Question

Which of the following is responsible for the formation of secondary medullary rays?

• A. a = spiral trachea, b = annular trachea, c = scalariform trachea, d = reticulate tracea, e = simple pitted trachea,f = bordered pitted trachea
• B. a = annular trachea, b = spiral trachea, c = reticulate trachea, d = scalariform trachea, e = simple pitted trachea, f = bordered pitted trachea
• C. a = annular trachea, b = spiral trachea, c = scalariform trachea, d = reticulate trachea, e = simple pitted trachea, f = bordered pitted trachea
• D. a = annular trachea, b = spiral trachea, c = scalariform trachea, d = simple pitted trachea, e = reticulate trachea, f = bordered pitted trachea

Answer 1

The correct option is B

a = annular trachea, b = spiral trachea, c = reticulate trachea, d = scalariform trachea, e = simple pitted trachea, f = bordered pitted trachea

During the secondary growth, the secondary xylem grows outwards and crushes the secondary phloem. However, the cambium forms a band of parenchyma cells that grows through the secondary xylem and secondary phloem and forms the secondary medullary rays.