You're discussing a forensic crime scene show your roommate, who insists that fingerprints are left behind due to the sebum on our fingertips. what do you tell him?

Fingerprints are left behind due to the sweat on our fingertips as well as sebum that sticks to or fingertips from our face and hair.

Explanation:

The ridges along the finger tips contain pores connecting to sweat glands. The sweat gland which is found in greater number in hands and feet is the eccrine gland. The sweat contains water in major amount and also contains lipids. Sebaceous glands on our face and hair secrete sebum.

When we touch our face and hair sebum sticks to the fingertips and the oily residue made by sweat and sebum coats our fingers. It is the residue and not just sebum on our fingertips that leaves a fingerprint when we touch a surface.  

69 is the correct math for the amino acids

answer and explanation;

volcanic rocks are igneous rocks which form from lava, molten rock which has been thrust out of a volcano onto the surface of a rocky body such as an asteroid, planet, or dwarf planet.  

plutonic rocks are igneous rocks which form from subterranean chambers of molten rock or magma. plutonic rocks make up the base of continental crust as well as oceanic crust. their slow rate of formation causes them to be coarse grained since there is plenty of time for large crystals to form before the magma solidifies into rock.

the textural difference is that plutonic rocks are more coarse grained than volcanic rocks. plutonic rocks are coarse grained while volcanic are fine grained ; glassey or fragmental. since fine and coarse are adjectives the decision as to whether a rock is fine or coarse grained is generally made on the bases of whether or not the individual crystals can be seen in most if the rock.