A scientist was interested in knowing how the amount of sleep a student gets the night before an exam affects the score that a student gets on the exam. He divided his subjects (students) into 3 groups. Group A took the exam after sleeping 6 hours. Group B took the test after sleeping 8 hours (normal amount). Group C took the test after sleeping 10 hours. He then looked at the test scores to see if there was any difference between the 3 groups. What is the independent variable in this experiment?

Indicate whether the following statements about the biases in the fossil record are true or false. a) inland species are more likely to be preserved than marine species b) organisms with hard body parts are more likely to be preserved than are those composed soft tissues. c) species that existed over a larger area are more likely to be preserved than species existing over a smaller area. d) organisms that lived very long ago are more likely to be found as fossils than organisms that lived relatively recently e) the fossils of larger organisms are more likely to be found than the fossils of smaller organisms

When mendel crossed a true-breeding short plant with a true-breeding tall plant all the offspring were tall. which term describes the gene for tallnes?

What does the hardy-weinberg principle relate to? a. chances of survival of an organism b. frequency of alleles in a population c. natural selection in a species d. causes of evolution among organisms