Amuscle fiber 1 pt a muscle cell a rod-like structure consisting of sarcomeres placed end to end an arrangement of actin and myosin filaments deep within a muscle cell the elaborate arrangement of smooth endoplasmic reticulum inside a muscle cell

The correct answer to the question: A muscle fiber is:, would be: A rod-like structure consisting of sarcomeres placed end to end.

Explanation:

Muscle fibers are the units that form that organ system that we call the musculoskeletical system. Their purposes are various, but maybe the central one is movement. There are different types of muscle in the body, but essentially their structure is the same. Muscle is formed by sarcomeres, better known as muscle cells, and these sarcomeres, each one, is composed of myofribils known as actin and myosin. Together with other elemental structures, actin and myosin are responsible for the capacity of muscle fibers to perform activity and movement. Sarcomeres in muscle are not separated, individualized units, but rather they are a tightly packed group that comes together within muscle fibers. These muscle fibers then are really rows of sarcomeres grouped  together in a rod-like structure that is surrounded and divided from other such fibers by connective and protective layers called fascicles. A muscle, then, is formed by the clustering, or grouping, of several muscle fibers.

Explanation:

Muscle fibers can be categorized into 3 types:

Cardiac muscle cells: Cardiac muscle cells or cardiomyocytes are the muscle cells (myocytes) that make up the cardiac muscle (heart muscle).

Skeletal muscle cells: An individual skeletal muscle may be made up of hundreds, or even thousands, of muscle fibers bundled together and wrapped in a connective tissue covering. Many muscles are named by the action the muscle performs. These include:

Smooth muscle cells: Also called involuntary muscle and non-striated    muscle, it  shows no cross stripes under microscopic magnification. It consists of narrow spindle-shaped cells with a single, centrally located nucleus. Smooth muscle tissue, unlike striated muscle, contracts slowly and automatically. It constitutes much of the musculature of internal organs and the digestive system.

step 1 ammonium can be absorbed by plants, but some is converted into nitrates which are better for plants to absorb. this is called nitrification. 2. step 2 the deer eats the plants and uses the nitrogen-containing proteins for cell growth. 3. step 3 bacteria in the soil conduct nitrogen fixation to convert nitrogen gas from the atmosphere into ammonium. 4. step 4 some of the nitrates are absorbed back into plants, but denitrification breaks down the nitrates into nitrogen gas released back into the atmosphere. 5. step 5 nitrogen is found in the urine, which gets broken down into ammonium through the process of ammonification. 6. step 6 plants absorb the ammonium and begin assimilation, the process to add the nitrogen to protein.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products