Animals Homework Practice
| # | Answer |
|---|---|
| 1 | Epithelial tissue covers and protects surfaces; muscle tissue contracts to produce movement; nervous tissue transmits signals and coordinates body functions. |
| 2 | Radial symmetry means body parts are arranged around a central axis, while bilateral symmetry means the body can be divided into two mirror-image halves along one plane. |
| 3 | Animals are multicellular and heterotrophic. Other acceptable answers include cells without cell walls and the ability to move at some life stage. |
| 4 | A digestive system allows larger food particles to be broken down efficiently and provides specialized regions for digestion and absorption, supporting larger body size and more complex organization. |
| 5 | In an open circulatory system, circulatory fluid is not always confined to vessels and directly bathes organs. In a closed circulatory system, blood remains within vessels and is pumped through a continuous network. |
| 6 | Acoelomate: no body cavity between the gut and body wall. Pseudocoelomate: body cavity not fully lined by mesoderm. Coelomate: true body cavity fully lined by mesoderm. |
| 7 | Bilateral symmetry is often associated with directional movement because it provides a defined front and back end and a body plan suited for moving forward. |
| 8 | Cephalization concentrates sensory organs and nerve tissue at the head end, improving the animal’s ability to detect and respond to its environment quickly. |
| 9 | It likely belongs to the cnidarians. Stinging cells help capture prey and provide defense. |
| 10 | An exoskeleton is a hard external covering that protects the body and reduces water loss. An endoskeleton is an internal support structure that can grow with the animal and allows larger body size. |
| 11 | It most likely belongs to phylum Annelida because annelids are segmented worms and many have a closed circulatory system. |
| 12 | Insects have an external skeleton made of chitin that does not expand enough for continuous growth, so they must shed it and form a new, larger exoskeleton. |
| 13 | Fish gills have many thin, folded filaments and lamellae that provide a large surface area and short diffusion distance, allowing efficient oxygen uptake and carbon dioxide release. |
| 14 | No. Animals with backbones are vertebrates, which include fish, amphibians, reptiles, birds, and mammals. |
| 15 | Amphibians generally have a three-chambered heart, which can allow some mixing of oxygen-rich and oxygen-poor blood and is less efficient. Mammals have a four-chambered heart that fully separates oxygenated and deoxygenated blood, making circulation more efficient. |
| 16 | Blood and water flow in opposite directions across the gills, maintaining a diffusion gradient along the entire gill surface so oxygen continues to move into the blood efficiently. |
| 17 | Individuals with traits that make them harder to detect are more likely to survive and reproduce. Over generations, these camouflage traits become more common in the prey population. |
| 18 | Direct development produces offspring that resemble smaller versions of adults, such as humans. Metamorphosis involves major body changes during development, such as in butterflies or frogs. |
| 19 | Possible answers include a highly efficient respiratory surface, a closed circulatory system, or a four-chambered heart. Such features help transport oxygen efficiently to tissues and support a larger body in low-oxygen conditions. |
| 20 | It is most likely an arthropod. Arthropods have bilateral symmetry, segmented bodies, coeloms, exoskeletons, and jointed appendages. |