What is a cross-bridge?
a. a protein found along the groove of the F-actin double helix
b. a T tubule and two adjacent terminal cisternae
c. the combination of myosin heads with active sites on actin molecules
d. the movement of myosin head while attached to actin myofilament
e. after exercise, the oxygen taken in that exceeds the oxygen required for resting metabolism

The correct answer is - option C.

Explanation:

Cross bridge is a structure that is globular made up of the actin filaments and activated myosin attachments. The head of the myosin binds to the binding site that is present on the actin filaments that are exposed to the actin molecules.

Due to this structure, the movement in muscle occurs as they contract while attaching temporarily to the actin filament that is present near and exposed.

Thus, the correct answer is - option C.

a neutral ph of 7 and normal organism temperature is needed for a certain enzyme to be effective.  

what would happen to the enzyme if the ph and/or temperature fluctuate greatly from the norm?  

a.the enzyme’s hydrogen bonds will break.  

b.the activation energy will increase.  

c.more product will be formed.

d.the ideal temperature and ph for the enzyme function will decrease.  

explanation:

yes you are doing it right great gob