3 a Why is it useful for crabs that live on the sea shore to have both lungs and gills.
b If equal volumes of blood go through the lungs and gills of light-blue
soldier crabs, suggest the mean percentage of oxygen that would be found in
the blood having gone through only the gills. Explain your reasoning.
c What does this tell you about how efficient both lungs and gills are in these
crabs?
d Suggest three reasons for this difference.

Which of the following are causes of coastal erosion? check all that apply. beach grasses and other plants trap windblown sand. wave action carves away the coastline. groundwater under pressure is forced to earth’s surface. artificial structures stop the natural flow of sand along the coast. underground caves collapse as bedrock is dissolved.

What percentage of light hits earth's surface directly?

Cpr, or cardiopulmonary resuscitation, is a first-aid technique to save lives. it involves compressions of the patient's chest cavity. which description is the best description of the functions of chest compressions in cpr? chest compressions are done to pump the heart. chest compressions are done to strengthen the rib bones. chest compressions increase carbon dioxide inhalation. chest compressions allow the patient's muscles to wake up.