Which of the following statements is incorrect?
1. The tracheal mucosa consists of pseudostratified ciliated columnar epithelium.
2 .The trachealis muscle and elastic connective tissue allow for changes in the diameter of the trachea.
3. The trachea is located posterior to the esophagus and extends from the larynx to the superior border of the fifth thoracic vertebra.
4. The trachea has incomplete hyaline cartilage rings.

The trachea is located posterior to the esophagus and extends from the larynx to the superior border of the fifth thoracic vertebra.

Explanation:

This is a wrong  statement. Anatomically ,this organ of upper respiratory system is located anterior to the oesophagus.Thus it  is the oesophagus that is located posterior to the trachea.

It passes through the posterior mediastanium to branch into the left and right main bronchi.

it  bends towards it ends to the right,which results in the crossing of the left main bronchus anteriorly to the oesophagus.

It is lined by mucus gland produced by pseudo stratified columnar cells and some ciliated and non ciliated cells.

The mucus helps in warming up inhaled air and filtration of the air of dust particles.

you are certainly talking about this picture:

a: is the label of the white square, it is showing the  replication fork, formed by helicase (d) ==> so it is the site of dna separation and replication 

b: is a new dna brand that is following directly the replication fork, so it is continuous ==> built continuously from 5' to 3

c: dna polymerase cannot replicate dna on its own, it needs the of their proteins, and one of them plays the role of a clamp which fixes  the dna with the dna template and increases  the processivity of the enzyme. ==>   stops polymerase from falling off the  template.

d: is the enzyme responsible for forming the replication fork (helicase) ==> unwinds and separates dna into two strands

e: is the delayed strand, it is built  in the opposite sense of the helicase, so dna will be built in fragments ==> built  fragments from 5' to 3 joins

and finally f: is the enzyme that builds  the new dna strand (dna polymerase) ==>   adds nucleotides to make a new dna helix.

credit: gradman555p98x9p

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answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation: