Biology Exam 7 Circle T if the statement is true; F if it is false. 10, T F At l
ID: 303310 • Letter: B
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Biology Exam 7 Circle T if the statement is true; F if it is false. 10, T F At least 95% of all animal species are invertebrates. Im. T F A zygote forms when a sperm cell penetrates and fertilizes an egg. 12. T FMitotic cell divisions of a zygote lead to the formation of a fluid-filld ball of Bio Cely Fo called a blastula 13. T F Animals that produce egg and sperm in the same body are called hermaphrod 14. TFWhen the mouth develops from the first opening in the gastrula, the organism i called a deuterostome. Sponge embryos develop ectoderm, endoderm, and mesoderm like other animal Most enidarians have two layers of cells that are organized into tissues that have 15. TF 16. T F specific functions. 17. T FFlatworms can reproduce only by sexual reproduction. 8. T FRoundworms reproduce sexually with external fertilization. 19. TFMost mollusks have a closed circulatory system where blood is confined to vessels as it moves through the body. 20. T F The anterior portion of the body of most annelids, such as the earthworm, is adape for sensing the environment. 21. TF The muscles of arthropods are attached to the outside of their exoskeletons, which are made of chitin. 2. TFInsects have at least four pairs of legs. 23. TF Echinoderms generally have endoskeletons. 4. T F In invertebrate chordates, the notochord is eventually replaced by bone or cartilaExplanation / Answer
10. true. 95 % of animals are invertebrates, animals without bones , many tiny and microscopic.
11. true . nucleus of both sperm and egg fused to form a diploid cell known as zygote during fertilization.
12.true .The first week of human development begins with fertilization of the egg by sperm forming the first cell, the zygote. Cell division leads to a ball of cells, the morula. Further cell division and the formation of a cavity in the ball of cells forms the blastocyst.when the fluid will cavity blastovoel is formed , it becomes blastula
13.true. animals that produce egg and sperm in the same indivijual is called hermaphrodite.
14. false,. in protostome development the first opening in dvelopment , the blastopore becomes the animals mouth nad in Dueterostome development , the blastopore becomes animals anus.
15.true
17.true
20.true
21. true. chitin forms the exoskeleton in arthropods
22.true.
23. true. echinoderm skeletons are madeup of interlocking calcium carbonate plates and spines .this skeleton is enclosed by epidermis ,thus it is called nedoskeleton
24.True. The embyonic notochord ie replaced by series of elements made up of bone and cartilage .
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