All animals are heterotrophs that obtain their energy and carbon by consuming other organisms.
Correct Answer
True
True. Animals cannot make their own food, unlike most plants, so they must eat other organisms or their products. Animals are also multicellular eukaryotes, and most are motile at some stage of life.
Category: Body Plans and Phylogeny
Question 2
Sea anemones have bilateral symmetry, with a distinct left and right side.
Correct Answer
False
False. Sea anemones have radial (more precisely biradial) symmetry arranged around a central oral-aboral axis, with no distinct left and right side. Bilateral symmetry, with a single plane dividing left and right halves, is seen in animals such as worms, insects and vertebrates.
Category: Body Plans and Phylogeny
Question 3
Bilaterally symmetrical animals have distinct anterior and posterior ends as well as dorsal and ventral sides.
Correct Answer
True
True. A bilateral animal has a head end and a tail end, and a back and a belly side, with one plane dividing it into left and right mirror images. This body plan suits animals that move forward through their environment.
Category: Body Plans and Phylogeny
Question 4
Earthworms, insects and vertebrates all have a true coelom that forms entirely within the mesoderm.
Correct Answer
True
True. These animals are eucoelomates, with a fluid-filled body cavity lined by tissue derived from mesoderm. The coelom cushions organs and gives them room to grow and move.
Category: Body Plans and Phylogeny
Question 5
Sponges are classified among the Eumetazoa because they have specialized true tissues.
Correct Answer
False
False. Sponges belong to the Parazoa, the animals without true tissues. Eumetazoa, which includes cnidarians and all bilateral animals, is defined by having specialized tissues.
Category: Sponges and Cnidarians
Question 6
Adult sponges are sessile, while their larvae are free-swimming.
Correct Answer
True
True. Adult sponges stay attached to one spot and filter water through their bodies. Their larvae swim freely before settling to grow into adults.
Category: Sponges and Cnidarians
Question 7
The gastrovascular cavity of a cnidarian has separate openings for taking in food and for expelling waste.
Correct Answer
False
False. The cnidarian gastrovascular cavity has a single opening that serves as both mouth and anus, so the digestive system is incomplete. Digestion starts outside cells with secreted enzymes and finishes inside cells.
Category: Sponges and Cnidarians
Question 8
Cnidarians have a nerve net rather than a centralized brain.
Correct Answer
True
True. Cnidarian nerve cells form a diffuse net spread through the body. Cnidarians have true tissues but no organs or organ systems.
Category: Sponges and Cnidarians
Question 9
Nematodes have a complete digestive system with both a mouth and an anus.
Correct Answer
True
True. Roundworms have a one-way digestive tract running from a distinct mouth to an anus. Flatworms, by contrast, have a gut with only one opening.
Category: Worms and Arthropods
Question 10
Arthropods have a closed circulatory system in which blood stays inside vessels at all times.
Correct Answer
False
False. Arthropods have an open circulatory system: a heart pumps blood into the hemocoel, a body cavity where the blood bathes the organs directly.
Category: Worms and Arthropods
Question 11
In insects, the legs and wings are attached to the abdomen.
Correct Answer
False
False. An insect's three pairs of legs and its wings are attached to the thorax, the middle of its three body regions. The abdomen holds most of the digestive and reproductive organs.
Category: Worms and Arthropods
Question 12
Clams and other bivalves scrape their food from surfaces using a well-developed radula.
Correct Answer
False
False. Bivalves lack a radula and are filter feeders that strain food from water passing over their gills. A radula is present in other mollusks such as snails.
Category: Mollusks and Annelids
Question 13
Earthworms have a closed circulatory system with dorsal and ventral blood vessels and muscular pumping hearts.
Correct Answer
True
True. Annelids keep their blood inside vessels: dorsal and ventral vessels run the length of the body, pumping hearts sit in the front segments, and capillaries serve the tissues.
Category: Mollusks and Annelids
Question 14
Echinoderm larvae are radially symmetrical, while the adults are bilaterally symmetrical.
Correct Answer
False
False. It is the reverse: echinoderm larvae are bilaterally symmetrical, and the adults develop pentaradial, or five-part radial, symmetry.
Category: Echinoderms and Chordates
Question 15
Echinoderms have an endoskeleton made of calcareous plates called ossicles.
Correct Answer
True
True. The internal skeleton of a sea star or sea urchin is built of calcium-containing plates called ossicles, secreted by cells beneath the outer skin.
Category: Echinoderms and Chordates
Question 16
In adult vertebrates, the notochord remains the main skeletal support of the body.
Correct Answer
False
False. In vertebrates the notochord appears in the embryo and is replaced by the vertebral column during development. Some invertebrate chordates, such as lancelets, keep a notochord as adults.
Category: Echinoderms and Chordates
Question 17
Adult lancelets retain all four chordate characteristics.
Correct Answer
True
True. Lancelets keep a notochord, a dorsal hollow nerve cord, pharyngeal slits and a post-anal tail throughout life. Their notochord extends into the head, which gives the subphylum Cephalochordata its name.
Category: Echinoderms and Chordates
Question 18
Hagfish have a complete vertebral column made of bone.
Correct Answer
False
False. Hagfish have a cartilaginous skull and a notochord but no vertebral column, which is why they are often not considered true vertebrates. They are jawless marine scavengers.
Category: Vertebrates
Question 19
In birds, air sacs move air through the lungs in one direction during both inhalation and exhalation.
Correct Answer
True
True. Air sacs connected to the lungs create a one-way flow of air, which makes gas exchange in bird lungs more efficient than in mammalian lungs.
Category: Vertebrates
Question 20
Marsupials have a more complex placenta than eutherian mammals.
Correct Answer
False
False. Eutherians, the placental mammals, have the more complex placenta. Marsupials have a simpler placental connection and give birth to underdeveloped young that typically finish developing in a pouch.
Category: Vertebrates