Answer:
False
Explanation:
Most scientists were not yet concerned about global warming. This was because the major issue during the period between 1940 and 1970 was global cooling with little or no attention on global warming.
However things started to change due to more pollution as a result of technological advances. Global warming started becoming a concern between 1970s and 1990s because of the increase in steady surface temperature.
(1) The varying number of muscle fibers that contract
<span>In most muscles, the number of muscle fibers in different motor units ranges from a few to hundreds. The nervous system can thus regulate the strength of contraction in a muscle by determining how many motor units are activated at a given instant and by selecting large or small motor unties to activate. </span>
some muscles are almost always partially contracted. In such muscles, the nervous system my alternate activation among the motor units, reducing the length of time any one set of fibers is contracted. Prolonged contraction can result in muscle fatigue due to the depletion of ATP and dissipation of ion gradients required for normal electrical signals.ing.
<span>(2) varying the rate at which muscle fibers are stimulated </span>
<span>single action potential produces a twitch lasting about 100 msec or less. If a second action potential arrives before the muscle fiber has completely relaxed, the two twitches add together, resulting in greater tension. Further summation occurs as the rate of stimulation increases. When the rate is so high that the muscle fiber cannot relax at all between stimuli, the twitches fuse into one smooth, sustained contraction called tetanus.</span>
<u>Answer:</u>
Limited resources contribute to evolutionary change in animals by increasing Intra-specific competition.
<u>Explanation:</u>
- Intra-specific competition means competition among the members of same species.
- Individual of same species have same ecological niche i.e. how an organism is related with biotic and abiotic aspect of environment.
- So they require same resources of their survival. When population of any species increases then there is high chance of intra-specific competition because of limited resources.
- Intra-specific competition also determine the population size of species. For example, competition among shark rodents.
