Chapter 4: Animal Kingdom

Answer: The notochord is a mesodermally derived rod-like structure that provides skeletal support. In chordates, it offers a site of attachment for muscles, promoting coordinated movement. Its evolution was crucial for the development of a central nervous system and is a defining characteristic separating chordates from non-chordates.

Answer: Reptiles have adaptations such as dry, cornified skin covered with scales to prevent water loss, lung-based respiration suited for life on land, and internal fertilization that protects embryos from desiccation in terrestrial habitats.

Answer: Fishes typically respire using gills that extract oxygen from water, while mammals use lungs to take in air from the environment. Mammalian lungs are more efficient in oxygen exchange due to alveoli which greatly increase the surface area for gas exchange.

Answer: Segmentation in annelids allows for specialization of body regions and provides a greater range of motion. Each segment can move independently, facilitating more complex locomotion and efficiency in burrowing, which is advantageous for survival.

Answer: In an open circulatory system, blood flows freely through body cavities, bathing organs directly. In a closed system, blood circulates entirely within vessels, providing more efficient transport of nutrients and gases. Closed systems are typically associated with more active and complex organisms.

Answer: Insects are highly adaptable due to their exoskeleton, small size, ability to fly, and high reproductive rates. They can exploit diverse habitats and resources, leading to their vast diversity and ecological success.

Answer: Metamerism is the segmentation of the body into repetitive sections. It allows organisms to specialize certain segments for specific functions, such as locomotion or feeding, enhancing adaptability and survival.