Parasitic strains of E. coli may produce poison- ous chemicals that attack living tissue and cause
disease in humans. These chemicals are called
(1) antibodies
(2) toxins
(3) viruses
(4) antibiotics

Aflashlight battery is an example of a) potential energy b) kinetic energy c) thermal energy d) solar energy

Which of these is an example of land degradation? a. containers designed to store pollutants leak. b. fertilizers provide too many nutrients to crops. c. garbage is buried so the land can be reclaimed later. d. a drought kills all the plants in an area, leaving bare land

The current thought on the structure of the cell membrane is: a. a static phosphate sandwich of lipids b. a fluid-mosaic of phospholipids and proteins c. a bilayer of proteins with static lipid molecules d. an impermeable bilayer of protein molecules e. a static and permeable phospholipid single layer