Veins take blood back to the heart. which gas would be most abundant in a vein that takes blood from muscle cells in the arm back to the heart?
carbon dioxide
oxygen
nitrogen
hydrogen

What is the next step in muscle contraction after the actin changes shape? (apex)

Which is not a likely outcome after extensive irrigation of dry farmland? useless, unproductive soil salinization of the soil depletion of groundwater nutrient-rich soil

In 2015, about ten percent of total u. s. energy consumption was from renewable energy sources. renewable energy plays an important role in reducing greenhouse gas emissions. when renewable energy sources are used, the demand for fossil fuels is reduced. sanjay and his family want to cut back on their use of non-renewable resources at home. they are thinking of an alternate way to heat their home without adding more greenhouse gases or pollutants to the environment. which renewable resource would not fit into their plan? a) solar power b) burning wood c) constructing a wind turbine eliminate d) generating hydroelectric power