Which of the following structures is present in both prokaryotic and eukaryotic cells

The gray matter of the brain primarily consists of neuron cell bodies, along with dendrites, glial cells, and unmyelinated axons. It appears gray because it lacks the white fatty myelin sheath that covers many nerve fibers.

The pituitary gland produces prolactin, which regulates milk production

Urea is a nitrogenous waste product that is produced when the liver breaks down proteins and amino acids. It is then excreted from the body via sweat.

The vermiform appendix is a small, finger-like projection that extends from the cecum, which is the first part of the large intestine.

Biological macromolecules are large organic molecules such as carbohydrates, lipids, nucleic acids, and proteins. They are built from smaller molecules, which are linked commonly by covalent bonds, and these can be broken down.

Objects A and B have the same and are subjected to the same gravitational pull. However, object B falls faster than A. This is due to a greater air resistance for A than B.

This is because when a proton is emitted from an atom, the atomic mass decreases by one unit, and the atomic number decreases by one unit. The atomic mass is the sum of protons and neutrons in the nucleus, and the atomic number is the number of protons in the nucleus. Therefore, if a proton is lost, both numbers decrease by one.

Psoriasis is a chronic skin condition that causes red, scaly patches on the skin. It is not contagious, and it is not caused by any microorganism. It is believed to be an autoimmune disorder where the immune system attacks healthy skin cells.

From the heart, blood flows through major arteries, which then branch to give rise to arterioles, which then divide into capillaries that deliver blood to the target organ.

Melanocytes are specialized skin cells that produce melanin, which is the protective skin-darkening pigment. They are found mainly in the epidermis, though they occur elsewhere, such as in the hair.