Zoology MCQs for NEET — Practice Questions with Answers

The body cavity (coelom) of earthworm is filled with an alkaline, colourless or milky coelomic fluid containing water, salts, some proteins and four types of coelomic corpuscles, i.e., phagocytes, mucocytes, circular nucleated cells and chloragogen cells. The coelomic fluid becomes turgid and acts as a hydraulic skeleton during burrowing.

Earthworm (Pheretima posthuma) living in burrows which are made in moist earth. It makes its burrow partly by boring with its points anterior end and partly by sucking and swallowing the earth. The body shows metameric segmentation. About the middle of each segment there is a ring of tiny curved bristles called setae or chaetae, formed of a horny nitrogenous organic substance known as chitin. The setae and musculature serve for locomotion as well as for anchoring body firmly in burrow.

The blood of earthworm is composed of a fluid plasma and colourless corpuscles, physiologically comparable to the leucocytes of vertebrates.

The respiratory system of cockroach consists of tracheae, tracheoles and spiracles. The main tracheal trunks open to exterior on body surface through 10 pairs of segmentally arranged spiracles. Two pair of spiracles are thoracic (one between pro and mesothorax and other between meso and meta thorax). Eight pairs of spiracle are abdominal (one pair in each of the first eight abdominal segments).

Alimentary canal of earthworm is complete and functionally regioned into buccal chamber, pharynx, oesophagus, gizzard, stomach and intestine.

Frog's body has two main pans, ie, head and trunk. Absence of neck and tail provide convenience in both hopping and swimming.

In annelids like Nereis, earthworm, leech etc the tubular coiled structures called nephridia are excretory organs. In phylum-Arthropoda, insects, centipedes, millipedes and arachnides possess Malpighian tubules as their principal excretory organ.

Analogous organs have almost similar appearance and perform the same function but develop in totally different groups and are developmental origin, eg, wings of butterfly, birds, bats.

The homologous organs have common origin, perform varied functions and have different appearance, eg, thorns of Bougainvillea and tendrils of Cucurbita.

Vestigial organs are useless remnants, which might have been lagre and functional in the ancestors, eg, nictitating membrane, venmiform appendix, etc. 

Specialized cell junctions occur at many points of cell-cell and cell matrix contact in all tissues, but they are particularly important and plentiful in epithelium.

Class Oligochaeta  includes terrestrial earthworms and some other species that live in fresh water. Aquatic oligochaetes excrete ammonia while terrestrial oligochaetes excrete urea but Lumbricus produces both ammonia and urea.

Desmosomes are intercellualr cell junctions that are often narrow gaps between adjacent cells in animal tissues. In these regions, circular patches of cell membrane are held together by interaction of proteins that exten thorugh each mebrane into the space between the cells. The cell membrane has on the inner side a dense plate of protein and bears fine filaments called tonofibrils, radiating into the cell. Desmosomes act as "sport welds" and keep the cells firmly together. They occur between epithelial cells. 

The tadpole excretes ammonia, but the adult frog shifts to urea excretion. Amphibians actively transport ions in through the skin. Tadpole liver usually does not have high levels of the urea cycle enzymes and the levels do not increase until metamorphosis.

Cuboidal epithelium consists of cuboidal cells which are tall and wide with centrally placed nucleus (polygonal in outline). It lines the respiratory bronchioles, sweat glands, salivary glands and thyroid follicles. (secretory in nature). The cells of cuboidal epithelium often forms microvilli on their free surfaces which gives a brush like appearance, hence called brush bordered cuboidal epithelium (e.g., proximal part of uriniferous tubules). It also lines pancreatic duct (non-secretory), testis (seminiferous tubules) and ovary. In ovaries and testis it is called germinal epithelium because these cuboidal cells are capagble of producing gametes (ova and sperms respectively). Cuboidal cells also have cilia which occurs in certain parts of nephrons of the kidney. Hence called ciliatged cuboidal epithelium.

Ciliated columnar epithelium lines the Fallopian tube.

Factual

Ciliated epithelium is a region of epithelium consisting of columnar or cuboidal cells bearing hair like appendages called cillia, that are capable of beating rapidly. Ciliated epithelium performs the functions of moving particles of fluids over the epithelial surface. Cuboidal ciliated epithelium occurs in certain parts of uriniferous tubules whereas columnar ciliated epithelium occurs in fallopian tubules, nasal passages, bronchioles, small bronchi and buccopharyngeal cavity of frog. It often occurs in the vicinity of mucus secreting goblet cells. 

Squamous epithelium are found in lining of alveoli in the lungs and Bowman's capsule in the kidney. Columnar epitjelium are found in the lining layer of gastrointestinal tract, gall bladder, uterus etc. and cubical or cuboidal epithelium lines the salivary ducts, pancreated ducts, gastric glands, thyroid follicles, germinal epithelium of ovary, proximal part of uriniferous tubules etc.