Explanation: Photomorphogenesis is the process of growth and development of plants, which is completed in the presence of light.

Explanation: There are two light sensitive systems involved in photomorphogenesis. One is the red light response and the other one is the blue light response. Red light sensitive system is known as phytochrome while blue light system is called as cryptochrome.

Explanation: Chromophore is the bound pigment molecule which is responsible for the red colour light in the phtochrome.

Explanation: There are two classes of phytochrome i.e., Type I and Type II phytochromes. These phytochromes proteins encoded by the phytochrome gene family named PHY.

Explanation: Cryptochrome is a chromoprotein which works as a blue light photoreceptor of plants. It is a flavoprotein i.e., Flavin complexed with protein.

Explanation: Seed germination is mediated by phytochromes while inhibition of stem elongation, stimulation of leaf expansion, and regulation of floral initiation is the function of cryptochrome.

Explanation: CRY1 and CRY2 mediate gene expression and the circadian clock in response to light. These are the nuclear proteins found in Arabidopsis.

Explanation: Phototoropin acts as a blue light receptor, it is a flavoprotein which has a major role in regulation of chloroplast movement and photropism.

Explanation: Photoperiodism is defined as the ability of the plant to measure the length of the photoperiods. The length of the photoperiod varies between the species.

Explanation: Long day plants are those which flower only when the day length is longer as compared to usual critical day length.