Questions

The statements true about viruses are :

1. The capsid enters the host cell if the virus is enveloped.

2. Enveloped viruses bud from the host cell. 

3. HIV contains reverse transcriptase.

4. A retrovirus contains RNA.

Answer: U

Explanation:   Starting on the left, and moving along the line to the right, letters follow the alphabetic sequence, in steps of 1,2,3 and then 4, before repeating the sequence.

Romans (753 BC - AD 410) began public health and sanitation systems.

Romans established the first public health and sanitation systems by building sewers and aqueducts.

They also treated diseases with diet, exercise and meditation.

Assessing opportunity cost involves making choices and dealing with consequences.

A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. The capacity of the air conditioning depends entirely on the capacity of the compressor. The reciprocating compressor is usually used in AC.

The reciprocating compressor have piston and cylinder arrangement like the automotive engine. The reciprocating motion of the piston due to external power compresses the refrigerant inside the cylinder.

There are three types of reciprocating compressors:

hermetically sealed,

semi-hermetically sealed and

open type.