Answer: Option D. -> All of these
:
D
The meristems of the root and shoot apex or the cambial cells of the vascular and cork cambium show arithmetic growth.

Answer: Option A. -> Photonasty
:
A
Photonasty is the response ofplants to the availability of light.

:
The widely used compound or a source of ethylene is ethephon, 2-chloroethyl phosphonic acid.

Answer: Option C. -> Both extrinsic and intrinsic factors
:
C
Growth and differentiation together is termed as development and in plants it is dependent on both intrinsic and extrinsic factors.The former includes both intracellular (genetic) or intercellular factors (chemicals such as plant growth regulators) while the latter includes light, temperature, water, oxygen, nutrition, etc.

Answer: Option A. -> Differentiation
:
A
The cells derived from root apical and shoot-apical meristems and cambium differentiate and mature to perform specific functions. This act leading to maturation is termed asdifferentiation.During differentiation, cells undergo few to major structural changes both in their cell walls and protoplasm. For example, to form a tracheary element, the cells would lose their protoplasm. They also develops a very strong, elastic, lignocellulosic secondary cell walls, to carry water to long distances even under extreme tension.

Answer: Option A. -> Fungi
:
A
GAs were first discovered in thefungusGibberella fujikuroi, from whichgibberellic acid(GA3) and other GAs are produced commercially.

Answer: Option C. -> Secondary meristems - Increase girth of monocot plants
:
C
Secondary lateral meristems like vascular cambium and cork cambium are seen in dicotyledonous plants and gymnosperms and are absent in monocotyledons.

Answer: Option D. -> Growth
:
D
Anauxanometeris an apparatus for measuring increase or rate of growth in plants.

Answer: Option D. -> Cytokinin
:
D
Coconut milk factor is a cytokinin.Kinetin does not occur naturally in plants. Search for natural substances with cytokinin-like activities led to the isolation of zeatin from corn-kernels and coconut milk.

Answer: Option A. -> Bolting in cabbage
:
A
Bolting (internode elongation) just prior to flowering in cabbage is a test for gibberellin. Gibberelin helps in stem elongation.