Statement I : When a piece of brick lying on grass for a number of days is removed, the covered part of the grass appears pale. Statement I : Synthesis of chlorophyll, which gives green pigment, occurs in presence of sunlight.

Statement I is true as grass covered by a brick undergoes chlorosis, a process where it loses its green pigment and turns pale due to the absence of light [2]. This phenomenon is part of etiolation, where plants develop etioplasts instead of chloroplasts in darkness [2]. Statement II is also true and provides the correct explanation: the synthesis of chlorophyll is a light-dependent process [2]. In the absence of sunlight, the enzymatic production of chlorophyll ceases, and existing chlorophyll decomposes [2]. Sunlight is essential not only for photosynthesis but specifically for the maturation of chloroplasts and the biosynthesis of the green pigment chlorophyll [2]. Therefore, when the brick blocks sunlight, the grass cannot synthesize new chlorophyll and loses its green color, appearing pale.

Sources

1. [2] https://www.sciencedirect.com/topics/medicine-and-dentistry/etioplast
2. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > Photosynthesis and respiration > p. 15