TRUE OR FALSE (each sentence) 1. t/f Macrophages and dendritic cells can both be antigen-presenting cells.

2. t/f Complement proteins are antibodies produced by skin cells.

3. t/f Dendritic cells are the histamine-producing cells of the immune system.

4. t/f Stomach acid is one of our natural defenses against bacteria in food.

5. t/f Cytokines are molecules that cut holes in bacterial membranes.

6. t/f There are different Toll-Like Receptors for bacteria and viruses.

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explanation:

plate tectonics and volcanic euptions

over time, plate tectonic processes cause continents to move to different positions on the globe.

for example, britain was near to the equator 300 million years ago, and therefore was hotter than it is today. for further details look at our climate through time poster or online map.

the movement of the plates also causes volcanoes and mountains to form and these too can contribute to a change in climate.

mountain ranges formed by plate tectonics. large mountain chains can influence the circulation of air around the globe, and consequently influence the climate.   warm air might be deflected somewhere cooler by the mountains.

just go with your heart buddy

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.