The glands of the system secrete chemical substances that are collectively known as . these chemicals diffuse into the bloodstream and communicate with distant cells called cells.

The correct answer will be option-

1. Endocrine glands

2. Hormones

3. Target cells

Explanation:

Animal cells communicate with each other through one of the signalling ways: autocrine, Paracrine and endocrine signalling.

Endocrine signalling occurs when a chemical is secreted by a cell acts on a target cell which is distant from the producer cell.

The group of cells called tissues (glands) which secretes the chemical is thus known as an endocrine gland and the chemical secreted by the endocrine gland is known as the hormone.  

A hormone acts on the distant cell after it gets diffused in the bloodstream and gets transported to the target cell.

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.

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