The herbaceous plant Achillea lanulosa is widespread in the Northern Hemisphere. Phenotypic variation in the species has been extensively studied along an altitudinal gradient from sea level to over 3,000 meters. In California there is conspicuous variation in  height; alpine plants are only several centimeters tall  while  those in  the San Joaquin Valley may reach a height of 1.8 meters. Adaptation to different local environments also results in variation in physiological processes such as photosynthetic rate, resistance to cold, and the timing of dormancy.

The morphological variation shown by Achillea lanulosa illustrates

#Question id: 11544

#Unit 7. System Physiology – Animal

When a steroid hormone and a polypeptide hormone exert similar effects on a population of target cells, then ________.

#Question id: 11545

#Unit 7. System Physiology – Animal

Growth factors are local regulators that ________.

#Question id: 11546

#Unit 7. System Physiology – Animal

Steroid and polypeptide hormones typically have in common ________.

#Question id: 11547

#Unit 7. System Physiology – Animal

A cluster of tumor cells that produces and secretes growth factors to induce surrounding cells to grow and divide is showing which type of cell-to-cell signaling?

#Question id: 11548

#Unit 7. System Physiology – Animal

If a portion of the pancreas is surgically removed from a rat and the rat subsequently loses its appetite, one explanation is that the removed portion contains cells that secrete a chemical signal that somehow stimulates appetite. Given this scenario, what type of chemical signaling is occurring?

#Question id: 11549

#Unit 7. System Physiology – Animal

If a biochemist discovers a new molecule, which of the following pieces of data would allow her to draw the conclusion that the molecule is a steroid hormone?

I) The molecule is lipid soluble.

II) The molecule is derived from a series of steps beginning with cholesterol.

III) The molecule acts at a target tissue some distance from where it is produced.

IV) The molecule uses a transport protein when in an aqueous solution such as blood.