The notochord in vertebrates is replaced by which structure during embryonic development?
Answer: A
During embryonic development, the notochord is replaced by the vertebral column in adult vertebrates, though remnants persist as the nucleus pulposus of intervertebral discs.
Q.62Easy
Which characteristic is unique to members of class Aves among all vertebrates?
Answer: B
While many vertebrates have lungs, internal fertilization, and four-chambered hearts, hollow bones with air sacs are unique to birds, enabling them for flight.
Q.63Medium
Segmentation is a key characteristic that distinguishes Annelida from which other phyla?
Answer: B
While Annelida and Arthropoda both show segmentation, Mollusca lacks true segmentation. Echinodermata and Chordata also lack typical segmentation seen in Annelida.
Q.64Medium
A student observes an organism with radial symmetry, stinging cells (cnidocytes), and a gastrovascular cavity. It belongs to which phylum?
Answer: B
The presence of cnidocytes (stinging cells), radial symmetry, and gastrovascular cavity are defining characteristics of Cnidaria (corals, jellyfish, hydra).
Q.65Medium
Which of the following amphibians shows neoteny in its life cycle?
Answer: B
Axolotl (a salamander) exhibits neoteny, retaining larval characteristics (external gills) throughout its life even after sexual maturity.
Advertisement
Q.66Medium
In the evolutionary progression of vertebrates, which feature first appeared in fish and was retained in all subsequent vertebrate groups?
Answer: B
The notochord and dorsal neural tube are fundamental chordate features appearing first in fish and retained throughout vertebrate evolution.
Q.67Medium
Which reptilian adaptation specifically reduces water loss while maintaining efficient gas exchange?
Answer: D
All three adaptations—keratinized skin, shelled eggs, and scales—collectively reduce water loss in reptiles while maintaining respiration and reproduction efficiency.
Q.68Medium
A marine organism displays a water vascular system and tube feet. Based on this, identify its phylum and larval symmetry type.
Answer: C
The water vascular system and tube feet are unique to Echinodermata. Despite radial adult symmetry, echinoderms have bilateral larvae, indicating deuterostome origin.
Q.69Hard
Which of the following correctly represents the germ layer origin of the notochord in chordates?
Answer: D
The notochord arises from the chordamesoderm (axial mesoderm) derived from the primitive streak during early development.
Q.70Hard
Comparing Class Mammalia with Class Reptilia, which feature represents a derived character state exclusive to mammals?
Answer: B
While both have amniotic eggs, only mammals possess a diaphragm and mammary glands. Mammals have two occipital condyles, and are endothermic.
Q.71Medium
A researcher discovers that an organism lacks a true body cavity but possesses bilateral symmetry and specialized organ systems. Which phylum does it likely belong to?
Answer: B
Platyhelminthes (flatworms) are acoelomate with bilateral symmetry and organ systems. Cnidaria lacks bilateral symmetry; Nematoda has pseudocoel; Annelida has true coelom.
Q.72Hard
Which adaptation in birds is most directly related to their high metabolic rate and endothermic nature?
Answer: B
The unidirectional airflow system in bird lungs ensures continuous oxygen supply needed for high metabolism. Feathers insulate; hollow bones reduce weight; vision aids hunting.
Q.73Easy
In the classification of animals, which of the following represents the correct hierarchical order?
Answer: B
The correct taxonomic hierarchy is Kingdom → Phylum → Class → Order → Family → Genus → Species (KPCOFGS).
Q.74Easy
Which characteristic distinguishes members of Class Insecta from other arthropods?
Answer: B
Insects characteristically have three body regions (head, thorax, abdomen) and three pairs of legs on the thorax. Other arthropods vary in body segmentation and leg numbers.
Q.75Medium
The presence of a pseudocoelom distinguishes which phylum from true coelomate animals?
Answer: B
Nematodes (roundworms) possess a pseudocoelom, a body cavity incompletely lined by mesoderm, distinguishing them from both acoelomates (Platyhelminthes) and eucoelomates (Annelida, Mollusca).
Q.76Medium
Among vertebrate classes, which one shows the transition from aquatic to terrestrial life with specific embryonic membranes?
Answer: B
Reptilia (and subsequent classes) show the complete adaptation to terrestrial life with amnion, chorion, and allantois. Amphibia still requires water for reproduction.
Q.77Hard
A systematic study comparing dorsal nerve cord, notochord, and gill slits in different organisms would place which organism outside the Phylum Chordata?
Answer: C
Earthworms belong to Annelida and lack notochord, dorsal nerve cord, and gill slits. Lamprey, Amphioxus, and frog tadpoles possess all three chordate characteristics.
Q.78Hard
Which of the following represents the most significant evolutionary advancement in the transition from Pisces to Amphibia?
Answer: B
The evolution of paired limbs from fins (fins → limbs) allowed movement on land. While lungs evolved in fish, limbs were crucial for terrestrial locomotion in amphibians.
Q.79Medium
In comparative anatomy, the presence of homologous structures in different vertebrate classes primarily indicates:
Answer: B
Homologous structures (like limbs in vertebrates) indicate common ancestry and evolutionary relationships, supporting the concept of descent with modification.
Q.80Easy
Which of the following phyla contains organisms with a complete digestive system and segmented body?
Answer: A
Annelida is characterized by true body segmentation (metamerism) and a complete digestive system with distinct mouth and anus, unlike other options.
