Molecular Structure of Inheritance Class 12 CBSE Biology

What is the basic unit of DNA?

• amino acid

• gene

• chromosome

• nucleotide

Explain the structure of a nucleotide.

• A nucleotide consists of a phosphate group, a six-carbon sugar, and a nitrogenous base.

• A nucleotide consists of a phosphate group, a five-carbon sugar, and a nitrogenous base.

• A nucleotide consists of a phosphate group, a five-carbon sugar, and a carbon base.

• A nucleotide consists of a nitrogen group, a five-carbon sugar, and a phosphate base.

What are the four nitrogenous bases found in DNA?

• Adenosine

• Adenine, Thymine, Guanine, Cytosine

• Guanosine

• Thymidine

• Uracil

Describe the double helix structure of DNA.

• The sugar-phosphate backbone of DNA is formed by lipids

• DNA is a single-stranded linear structure

• The double helix structure of DNA is composed of three strands

• DNA has a double helix structure consisting of two strands that are twisted around each other, made up of nucleotides with a sugar-phosphate backbone and nitrogenous bases (adenine, thymine, cytosine, and guanine) forming complementary base pairs (A-T and C-G).

What is the role of hydrogen bonds in DNA structure?

• Hydrogen bonds break down the DNA structure

• Hydrogen bonds hold together the complementary base pairs in DNA structure.

• Hydrogen bonds have no role in DNA structure

• Hydrogen bonds are responsible for protein synthesis in DNA

Explain the concept of complementary base pairing in DNA.

• Complementary base pairing in DNA includes A pairing with U and G pairing with C.

• Complementary base pairing in DNA involves A pairing with T and G pairing with C.

• In complementary base pairing, A pairs with C and G pairs with T.

• Complementary base pairing involves A pairing with G and T pairing with C.

What is the significance of the sugar-phosphate backbone in DNA?

• It acts as a source of energy for DNA replication

• It provides structural support and stability to DNA.

• It is responsible for the transmission of genetic information

• It determines the genetic code of DNA

How does DNA differ from RNA in terms of structure?

• DNA is single-stranded with ribose sugar and thymine base, while RNA is double-stranded with deoxyribose sugar and uracil base.

• DNA and RNA are both double-stranded with deoxyribose sugar and thymine base.

• DNA and RNA have the same structure but differ in function.

• DNA is double-stranded with deoxyribose sugar and thymine base, while RNA is single-stranded with ribose sugar and uracil base.

What is the function of histones in DNA packaging?

• Histones are responsible for DNA repair

• Histones regulate gene expression

• Histones aid in DNA compaction and organization

• Histones help in DNA replication

Describe the structure of a chromosome.

• A chromosome is made of DNA and proteins, organized into genes, with two sister chromatids connected by a centromere.

• A chromosome consists of a single gene

• A chromosome is a single long strand of DNA

• A chromosome is composed of lipids and carbohydrates