Answer:
C. But see the answer under C. Apparently C is the accepted answer.
Explanation:
A. Not A.I don't think that's a problem for gulls especially on beaches.
B. Not B. Their feather do not look like they need much help in keeping their feathers attached when in flight.
C. This is not really the answer, but it is the best answer of these 4. The actual answer is that the bones are porous for better air intake which provides more oxygen and hence they are better able to fly.
D. Not D. Food has nothing to do with the problem. Birds get an adequate amount of food without their wings being porous. See the answer for C.
The Cell to Mentee
A cell is the basic unit of life of a human. The body cell contains cytoplasm in which organelles are present . There is a nucleus found in eukaryotic cell. It contains the genetic material in the form of DNA with proteins and chromosomes. Inside there is nuclear membrane. Outside the nucleus, there are many other organelles like mitochondria, ribosomes, golgi apparatus, endoplasmic reticulum, and many more.
D. Water light and CO2 are needed for the process of photosynthesis.
The right answer is <span>Refractory period.
At the moment when the action potential is emitted, the fiber being depolarized, it is impossible to depolarize it again. It is, therefore, necessary to wait until the membrane potential returns to a value below the critical threshold in order to be able to excite it again. We are thus led to distinguish two periods that characterize its excitability.
An absolute refractory period: during which any stimulation, even supraliminal, is ineffective since the fiber is already depolarized.
A relative refractory period: during which a second action potential can be omitted provided that the depolarization produced by the excitation reaches the critical threshold, which implies that it is more important since the value of the resting potential has not been restored yet.</span>