1. Contraction
2. Actin
3. Tendons
4. Epidermis
5. Dermis
6. Acne
7. A nerve signal from the brain arrives at the intersection of the nerve and muscle cells and releases acetylcholine from the neuron. This triggers chemical changes in the muscle cell involving ions, including Ca2+. Calcium triggers the thick filaments, made of myosin, to attach to the thin filaments, made of actin, in the muscle cell, and the myosin pulls the actin toward the center of the muscle cell. ATP causes the release of the actin fibers, allowing the muscle to relax and the process to begin again.
For Penn Foster.
Charles Darwin made the observations which led to the theory of evolution.
The photosynthesis equation is as follows: 6CO2 + 6H20 + (energy) → C6H12O6 + 6O2 Carbon dioxide + water + energy from light produces glucose and oxygen.
The nutrients in some soils could be toxic to microorganisms/fish in those ponds or lakes.
