- 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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Answer:
362 nucleosomes
Explanation:
A nucleosome repeat is made up of the DNA (146 bp) wrapped around the core nucleosome particle and the linker DNA (110 bp as in this situation). We can conclude that, every repeat stands for 256 (146 + 110) base pairs of DNA.
We are given the length of the entire region to be 92,672 bp long,
To determine the number of nucleosomes to organize the region into the 10nm fiber structure
Let,
Number of nucleosomes =
the length of the entire region
------------------- -----
base pairs of DNA.
= 92,672
-------
256
= 362 nucleosomes
Therefore, 362 nucleosomes is needed to structure the region into the 10nm fiber structure.
Answer:
muscle cells in the legs of a marathon runner
Explanation:
Mitochondria are the powerhouse of cells and serve as a site for the aerobic stage of cellular respiration. Cellular respiration is complete oxidation of nutrients in the presence of oxygen to produce a large number of ATP molecules. Therefore, the cells that require more ATP molecules as an energy source would most likely have a greater number of mitochondria.
Muscle cells are responsible for body movement. Muscle cells in the legs of a runner would require a constant supply of ATP during running since muscle contraction requires ATP. To sustain the continuous muscle contraction during the marathon, the muscle cells in the legs of the runner would have most number of mitochondria.
it just as it is tempting to take natural selection to extreme so no not all
