Since they have no predators the zebra mussel population will grow rapidly. Whatever the zebra mussels consume will have a major decrease in population since there are so many zebra mussels.
- 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.
Almost all viruses are so small they cannot be seen without an electron microscope, and they often consist of just a nucleic acid (either DNA or RNA) in a protein capsule.
Answer:
The policy for controlling environmental mercury pollution should address ways to prevent and control this pollution. Policy:
- Ban the incineration of waste
- Require that coal-burning companies remove mercury from the coal
- Allocate funds towards research and development for renewable energy resources in the hopes of switching away from coal.
- Require that products containing mercury be labeled as such.
- Set up programs that will recycle batteries and mercury-filled products.
- Set up education programs that will help inform people about mercury pollution.
This policy works by addressing the ways to prevent and control mercury pollution.
Three problems that could result from implementing this policy:
- Backlash from coal-burning companies.
- It could take a while before we completely shift away from using coal.
- Some of the programs that can be set up in this policy can be too expensive to set up and maintain.
