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<u>cardic muscles:</u> are present only in the heart .single cell is not very strong by itself, millions of cardiac muscle cells working together are easily able to pump all of the blood in the body through the heart in less than a minute. Cardiac muscle cells have a branched shape so that each cell is in contact with three of four other cardiac muscle cells.
<u>characteristics of cardic muscles: </u> one nucleus ,striated, involuntary, branched and joined to one another by intercalated discs that contain gap junctions for depolarization between cells and hold the fibers together when the heart contracts.
Trees are very important natural resources. They are the source of food, shelter and habitat. We get various woods, timber , fodder from the forest. Trees hold the soil firmly. Forests helps in conducting water cycle. If trees are cut down then environmental pollution will increase because trees purify the Air. Land pollution , air pollution , water pollution may increase. Biodiversity can be affected.
Science<span> is the study of the nature and behavior of natural things and the knowledge that we obtain about them
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The excretory system allows animals to remove metabolic waste their bodies. Many of these substances are potentially toxic. in Mammals nitrogenous toxins like urea are expelled through liquid urine while in reptiles and birds the nitrogenous compounds are expelled as a solid. This allows birds and reptiles to use less water in the processes of metabolism.
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the answer is all of the above
