Their valency is one and both belong to the third period
Answer:
When the frequency of stimulation of a muscle increases -without it having the opportunity to relax- a process called summation (addition) occurs, promoting an increase in the generation of force in the isolated skeletal muscle.
Explanation:
Summation is a phenomenon that occurs as a consequence of the arrival of successive stimuli that produce the contraction of the skeletal muscle before it achieves its partial or total relaxation, between subsequent stimuli.
<em>When the summation occurs in the muscle, the force generated on it increases its magnitude proportionally to the number of stimuli received, maintaining the muscle contraction in time</em>.
Tetany is the prolonged contraction of a muscle in an abnormal way, by the summation of stimuli received , as some bacterial toxins can produce. The summation can be temporary -when multiple stimuli reach the muscle in a determined time- or spatial, when the amount of stimuli activates a greater amount of motor units.
Learn more:
Spatial summation in a post synaptic neuron brainly.com/question/9632682
D the expansion of their territory
Answer:
The correct answer is option 3. a nucleus.
Explanation:
The first genetic material present in the early organisms were RNA which was present in the microscopic organisms back then 3.5 billion years ago which means it is normal to have RNA in such microfossils chemical analysis.
Since, the nucleus was not present in early life forms of prokaryotes like bacteria. so, it is unusual to find nucleus in the fossils of stromatolite rocks.
Thus, option III is the correct answer.
