D&E Biology Chapter 33

Part B Which of the following allows dragonflies to maneuver so well?

Their wings can move independently of one another.

Part A Which of the following is characteristic of the phylum Platyhelminthes?

They are dorsoventrally flattened. Correct: This is why they are also called flatworms.

Part A Which of the following is true of annelids?

They perform gas exchange across their skin. Correct: Cutaneous respiration occurs across their skins. Polychaetes have lateral extensions, called parapodia, which provide even more surface area for cutaneous respiration.

Part A Which of the following is a hypothesis the researchers were testing in this study?

Through evolution, periwinkle populations with a history of predation by crabs have become less vulnerable to crab predation. Correct: The researchers' hypothesis was that southern periwinkle populations with a history of predation by crabs have become less vulnerable to crab predation through evolution.

Part A A marine biologist dredges up a small animal from the bottom of the ocean. It is uniformly segmented, with short, stiff appendages and soft, flexible skin. It has a complete digestive system and a closed circulatory system, plus multiple true coeloms. Based on this, you determine that the animal must be a(n) _____.

annelid Correct: The description matches the characteristics of annelids.

Part A Members of the phylum Mollusca _____.

are soft-bodied and often covered by a shell Correct: Members of the phylum Mollusca are soft-bodied and are often covered by a shell.

Part E You are an entomologist specializing in the closest relatives of the dragonflies. What do you study?

damselflies

Part A Which of the following is a characteristic of cnidarians?

gastrovascular cavity Correct: The gastrovascular cavity, characterized by a single opening, is the digestive compartment of cnidarians.

Part A The animal phylum most like the protists that gave rise to the animal kingdom is _____.

Porifera Correct: Evidence that supports this includes the lack of true tissue in sponges and the close similarity between choanocytes and choanoflagellates.

Part C Which of the following is true?

Both larval and adult dragonflies are carnivorous.

Part A Nematodes and arthropods are the largest ecdysozoan phyla. Which of the following statements are true?

-Both nematodes and arthropods possess an external covering, or cuticle. -Both nematodes and arthropods must molt in order to increase in size. -Arthropods are named for their jointed appendages. -Arthropods possess an open circulatory system. -Some nematodes are parasitic on humans. Correct: The ecdysozoans include nematodes, arthropods, and other phyla that have tough external coats, or cuticles, that must be shed as they grow. This process of shedding, or molting, is called ecdysis. Nematodes, or roundworms, are unsegmented pseudocoelomate worms that lack a circulatory system. Although most nematodes are free-living, some well-known nematodes, such as hookworms and pinworms, are parasitic. Arthropods have a reduced coelom and an open circulatory system. Arthropods have segmented bodies that enable specialization of body structures such as appendages.

Part B The phylum Arthropoda includes four major lineages: cheliceriforms (also called chelicerates); myriapods; insects and their relatives (together called hexapods); and crustaceans. Drag each word or phrase to the appropriate bin.

Cheliceriformes: possess clawlike feeding appendages, horseshoe crab, arachnids Myriapods: millipedes and centipedes, exclusively terrestrial Insects: butterfly, wings allow flight, body divided into head, thorax, and abdomen, three pairs of walking legs Crustaceans: two pairs of antennae, crabs and isopods, primarily aquatic Correct: Cheliceriformes, which are named for their clawlike feeding appendages, called chelicerae, include sea spiders, horseshoe crabs, spiders, scorpions, ticks, and mites. Myriapods include millipedes and centipedes, which are terrestrial species. Crustaceans are primarily aquatic animals such as lobsters, crabs, and crayfish. Insects possess three body regions (head, thorax, and abdomen), may have one or more pairs of wings, and have six legs. Insects are the largest and most diverse group of arthropods, including numerous species of butterflies, beetles, flies, ants, and many others.

Part F Which of the following best summarizes the results shown in the graph?

Crabs are more successful in preying on northern periwinkles.

Part D You are interested in attracting dragonflies to the area around your home. Doing which of the following would attract them to mate?

Creating a freshwater pond.

Part G Based on the results shown in the graph, how has natural selection affected populations of flat periwinkles in the southern Gulf of Maine over the last century?

Southern populations of flat periwinkles have accumulated traits that make them less vulnerable than northern populations to predation by European green crabs.

Part C Insects are the most diverse group of organisms, in terms of numbers of species, dominating terrestrial habitats. More than 30 orders of insects have been described, with the order Coleoptera being the largest. Classification is based on traits such as wings and mouthparts. All insects have a three-part body plan consisting of a head, thorax, and abdomen; three pairs of walking legs; and one or two pairs of wings. The chart below indicates defining characteristics for eight of the more than 30 orders of insects. Labels can be used once or not at all.

a. hard forewings protect membranous hindwings (Coleoptera, Wing characteristics) b. hindwings reduced to stabilizers (Diptera, Wing characteristics) c. wings have scales (Lepidoptera, Wing characteristics) d. hairy wings (Trichoptera, Wing characteristics) e. complete metamorphosis (Hymenoptera, Type of Development) f. incomplete metamorphosis (Orthoptera, Type of Development) g. flies (Diptera, Examples) h. "true bugs" (Hemiptera, Examples) i. butterflies, moths (Lepidoptera, Examples) j. caddisflies (Trichoptera, Examples) Correct: Insects and their relatives are the most species-rich group of living organisms. The diversity of characteristics such as wing shape, mouthparts, and reproductive tactics enable insects to live in most terrestrial and freshwater habitats. The evolutionary tree below shows the relationship between the phyla and subphyla within the clade Ecdysozoa, which includes animals with tough outer coverings that must be shed for growth to occur. Myriapods, cheliceriforms, crustaceans, and insects and their relatives (hexapods) together comprise the phylum Arthropoda, which is marked by jointed appendages, segmented bodies, and hard exoskeletons. Note that the tree does not show all phyla in the clade Ecdysozoa, nor does it show all orders of insects and their relatives in the subphylum Hexapoda.

Part A Which of the following are thought to be most closely related to humans?

sea stars Correct: Humans and sea stars are deuterostomes.

Part C Identify the dependent variable in this experiment.

the number of periwinkles killed by crabs Correct: The dependent variable was the number of northern and southern periwinkles killed by crabs.

Part B Identify an independent variable in this experiment.

the source of the periwinkles (northern or southern sites in the Gulf of Maine) Correct: One of the independent variables was the source of the periwinkle population--northern or southern sites in the Gulf of Maine. The source of the crab population was also an independent variable.

Part A You are an entomologist interested in learning more about the flight motor center of the dragonfly. Which part of its body should you study?

thorax

Part E Why did the researchers present unshelled northern and southern periwinkles to northern and southern crabs in the second experiment?

to test if either population of periwinkles was unpalatable to either population of crabs Correct: The researchers wanted to rule out the possibility that northern crabs didn't like the taste of southern periwinkles or that southern crabs didn't like the taste of northern periwinkles. This experiment allowed researchers to conclude that differences in numbers of southern and northern periwinkles killed were due to differing vulnerability to crab predation, not due to crab preferences.

Part D Why did the researchers set up four treatments?

to test whether the origin (northern site or southern site) of the crabs and periwinkles affected their interactions