The lac operon consists of 

• four regulatory genes only

• one regulatory gene and three structural genes

• two regulatory genes and two structural genes

• two regulatory genes and two structural genes

52.

Study the pedigree chart of a certain family given below and select the correct conclusion which can be drawn for the character.

• The female parent is heterozygous

• The parents could not have a had a normal daughter for this character

• The trait under study could not be colour blindness

• The trait under study could not be colour blindness

Study the cycle shown below and select the option which gives correct words for all the four blanks A, B, C and D.

• A	B	C	D
  Nitrification	Ammonification	Animals	plants

• A	B	C	D
  Dentirificiation	Ammonification	Plants	Animals

• A	B	C	D
  Nitrification	Denitrification	Animals	Plants

• A	B	C	D
  Nitrification	Denitrification	Animals	Plants

Given below is the diagram of a bacteriophage in which one of the options, all the four parts A, B, C and D are correct?

• A	B	C	D
  Tail fibres	Head	Sheath	Collar

• A	B	C	D
  Sheath	Collar	Head	Tail fibres

• A	B	C	D
  Head	Collar	Sheath	Tail fibres

• A	B	C	D
  Head	Collar	Sheath	Tail fibres