The scientific investigation is the systematic approach of the scientists to answer the questions about the world. It is applied almost all of the theories including the Theory of Natural Selection. Darwin's theory of evolution is a result of scientific investigation. In this theory, they investigate by observing the distribution of species.
The continental shelf is a gently sloping feature found at the edge of a continental landmass going seaward from the coast. Rivers that empty into the sea can produce currents that are strong enough to erode the material that builds the shelf. When this occurs channels or submarine canyons are formed. These canyons are deep and dark as no light can penetrate these regions. The canyons often lead out to sea towards the edge of the shelf.
The human body comprises of more than 600 muscles differentiated in three classifications, and all are under the control of the nervous system. The activities like picking up a dropped pen or leaning over incorporate the combined effort of various muscle groups.
The alert mind relays this instruction to the central nervous system that conducts it in the form of electrical impulses. These are then mediated via the somatic segment of the peripheral nervous system to the nerves accountable for monitoring the essential muscles.
When the signals arrive, a chemical known as acetylcholine gets discharged from the nerve terminals, activating the membranes of muscle fibers and making them to contract. The receptors present in the muscles provide the brain with the instruction regarding the movement and position of the body, the brain monitors the contraction of skeletal muscles.
4, even plant cells have cell membranes.
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