Answer:
The third one
Explanation:
electrons are found in the nucleus of an atom
b. carbon dioxide
c. chitin
The correct answer is a - silicon dioxide.
Diatoms are single celled algae. They have a silica - based cell wall called a frustule, which gives each diatom a particular shape.
Diatoms exist as separate single cells although some may be found in groups or colonies. The ones found in colonies create very pretty forms: leaf shaped, oval , star and even like a period.
Outer shells of diatoms are quite valuable. They are used in industry in the manufacture of toothpaste to give it grit.
Answer:
Diatoms have cell walls composed of silicon dioxide.
An action potential in a muscle cell is initiated by acetylcholine, which binds to receptors on the muscle cell membrane, causing depolarization. This triggers voltage-gated sodium channels to open, allowing sodium influx into the cell, which propagates the action potential. The action potential then leads to muscle contraction.
An action potential on a muscle cell is initiated through a complex sequence of events. First, a neurotransmitter called acetylcholine (ACh) is released from the motor neuron and binds to receptors on the muscle cell membrane or sarcolemma. This binding opens up a channel in the ACh receptor, allowing positively charged sodium ions to enter the muscle fiber.
This ion movement causes the muscle fiber to depolarize, or become less negative, changing the membrane potential. As the membrane depolarizes, another set of ion channels, the voltage-gated sodium channels, are activated and trigger an influx of more sodium ions into the muscle fiber.
This flooding of sodium ions propagates an action potential, or electrical signal, across the entire muscle cell membrane. This action potential then interacts with the sarcoplasmic reticulum to release calcium ions, leading to muscle contraction.
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B) a haiku
C) a ballad
D) a sonnet