Smoking cigarettes causes lung cancer because A. nicotine destroys the membranes of alveoli, the microscopic air sacs. The alveoli expand, and the person cannot completely exhale. B. nicotine is deposited as black, sticky tar in respiratory passages. C. nicotinic receptors in the lungs bind carcinogens in cigarette smoke. D. nicotine binds the A1 allele of the dopamine D(2) receptor. E. nicotine accelerates the cell cycle of lung cells.

Study this image. which statements best describe the rock shown? check all that apply. the grains of this rock are jagged. this rock has several coarse grains. the grains in this rock are very large. this rock has a non-banded pattern. the color of this rock is determined by its texture.

Complete the sentences by matching the names of trees to the appropriate blanks. to do this, drag the names on the left into the appropriate blanks in the sentences on the right. match the words in the left column to the appropriate blanks in the sentences on the right. terms may be used more than once. make certain you have filled every blank with a term before clicking submit. 1. deciduous trees lose their leaves seasonally and include trees such as maple and elm. 2. conifer leaves are generally thin and needle-like, while seeds are contained in cones. conifers include cedar and pine. 3. evergreens are plants that maintain their leaves in all seasons and include trees such as cedar, elm, and pine. 4. hardwoods reproduce using flowers and have broad leaves; hardwoods include trees such as maple, , and cedar. elm returned you filled in 2 of 10 blanks incorrectly. mango trees are tropical broad leaf plants that maintain their leaves all year long. no credit lost. try again.

What best explains the inability for life to exist in earth early atmosphere