The graphs show the age structure for each of three countries. The horizontal bars show the percentages of the population in each age group, by gender. Note that for Country 1, about 20 percent of the population is between the ages of 0 and 4. This is the greatest percentage of any 4-year age span in all three countries. Which conclusion about Country 1 does its age structure support?

How many trophic levels are there in the following food chain? phytoplankton - shrimp - perch - pike - osprey

Hormones are chemical molecules produced by endocrine glands. one such endocrine gland is the thyroid gland, which synthesizes the thyroid hormone, which in turn affects the heart muscles. which two statements describe the probable reason for the function of the hormone? the cells in the heart have specific receptors that allow for the intake of hormones. the heart and the endocrine glands have the exact same types of cells. all cells make the same types of hormones. thyroid hormones show their effect on the heart by means of specialized cells. thyroid cells and cardiac cells have different dna.

Scientists are conducting a study on the effectiveness of a new drug on memory loss. they are giving some of the test subjects the new drug to find out if it improves their long-term memory. which are possible limitations of this study? check all that apply. a) test subjects may want to participate in additional experiments. b) test subjects may think they should be paid more. c) test subjects may get bored and want to quit early. d) test subjects may have to travel during the experiment. e) test subjects may have full-time jobs. this is multiple choice. you for the !