905.
• In human beings, in each cell, there are 46 (23 pairs) chromosomes.
• Twenty-two of these pairs are autosomes and 23^rd pair, the sex chromosome differs in male and females.
• Females have 2 copies of the X chromosome while males have one X and one Y chromosome.
• Mendel was the first scientist to visualise a gene as an inheritance in 1885.
• A Deoxyribonucleic acid (DNA) is a long polymer of deoxyribonucleotides.
• A DNA molecule is made up of two long polynucleotide strands forming a double helical structure (double helix) just like a spiral staircase.

The correct answer is option 4) Amino acid.

Key Points

• Amino acids are not a part of the nucleotide structure of DNA.
• The nucleotide is the building block of DNA and is composed of three parts: a nitrogenous base (adenine, guanine, cytosine, or thymine), a deoxyribose sugar, and a phosphate group.
• The nitrogenous base and deoxyribose sugar make up the nucleoside, and the addition of a phosphate group forms the nucleotide.
• Amino acids, on the other hand, are the building blocks of proteins, and are not directly involved in the structure of DNA. 

Additional Information

• Nitrogenous base: Nitrogenous base is one of the three parts that make up a nucleotide, along with a deoxyribose sugar and a phosphate group. The nitrogenous bases in DNA are adenine, guanine, cytosine, and thymine. These bases pair up with each other in a specific way to form the rungs of the DNA ladder, which is the double helix structure of DNA.
• Deoxyribose sugar: Deoxyribose sugar is another component of a nucleotide. It is a five-carbon sugar that makes up the backbone of DNA along with the phosphate group. The nitrogenous bases are attached to this sugar molecule, and it is the specific sequence of these bases that determines the genetic information encoded in DNA.
• Phosphoric acid: Phosphoric acid, also known as a phosphate group, is the third component of a nucleotide. It is a molecule made up of phosphorus and oxygen atoms, and it gives DNA its negative charge. The phosphate groups form the backbone of the DNA strand along with the deoxyribose sugar.