
Hormones are chemical messengers or signaling molecules secreted by the endocrine glands into body fluids. Hormones travel to target cells through the bloodstream and stimulate response. Hormones can bind only to the target cells based on the presence of specific receptors. Hormones are involved in the regulation of growth, development,

Answer to Problem 1TQ
Hormones are signaling molecules and they coordinate various internal activities. Such internal activities are important for the growth and reproduction of an organism.
Therefore, option (c) is correct.
Explanation of Solution
Justify reasons for the correct statement:
Hormones are signaling molecules that regulate various cellular activities under specific situations in the life cycle of an organism. Secretory cells of the endocrine system produce hormones. Hormones enable communication of cells with one another. Lower concentrations of hormones can generate a large amount of internal signal in the target cells due to their specificity.
Option (c) is given as “signaling molecules”.
Hence, option (c) is correct.
Justify reasons for the incorrect statements:
Option (a) is given as “secretory cells”.
The specialized secretory cells of the endocrine system produce hormones. Hence, it is a wrong answer.
Option (b) is given as “endocrine glands”.
Secreted cells are organized into discrete organs and they are known as endocrine glands. Endocrine glands release hormones into the circulatory system for the transportation of hormones to the target cells. Hence, it is a wrong answer.
Option (d) is given as “target cells”.
Hormones travel to the target cells through body fluids and produce a response. The binding of hormones to their target cell receptors serves to exert effects of hormones. Hence, it is a wrong answer.
Hence, options (a), (b), and (d) are incorrect.
Hormones are signaling molecules produced by the secretory cells.
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