Gas exchange in an echinoderm takes place through

A. book lungs.

B. skin gills.

C. lungs.

D. none of the above.

True or false. Is sympatric speciation, a physical barrier arises and separates two populations l, ending flow between them

Identifying the Laws of Inheritance Mendel studied pea plants for particular traits. When observing the results of his experiments, he created two laws of inheritance. How is a scientific law formed?

carbohydrates may for larger carbon based macromolecules by combining with which elements A) sodium, potassium, nitrogen B) nitrogen, sulfur, phosphorus C) potassium, sodium, sulfer D) silicon, phosphorus, sodium

What type of tissue are bone, fat, or blood cells examples of?

Which of the followering would not be considered a foul

Which are biotic factors in an American alligator's environment? Choose all answers that are correct. A. temperature of the water B. amount of oxygen gas in the water C. type of grass needed for nests D. number of available mates

If you are told that the frequency of a recessive allele in a population is 10%, you are directly given q, since by definition q is the frequency of the recessive allele.

Which individual is at the least risk for osteoporosis? thin, elderly male male weight lifter in his 20s petite asian female thin caucasian female in her 40s?

What is the condition of the atmosphere at a particular time and place?

4. What did the mitochondrial DNA testing show? What do scientists believe happened to Anastasia?