Part 5 — Chordates: Protochordates & Pisces (Q.101–125)

Part 5 — Chordates: Protochordates & Pisces (Q.101–125)

Q101. Which of the following is NOT a chordate characteristic at some life stage?

A) Notochord
B) Dorsal hollow nerve cord
C) Pharyngeal slits (gill slits)
D) Jointed limbs with exoskeleton
Answer: D
Explanation:
A/B/C) Fundamental chordate features present in embryo or adult.
D) Jointed appendages are arthropod features, not chordate diagnostic.

Q102. Urochordata (Tunicates) in adult form:

A) Retain all chordate features and are free-swimming
B) Are sessile filter-feeders; adult tunicates usually lose notochord and tail but larval tadpole stage shows chordate features
C) Are terrestrial
D) Are arthropods
Answer: B
Explanation:
A) Larval tunicate shows chordate features; adult often sessile and reduced.
B) Correct.
C/D) Incorrect.

Q103. Cephalochordata (e.g., Branchiostoma) show which of the following?

A) Notochord persists throughout life extending into head; small fish-like filters, lack distinct heart, segmented muscles (myotomes)
B) Have exoskeleton
C) Are free-floating planktonic only
D) Are vertebrates
Answer: A
Explanation:
B/C/D) False.
A) Correct — amphioxus (Branchiostoma) retains chordate features into adulthood.

Q104. Which of the following is true for vertebrates?

A) Lack vertebral column always
B) Possess cranium and usually vertebral column protecting dorsal nerve cord
C) Are acoelomates
D) Do not possess neural crest cells
Answer: B
Explanation:
A) False — vertebrates usually have vertebrae.
B) Correct — defining features include cranium and vertebral column.
C/D) False.

Q105. Which class of chordates are jawless fishes?

A) Agnatha (e.g., lampreys and hagfishes)
B) Chondrichthyes
C) Osteichthyes
D) Amphibia
Answer: A
Explanation:
B) Cartilaginous fishes with jaws.
C) Bony fishes with jaws.
D) Amphibians terrestrial/aquatic.
A) Correct — Agnatha lack jaws.

Q106. Chondrichthyes (sharks, rays) are characterized by:

A) Bony skeleton only
B) Cartilaginous skeleton, placoid scales, and often internal fertilization with claspers in males
C) Habitat only freshwater
D) Presence of swim bladder
Answer: B
Explanation:
A) False.
B) Correct — cartilage skeleton and placoid dermal denticles.
C) Many are marine; some freshwater.
D) Swim bladder is in most bony fishes, not chondrichthyans.

Q107. Osteichthyes (bony fishes) are divided into:

A) Only cartilaginous fishes
B) Actinopterygii (ray-finned) and Sarcopterygii (lobe-finned) — bony endoskeleton and operculum in many, possess swim bladder in many species
C) Birds and mammals
D) Amphibians
Answer: B
Explanation:
B) Correct — two major classes of bony fishes.
A/C/D) Incorrect.

Q108. The lateral line system in fishes helps to:

A) Detect light intensity only
B) Sense water movements and vibrations around the fish (mechanoreception)
C) Filter feeding exclusively
D) Respire underwater
Answer: B
Explanation:
A/C/D) Not true.
B) Correct — lateral line detects pressure changes and water flow.

Q109. In fishes, gill lamellae maximize:

A) Surface area for efficient gas exchange in water via counter-current exchange mechanism
B) Protection from predators only
C) Digestion
D) Excretion of solid wastes
Answer: A
Explanation:
B–D) Not accurate.
A) Correct — lamellae provide huge surface area for respiration.

Q110. Swim bladder function in most bony fishes is to:

A) Aid in buoyancy and sometimes respiration (physostomous/physoclistous variations)
B) Digest food
C) Store gametes
D) Pump blood
Answer: A
Explanation:
B–D) Incorrect.
A) Correct — swim bladder controls buoyancy; in some fishes aids aerial respiration.

Q111. Which fish group gives birth to live young (viviparous) in some members?

A) Some Chondrichthyes (e.g., some sharks) and some teleosts are viviparous; many fishes are oviparous
B) All Osteichthyes only lay eggs
C) No fishes are viviparous
D) Only amphibians give live birth
Answer: A
Explanation:
B/C/D) Incorrect generalizations.
A) Correct — viviparity occurs in various fish groups.

Q112. Lampreys are parasites on other fishes. They belong to class:

A) Osteichthyes
B) Agnatha (jawless fishes) with sucking oral disc and keratinized teeth for attachment and feeding
C) Chondrichthyes
D) Amphibia
Answer: B
Explanation:
A/C/D) Incorrect.
B) Correct — lampreys are jawless ectoparasites.

Q113. The transition of vertebrates from water to land first occurred in which group?

A) Reptiles
B) Amphibians — evolved from lobe-finned fishes (Sarcopterygii) and represent first tetrapods able to exploit terrestrial habitats though still tied to water for reproduction
C) Birds
D) Mammals
Answer: B
Explanation:
A/C/D) Later groups.
B) Correct — amphibians are first terrestrial vertebrates evolved from fish ancestors.

Q114. Gill arches in fishes have been modified in terrestrial vertebrates to form:

A) Teeth only
B) Jaws and structures like the inner ear bones in mammals — evolutionary modification of gill arches contributed to jaw, hyoid and middle ear elements
C) Wings
D) Scales
Answer: B
Explanation:
A/C/D) Not comprehensive.
B) Correct — gill arch derivatives gave rise to various cranial structures.

Q115. Which of the following is a lobe-finned fish with significance in tetrapod evolution?

A) Perch
B) Coelacanth (Latimeria) and lungfishes (Dipnoi) — sarcopterygians related to tetrapod ancestors
C) Shark
D) Salmon
Answer: B
Explanation:
A/C/D) Ray-finned fishes or cartilaginous; not direct tetrapod ancestors.
B) Correct.

Q116. Which fish class has placoid scales?

A) Osteichthyes
B) Chondrichthyes (sharks and rays have placoid dermal denticles)
C) Amphibia
D) Reptilia
Answer: B
Explanation:
A/C/D) Not placoid.
B) Correct.

Q117. The operculum in bony fishes covers:

A) Digestive tract
B) Gills; operculum protects gills and helps ventilate them in many bony fishes
C) Heart only
D) Swim bladder
Answer: B
Explanation:
A/C/D) Incorrect.
B) Correct.

Q118. Which of the following is NOT a function of the swim bladder?

A) Buoyancy control
B) Sound production or reception in some fishes
C) Respiration in some species (air-breathing)
D) Photosynthesis
Answer: D
Explanation:
A/B/C) True functions.
D) Impossible — swim bladder not photosynthetic.

Q119. Which structures in fishes are homologous with the tetrapod lung?

A) Gill filaments
B) Swim bladder in many bony fishes and lungs in lungfishes are homologous structures evolutionarily related to respiratory sacs
C) Fins
D) Scales
Answer: B
Explanation:
A/C/D) Not correct.
B) Correct — swim bladder/lungs share evolutionary origin.

Q120. Which of the following statements about fish reproduction is correct?

A) All fishes are viviparous
B) Fishes show a wide variety: oviparity (most), ovoviviparity, viviparity; external fertilization common in many teleosts
C) No fish lays eggs
D) All fish engage parental care equally
Answer: B
Explanation:
A/C/D) Overgeneralizations.
B) Correct — reproductive strategies vary widely across fishes.

Q121. Scales of bony fishes are derived from:

A) Placoids from dermal denticles
B) Dermal bone and epidermal contribution; ganoid/cycloid/ctenoid scales vary in composition (ganoid enamel-like ganoine in gar)
C) Keratin only
D) Chitin
Answer: B
Explanation:
A) Placoid scales are in sharks (chondrichthyes).
B) Correct — bony fish scales are dermal in origin with various types.
C/D) Not major constituents.

Q122. The basic structural unit of vertebrate pharyngeal slits was originally used for:

A) Respiration and filter-feeding in early chordates (gill slits)
B) Reproduction only
C) Locomotion only
D) Excretion only
Answer: A
Explanation:
B–D) Not accurate.
A) Correct — pharyngeal slits are ancestral for respiration/filter-feeding and later modified.

Q123. Which of the following is true for lampreys and hagfishes?

A) They have jaws and paired fins
B) They are jawless vertebrates with eel-like bodies; hagfishes lack vertebrae but are often placed in Agnatha; lampreys have rudimentary vertebral elements
C) Both are amphibians
D) Both are mammals
Answer: B
Explanation:
A/C/D) Incorrect.
B) Correct.

Q124. Lateral line canals in fishes are derived from:

A) Endoderm only
B) Placodes of ectoderm forming neuromasts as mechanoreceptor organs
C) Mesoderm exclusively
D) Neural crest only
Answer: B
Explanation:
A/C/D) Not correct.
B) Correct — neuromasts originate embryologically from ectodermal placodes.

Q125. The transition to terrestrial life required which of the following adaptations in vertebrate ancestors?

A) Development of limbs capable of supporting body weight, lungs for aerial respiration, cutaneous modifications to reduce desiccation, and internal fertilization in many terrestrials
B) Retention of gills and aquatic eggs only
C) Loss of limbs entirely
D) Photosynthetic ability
Answer: A
Explanation:
B/C/D) Not adaptations facilitating terrestrial colonization.
A) Correct — key morphological and physiological adaptations. (more…)