<span>a. Fish have a single central heart; earthworms have several hearts.
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Multi cellular organisms are made up of billions of cells each specialized to a unique role and these cells are organized into structural and functional units such as tissues and organs.
For each cell and organ to function optimally, it requires oxygen and nutrients and needs carbon dioxide and metabolic waste taken away in a continuous, never ending process.
<span>A mechanism is needed to accomplish the important function of transporting the relevant materials to and from the cell. The circulatory system fits this bill splendidly. It is a specialized organ system which allows blood and lymph to flow through the entire body carrying nutrients such as glucose, amino acids and electrolytes as well as oxygen to each cell, at the same time carting away carbon dioxide and all sorts of metabolic waste over to excretory organs to be expelled from the body.
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Answer:
B
Explanation:
The whole point of natural selection is for animals to compete to survive in that specific environment
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Answer:
C) Unrestricted whaling could lead to their extinction.
Explanation:
The whaling is a process of hunting and killing whales so as to get the meat, oil and whalebone so that they can be sell it out commercially. The trade of whale resources was firstly in France and Spain in 16th century but they have been spread worldwide. However, the conservation groups worldwide are pushing the restriction on whaling as unrestricted whaling can lead to complete extinction of the whale species from the Earth.
Explanation:
Echolocation is one of the methods of orientation mainly used by the microchiropteran or insectivorous bats. While flying, these bats emit high frequency ultrasound. These sound pulses hit obstacles like rocks, trees, walls etc. and their echoes are heard by bats.
