Twins can be either monozygotic ("identical"), meaning that they develop from one zygote, which splits and forms two embryos, or dizygotic ("fraternal"), meaning that they develop from two different eggs. In fraternal twins, each twin is fertilized by its own sperm cell.

The most common compound in cytoplasm is water. Cytoplasm consists of about 70-80% cytosol (hyaloplasm).

The species Euglena gracilis has been used extensively in the laboratory as a model organism. Most species of Euglena have photosynthesizing chloroplasts within the body of the cell, which enable them to feed by autotrophy, like plants. However, they can also take nourishment heterotrophically, like animals.

An antibody (Ab), also known as an immunoglobulin (Ig), is a large Y-shaped protein, produced mainly by plasma cells that is used by the immune system to identify and neutralize pathogens such as bacteria and viruses. They are proteinaceous in nature.

Common cold, also known simply as a cold, is a viral infectious disease of the upper respiratory tract that primarily affects the nose.

The main cause of anemia is iron.

Syphilis is a sexually transmitted, infectious disease caused by the spirochete bacterium Treponema pallidum. This bacterium causes infection when it gets into broken skin or mucus membranes, usually of the genitals.

Lactic acid is a compound produced when glucose is broken-down and oxidized. During intense exercise, when oxygen levels are lower, more lactic acid is produced.

Invertebrates are animals that neither possess nor develop a vertebral column derived from the notochord. This includes all animals apart from the subphylum Vertebrata.

Alga are photosynthetic and can produce their own food.

Louis Pasteur was a French chemist and microbiologist renowned for his discoveries of the principles of vaccination, microbial fermentation and pasteurization.

Manihot esculenta (commonly called cassava, Brazilian arrowroot, manioc, tapioca) is a woody shrub native to South America of the spurge family Euphorbiaceae. It is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, a major source of carbohydrates.

Cocaine was first isolated (extracted from coca leaves) in 1859 by German chemist Albert Niemann.

Vitis vinifera (grapevines) is a genus of 79 accepted species of vining plants in the flowering plant family Vitaceae. The genus is made up of species predominantly from the Northern hemisphere. It is economically important as the source of grapes for direct consumption of the fruit and for fermentation to produce wine. The study and cultivation of grapevines is called viticulture.

Rhizome is a continuously growing horizontal underground stem which puts out lateral shoots and adventitious roots at intervals. Banana is cultivated as a rhizome.

Lysergic acid diethylamide, also known as acid, is a psychedelic drug known for its psychological effects. It is obtained from cannabis.

Nutmeg is one of the two spices; the other being mace; derived from several species of tree in the genus Myristica.

The oldest cultivated fruit is mango.

Spleen is an abdominal organ involved in the production and removal of blood cells in most vertebrates and forming part of the immune system.

Mustard gas caused genetic damage in all systems in which it was tested. It caused DNA damage.

CDRI is a governmental body engaged in research of drugs and pharmaceuticals, and related studies. It is located in Lucknow.

Pheromone is a chemical substance produced and released into the environment by an animal, especially a mammal or an insect, affecting the behaviour or physiology of others of its species. These are used in animals for attracting the opposite sex.

Emasculation is the process of removing anthers from bisexual flowers without affecting the female reproductive part (pistil), which is used in various plant hybridization techniques. Emasculation is performed by plant breeders in bisexual flowers to obtain the desired variety of a plant by crossing a particular plant with the desired pollen grain.

The postulates were formulated by Robert Koch and Friedrich Loeffler in 1884, based on earlier concepts described by Jakob Henle, and refined and published by Koch in 1890. Koch applied the postulates to describe the etiology of cholera and tuberculosis.

Rice is the edible starchy cereal grain and the plant by which it is produced. Roughly one-half of the world population, including virtually all of East and Southeast Asia, is wholly dependent upon rice as a staple food; 95 percent of the world's rice crop is eaten by humans.