Select the Taxon mentioned that represents both marine and fresh water species: 
Members of Ctenophora, Cephalochordata and Echinodermata are exclusively marine.
Which one of the following living organisms completely lacks a cell wall? 
Gorgonia (sea-fan) is an animal. All animals lack cell wall.
Planaria possesses high capacity of: 
Planaria is a flatworm which possesses a high power of regeneration.
A marine cartilaginous fish that can produce electric current is: 
Torpedo is a sluggish fish. It is carnivorous. The prey is first killed by electric shock. The shock can also be harmful for human beings.
Which of the following animals is not viviparous? [2015 RS]
Platypus is oviparous (egg laying animal). It belongs to class-mammalia.
Which of the following represents the correct combination without any exception?
(i) Aves possess dry skin, without glands except oil gland near the base of tail.
(ii) Pinnae are not found in aquatic animals and egg laying mammals.
(iii) In cyclostomes, unpaired appendages (joints) are found.
A jawless fish, which lays eggs in fresh water and whose ammocoetes larvae after metamorphosis return to the ocean is: [2015 RS]
Petromyzon (Lamprey) belongs to the Class- Cyclostomata of Phylum-Chordata. It is a jawless fish which lays eggs in fresh water. The eggs hatch in about 3 weeks into minute transparent larvae called ammocoetes. After metamorphosis, the young lampreys swim down to the sea where they remain for 3 or 4 years before reaching maturity, when they once again migrate to streams or rivers to spawn and die. Gonads become mature at that time when adults return to rivers for spawning.
Body having meshwork of cell, internal cavities lined with food filtering flagellated cells and indirect development are the characteristics of phylum. [2015 RS]
Phylum Porifera (the sponges) has cellular level of body organisation, with inner cellular layer consisting of highly specialised flagellated cells called choanocytes (or collar cells). The development in this phylum is indirect as it includes a free swimming larva called amphiblastula or parenchymula for dispersal of the species.
Which of the following features is not present in the phylum-Arthropoda?
Parapodia are present in aquatic annelids like Nereis, which help them in swimming. Other three features, i.e. metameric segmentation, jointed appendages and chitinous exoskeleton are present in phylum-Arthropoda. Out of these metameric segmentation is visible as tagmetisation.
Which of the following characteristic feature always holds true for the corresponding group of animals? 
Chondrichthyes always have cartilaginous endoskeleton. Most mammals are viviparous, giving birth to live young. However, the five species of monotreme, the platypuses and the echidnas, lay eggs. Chordates have jawless animals (Agnatha) as well. Most reptiles have 3 chambered heart. Crocodilians have 4 chambered hearts. Turtles have 3 chambered heart but with an incomplete wall in the single ventricle, so their hearts are functionally 4 chambered.
Which one of the following characteristics is not shared by birds and mammals ? 
Giving birth to living young that develop within the mother's body rather than hatching from eggs. All mammals except the monotremes are viviparous.