Final answer:
Without calcium ions, a muscle fiber cannot undergo typical contractions, but some muscle tone may be maintained through latch bridges in smooth muscle.
Step-by-step explanation:
If all of the calcium within a muscle fiber was removed but ATP was still present, the muscle fiber would not be able to undergo a typical contraction because calcium ions (Ca2+) are crucial for muscle contraction.
Calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from the actin-binding sites, which allows myosin heads to bind to actin and carry out the power stroke. However, some level of muscle tone might be maintained due to the presence of latch bridges in smooth muscle, which can keep the thick and thin filaments linked together for a prolonged period without the need for ATP or calcium.