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A(n) ______ develops from a two-layer embryo.
| a. sea star | c. butterfly |
| b. sea anemone | d. earthworm |
Introduction:
The environment is composed of a variety of organisms. Animals are the most complex living organisms. They are eukaryotes as they contain a well-defined nucleus enclosed in a nuclear membrane. All kinds of animals reproduce to give rise to their offspring. Animals do not contain a cell wall, and they cannot prepare food. All animals are heterotrophs as they depend on other organisms for their food.
Answer to Problem 1SA
Correct answer:
A sea anemone develops from a two-layer embryo. Hence, the correct answer is option b.
Explanation of Solution
Reason for correct answer:
Option b. is given as “sea anemone.”
The collection of similar type of cells forms tissue. Animals contain tissue and similar kinds of tissue join together to form the organs. Cnidarians are the simpler animals that live in water bodies. The embryo of cnidarians contains two-layer, an outer layer called ectoderm, and the inner layer that is known as endoderm. Sea anemones are the cnidarians that develop from a two-layer embryo.
Reason for incorrect answer:
Option a. is given as, “sea star.”
Seastar is also known as starfish, and it belongs to the phylum “Echinoderm.” Sea star arises from a three-layered embryo. These three layers are outer layer (ectoderm), middle layer (mesoderm), and inner layer (endoderm). This indicates that sea star does not form from a two-layer embryo. Hence, option a. is incorrect.
Option c. is given as, “butterfly.”
Butterfly is not a cnidarian. It is a complex insect that forms from a three-layered embryo. These three layers are outer layer (ectoderm), middle layer (mesoderm) and inner layer (endoderm). This indicates that the butterfly does not arise from a two-layer embryo. Hence, option c. is incorrect.
Option d. is given as, “earthworm.”
Earthworm belongs to the phylum named “Annelid.” It is formed from a three-layered embryo. These three layers are outer layer (ectoderm), middle layer (mesoderm) and inner layer (endoderm). This indicates that earthworm does not arise from a two-layer embryo. Hence, option d. is incorrect.
Hence, the options a., c., and d. are incorrect.
The organism that arises from a two-layer embryo is a sea anemone. Thus, the correct option is b.
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Chapter 23 Solutions
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