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All physical quantities that we measure with instru­ments can be classified into two broad categories – scalar quantities and vector quantities. Some quanti­ties may be completely specified by stating a single number, for example, the age of a person, the mass of an object, and volume of air or temperature of the room.

The female reproductive organs include a pair of ovaries, a pair of oviducts (fallopian tubes), the uterus and the vagina. The human ovaries are two small-almond-like flattened bodies lying on the sides of vertebral column behind the kidneys in the pelvic cavity.

The sense organs or the receptors are structures specialized to perceive conditions outside and to some extent inside the body. They provide information to the central nervous system upon which action may be taken.

Endocrine system generally controls long term activities of target organs as well as physiological processes such as digestion, metabolism, growth, development and reproduction.

The central nervous system consists of brain and spinal cord which are covered by membranes called meninges. The brain is divided into three parts; (i) fore-brain (ii) mid-brain and (iii) the hind-brain.

In multicellular organisms, the various activities of the body are controlled or regulated by two different systems. One is chemical system which includes specific substances called hormones secreted by endocrine cells.

Excretion is a process by which the by-products of cellular metabolism are so treated that they take no further part in the metabolism. These by-products are removed from the body in aqueous solution.

A force can bring about a change in the state of motion of a body, or

In Physics, work is defined in a very specific way to describe what is accomplished by the action of force on an object. Work is said to be done if the force applied on the object succeeds in moving it. If no motion takes place, no work is said to be done. For example, an […]

Energy can be defined as the capacity or ability to do work and is measured by the amount of work a body can do. Like work, energy is a scalar quantity. It can take on any forms.

The scientists, until the nineteenth century, believed that heat was some kind of a fluid called Caloric which flows like any actual fluid (liquid or gas). According to the caloric theory, every object has a certain amount of caloric in it.

It is also an important aspect of protein metabolism. Urea is formed in the liver from ammonia, amino groups and CO2 in the presence of ATP and some enzymes.

Blood is a highly complex, liquid tissue composed of loose cells or corpuscles (45%) and fluid, plasma (55%). Specific gravity of blood ranges between 1.05 to 1.06 and it is salty in taste.