Biology 1402 Exam 2 (Part 1)

This choice accurately describes the developmental characteristics of protostomes and deuterostomes. In protostomes, the mouth develops from the blastopore, while the anus or anal pore develops from the second opening. In deuterostomes, the anus develops from the blastopore, and the mouth develops secondarily later in their development.

The biologist observed radial cleavage and the blastopore developing into an anus. These characteristics are indicative of deuterostomes. In deuterostomes, the first opening that forms during embryonic development becomes the anus, and the mouth develops later. This is in contrast to protostomes, where the first opening becomes the mouth. Therefore, based on the observations made by the biologist, the animal can be categorized as a deuterostome.

The correct answer is acoelomates. Acoelomates are solid worms that lack a body cavity. A body cavity, also known as a coelom, is a fluid-filled space between the body wall and the digestive tract. Pseudocoelomates have a body cavity that is partially lined with mesoderm, while coelomates have a body cavity completely lined with mesoderm. Triploblastic refers to organisms with three germ layers, while diploblastic refers to organisms with two germ layers.

The given statement is incorrect because it states that "Includes most bilaterians, including flatworms, nematodes, mollusks, annelids and arthropods" is a characteristic of deuterostomes. However, this statement is actually a characteristic of protostomes, not deuterostomes. Deuterostomes include echinoderms and chordates, not the listed bilaterians.

Protostomes develop through spiral cleavage, which is a type of early embryonic development characterized by the orientation of the cell divisions. In spiral cleavage, the cells divide at oblique angles to each other, resulting in a spiral pattern of cells. This type of cleavage is commonly seen in many protostomes, such as mollusks, annelids, and arthropods. The spiral cleavage pattern plays a crucial role in determining the body plan and differentiation of cells during embryonic development.

Chordata is the correct answer because it is the only phylum listed that includes coelomate, bilaterian animals with a notochord. The notochord is a flexible rod-like structure that runs along the length of the body and provides support. Chordates also have a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail at some point in their life cycle. Examples of chordates include fish, amphibians, reptiles, birds, and mammals.

Animals were not some of the first organisms on Earth. The first organisms on Earth were likely simple, single-celled organisms such as bacteria. Animals evolved much later in the history of life on Earth.

Mollusca, Arthropoda, and Chordata are the three animal phyla that dominate animal life on land. Mollusca includes organisms like snails and slugs, Arthropoda includes insects and spiders, and Chordata includes mammals, birds, and reptiles. These three phyla have successfully adapted to terrestrial environments and have a wide range of species that inhabit land habitats.

Bilateral symmetry in animals refers to a body design that can be divided into two mirror images. This symmetry allows for greater efficiency in movement, as animals with bilateral symmetry have a distinct anterior (head) and posterior (tail) area, enabling them to move in a directed manner. It also confers efficiency in seeking food and mates, as animals can move towards or away from stimuli. Being sessile, on the other hand, means being fixed in one place and unable to move. This contradicts the concept of bilateral symmetry, as sessile organisms do not have distinct anterior and posterior areas and cannot exhibit efficient movement.

Sponges exhibit all of the following general characteristics except having a head or appendages, mouth or anus. Sponges lack specialized tissues and organs, have a lack of symmetry (although they may have radial symmetry in small species), and exhibit a unique way of eating by the flow of water through canals and pores. Additionally, sponges have a life cycle that includes free-swimming larvae and sessile adults.

The term "diploblastic" refers to organisms that have two germ layers, namely ectoderm and endoderm, but do not possess a mesoderm. Therefore, the term "diploblastic" is mismatched with its meaning or characteristics in the given options.

Tapeworms are parasitic flatworms that typically inhabit the intestines of vertebrates. They have a specialized structure called a scolex that allows them to attach to the intestinal wall and absorb nutrients from their host. While there are some exceptions, the majority of tapeworm species have adapted to live in the intestines where they can thrive and reproduce. Living in the intestines provides tapeworms with a suitable environment for their survival and ensures a steady supply of food from the host's digestive system. Therefore, the correct answer is "intestines of vertebrates."

The term "diploblastic" refers to organisms that have two germ layers during embryonic development, namely the ectoderm and endoderm. However, the phylum Chordata is characterized by having three germ layers, including the mesoderm. Therefore, the term "diploblastic" does not apply to the phylum Chordata.

Diploblastic is not a characteristic of a vertebrate. Vertebrates are organisms that have a backbone or spinal column, and they are typically triploblastic, meaning they have three germ layers during development. Diploblastic organisms, on the other hand, only have two germ layers. This means that diploblastic organisms lack certain structures and tissues that are present in vertebrates, such as muscles and organs. Therefore, diploblastic is not a characteristic of a vertebrate.

Sponges are unique in possessing special flagellated cells called choanocytes. These cells have a beating motion that helps to drive water through the body cavity of the sponge. Cnidocytes, planulae, nematocysts, and spicules are not the correct answer because they do not refer to the specialized cells in sponges that perform this function.

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The number of primary germ layers is not a major difference between deuterostomes and protostomes in embryonic development. Both deuterostomes and protostomes have three primary germ layers - ectoderm, mesoderm, and endoderm. These germ layers give rise to different tissues and organs in the developing embryo. The major differences between deuterostomes and protostomes lie in other aspects such as the pattern of blastopore formation, radial cleavage pattern for cell division, and the ability of a single cell to develop into a complete organism.

The correct answer is Nematoda and Arthropoda because both phyla belong to the Ecdysozoan clade. Ecdysozoa is a major group of protostome animals that are characterized by their ability to molt or shed their exoskeleton. Nematoda, also known as roundworms, and Arthropoda, which includes insects, crustaceans, and spiders, are both part of this clade. Platyhelminthes belong to the Lophotrochozoa clade, Annelida belongs to the same clade, and Mollusca belongs to the Mollusca clade. Therefore, the correct answer is Nematoda and Arthropoda.

The correct answer is "are animals in which the blastopore develops into the mouth." This statement is incorrect because deuterostomes are animals in which the blastopore develops into the anus, not the mouth.

The given correct answer is "bilaterial symmetry". This means that cniderians branched off from the rest of animals before the evolution of bilateral symmetry. Bilateral symmetry refers to the arrangement of body parts in a way that the left and right sides are mirror images of each other. This evolutionary trait is found in many animal phyla, including arthropods, mollusks, and echinoderms. Therefore, the fact that cniderians branched off before bilateral symmetry evolved suggests that they have a different body plan and do not exhibit bilateral symmetry.

Comb jellies belong to the phylum Ctenophora. This is because comb jellies, also known as ctenophores, are a group of marine animals that have a unique comb-like structure of cilia for locomotion. They are gelatinous and transparent organisms that can be found in oceans worldwide. Comb jellies are distinct from other organisms listed in the question, such as hydra, jellyfish, anemones, and corals, as they belong to different phyla.

The term "pseudocoelomate" applies to the phylum Nematoda. Pseudocoelomates are organisms that have a fluid-filled body cavity called a pseudocoelom, which is not completely lined by mesoderm. Nematodes have a pseudocoelom, which separates their digestive tract from the outer body wall. This characteristic distinguishes them from other phyla like Parazoa, which lack a true body cavity, and deuterostomes, which have a true coelom.

Platyhelminthes is the correct answer because it is the only phylum listed that fits the given criteria. Platyhelminthes, also known as flatworms, are unsegmented, acoelomate (lack a body cavity), and have a digestive cavity with a single opening called a gastrovascular cavity. Annelida, Nematoda, Cnidaria, and Rotifera do not meet all of these criteria. Annelida, for example, are segmented and have a coelom, while Nematoda have a pseudocoelom and Rotifera have a specialized digestive system with both a mouth and an anus.

In animals that display indeterminate development, early embryonic cells have the ability to develop into complete organisms even if they are separated from the embryo. This means that these cells are totipotent, meaning they have the potential to differentiate into any cell type and form a whole organism. This is a unique characteristic of indeterminate development, where the fate of the embryonic cells is not predetermined and can be influenced by external factors. This ability allows for regeneration and a higher degree of flexibility in the development of these animals.

The correct answer is "they are homotrophic". This is because animals are heterotrophic, meaning they obtain their energy by consuming other organisms. They cannot produce their own food through photosynthesis like autotrophic organisms.

The term "protostome" applies to the phylum Mollusca. Protostomes are a group of animals that develop their mouth first during embryonic development. This is in contrast to deuterostomes, which develop their anus first. Mollusks, such as snails, clams, and octopuses, are examples of protostomes.

Echinodermata is the correct answer because it includes deuterostome animals that are exclusively marine and have radial symmetry as adults. Echinoderms, such as starfish, sea urchins, and sea cucumbers, exhibit radial symmetry and are found only in marine environments. They are characterized by a water vascular system and a unique endoskeleton made of calcified plates.

The term "lophophore" applies to the phylum Bryozoa. A lophophore is a specialized feeding structure found in certain aquatic invertebrates, including bryozoans. It is a horseshoe-shaped or circular organ that bears ciliated tentacles used for filter feeding. Bryozoans use their lophophores to capture food particles from the water and bring them towards their mouths. This unique characteristic sets them apart from other phyla and is a defining feature of Bryozoa.

The term "often bioluminescent marine animals" applies to the phylum Ctenophora. Ctenophores, also known as comb jellies, are a group of marine animals that are known for their ability to produce light through bioluminescence. They have specialized cells called photocytes that emit light, which they use for various purposes such as attracting prey or mates, camouflage, or communication. This characteristic sets them apart from other phyla and is a defining feature of Ctenophora.

The Hox genes are a group of genes that play a key role in determining the body plan and development of organisms. They control the expression of other genes, regulating the formation of body structures and organs. The rapid diversification during the Cambrian explosion may have been facilitated by the evolution of Hox genes, as they allowed for the development of new body plans and the differentiation of distinct body segments. This would have led to the evolution of new species with different shapes and symmetries, as well as the organization of tissues into organs and organ systems.

Arthropoda is the correct answer because it is the only phylum listed that includes protostome animals that are segmented, bilaterally symmetric, and have a chitinous exoskeleton. Annelida, Mollusca, Brachiopoda, and Platyhelminthes do not have all of these characteristics.

Cnidarians are known for their gelatinous composition and lack of distinct organs. They exist in two forms, either as polyps or medusae. They also possess specialized cells called "cnidocytes" which contain nematocysts. However, unlike higher organisms, cnidarians do not have well-defined organs. Their body structure is more simple and decentralized, consisting of a sac-like body with a central digestive cavity.

Adults in the phylum Echinodermata do not exhibit bilateral symmetry. Echinoderms are known for their unique radial symmetry, which means their bodies are arranged around a central axis. This symmetry is characterized by multiple planes of symmetry rather than a single plane dividing the body into two equal halves. Therefore, the term "bilateral symmetry" does not apply to adults in the phylum Echinodermata.

Pseudocoelomates have a body cavity that is located between the ectoderm and the endoderm. This statement is incorrect because pseudocoelomates have a body cavity that is not completely lined with mesodermal cells, unlike true coelomates. Instead, their body cavity is partially lined with mesodermal cells and partially lined with endodermal cells.

Tapeworms have long, flat bodies made up of repeating segments called proglottids. Each proglottid contains both male and female reproductive organs, allowing the tapeworm to self-fertilize and produce eggs. As the tapeworm grows, new proglottids are continuously formed at the posterior end of the body, pushing the older ones towards the anterior end. This unique feature of tapeworm anatomy allows for efficient reproduction and survival within the host organism.

Cnidaria is the correct answer because it is the phylum in which symmetrical body plans first evolved in marine animals. Cnidarians, such as jellyfish and corals, exhibit radial symmetry, meaning their body parts are arranged around a central axis. This is in contrast to bilateral symmetry, which is found in more advanced animal phyla. The evolution of symmetrical body plans in Cnidaria was an important step in the development of animal diversity and complexity.

The term "indeterminate cleavage" does not apply to the phylum Annelida. Indeterminate cleavage refers to a type of embryonic development where the fate of each cell is not determined early on, and any individual cell has the potential to develop into a complete organism. However, in the phylum Annelida, the cleavage is determinate, meaning that the fate of each cell is determined early on in development and they have specific roles in forming different structures of the organism.

The given statement, "They contain a bony skeleton," is not true about pseudocoelomates. Pseudocoelomates are a group of organisms that possess a pseudocoel, which is an internal body cavity. While some pseudocoelomates may have a hydrostatic skeleton or a simple framework of supportive structures, they do not possess a bony skeleton like vertebrates.

The correct answer is Ctenophora. Ctenophores, also known as comb jellies, are radially symmetrical marine animals that use eight comb-like plates of fused cilia to propel themselves through the water. Cnidaria, on the other hand, includes animals such as jellyfish and corals, which have radial symmetry but do not have the comb-like plates of cilia. Platyhelminthes refers to flatworms, which do not have radial symmetry. Eumentazoan and Parazoa are not valid phyla.

True segmentation is found in Arthropoda, Annelida, and Chordata. These phyla exhibit a segmented body plan, where the body is divided into repeated segments. In Arthropoda, such as insects and crustaceans, the body is divided into distinct segments with jointed appendages. Annelida, which includes earthworms and leeches, also have a segmented body with repeated units called metameres. Chordata, which includes vertebrates like humans, exhibit segmentation during embryonic development, with the formation of somites that give rise to the segmented structures in the body.

The statement that molecular data suggests that arthropods and annelids are part of the same clade is false. Molecular data actually suggests that arthropods and annelids are not part of the same clade, but rather belong to different clades. Clades consist of monophyletic taxa sharing the same gene sequences, and different molecules sometimes support different taxonomic relationships. Additionally, molecular data suggests that a new group of "molting" animals, the Ecdysozoa, is monophyletic. Combining data from many different molecules gives the best picture of phylogenetic relationships.

Schistosomiasis is a serious disorder mainly found in tropical regions and is caused by a fluke. Flukes are parasitic flatworms that can infect humans and cause various health issues. In the case of schistosomiasis, the fluke species Schistosoma infects humans through contact with contaminated freshwater. These flukes have a complex life cycle involving snails as intermediate hosts. Once inside the human body, the flukes can cause damage to the liver, intestines, and other organs, leading to severe symptoms and complications. Therefore, the correct answer is fluke.

The term "radial symmetry" applies to the phylum Chidaria because organisms in this phylum, such as jellyfish and sea anemones, have body parts arranged around a central axis, resembling spokes on a wheel. This type of symmetry allows for equal distribution of body parts and efficient movement in any direction.

The term "diploblastic" refers to organisms that have two germ layers (ectoderm and endoderm) during their embryonic development. However, the phylum Porifera, which includes sponges, does not have true tissues or germ layers. Therefore, the term "diploblastic" does not apply to Porifera.

Phylum Platyhelminthes is a group of organisms that are characterized by several features, including bilateral symmetry, solid bodies with an inner digestive cavity, flat ribbon-shaped bodies with dorso-ventral parts and an anterior head, and possessing an excretory system. However, not all organisms in this phylum are free-living. Some members of this phylum are parasitic, living inside or on other organisms. Therefore, the statement "all are free-living" is incorrect.

The term "acoelomate" applies to the phylum Platyhelminthes. This term refers to organisms that lack a coelom, which is a fluid-filled body cavity. Platyhelminthes, commonly known as flatworms, do not possess a true coelom, as their body cavity is filled with mesenchyme, a loose connective tissue. This characteristic distinguishes them from other organisms that have a coelom, such as protostomes and diploblastic animals. Additionally, the terms "spiral cleavage" and "radial symmetry" do not specifically apply to Platyhelminthes.

The feature of movement associated with muscle tissue and nervous tissue is unique to animals. While other options such as cells organized into tissues, heterotrophism, cells without walls, and embryonic development are also characteristic of animals, the ability to move using muscle tissue and nervous tissue sets animals apart from other organisms. This feature allows animals to actively respond to their environment, seek out food, and escape from predators.

Segmentation is a process in which the body of an organism is divided into repetitive segments. The statement "Only three phyla show true segmentation" is false because segmentation is observed in more than three phyla. In fact, segmentation is a widespread phenomenon in the animal kingdom, seen in various phyla including Annelida, Arthropoda, Chordata, and many others. Therefore, the statement is incorrect as it underestimates the occurrence of segmentation in different phyla.

The term "asymmetry" does not apply to the phylum Nematoda because nematodes have a bilateral symmetry, meaning they have a distinct left and right side. Asymmetry refers to organisms that lack any symmetry or have irregular shapes. Nematodes are also protostomes, meaning their mouth develops before their anus, and they are coelomate, meaning they have a body cavity. They are triploblastic, meaning they have three germ layers, and exhibit determinate cleavage, where the fate of each cell is determined early in development.

The correct answer is a digestive cavity lined with enzyme-secreting cells. This is because sponges are filter feeders and they obtain their food by filtering water through their bodies. They do not have a digestive cavity like other animals, such as a stomach, where enzymes are secreted to break down food. Instead, they have specialized collar cells or choanocytes that trap and ingest food particles.