A(n)\ an space that presents the right conditions for an individual, population or species to liveit can be as big as the Atlantic Ocean for some species of fish , or as small as a pond where a species of bacteria lives 1.environment 2.biome
3.ecosystem
4.habitat

The answer would be sand and gravel

Where is the picture at

The answer to this will be from your lab notes/procedure. it would be best to ask another student who participated in the lab as we do not know what was done, what enzyme or if the temperature is celsius or fahrenheit. if i were to guess though i'd say the rate stopped due to enzyme denturing at high temperature