(a) What is a granum (pleural grana) in a chloroplast ? How many grana are there in the matrix of each chloroplast ?
(b) Name the photosynthetic pigments that are present in the thylakoid membrane of chloroplast.

Explanation

(a) The infolds of the inner membrane of chloroplast become free to lie as lamellae in the matrix. These lamellae usually take the form of closed, flattened, ovoid sacs called thylakoids which lie closely packed in piles called grana.
A chloroplast may have 40 to 100 grana in its matrix.
(b) The thylakoid membrane contains photosynthetic pigments such as chlorophyll a , chlorophyll b, carotenoids ( carotene, xanthophylls ) and plastoquinone.