1. The cell wall has lignin (hard substance): to prevent the xylem vessel from collapsing and withstand high pressure.
2. The absence of protoplasm (nucleus + cytoplasm) and cross wall: to allow water to move through the lumen easily.
Hope it helped!
<span>The female frog's reproductive system is consist of a pair of ovaries and a pair of oviducts. The ovaries are attached to the kidneys. The kidneys carry countless ova which are released to outside through the oviducts. </span><span>In the breeding season, the male and the female frogs enter into a temporary union called amplexus. The male holds the female, presses her trunk and thereby forces the female to release the eggs, the male frog then releases the sperms immediately to bring about exterior fertilization.</span>
Mitochondria are found in all body cells.
