During precambrian time, simple life forms existed in the oceans of earth. this was followed, during the paleozoic era, by the "great explosion" when many new life forms appeared on earth in a very short period of time. a) burgess b) cambrian c) geologic d) jurassic

Select the correct answer from each drop-down menu. in an experiment, dr. travis examined the effects of calcium intake on osteoporosis, a condition that causes an increased risk of bone fractures. the amount of calcium is variable. the risk of bone fractures .

'which of these statements about the scientific method is not true? all experiments must follow the same number of steps in the procedure. experiments may be repeated several times. some unexpected results can be beneficial. experimental results may or may not support the hypothesis.

Aflame cell is at the end of each tubule of the nephridium malpighian tubules kidneys none of the above