Shailesh Koirala 
Most kinds of food are readily decomposed by microorganisms unless special methods are used for their preservation. The chief methods of food preservation are as follows: Asepsis, or keeping out microorganisms. Removal of microorganisms. Maintenance of anaerobic conditions, e.g., in a sealed, evacuated container. Use of high temperatures. Use of low temperatures. Drying; this includes … Read more
The prevalence of tuberculous infection may be estimated by the use of the tuberculin test in contradistinction to the clinical disease. The positive test indicates that the individual has been infected by the tubercle bacillus sometime without necessarily showing overt signs or symptoms of disease. A standardized tuberculin is available now through the World Health … Read more
Self-pollination is the transference of pollen grains from the anther of a flower to the stigma of either the same or genetically similar flower. It is generally not dependent on any external agency for pollination. It is of two types: 1.Autogamy It is the transfer of pollen grains from anther of a bisexual flower to … Read more
Breathing is a physical process of taking or inhaling the fresh air in and expelling CO2 out. It is accomplished through changes in the volume and air pressure of the thoracic cavity. It is accomplished by the movement of ribs, internal and external intercostal muscles between each pair of ribs, diaphragm and abdominal muscles. Breathing … Read more
Human heart is a roughly triangular structure and a muscular organ. It is situated in the thoracic cavity between the two lungs. One third of its part lies on the right side and two third on the left side. An average human heart weighs about 300-350 grams which is about 12 cm long and 9 … Read more
The central nervous system consists of two parts. They are – a)Brain and b)Spinal cord A)Brain It is highly specialized delicate organ of the human body. It weighs about 1.3-1.5kg depending on the gender (in case of human). It is protected by a bony brain case or cranium. It is composed of soft nervous tissues … Read more
The phenomenon of separation of linked genes is termed as crossing over. Linked genes separate during inheritance and produce new or non-parental combinations in case of incomplete linkage. The parental combinations are more than the non-parental combinations. It is also a physical process of exchange of genetic materials or segments between non-sister chromatids of two … Read more
The blood clots or coagulates within 2-6 minutes if it gets collected in a tube. It changes into semisolid jelly. This phenomenon is called coagulation or clotting. When skin or any other body part is cut, the blood flows out. But it quickly clots and thus stops the blood oozing out. It is called blood … Read more
The differences that are found between the individuals of same species are called variation. It is very difficult to find out two individuals exactly similar in the nature. It may be harmful, useless and useful. Harmful or useless variations make individuals unfit for struggle for existence, whereas the useful variations are quite significant and make … Read more
S.N Genotype Phenotype 1. It is the genetic make-up of an organism. It is the morphological appearance of an organism. 2. By knowing the genotype, phenotype of individual can be assessed. By knowing the phenotype, genotype may or may not be assessed. 3. It remains the same throughout the life of … Read more