If a river originates 200 meters above sea level and travels 400 kilometers to the ocean, what is the average gradient in meters per kilometer? 0.2 m/km 2 m/km 5 m/km 0.5 m/km

The oxidizing agent our bodies use to obtain energy from food is oxygen (from the air). if you breathe 15 times a minute (at rest), taking in and exhaling 0.5 l of air with each breath, what volume of air do you breathe each day? air is 21% oxygen by volume. what volume of oxygen do you breathe each day?

Apea plant that is heterozygous for the tall phenotype can produce short offspring when self pollinating. which of the following explains why this occurs? a. segregation of allels b. condominance of traits c. polygenic expression of traits d. independent assortment of alleles

Tropical rain forests support more species per unit area than any other terrestrial ecosystem. what is one way rain forests are important to the health of the biosphere?