<span>Some minerals have different hardnesses. Some minerals are harder than the streak plate and, therefore, will not leave a marking. Only those that are softer than the plate will be able to leave a streak. Those harder than a 6.5 Mohs reading will possibly scratch the plate itself.</span>
Answer alveoli and blood vessels
The respiratory bronchioles have single alveoli off their walls. ... The respiratory bronchioles lead into alveolar ducts, (which are surrounded by smooth muscle, elastin and collagen), which lead into the alveolar sacs. These have several alveoli, surrounded by blood vessels - from the pulmonary system.
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Answer:
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