Which gas makes
up most of the atmosphere, and is needed to build
proteins and DNA *
1 poi
Carbon
Water
Oxygen
Nitrogen
CO2
O Hydrogen

Match the examples to the correct level of organization. 1. system level roses, snakes, puppies 2. organism level roots, stamens, leaves 3. tissue level bone, cartilage, blood 4. organ level heart, veins, arteries

Which best describes a gene? a. a sister chromatid b. a chromosome c. a tetrad d. a piece of a chromosome

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