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.
Answer:
Reproductive isolation is the very factor that causes the development of what we call "species" according to the biological species concept. The reason cats and dogs are different species is that they can't mate, so we call them "reproductively isolated."
Answer:
Explanation:
Genes with recombination frequencies(RF) of 50 assort independently and are not genetically links together but gene that have less than 50 RF are genetically linked.
The Linked genes included
a-d 12 c-e 26
a-g 4 d-g 8
b-c 10
b-e 18
Starting the order from the most tightly linked to the least
a-g 4, genetic distance is 4cM
d-g 8 genetic distance is 8cM
b-c 10 genetic distance is 10cM
a-d 12 genetic distance is 12cM
b-e 18 genetic distance is 18cM
c-e 26 genetic distance is 26cM
<span> The right answer is </span><span> c. human activity. Phosphorus cycle takes place even without human involvement but it can still affect or cause major changes in this nutrient cycle. </span>Humans use fertilizers and raise livestock (hogs). Waste from livestock and fertilizers are high in phosphate that gets into the soil and bodies of water through drainage and run-off.