Why do scientist prefer to use food webs over food chains

Suggest why placing wheels under a heavy box reduces the neccessary force required to push it along at a constant speed.

Which set of characteristics best describes sedimentary rock? a) largest type of rock, made of organic matter, hardest type of rock b) often contains layers, forms near sources of water, contains fossils c) least abundant type of rock, made of other rocks, made mostly of minerals d) most abundant type in earth's crust, made of magma/lava, contains no fossils

Hemoglobin is a proton that carries oxygen around your body what is hemoglobin made from