Important multidisciplinary issues including the dynamics and predictability of global climate and the sustainability of human use in coastal and estuarine regions.
Answer:
Recent studies have shown that dark skin colour was developed in the past for protection against cancer. Scientists claim that in the past natural selection favoured humans having dark colour as compared to humans having a fair colour. This is because humans having a darker colour produced more melanin which protected them from ultraviolet radiation. As a result, this skin colour protected more against skin cancer. Hence, Having a darker skin colour protected in survival and reproduction to people thousands of years ago.
- 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 glyptodon is found to be similar to the armadillo.
Explanation:
A piece of evidence that supports the theory of evolution is that the glyptodon is found to be similar to the armadillo. Glyptodons and armadillos have many things in common, expect that glyptodons are much larger (the size of a Volkswagen beetle!) than an armadillo. The change from the prehistoric glyptodon to our modern day armadillo helps support that there is evolution because they still have many things in common. They are genetically related.
