Answer:
Muscle contraction thus results from an interaction between the actin and myosin filaments that generates their movement relative to one another.
<span>Pond organism is unicellular and crab is multi cellular.
The simplest level at which life exist is called the cell. Unicellular organism contain only one cell while multi cellular organisms contain more than one cell. Multi cellular organisms can be organized into various levels such as Cells>tissues> organs>organ systems> organism. Thus pond organism is unicellular under microscope and crab is multi cellular.</span>
The oak tree fungal pathogen, Phytophthora ramorum, has migrated 800 kilometers in 15 years. West Nile virus spread from New York State to 46 other states in 5 years. The difference in the rate of spread is probably related to the mobility of their hosts
<h3>What is
West Nile virus ?</h3>
West Nile fever is brought on by the single-stranded RNA virus known as the West Nile virus (WNV). It belongs to the same genus as the Zika virus, dengue virus, and yellow fever virus, Flavivirus, and is a member of the family Flaviviridae. Mosquitoes, primarily Culex species, are the main vectors of the virus. Since birds are the major hosts for WNV, the virus continues to spread via a "bird-mosquito-bird" cycle. The virus shares genetic ancestry with the family of viruses that cause Japanese encephalitis.
The virus causes disease symptoms in both humans and horses, and symptoms are hardly seen in other animals. In Uganda, the human sickness was first recognized in 1937, and in the second half of the 20th century, it spread to many other countries.
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Its important because it produces the make gameotophyte called pollen.
