All choices correctly describes physical barriers. Physical barriers after composed of tight junctions wherein it is difficult for the bacteria and viruses to penetrate. Examples of these physical barriers are the skin and the mucous membranes and these work in conjunction with secretions like tears and mucus (as tears and mucus contain IgA, a special type of immunoglobulin that is secreted to fight harmful organisms).
Correct answer: B). Food and fossil fuels
The energy can not be created nor destroyed but it can be transformed into another form. The ultimate source of energy on this planet is the sun, the sun provides sunlight where sunlight is converted into chemical energy, which is used by plants to prepare food. Then we consume food prepared by plants to get energy and perform various types of work like movement, reproduction, growth etc. In this, the chemical energy is converted into mechanical energy.
DNA or deoxyribonucleic acid is a long molecule that contains our unique genetic code. Like a recipe book it holds the instructions for making all the proteins in our bodies. Your genome? is made of a chemical called deoxyribonucleic acid, or DNA for short.
The process of translating the sequence of a messenger RNA
