Hormones signal through two major mechanisms: via second messengers or direct gene action. since water-soluble hormones (most amino-acid based hormones) cannot enter the target cell directly, they act through plasma membrane receptors and intracellular second messengers. lipid-soluble hormones (steroid and thyroid hormones) can diffuse through the plasma membrane and act on intracellular receptors in the target cells to directly activate genes. watch the a& p flix mechanism of hormone action — second messenger camp video and then complete the activity and question below.

What is the difference between sex-linked traits and autosomal traits in humans? a. sex-linked traits can only be passed from fathers to sons, while autosomal traits can be passed on from both parents to offspring of any sex. b. sex-linked traits are passed on through the x and y chromosomes, while autosomal traits are passed on through the other 22 chromosomes. c. sex-linked traits only affect females, while autosomal traits affect both males and females. d. sex-linked traits refer to genes that are on the x and y chromosomes, while autosomal traits refer to genes on all 23 chromosomes.

What are the pros and cons of quadrat sampling?

Which of the following is likely not involved in this example of ecological succession? a) the rotting remains of plants add to the fertility of the soil. b)the soil becomes so fertile that eel grass is replaced by other plant species. c) the roots from plants stabilize the sediment, keeping it in place. d) the concentration of salt becomes so high that all plant life is destroyed.