Primary succession is one of two types of biological and ecological succession of plant life, occurring in an environment in which new substrate devoid of vegetation and other organisms usually lacking soil, such as a lava flow or area left from retreated glacier, is deposited. In other words, it is the gradual growth of an ecosystem over a longer period.
Answer:
Option-D
Explanation:
Casparian strips are the strips or band composed of a hydrophobic substance called the suberin which forms the ring-like structure in the endodermis of the vascular plants.
The Casparian strips are present around the vascular bundles in the endodermis to allow the uptake of the selective nutrients as the substance has to pass through the cell membrane before it enters the centre of the root or stele or vascular bundles.
The Casparian strips allow the movement of a substance through symplast mode only, therefore, is ensures the substance to pass through the cell membrane.
Thus, Option-D is correct.
