Govt. Exams
Entrance Exams
In triploblastic animals: Ectoderm forms nervous system and epidermis, Mesoderm forms muscles and connective tissue, and Endoderm forms the digestive tract and associated glands.
Radial and indeterminate cleavage are characteristics of deuterostomes, which include Echinodermata and Chordata. This contrasts with the spiral cleavage of protostomes.
Amphibian skin is moist, permeable, rich in mucous glands, and participates in respiration. Unlike reptiles, it is NOT heavily keratinized, which would reduce water absorption.
Parthenogenesis allows rapid population growth in isolated or newly colonized environments where finding mates might be difficult, without requiring genetic diversity maintenance.
Birds retain scales on their legs/feet, a feature inherited from theropod dinosaur ancestors. This homologous structure provides evidence of their evolutionary relationship.
Echinoderms are enterocoelomates where the coelom develops from the wall of the archenteron (primitive gut). This is a characteristic of deuterostomes.
Echinoderms have distinct oral (mouth) and aboral (opposite of mouth) surfaces. This is related to their radial symmetry pattern.
Agnathans (lampreys, hagfish) lack paired fins and jaws, while gnathostomes possess these structures along with true jaws derived from gill arches.
Insects represent over 80% of described animal species due to their adaptability, rapid reproduction, metamorphosis, and ability to occupy diverse ecological niches.
The amnion protects the embryo in fluid, and allantois stores waste products, allowing amniotes to reproduce on land without dependence on water.
