Answer:
Ozone layer... pollution
Explanation:
The ozone layer is a layer in the atmosphere which provides a barrier between harmful UV rays and the Earth. However, pollution is quickly depleting the layer which in turn creates a higher risk of skin cancers and other conditions caused by harmful UV rays.
Answer:
<em>The sun or solar energy is at the start of almost every energy
</em>
<em>
chain.</em>
Explanation:
Answer: Option D. Vestigial trait
Explanation:
Vestigial traits simply involves those traits (such as organs, structurrs or behaviors) which are found or occurs in organisms or animals, that have lost all or most of their original function through evolution. These vestigial structures were organs that performed some important functions in the organism at one point in the past. In most cases, organs or traits once identified as vestigial simply had an unrecognized function.
Answer:
1. Acetylcholine binds to receptors on the motor end plate
2. Ligand-gated channels open leading to depolarization
3. End plate potential triggers an action potential
4. Transverse tubules convey action potentials into the interior of the muscle fiber
5. Calcium is released from the sarcoplasmic reticulum
6. Calcium ions bind to troponin, which then moves tropomyosin
Explanation:
Acetylcholine (ACh) is a signaling molecule (neurotransmitter) that binds to receptors on muscle cells. This binding triggers the opening of ligand-gated sodium channels, thereby ions enter into muscle cells, which causes the depolarization of the sarcolemma and thus promotes the release of Ca2+ ions from the sarcoplasmic reticulum. The myoneural junction, also known as the motor endplate, is the site of synaptic contact between a motor axon and a skeletal muscle fiber. The endplate potential is the voltage that produces the depolarization of muscle fibers when ACh molecules bind to their receptors in the cell membrane. This depolarization spreads in the sarcolemma through transverse tubules (T tubules) and thus generates an action potential. Finally, this action potential induces the release of Ca2+ in the sarcoplasmic reticulum, which activates troponin protein and induces muscle contraction.
