- Xylem contains tracheids, vessels, xylem parenchyma and xylem fibre.
- Tracheids: They are elongated, tubular dead cells with tapering end walls.
- Vessels: These are also known as trachea. They are elongated, tubular dead cells. They are joined to each other by end to end forming a continuous pipe. The cells are thick and lignified.
- Xylem parenchyma: They are also called wood parenchyma. This is the only living tissue of xylem.
- Xylem fibre: They are dead cells with thick walled fibre.
- Phloem consists of sieve tubes, companion cells, phloem parenchyma and phloem fibres.
- Sieve tubes: These are elongated, tubular living cells arranged in a row, with their perforated end walls forming a sieve. They are non-nucleated. Their protoplasm are inter-connected through sieve plates. They possess vacuoles.
- Companion cell: They are elongated, lens-shaped cells containing dense cytoplasm and prominent nuclei. These cells maintain connection with sieve cells through pits.
- Phloem parenchyma: They are living thin walled parenchyma cells.
- Phloem fibre: They are also known as bast fibre. They are elongated fibre like sclerenchymatous dead cells with thick walls containing pits and interlocked ends. Phloem fibre are the only dead cells in phloem.
Hope you could get an idea from here.
Doubt clarification - use comment section.
Answer:
Cell Theory
1. All living organisms are made of cells
2. Cells arrive from previously existing cells
3. Cells are the basic unit of structure...
Explanation:
Answer:
Almost twice
Explanation:
Human being have estimate 24,000 genes, while fruit flies have an estimate of 14,000 genes: meaning it is almost twice
Answer:
Rain makes up part of earth's water cycle
Water evaporates from streams, lakes, and oceans, then condensation and precipitation occur in the form of rain.
Explanation:
I'm pretty sure this question is implying that the answers should be directly related to the water cycle. While some of the other sentences might have some truth to them, they are too vague to be considered fact, and they're not necessarily related to the process of the water cycle.
The word biology comes from the Greek word <em>bios</em>, meaning life, and <em>logos</em>, meaning study.
