Junior Inter Zoology Model Questions with Answers

Here are model questions from Junior Intermediate Zoology for the students from Andhra Pradesh Intermediate Board. Model questions are given for the lesson - Animal Organization. The question ans answers include very short answers.

Very Short Answer Type Questions

Q. Name three primary germ layers of a triploblastic animal. Mention the subkingdom and grade to which they belong in the system of classification.
A. Ectoderm, Endoderm, and Mesoderm. Triploblastic animals belong to subkingdom ‘Eumetazoa’ and grade ‘Bilateria’.

Q. Which symmetry is known as homaxial apolar symmetry? Give an example.
A. Spherical symmetry is also known as homaxial apolar symmetry. Examples include Heliozoans and Radiolarians of phylum Protozoa.

Q. Which symmetry is known as monaxial heteropolar symmetry? Give an example.
A. Radial symmetry is also known as monaxial heteropolar symmetry. Examples include Hydras and Jelly fishes of phylum ‘Cnidaria’.

Q. Distinguish between blastocoel and archenteron.
A. The central cavity of the blastula is called blastocoel or segmentation cavity or primary body cavity. The open cavity of the gastrula lined by endoderm is called archenteron or primary gut which opens out through blastopore.

Q. How does coelom differ from pseudocoelom?
A. Coelom is formed within mesoderm, blstocoel persists as pseudocoelom is lined by mesodermal epithelium whereas pseudocoelom
is lined by a portion of mesodermal epithelium on body wall only.

Q. What are retroperitoneal organs?
A. Some organs (e.g. Kidneys) of the vertebrates (e.g. Rabbits) that occur outside the coelom and are covered by peritoneum only
on the surface facing the coelom are called retroperitoneal organs.

Q. What is schizocoelom? Name the phylum in which schizocoelom is the principal body cavity in adults.
A. The cavity formed by the splitting of mesodermal band in the gastrula is the schizocoelom. Phylum Annelida shows it.

Q. What is enterocoelom? Name an enterocoelomate phylum.
A. The secondary body cavity of gastrula formed by enlargement and
union of archenteron pouches is enterocoelom. Phyla Echinodermata,
Hemichordata, and Chordata show it.

Q. What are polyribosomes?
A. The clusters of ribosomes connected by a strand of mRNA are called polyribosomes or polysomes.

Q. Mention two differences between rough ER and smooth ER.
A. The ER attached to ribosomes are rough ER or RER and ER without attachment with ribosomes are smooth ER or SER. RER is the site
for protein synthesis whereas SER is the site for lipid metabolism and detoxification.

Q. What are the functions of Golgi apparatus?
A. The proteins that are released from ER as transport vesicles, reach the Golgi apparatii, where they are concentrated, modified, and packaged into secretory vesicles.

Q. What do you know about microtubuleorganizing centre.
A. A dark region in the cytoplasm near the nucleus is called centriole. It is a microtubule- organizing centre and has a pair of

Q. What is transitional epithelium? What is its significance?
A. The transitional epithelium is specialized to withstand a greater
degree of stretch and is composed of four or five layer thick located in the wall of urinary bladder when it is in undistended state, and becomes into three layer thick when urinary bladder is distended with urine filled.

Q. Describe mast cells of connective tissues.
A. Mast cells produce inflammatory agents such as histamine, bradykinin, and anticoagulant called heparin.

Q. Distinguish between tendons and ligaments.
A. Tendons and ligaments are made up of dense regular connective tissue. Tendons connect the muscles to the bones, whereas ligaments connect the bones to other bones.

Q. Distinguish between osteoblasts and osteoclasts.
A. Osteoblasts synthesize organic components of the matrix, then become osteocytes that are destined to be confined in the lacunae.
Osteoclasts are involved in resorption and remodeling of bone tissue.

Q. Define Osteon.
A. The structural unit of a mature bone composed of centrally located Haversian canal, and surrounding concentric lamellae and
osteocytes containing lacunae. Also called Haversian system.

Q. What is haematocrit?
A. The volume, after centrifugation, occupied by the cellular elements of blood in relation to the total volume, is called haematocrit.

Q. What are pseudounipolar neurons?
A. Unipolar neurons are also called pseudopolar neurons. They have single cell process, after short distance, it divides into two axonal branches. Their cytons are found in the dorsal root ganglia of spinal nerves.

Q. What is myelin sheath? What is its functional significance?
A. The layers of cell membranes unite to form myelin sheath, surrounding the axons of myelinated neurons. The propagation of
action potentials on myelinated neuron is very rapid.

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