- 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:
The X-shaped structure is made of strands of DNA.
Explanation:
The chromosomes are thread-like structures located in the nucleus of each cell in the body. In a human cell, there are 23 pairs of chromosomes found in the nucleus. Each chromosome is made up of strands of DNA tightly coiled many times around proteins called histones which gives support to its structure.
The chromosomes are X-shaped and are observed only in a cell undergoing division by mitosis or meiosis. Each of these X-shaped chromosomes consists of two identical sister chromatids. The sister chromatids are connected to each other by a region of the chromosome called the centromere. The centromere are located around the depression point of the chromosome which divides the sister chromatids into two regions: long arm called the q arm and a shorter arm called the p arm. During mitosis, spindle fibers attach to this region, and they eventually pull the sister chromatids apart to form two separate chromosomes, one for each daughter cell.
Multicelluar is the answer to your question
