Question

What is a callus in plant tissue culture?
A) Mass of parenchyma cells
B) Mass of collenchyma cells
C) Mass of smooth cells
D) None of the above

Answer 1

Hint: Plant callus (plural calluses or calli) may be a growing mass of unorganized plant parenchyma cells. The medium is supplemented with plant growth regulators, like auxin, cytokinin, and gibberellin, to initiate callus formation or somatic embryogenesis.

Complete answer:
The parenchymal cell mass in parathyroid glands from 368 autopsy cases without apparent parathyroid or renal disorder was investigated. By measuring the glandular density with a density gradient technique and therefore the glandular weight, the parenchymal to adipose cell ratio and therefore the weight of the parenchymal cell mass might be determined.
The mean parathyroid parenchymal cell weight was calculated to be 22 mg and therefore the maximal normal parenchymal cell weight 39 mg. The glandular weight was evidently hooked into the body constitution, because the fat tissue content of the glands was associated with the quantity of fat tissue within the body as an entire.
The parenchymal cell weight was much less variable. Also, the quantity of fat tissue within the parathyroid glands was positively correlated to the dimensions of glands. Thus, the quantity of fat cells within parathyroid glands seems less adequate as a histological criterion and therefore the parenchymal cell weight should be of greater value within the histological diagnosis than the load of the entire gland.
The age-and-sex-related variations of the parenchymal cell mass were slight and thus a worth of 39 mg could also be considered an appropriate upper limit of the load of this mass in parathyroid glands of adult persons.

Hence; the option (A) is the correct answer.

Note:
Calluses and corns are caused by repeated pressure or friction on a neighborhood of skin. The pressure causes the skin to die and form a tough, protective surface. A flour corn is made in the same way, except that when sweat is trapped where the corn develops, the clique softens.