<span>Answer: Cellular differentiation is responsible for one daughter cell becoming a sieve tube whereas the other becomes a companion cell. Cell differentiation occurs as different genes are switched on and off.
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This is the chronicle of evolution over millions of years of geologic time engraved in the order which fossils appear in rock strata.
Chemoreceptor is a specialized sensory receptor cell, which responds to a chemical substance and generates a biological signal.
The type of chemoreceptor responsible for our sense of smell is called olfactory receptor. It is also known as odorant receptor, these are found in a small patch of tissue high inside the nose. These cells directly connected to the brain.
