Answer:
In an ancestral elm species, mutations gave rise to the phenotypic trait "winged-seeds". Subsequently, selection favored elm plants with winged-seeds that diverged over time to become a separate species
Explanation:
A mutation is a genetic change in the DNA sequence. In general, mutations have a negative impact on the fitness of the individual (i.e., mutations are generally deleterious) and therefore they disappear from the population. However, there are situations where mutations are beneficial and confer an adaptive advantage, thereby increasing their frequency in the population. In this case, mutations associated with the formation of winged-seeds conferred an adaptive advantage (i.e., higher seed dispersal capacity) to individuals who had this phenotypic trait, thereby these individuals had more chances to reproduce and pass their genes to the next generation. Eventually, Elm plants with winged-seeds accumulated sufficient genetic differences to prevent interbreeding, leading to the formation of a separate species.
Answer:
The correct answer is principle of superimposition.
Explanation:
According to the superimposition principle, in the undisturbed rocks, the youngest rocks are situated on the top and the oldest rocks are found in the bottom. The phenomenon takes place due to withering. The rocks get withered because of the influence of air and water.
The soil particles or the sediments get gathered at another site. The deposits of sediments get concentrated with time and result in the production of rocks. The mature rocks get surrounded by the layers of sediments with time passing by. These sediments get concentrated again to produce novel rocks. Through this procedure, the fresh young rocks get produced over the older ones.
Answer:
The correct answer is A. The larynx moves up against epiglottis when food is swallowed to prevent passage of food into it.
Explanation:
The epiglottis is a moist, cartilaginous structure that is part of the cartilaginous skeleton of the larynx. It also marks the boundary between the oropharynx and the laryngopharynx. The epiglottis obstructs the passage of the bolus at the time of swallowing preventing it from going to the respiratory system.
Larynx closure occurs when the vestibular and vocal folds approach the midline during swallowing. Occasionally, when you eat very fast, solid foods or liquids can enter the larynx.
<span>Membrane receptor proteins relay signals between the cell's internal and external environments.
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Transport proteins move molecules and ions across the membrane.</span></span>