Concept explainers
Introduction:
Clade refers to a grouping that includes an ancestor and all of its descendents.
Answer to Problem 1TYU
Correct answer:
The bilaterian is the clade that contains the greatest number of animal species. Therefore, option (B) is correct.
Explanation of Solution
Reason for the correct statement:
The division of body into two equal halves and presence of three germ layers are the shared derived characters that define the clade “Bilateria”. This clade comprises the most of the animal phyla and it members.
Option (B) is given as “the bilaterians”.
As,” the bilaterian is the clade that contains the greatest number of animal species”, it is the right answer.
Hence, option (B) is correct.
Reason for the incorrect statements:
Option (A) is given as “the vertebrates”.
The vertebrates are those animals that are characterized by the presence of notochord, pharyngeal gill slits, dorsal nerve cord and post-anal tail. They do not comprise the greatest number of animal species. So, it is a wrong answer.
Option (C) is given as “the deuterostomes”.
The deuterostomes are those animals that develop anus first and mouth later and they do not comprise the greatest number of animal species. So, it is a wrong answer.
Option (D) is given as “the insects”.
The insects are hexapod animals with two pair of wings, exoskeleton and antennae, and they do not comprise the greatest number of animal species. So, it is a wrong answer.
Hence, options (A), (C), and (D) are incorrect.
The bilaterians is the clade that contains the greatest number of animal species.
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Chapter 27 Solutions
Campbell Biology In Focus, Loose-leaf Edition (3rd Edition)
- Which of the following statements is NOT true regarding protostome diversity? A. Of the 30 animal phyla, more than 2/3 (22 phyla) are protostomes. B. There are more mollusk species than Priapula. C. There are more lophotrochozoans than ecdysozoans. D. A major feature distinguishing different developmental characteristics.arrow_forwardWhich of the following statements about bilaterian animals is false? A. Many bilaterians are invertebrates but some are not. B. All bilaterians are triploblastic (have three germ layers). C. All bilaterians have bilateral symmetry. D. Most bilaterians have tissues but some do not.arrow_forwardWhich of the following features does not distinguish humans as a member of phylum Chordata? a. Human embryos undergo indeterminate cleavage. b. A spinal cord runs along an adult human’s dorsal side. c. Human embryos exhibit pharyngeal arches and gill slits. d. The human coccyx forms from an embryonic tail.arrow_forward
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- You discover a new species of animal that has a backbone running down the length of its body. What phylum would you put it in? Group of answer choices A. Echinodermata B. Chordata C. Reptilia D. Mammalia E. Avesarrow_forwardWhich of the following groups includes all of the others? a. Protostomes c. Eumetazoans b. Echinoderms d. Ecdysozoansarrow_forwardWhat do scientists in the field of systematics accomplish? a. discover new fossil sites b. organize and classify organisms c. name new species d. communicate between field biologistsarrow_forward
- In your garden you find a segmented animal with jointed legs. It has a distinct head capsule but the body segments are all quite similar. You cut it open and find mature gonads and a tracheal system. The animal is ... A. a spider B. a woodlouse (isopod) C. an insect D. a myriapodarrow_forwardEach of the following is a critical difference between protostomes and deuterostomes except A. deuterostomes have bilateral symmetry B. the blastopore becomes the anus in deuterostomes C. the blastopore becomes the mouth in protostomes D. protostomes have radial symmetryarrow_forwardThe amniotes include all but the a. birds. c. mammals. b. reptiles. d. amphibians.arrow_forward
- Concepts of BiologyBiologyISBN:9781938168116Author:Samantha Fowler, Rebecca Roush, James WisePublisher:OpenStax College