NEET Test 61

SO₂ has a bleaching effect due to which it bleaches chlorophyll and prevents the process of photosynthesis.

NaCl is added as an electrolyte which forms precipitate of gold sol

Gene which controls more than one character is called a Pleiotropic gene. This gene show multiple phenotypic effects. Example: Sickle cell anaemia 
• Gene Hb^s_β provides a classical example of pleiotropy. It does not only cause haemolytic anaemia but also results increased resistance to one type of malaria caused by parasitic Plasmodium falciparum. The sickle cell Hb^s_β allele also have a pleiotropic effect on the development of many tissue and organ such as bone, lungs, kidney, spleen, heart. 

• ABO Blood grouping is an example of multiple alleles. 

• Fruit colour in summer squash is an example of Dominant epistasis. 

• Coat colour in mice is an example of the supplementary gene.

Matthew Meselson and Franklin Stahl experiment where he proved that DNA replication is semi conservative performed using heavy Nitrogen ¹⁵N in E.coli 

• He grow E.coli in medium containing ¹⁵NH₄CL as the nitrogen source. 

• ¹⁵N was incorporated into the new synthesised DNA as well another Nitrogen containing compounds. 

• This heavy DNA molecule can be distinguished from the normal by centrifugation with caesium chloride density gradient. 

• Its forms the density gradient bands of the solution of lower density at the top that increase gradually towards the bottom with highest density.