IGCSE Biology Paper-2: Specimen Questions with Answers 153 - 153 of 203

Question 153




Johan caught a fish.

He was curious that what are the characteristics of a fish?


√ Present

× Absent


Choice (4)
a.Scales-√, External ears-×, constant body temperature-√, Gills- ×
b.Scales-×, External ears-×, constant body temperature-×, Gills- ×
c.Scales-√, External ears-√, constant body temperature-×, Gills-√
d.Scales-√, External ears-×, constant body temperature-×, Gills-√




Features of Fishes

  • Includes jawed fishes
  • Aquatic, mostly marine
  • Poikilothermic or cold blooded
  • Locomotion by fins
  • Fins of 2- types paired and unpaired. Paired or lateral fi ns include Pectoral and Pelvic fins, and unpaired or median fi ns include dorsal fin, caudal fin, ventral fin, and anal fin etc.
  • Exoskeleton of Ecto-mesodermal scales
  • Respiration by gills (5 - 7 pairs)
  • Excretion by mesonephros or opisthonephros kidney
  • Blood vascular system – closed type, with single circulation.
  • Heart 2- chambered with deoxygenated blood only (Venous heart).
  • Cranial nerves 10- pairs. Only internal ear present (for balancing only). Eye lids absent.
  • Internal nostrils absent except in lung –fishes.
  • Lateral line organ having neuromast cells present for detecting water vibrations (Rheoreceptor) Skull monocondylic (one occipital condyle in cranium).
  • Centrum (of vertebrae) Amphicoelous.
  • Ribs present.
  • Jaw suspensorium – Hyostylic (lower jaw articulates with Hyomandibular bone of upper jaw. )