Explanation

Promoter sites are specific DNA sequences where RNA polymerase binds to initiate transcription, the process of copying a gene's DNA sequence into RNA.

Explanation

If a person is tall, this physical expression is referred to as their phenotype

Explanation

Epistasis occurs when the expression of one gene is affected by another gene at a different locus.

This interaction can mask or modify the effects of the other gene, leading to variations in phenotypes.

Explanation

Both CS₂ (carbon disulfide) and SO₃ (sulfur trioxide) have zero dipole moment.

Note….: Here CS 2 and SO3 options are correct. However, FPSC did not give a choice of both A and B.

Explanation

Scorpions and spiders both belong to the class Arachnida.

This class includes arachnids, which are characterized by having eight legs and lacking antennae.

Explanation

Sieve tubes and companion cells are absent in the phloem of pteridophytes.

Explanation

Gap junctions are specialized structures that allow direct communication between adjacent cells.

They are formed by connexin proteins that create channels enabling the exchange of ions, metabolites, and other small molecules between cells. 

Explanation

Arachnids, such as spiders and scorpions, are distinguished by having eight legs, a characteristic feature of this class.

Explanation

In humans, the type of implantation is endometrial implantation,

which occurs when the embryo embeds itself into the lining of the uterus (endometrium).

Explanation

An organ transplant involves removing an organ from a donor and putting it into someone unwell with organ failure.

Organs and tissues that can be transplanted include the

• heart
• lungs
• kidneys
• liver
• skin 
• parts of the eye