Explanation

"Calamity آفت " means a great misfortune or disaster آفت

Explanation

If all the elements of a matrix are zero, the matrix is called a zero matrix or a null matrix. 

Explanation

Circinate vexation refers to the coiled arrangement of young leaves (usually in ferns) where the tip is rolled inward.

As the leaf matures, it gradually unrolls — a unique characteristic of fern leaves (fronds).

Explanation

The Born-Haber cycle is best example of Hess's law. 

The Born-Haber cycle uses the concept of Hess's law to calculate the lattice energy of an ionic compound by breaking down the formation of the compound into several smaller, easier-to-quantify steps

Explanation

A composite index number combines two or more variables into a single index value.

It's often used to measure overall trends, such as in economics or price levels.

Explanation

A standard normal distribution has:

Mean = 0

Standard deviation = 1

So, Variance = (Standard deviation)² = 1² = 1

Explanation

A circum-circle is a circle that passes through all the vertices of a triangle.

Its center is called the circumcenter.

Explanation

Interstitial cells, specifically Leydig cells in the testes, secrete androgens, primarily testosterone, in response to stimulation by luteinizing hormone (LH).

These hormones are crucial for the development of male secondary sexual characteristics and overall reproductive function. 

Explanation

Excess melanin-stimulating hormone (MSH) is secreted in Addison's disease

Because the adrenal glands are not producing enough cortisol

Which leads to an increase in ACTH (adrenocorticotropic hormone)

Which in turn stimulates the production of MSH, resulting in hyperpigmentation (darkened skin). 

Explanation

The tiny thin-walled ducts in the lungs of birds that open at both ends are called  Para-bronchi. 

In bird lungs, instead of alveoli, there are these thin-walled tubular structures called parabronchi where gas exchange occurs.