Which of the following is a disadvantage of animal endoskeletons?
a. endoskeletons allow organisms to grow large in size.
b. endoskeletons don't need to be molted as an organism grows.
c. endoskeletons enable a variety of movements, including swimming, crawling, and leaping.
d. endoskeletons don't protect the animal as well as other skeletal systems.

The table shows dates and appearance of index fossils. which rock layers can be dated most precisely? a) a layer containing both a fossil 4 and a fossil 3 b) a layer containing both a fossil 2 and a fossil 3 c) a layer containing both a fossil 1 and a fossil 4 d) a layer containing both a fossil 1 and a fossil 2

Which of the following statements best distinguishes a hypothesis from a theory? a. theories are hypotheses that have been proved. b. hypotheses are guesses; theories are correct answers c. hypotheses usually are relatively narrow in scope; theories have broad explanatory power. d. theories are proved to be true; hypotheses are often contradicted by experimental results.

Rna primer constructed during dna replication needs to be replaced because rna differs from dna. it contains ( adenine, cytosine, uracil ) instead of ( adenine, guanine, thymine ).