Explanation

• Crossing over occurs in Pachytene stage of Prophase I.
• Homologous chromosomes are fully paired and exchange genetic material at this stage.
• This leads to new gene combinations.

Last verified on 20-05-2026

Explanation

An invertebrate is an animal without a backbone.

Worms, like earthworms, are classified as invertebrates.

They lack a backbone and are found in various environments. 

Explanation

Thymine is the nitrogenous base which is not present in RNA

Thymine is one of the four nucleobases found in DNA (along with adenine, guanine, and cytosine)

Whereas RNA contains uracil (U) instead of thymine.

RNA uses uracil as a complementary base to adenine during transcription,

while DNA uses thymine as a complementary base to adenine during replication.

Explanation

The cell is the smallest unit of life.

Cells are called ‘structural’ and ‘functional’ units for a reason.

Cells are made of molecules which are in turn made up of atoms.

“Cell is the unit of LIFE” is that a cell is the smallest living entity in a living system.

Explanation

• Replication is the process by which a cell makes an exact copy of its DNA before cell division, ensuring that the new cell receives a complete set of genetic instructions.
• This process is crucial for the transmission of genetic information from one generation of cells to the next.

Explanation

 The pair "Fish - Internal Fertilization" is incorrect; most fish use external fertilization, meaning the sperm and egg meet outside the female's body, not inside. 

Explanation

The P generation refers to the parental generation in a genetic cross.

These individuals are considered "pure-breeding," meaning they have homozygous genotypes for a particular trait, and therefore exhibit that trait without any variation. 

Explanation

Triploblastic animals have three germ layers (ectoderm, mesoderm, endoderm).

Roundworms (Nematodes) are triploblastic.

Explanation

A nucleoside is composed of a Base + Sugar. 

A nucleoside is a molecule made up of a nitrogenous base (like adenine, guanine, cytosine, or thymine) 

Attached to a five-carbon sugar (ribose or deoxyribose).

It lacks the phosphate group that is found in a nucleotide. 

Explanation

On a DNA strand, nucleotides are linked together by phosphodiester bonds.

These bonds connect the 5' carbon of one nucleotide's sugar to the 3' carbon of the next nucleotide's sugar, forming a chain.