21. B. recessive
22. D. DD and dd
23. D. FF and ff
The independent variable is the type of food available.<span>The dependent variable is the frequency of each type of beak (or number of birds with each beak type)</span>
Answer:
Nerve cells release chemical signals into synapses between them (short distance). They also transverse their lengths with an electrical signal that can result in signal travel along a series of cells (long distance).
Explanation:
Nerve cells release neurotransmitters in the synaptic cleft which are capable of affecting nearby cells such as other nerve cells and muscle cells. Neurotransmitter molecules include, among others, serotonin, acetylcholine, dopamine, norepinephrine and histamine. Moreover, the synaptic cleft is the space that separates a neuron cell and its target cell. On the other hand, neurons transmit signals through electrical impulses. Electrical impulses travel long distances in the body carried by axons of the nerves. Thus, nerve impulses connect the brain and spinal cord and they carry signals to different parts of the body.
Answer:
mantle
Explanation:
The mantle has lava, and lava is hot. When lava gets close to water, it heats it.
