Revision: World of Microbes Science SSLC (English Medium) Class 9 Tamil Nadu Board of Secondary Education

Bacteriophages are virus that infect bacterial cells, e.g. T4 bacteriophage.

Viral particles which contain only protein. They do not contain nucleic acid.

The condition of nutrition in which the food is either in inadequate quantity or in excess or it lacks in some essential nutrient is called malnutrition.

Immunisation is body’s natural defence mechanism which acts by producing antibodies against the antigens infecting the body.

Atherosclerosis is a disease caused by the malfimtioning of heart wherein the arterial walls get hardened and thickened, reducing the flow of blood and raising the blood pressure.

A vaccine is a biological preparation of a weakened or killed pathogen (disease causing microbes) which stimulates the formation of antibodies and develops immunity against a particular disease.

The ability of an organism to resist and overcome infection is called immunity.

The diseases caused by inadequate intake of food or the lack of some essential nutrient in our diet are called deficiency diseases.

Deficiency in one or more of the nutrients causes various diseases. These are called deficiency diseases.

 Any disorder or abnormal working of an organ, part or system of the body leads to illness called as disease.

Any organism that is capable of causing disease is called a pathogen.

Examples : bacteria, virus or other microorganism.

Vaccination is a method of making the body immune to a particular disease by injecting killed or weakened disease causing microbe into a body to stimulate the formation of antibodies and develop immunity to that disease causing microbe.

Toxin:
The poisonous substances secreted by pathogens that cause diseases are called toxins.

Vector:
Vector is an agent that acts as an intermediate carrier of the pathogen.

• Ascariasis is caused by Ascaris and spreads through faeces-contaminated soil, water, vegetables, and fruits.
• Symptoms of Ascariasis - internal bleeding, muscular pain, fever, anaemia, and intestinal blockage.
• Filariasis is caused by Wuchereria bancrofti and W. malayi, transmitted by female Culex mosquito bite.
• Filarial worms live in the lymphatic vessels of the lower limbs, causing chronic inflammation for many years.
• Filariasis leads to deformity of limbs and genital organs due to long-term swelling.