When does facilitated diffusion occur? a) When certain large molecules are unable to move through the membrane
without the help of channel proteins
b) When one liquid has a higher osmotic pressure than the other
c) When ATP is available to assist in moving molecules
d) When there's a strong membrane potential present, with the inside of the cell
being more negative than the outside of the cell

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