World's major producers and consumers of pollutants met at Montreal (Canada) on September 16, 1987 to solve the problem of ozone thining in stratosphere. 24 countries signed the protocol that came into force on january 1, 1989. This protocol refers to the substances such as CFCs (chlorofluorocarbons), methane that deplete the ozone layer.

Genes that when acting individually have a small effect but that collectively produce a significant phenotypic expression are called polygenes, e.gr inheritance of kernel colour in wheat and skin colour in human.

The probe is 15-30 bases long radioactive labelled oligonucleotides (RNA or DNA) used to detect complementary nucleotide sequence, used for disease diagnosis, etc.

The Okazaki fragments in DNA chain growth polymerise in the 5' to 3' direction. The replicated DNA result in transcription.

Powdery mildew of wheat-Erysiphe graminis. Loose smut of wheat-Ustilago tritici. Black rust of wheat-Puccinia graminis tritici.

One gene-one enzyme relationship was initially proposed by Beadle and Tatum and based on the experiments conducted on Neurospora crassa. They were awarded by Nobel Prize in 1958 for this achievement.

According to Lindeman's law of trophic efficiency, the efficiency of energy transfer from one trophic level to next is about 10%.

Biological Oxygen Demand (BOD) is a meaure of polluting organic matter present in a sample of water. BOD is higher in polluted sewage water and is connected with both microbes and organic matters. When larger amount of sewage is dumped in to water, the BOD will increase.

In gymnosperms, the pollen chamber is a cavity in the ovule in which pollen grains are stored after pollination.

Double fertilization is the characteristic feature of angiosperms, e.g, Capsella. It includes fusion of one male gamete with egg and second male gamete with a secondary nucleus (this forms endosperm).