20. In single-gene traits, natural selection can lead to which of the following? A. Directional selection B. Founder effect C. Disruptive selection D. Allele frequency change

What was the original purpose of this research study

Discuss how to recognize the predator and the prey in a predation relationship

What causes cold, deep currents to form in the oceans near the poles?

2) Garrod hypothesized that "inborn errors of metabolism" such as alkaptonuria occur because A) metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies.

A biologist is studying a structure that is made up of two layers of phospholipids. What is she most likely studying?

What is the difference between a meteor and a meteorite? A meteor has more mass A meteorite reaches Earth and has not burned up A meteorite orbits the sun and a meteor does not A meteorite glows

Which of these was NOT characteristic of the first cells on Earth? A) anaerobic B) prokaryotic C) single-celled D) contained organelles

Which process occurs only in autotrophic organisms?

Nylon fiber is classified under which one of these headings? A. Protein B. Polyurethane C. Polyester D. Polyamide

What factors influence the growth of organisms and their ability to reproduce?