Answer:
A double helix shape of DNA
Explanation:
- 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.
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I think the answer is DNA
It has been found that the rainforests are accountable for about one-third, that is, 28 percent of the oxygen of the Earth, however, the majority of the oxygen, that is, about 70 percent in the atmosphere is generated by the marine plants. The left-over two percent of the oxygen comes from other sources.
The majority of the oxygen comes from the tiny plants in the ocean known as phytoplankton, which lives near the surface of the water and drifts with the currents. Similarly to plants, they perform the process of photosynthesis, that is, they utilize carbon dioxide and sunlight to prepare food, oxygen is the by-product of photosynthesis.
However, the concentration of the dissolved oxygen, which the water can hold relies on the salinity and temperature of the water. The cold water can withhold more oxygen in comparison to warm water and fresh water can hold more oxygen in comparison to salt water. So, the warmer and saltier the water is, the less will be the oxygen dissolved in it.
