Practice MCQ Questions and answers on Biology-GK

Two species occupying same or overlapping geographical areas are called as sympatric species. The species occupying distinct geographical areas are called as allopatric species.

A pond or lake ecosystem includes biotic (living) plants, animals and micro-organisms, as well as abiotic (nonliving) physical and chemical interactions. Pond and lake ecosystems are a prime example of lentic ecosystems. Lentic refers to stationary or relatively still water, from the Latin lentus, which means sluggish.

The venom of elapids, including sea snakes, kraits, cobras, king cobra, mambas, and many Australian species, contains toxins which attack the nervous system, causing neurotoxicity. The person may present with strange disturbances to their vision, including blurriness.

Calcitonin is a hormone that is produced in humans by the parafollicular cells (commonly known as C-cells) of the thyroid gland. Calcitonin is involved in helping to regulate levels of calcium and phosphate in the blood, opposing the action of parathyroid hormone.

The pituitary gland, which hangs by a thin stalk from the hypothalamus, is called the master gland of the body because it regulates the activity of the endocrine glands.

When the pituitary gland produces excess growth hormones the result is excessive growth, called acromegaly. The excessive growth occurs first in the hands and feet, as soft tissue begins to swell.

Gastrine is not a gland.

Oxytocin is produced in the hypothalamus and is secreted into the bloodstream by the posterior pituitary gland. Secretion depends on electrical activity of neurons in the hypothalamus – it is released into the blood when these cells are excited.

Enlargment of thyroid gland takes place due to deficiency of iodine.

Endocrine glands are the ductless glands that secrete their products into bloodstream from where they are carried to the target organs. Pancreas, testes and thymus are endocrine glands as they secrete hormones. Pancreas secrete insulin and glucagon, testes secrete testosterone and thymus secrete thymosin hormone. Liver is not an endocrine gland instead, it is a digestive organ which secretes bile juice which is necessary for emulsification of fats.