Sheep frequently give birth to twins. Identical twins grow up to be different sizes when adults. What is the main cause of this difference? 1. Environmental factors
2. Genetic differences between the twins
3. A combination of genetic and environmental factors
4. Nothing to do with genetic or environmental factors

Which type of scientific statement is defined as a hypothesis or group of hypotheses that can be accepted as true based on the repeated experimentation with similar results

The wings of insects, birds, and bats evolved independently but carry out similar functions. this is an example of a. analogous structures. b. embryonic structures. c. vestigial structures. d. homologous structures.

Which of the following best describes the purpose of the parathyroid hormone? a. it decreases the blood calcium level and decreases blood phosphorus level. b. it decreases the blood calcium level and increases the blood phosphorus level. c. it increases the blood calcium level and increases blood phosphorus level. d. it increases the blood calcium level and decreases blood phosphorus level.