In a sealed tank is a large sprig of Elodea and a snail. The tank is kept for several weeks on a sunny window sill. Both the plant and snail live and appear to be healthy. Why does this happen? a. The snail produces oxygen, and the plant produces carbon dioxide. b. Both the snail and the plant produce oxygen. c. The snail produces carbon dioxide, while the plant produces oxygen. d. Both the snail and plant produce carbon dioxide.

The human genome project is devoted to mapping the general dna sequence of our species. this could lead to the development of new medicines, as well as the possibility of using gene therapy to treat certain diseases. however, there are some ethical issues surrounding the mapping of individual genomes. one concern is a) that your genes may change over time, making the project useless. b) that insurance companies could discriminate based on genetic make-up. c) that since this has never been done before, we should probably not do it now. d) that sequencing our individual genomes is so expensive, it is a counter-productive strategy.

Hydrilla (hydrilla verticillata) is an invasive aquatic plant and one of the most serious aquatic pests in florida. hydrilla has already been introduced to hundreds of bodies of water throughout florida, hydrilla is difficult to control because it grows rapidly and survives in many different water depths and conditions. hydrilla • describe how hydrilla affects native plant and animal species. include both a biotic and an abiotic limiting factor. • suggest one biotic and one abiotic recommendation that could slow the spread of hydrilla

Which of the following cell structures is significantly different between gram- positive and gram-negative bacteria?