Q.

You are given a tissue with its potential for differentiation in an artificial culture. Which of the following pairs of hormones would you add to the medium to secure shoots as well as roots                  [2016]

1 IAA and gibberellin  
2 Auxin and cytokinin  
3 Auxin and abscisic acid  
4 Gibberellin and abscisic acid  

Ans.

(2)

Cytokinin and auxin are two plant hormones that are supplied to the tissue culture medium in definite proportions. They bring about cell division and differentiation of callus. A low auxin to cytokinin ratio promotes shoot formation whereas a high auxin to cytokinin ratio promotes rooting of callus.