Zoology 10th Edition by Stephen Miller,John Harley

Exercise 11

There are three types of nonmuscular movement. Amoeboid movement, as found in amoeba, occurs as pseudopods are formed where endoplasm flows forward and changes into ectoplasm. In ciliary movement, coordinated cilia beat in a specific direction to move the organism. Flagella are larger than cilia and can also move organisms by a coordinated movement. The different types of muscular systems found in invertebrates include pedal locomotion, looping movements, a water-vascular system, walking, flight, and invertebrate jumping. Muscular movement involves muscle contraction as a result of sliding of myofilaments within muscle myofibrils. It results from myosin's cross-bridges attaching to, and interacting with, actin filaments. During muscle contraction, the process of shortening is controlled by calcium ions released from the sarcoplasmic reticulum. The calcium ions bind to troponin, making myosin-binding sites in actin available. In addition, there are three types of muscle tissue found in animals: striated, smooth, and cardiac.
The nerve gas sarin inhibits the enzyme acetylcholine-esterase, required to break down acteylcholine. Based on this information, what are the likely effects of this nerve gas on human muscle function?
A)Jawless fishes such as lamprey and hagfish have comparatively thick skin. They have many epidermal glandular cells. Along with the production of mucous slime gland, hagfishes receives protection from external parasites and other external hazards.
Hence, option a. is incorrect.
C)Scales form the modification of skin of bony fishes.
Hence, option c. is incorrect.
D)Amphibians are the transitional organism between terrestrial and aquatic vertebrates. Thus, they show characteristic features of both aquatic and terrestrial organisms.
First, amphibians were more like aquatic organisms. Therefore have scales as a modification on the dermis. Whereas More evolved, amphibians have terrestrial nature and show the production of a tough, impermeable protein called keratin.
Keratin helps from the terrestrial abrasive, rigorous environment. Many other modifications of skin are seen. They are mucous glands and poisonous gland formation, warts of toad (specialized sensory structure), etc.
Hence, option d. is incorrect.
E)The skin of reptiles can be considered under two categories, such as the skin of non-avian reptiles and skin of avian reptiles.
Non-avian reptiles have heavily keratinized outer epidermis forming scales in lizards, scutes in snakes, forming claws and plaques, etc. They lack an integumentary gland leading to highly dry epidermis.
Avian reptiles have comparatively thin and soft epidermis with no epidermal glands. Even though the preen gland, is only observed epidermal gland. Characteristics modification is the formation of feathers.
Hence, option e. is incorrect.
B)Denticles are the specialized structures seen in the skin of cartilaginous fishes. They arise from dermis leading to the loss of epidermal covering.
Often denticles mimic vertebrate teeth. They show pulp chamber-like space carrying nerves and blood vessels. Thus, the hard part of denticle simulates enamel and dentin.
Hence, the correct option is