In response to being startled, an animal involuntarily contracts a skeletal muscle, causing it to shorten. what process is described by an animal's ability to involuntarily contract a skeletal muscle without receiving a direct signal from the brain, and which type of muscle contraction occurred as a result?

The answer is reflex action. Impulse that triggers a reflex action does not pass through the brain so as to shorten the time for response. It passes through a reflex arch and this is why the muscles are contracted even without time to think of what happened. The sensory and motor neurons only arch at the spinal cord.

lysosomes contain a variety of enzymes, enabling the cell to break down various biomolecules it engulfs, including peptides, nucleic acids, carbohydrates, and lipids (lysosomal lipase). the enzymes responsible for this hydrolysis require an acidic environment for optimal activity. hope i !