Because you cannot test it or observe it.
A scientific theory are created through the scientific method, in the scientific method you need to be able observe it and experiment.
The correct options are as follows:
1. ELECTRICAL TRANSMISSION THROUGH NEURONS AND CHEMICAL TRANSMISSION BETWEEN NEURONS [D].
Neurons, which are the nerve cells that carry nerve impulses are made up of cell body and dendrites. Electrical events propagate signals within a neuron and chemical processes transmit the signals from one neuron to the other.
2. SENSORY NEURON - BRAIN - SPINAL CORD - MOTOR NEURONS [B].
Waking up from sleep involves sensory neurons. Hearing of a strange sound is made possible by the activity of the brain. The man become alarm as a result of the message to the body from the brain via the spinal cord and running involves motor neurons.
3. MOTOR NEURONS AND SENSORY NEURONS [A].
The peripheral nervous system is one of the two components of the nervous system and is made up of the nerves and the ganglia outside the brain and the spinal cord. The neurons of the peripheral nervous system is made up of sensory and motor neurons. The sensory neurons bring signals to the central nervous system while the motor neurons carry signals out of the central nervous system.
Answer:
The correct answer is c) are plant cells.
Explanation:
The cells cannot be animal cells, because they have not wall (this kind of cells has only plasma membrane). In addition, eukaryotic cells have membrane-bound organelles (which are surrounded by a phospholipids membrane, such as endoplasmatic reticulum, Golgi apparatus, lysosomes, etc.), whereas prokaryotic cells lack them. Since plant cells are eukaryotic and bacterial cells are prokaryotic, the cells you are looking are plant cells.
Pyroclastic materials are classified according to their size, measured in milli meters: dust (less than 0.6 mm [0.02 inch]), ash (fragments between 0.6 and 2 mm [0.02 to 0.08 inch]), cinders (fragments between 2 and 64 mm [0.08 and 2.5 inches], also known as lapilli), blocks (angular fragments greater than 64 mm), and bombs (rounded fragments greater than 64 mm).
The fluid nature of a pyroclastic flow is maintained by the turbulence of its internal gases. Both the incandescent pyroclastic particles and the rolling clouds of dust that rise above them actively liberate more gas. The expansion of these gases accounts for the nearly frictionless character of the flow as well as its great mobility and destructive power.
Pyroclastic flow, in a volcanic eruption, a fluidized mixture of hot rock fragments, hot gases, and entrapped air that moves at high speed in thick, gray-to-black, turbulent clouds that hug the ground. The temperature of the volcanic gases can reach about 600 to 700 °C (1,100 to 1,300 °F). The velocity of a flow often exceeds 100 km (60 miles) per hour and may attain speeds as great as 160 km (100 miles) per hour.
To learn more about Pyroclastic materials here
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Sentense is absolutely TRUE
