in high elevation forests n Pennsylvania, ecologists have noticed a serious decline in certain tree species. Some scientists propose that increased soil acidity might be the cause. Whats the phenomenon? A. Mercury contamination B. Decreased in pH caused by climate change C. Acid rain, which is caused by SO2 from combustion mixed with atmospheric water vapor D. Ozone depletion

Fill in the blank 1. digestion occurs in the small intestine through the action of enzymes. 2. urea, excess water, and other waste materials are eliminated in a water fluid called 3. can cause infections by injecting dna or rna into hosts. 4. the human immune system produces in response to a vaccine, which later can bind to and destroy a pathogen if it invades. 5. are structures that link bone to bone at a joint 6. in the heart, blood flows from the right atrium to the right ventricle, where it is pumped to the the words i can use are: lymphocytes gliding pivot gas urine absorption dermis fulcrum lungs chemical viruses capillary vertebrae esophagus tendons antibodies synapses ligaments kidneys pathogens