a. Maximum growth is observed in exponential phase.

- In this phase, the cells are not dormant. Here cell numbers increase in a logarithmic pattern. It is a period characterized by cell doubling.

b. Apical dominance is due to presence of auxins.

Explanation: Auxins are responsible for apical dominance. So apical dominance occurs when more auxins are available in apical bud than in the lateral buds. In most plants, the growing apical bud inhibits the growth of the lateral buds. This is called apical dominance.

c. Auxins hormone initiate rooting.

They help to initiate rooting in stem cuttings. This application is widely used for plant propagation. High concentrations of auxin inhibits root elongation and instead promotes adventitious root formation.

d. Pigment involved in Photoperception in flowering plants is phytochrome.

Phytochrome is a photoreceptor protein (homodimer) that senses seasonal changes in length of night- photoperiod. It is a crucial pigment that regulates different aspects of plant growth and development like seed germination, chloroplast development, flowering, etc.