Correct answers to biology homework questions

Describe major characteristics shared by animals

The animal kingdom consists of various species, but they share many characteristics ranging from methods of development to reproduction. All animals are multicellular organisms whose cells do not have cell walls. The animal cells have specialized supportive tissues which provide structural support. All animals are heterotrophs meaning that they obtain their nutrients from other animals or plants. Animals have the ability to move from one place to another. Animal cells are diploid, meaning each cell has a homologous pair of chromosomes. Animals reproduce through the sexual mode of reproduction where male and female animal mate to produce offspring bearing DNA of both parents. All animals are eukaryotes with a well-defined nucleus and internal organelles.

Distinguish between invertebrate and vertebrate animals

Animals are classified into two groups; invertebrate and vertebrate animals. The invertebrate animals lack a spinal column while the vertebrate animals have a backbone or spinal column. Invertebrate animals have exoskeleton while the vertebrate animals have a well-defined skeleton and highly developed brain. About 97 percent of all species in the animal kingdom are invertebrates while 3 percent are vertebrates. The invertebrate animals have open respiratory system while vertebrates have a closed respiratory system. Invertebrates are usually small and move slower while vertebrates are large and faster-moving animals. Invertebrates have compound eyes while vertebrates do not have compound eyes. Invertebrates are made of one skin layer while vertebrates are composed of two skin layers; dermis and epidermis.

Describe how animals in Phylum Porifera feed

Phylum Porifera are considered the oldest animal group. These animals are multicellular but do not have any tissue or organs. Phylum Porifera do not have any symmetry, and their bodies are adapted to allow maximum efficiency of water flow. These animals have a unique feeding mechanism. They don’t have a mouth; instead, they have tiny poles in their outer through which water and food are drawn. The water movements in these animals are unidirectional as it directed by flagella. As the water flows in their body, they absorb the bacteria and other food particles which are present in the water.

Describe two body morphologies of the Cnidarians

Cnidarians have two distinct body plans; the Medusa and the polyp. The Medusa is an umbrella-shaped body structure with the mouth facing down. Medusa species such as planktons and jellyfish are free-swimming animals and can easily propel themselves through muscle contractions. The polyp cnidarians have a sessile, tabular body shape with the bottom attached to the basal plate and a mouth opening at the top. These animals include hydra, coral, and sea anemone.

Describe the difference between three groups of worms

There are three phyla of worms; flatworms, roundworms, and segmented worms. Flatworms are the flattened worms with true tissues and internal organs. These animals have bilateral symmetry and cephalization. They have unsegmented bodies with a mouth but no anus. They don’t have respiratory and circulation systems. They obtain nutrients and oxygen through diffusion directly in their cell bodies. Most of them live in water. The examples of flatworms include tapeworm and a marine flatworm. Roundworms are species of worms with the unsegmented body but have both mouth and anus. These worms are carnivores, but some are herbivores. They do not have respiratory or circulation system as they rely on diffusion for nutrients and oxygen absorption. They have a muscular body and move like snakes. Examples of roundworms include hookworms, lumbricoides, and heartworms. Segmented worms are types of worms with segmented bodies. Their bodies are filled with fluid, and most of them are predators with filter feeders. They have closed circulatory system and well-structures respiratory system. They also have an excretion system. The examples of segmented worms include bristle worms, earthworms, and leeches.

Describe the differences between the three groups of mollusks in Phylum Mollusca

There are three common groups of mollusks, which include cephalopods, bivalves, and gastropods. Cephalopods are shell-bearing mollusks with camouflaging abilities. These species are carnivorous and have a well-developed nervous system and closed circulatory system. They have three hearts which pump blue blood and use their muscular foot to move. Example of cephalopods is octopus and squid. Bivalves are a type of mollusks with two parts of the shell, which can open and close. These species have large valves which enable them to absorb oxygen and capture food particles from water. They have a mouth, gills, heart, stomach but not the head. They have a muscular foot which enables them to swim. Examples of bivalves are oysters, clams, and mussels. Gastropods have one shell and have foot-like bivalves for movement. They have mouth and head. They live in both terrestrial and aquatic habitats. Unlike other species, gastropods do not have the sense of hearing, but they can see and sense smell. Examples of gastropods include slugs and snails.

List example of animals in Phylum Echinodermata

Animals in Phylum Echinodermata are characterized by their calcareous endoskeleton, radial symmetry, and water vascular system. These animals include sea stars, sea urchins, sea cucumbers, starfish, Zoroaster, brittle stars, basket stars, epidermal, amphuria, Rhizocrinus, and Antedon.

List examples of arthropods in Phylum Arthropoda and their adaptation

Arthropods are invertebrate animals with an exoskeleton, jointed appendages, and segmented body. The examples of arthropods include insects (ants and flies), arachnids (spiders and scorpions), myriapods (centipedes and millipedes) and crustaceans (shrimp, crabs, and lobsters). They had different features which help them to adapt to their environments. They have hard exoskeletons to help them in extreme environments, they have bilateral symmetry which assists in movement, they are jointed legs which allow them to develop strong exoskeletons and they have segmented bodies which assist in movements.

List four shared characteristics of animals found in Phylum Chordata. Are all chordates vertebrates?

Chordates share four main traits; they have a notochord, pharyngeal slits, dorsal nerve chord, and post-anal tail. All vertebrates are chordates, but not all chordates are vertebrates. Phylum Chordata consist of three phyla; Vertebrata, Cephalaochordata, and Urochordata. The Cephalaochordata and Urochordata are invertebrate animals which show some attributes of chordates.

Define Vertebrate and which animals are vertebrates

Vertebrates are defined as the animals that have spinal column or backbone. The backbone supports the body and protects the spinal cord. The vertebrates include birds, mammals, reptiles, amphibians, and fish. These animals have unique characteristics which include spinal column, closed respiratory and circulatory system, central nervous system, and unequivocal sensory organs.

What are several adaptations of bony fish? What is the significance of lungfish in evolution?

Bony fish have a special adaptation which enables them to remain buoyant on the water. These adaptations include color vision which allows them to locate mates and predators; they have a swim bladder which help them in swimming, they have operculum which enables them to swim without breathing, and they have acoustic senses which enable them to detect predators. They have electroreceptors which produce electric field to enable them to detect prey.  Lungfish is important in the evolution timeline because it’s believed to be the actual ancestor of tetrapods.

Define Tetrapod. What does this transition represent in terms of evolution?

The term “Tetrapoda” was used in Greek to refer to four-legged animals. Tetrapod includes all land-living vertebrates such as amphibians, reptiles, and mammals. Some of the tetrapods have lost some or all four limbs their ancestors had. However, they are still tetrapods because of the ancestral background. Some tetrapods such as dinosaurs and mosasaurs have gone extinct. This transition shows how land animals evolved from a finned organism which lived in water.

List examples and characteristics of Amphibians

There are three major amphibian clades; frogs, salamanders, and worm-like caecilians. These animals share several characteristics such as unshelled eggs, carnivorous adults, permeable skin, cold-blooded, breath through the skin, and spent time in aquatic and terrestrial habitats.

List examples and characteristics of Reptiles

Reptiles are described as creeping animals. Examples of these animals include lizards, snakes, crocodiles, alligators, turtles, chameleons, and geckos. These animals share several characteristics such as cold-blooded, oviparous (egg-laying), four legs, breath through lungs, vertebrates, and have scales in their body.

List four shared characteristics among the mammals

Mammals share several characteristics which make them distinct from other animals. These traits include four-chambered heart and diaphragm, mammary glands, endothermic, and single-bone lower jaws. Examples of mammals include humans, elephants, bats, lions, dogs, cats, whales, and monkeys.





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