Question

The bases are held together in a DNA double helix by hydrogen bonds. These bonds are
A. Ionic bonds
B. Covalent bonds
C. Non-covalent bonds
D. Van der waals forces

Answer 1

Hint:
Hydrogen bonds are what hold the bases of DNA together in a double helix. The base sequence is made up of pairs of nitrogenous atoms that form these non-covalent bonds.
A non-covalent bond is one in which electron pair sharing does not occur. It is weaker than the covalent bond and mainly occurs between macromolecules. Numerous diverse processes can cause non-covalent interactions. Van der Waals interactions, hydrogen bonds, and electrostatic interactions are a few of them (also called ionic bonding). are weak interactions that exist in every molecule.
Because non-covalent forces are particular without imparting as much rigidity as covalent forces, they play a crucial role in biological function. The type of chemical bonding between electron pairs is determined by covalent forces, which are quantum mechanical forces.
There are numerous subcategories of non-covalent interactions, including electrostatic effects, van der Waals forces, and hydrophobic effects.

Complete answer:
Hydrogen bonds hold the nucleotides in the DNA's two helical strands together. The nitrogenous bases are located along the strand's inward orientation. The two antiparallel strands' nitrogenous bases form hydrogen bonds with one another, joining the two helical strands. So, the bases are held together in a DNA double helix by hydrogen bonds are non-covalent bonds.

Option ‘C’ is correct

Note:
Large molecules like proteins and nucleic acids have a three-dimensional structure that must be maintained by non-covalent interactions. Here are some more details on bases and their function in DNA:- In a DNA double helix, hydrogen bonds hold the bases together. The bonds in question are non-covalent.