Leaves are green because of chlorophyll. Chlorophyll is a pigment found in the thylakoid membranes of the chloroplasts in the leaves.
Simply, plants are green because they have green chloroplasts (organelles that carry out photosynthesis).
Axons with large diameters conduct impulse faster than those with small diameters. Also Myelinated axons conduct impulse faster than unmyelinated axons. Axons with the largest diameter are all myelinated, therefore they are capable of salatory conduction (Impulses jump from one myelinated node to another). The smallest diameter axons are unmyelinated, so their conduction is continuous.
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Seed dormancy allows for a seed to germinate only when the conditions are right to support the germination and growth of the plant. This adaptation, therefore, increases the chances of survival for the plant. Natural selection, which powers evolution, will always favor desirable traits which will be entrenched in a population through successive generations.
Answer:
A. Layer of soil that always stays frozen
