Answer:
The answer is bamboo.
Explanation:
Pandas eat 12 - 40kg of bamboo everyday
The correct answer here is "cell membrane". Generally it makes sure that nothing enters or leaves the cell, except by its highly guarded "gates", such as ion channels, that let some particles through - but they're very picky about whom to let in!
Enzymes are usually very specific as to which reactions they catalyze and the substrates that are involved in these reactions. The enzyme and the substrate possess specific complementary geometric shapes that fit exactly into one another. This is often referred to as "the lock and key" model.