List the order of the following layers from outermost to innermost of a root: g. Cortex
a. Phloem
b. Epidermis
c. Pericycle
d. xylem
e. Endodermis
Ty!

Epiblema, cortex, endodermis, pericycle

Explanation:

The outer most layer of monocot root is rhizodermis or epiblema which has compactly arranged tubular cells and unicellular root hair as their extension. Just beneath the epiblema are multiple layers of parenchymatous cells with ample intercellular space, it is cortex. The inner most layer of cortex forms endodermis which has compactly arranged barrel shaped cells with casparian strips at their anticlinal wall. The uniseriate layer of thin walled parenchymatous cells, present below endodermis, which are sclerified in old roots makes pericycle. The vascular bundles are present as alternating strands of xylem and phloem, the discrete xylem strands alternated with phloem strands. The central parenchymatous cells form pith.

fertilization, pictured in figure 24.23a is the process in which gametes (an egg and sperm) fuse to form a zygote. the egg and sperm each contain one set of chromosomes. to ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. in mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida. when a sperm binds to the zona pellucida, a series of biochemical events, called the acrosomal reactions, take place. in placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane, as illustrated in figure 24.23b. the fusion of these two membranes creates an opening through which the sperm nucleus is transferred into the ovum. the nuclear membranes of the egg and sperm break down and the two haploid genomes condense to form a diploid genome.

explanation: