Questions

Hubs are specified or operate at Layer1 i.e, the physical layer in the OSI model. Hubs regenerate electrical signals. A hub sends data packets (frames) to all devices on a network, regardless of any MAC addresses contained in the data packet.

Energy tranfer takes place either by means of Heat or Work only in Thermodynamics.

Heat :: Heat Energy is defined as Energy that can be transferred due to temperature change.

Whereas

Thermal Energy :: Thermal Energy is the Internal Energy stored in the system maintained at a certain Temperature.

A mixture is made from different substances that are not chemically joined.Compound:

•Two or more elements combine together chemically to form a new substance called compound.

•The different elements are chemically joined together.•Compounds are homogeneous, i.e. their properties are the same throughout

•The compound has properties different from the elements it contains.

•It can only be separated into its elements using chemical reactions. (not using physical methods)

•During the formation of a compound from its elements, a certain amount of energy in the form of heat, light, electricity is either absorbed or evolved

Carbohydrates are also called as saccharides are molecular compounds made from just three elements:

carbon, hydrogen and oxygen.

Carbohydrates are:

* a source of energy for the body e.g. glucose and a store of energy, e.g. starch in plants

* building blocks for polysaccharides (giant carbohydrates), e.g. cellulose in plants and glycogen in the human body

* components of other molecules eg DNA, RNA, glycolipids, glycoproteins, ATP

Types:

1. Monosaccharides (e.g. glucose) and

2. Disaccharides (e.g. sucrose) are relatively small molecules. They are often called sugars.

3. Other carbohydrate molecules are very large called Polysaccharides such as starch and cellulose.

All the carbon atoms in glucose ultimately incorporated during cellular respiration into carbon dioxide molecules.