Life originated in the _____
Fill in the blank(s) with correct word
Archaean eon, 3,800 - 2,500 mya.
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Which was an early tetrapod innovation?
a. limbs evolved from dorsal fins b. cartilaginous pectoral girdle c. four chambered heart d. stereoscopic vision e. inner ear changes to detect airborne sounds
Which of the following terms is mismatched with its meaning or characteristics?
A. Parazoa-lacks symmetry; no tissues B. Triploblastic-ectoderm, mesoderm, and endoderm C. Chordate-animal with notochord D. Eumetazoa-definite symmetry; tissues organized E. Diploblastic-ectoderm and mesoderm
Choose the best description of a covalent bond from the choices below.
A. Two water molecules interact due to partial charges on the oxygen and hydrogen atoms. B. A magnesium donates electrons and forms bonds with two chloride ions. C. A bond forms between a hydrogen from one molecule and a nitrogen from another molecule. D. A positive potassium ion forms a bond with a negative chloride ion. E. A nitrogen atom shares electrons with three hydrogen atoms.
Giardiasis involves
A. vector transmission. B. infection of the large intestine. C. symptoms of abdominal pain, flatulence, and diarrhea. D. a protozoan that does not form cysts. E. All of the choices are correct.