Table of Contents – pages iv-v Unit 1:What is Biology? Unit 2:Ecology Unit 3: The Life of a Cell Unit 4:Genetics Unit 5:Change Through Time Unit 6:Viruses, Bacteria, Protists, and Fungi Unit 7:Plants Unit 8:Invertebrates Unit 9:Vertebrates Unit 10:The Human Body
Table of Contents – pages iv-v Unit 1: What is Biology? Chapter 1:Biology: The Study of Life Unit 2: Ecology Chapter 2:Principles of Ecology Chapter 3:Communities and Biomes Chapter 4:Population Biology Chapter 5:Biological Diversity and Conservation Unit 3:The Life of a Cell Chapter 6:The Chemistry of Life Chapter 7:A View of the Cell Chapter 8:Cellular Transport and the Cell Cycle Chapter 9:Energy in a Cell
Unit 4: Genetics Chapter 10:Mendel and Meiosis Chapter 11:DNA and Genes Chapter 12:Patterns of Heredity and Human Genetics Chapter 13:Genetic Technology Unit 5: Change Through Time Chapter 14:The History of Life Chapter 15:The Theory of Evolution Chapter 16:Primate Evolution Chapter 17:Organizing Life’s Diversity Table of Contents – pages iv-v
Unit 6: Viruses, Bacteria, Protists, and Fungi Chapter 18:Viruses and Bacteria Chapter 19:Protists Chapter 20:Fungi Unit 7: Plants Chapter 21:What Is a Plant? Chapter 22:The Diversity of Plants Chapter 23:Plant Structure and Function Chapter 24:Reproduction in Plants Table of Contents – pages iv-v
Table of Contents – pages iv-v Unit 8: Invertebrates Chapter 25:What Is an Animal? Chapter 26:Sponges, Cnidarians, Flatworms, and Roundworms Chapter 27:Mollusks and Segmented Worms Chapter 28:Arthropods Chapter 29:Echinoderms and Invertebrate Chordates
Table of Contents – pages iv-v Unit 9: Vertebrates Chapter 30:Fishes and Amphibians Chapter 31:Reptiles and Birds Chapter 32:Mammals Chapter 33:Animal Behavior Unit 10: The Human Body Chapter 34:Protection, Support, and Locomotion Chapter 35:The Digestive and Endocrine Systems Chapter 36:The Nervous System Chapter 37:Respiration, Circulation, and Excretion Chapter 38:Reproduction and Development Chapter 39:Immunity from Disease
Unit Overview – pages 670 - 671 Invertebrates What is an animal? Sponges, Cnidarians, Flatworms and Roundworms Mollusks and Segmented Worms Arthropods Echinoderms and Invertebrate Chordates
Chapter Contents – page xi Chapter 25What is an animal? 25.1:Typical Animal Characteristics 25.1:Section Check 25.2:Body Plans and Adaptations 25.2:Section Check Chapter 25Summary Chapter 25Assessment
Chapter Intro-page 672 What You’ll Learn You will identify animal characteristics and distinguish them from those of other life forms. You will identify cell differentiation in the developmental stages of animals. You will identify and interpret body plans of animals.
25.1 Section Objectives – page 673 Section Objectives: • Identify the characteristics of animals. • Identify cell differentiation in the development of a typical animal. • Sequence the development of a typical animal.
Section 25.1 Summary – pages 673 - 679 Characteristics of Animals • Animals are eukaryotic, multicellular organisms with ways of moving that help them reproduce, obtain food, and protect themselves.
Section 25.1 Summary – pages 673 - 679 Characteristics of Animals • Most animals have specialized cells that form tissues and organs—such as nerves and muscles. • Animals are composed of cells that do not have cell walls.
Section 25.1 Summary – pages 673 - 679 Animals obtain food • One characteristic common to all animals is that they are heterotrophic, meaning they must consume food to obtain energy and nutrients. • All animals depend either directly or indirectly on autotrophs for food.
Section 25.1 Summary – pages 673 - 679 Animals obtain food • Scientists hypothesize that animals first evolved in water. • In water, some animals, such as barnacles and oysters, do not move from place to place and have adaptations that allow them to capture food from their water environment.
Section 25.1 Summary – pages 673 - 679 Animals obtain food • Organisms that are permanently attached to a surface are called sessile.
Section 25.1 Summary – pages 673 - 679 Animals obtain food • Some aquatic animals, such as corals and sponges move about only during the early stages of their lives. • Most adults are sessile and attach themselves to rocks or other objects.
Section 25.1 Summary – pages 673 - 679 Animals obtain food • There is little suspended food in the air. • Land animals use more oxygen and expend more energy to find food.
Section 25.1 Summary – pages 673 - 679 Animals digest food • In some animals, digestion is carried out within individual cells; in other animals, digestion takes place in an internal cavity. • Some of the food that an animal consumes and digests is stored as fat or glycogen, a polysaccharide, and used when other food is not available.
Section 25.1 Summary – pages 673 - 679 Animals digest food • In animals such as planarians and earthworms, food is digested in a digestive tract. Mouth Digestive tract Digestive tract Extended pharynx Anus
Section 25.1 Summary – pages 673 - 679 Animal cell adaptations • Most animal cells are differentiated and carry out different functions. • Animals have specialized cells that enable them to sense and seek out food and mates, and allow them to identify and protect themselves from predators.
Section 25.1 Summary – pages 673 - 679 Development of Animals • Most animals develop from a fertilized egg cell called a zygote. • After fertilization, the zygote of different animal species all have similar, genetically determined stages of development.
Section 25.1 Summary – pages 673 - 679 Fertilization • Most animals reproduce sexually. • Male animals produce sperm cells and female animals produce egg cells.
Section 25.1 Summary – pages 673 - 679 Formation of mesoderm • The mesoderm cells develop into the muscles, circulatory system, excretory system, and, in some animals, the respiratory system.
Section 25.1 Summary – pages 673 - 679 Formation of mesoderm • When the opening in the gastrula develops into the mouth, the animal is called a protostome. • Snails, earthworms, and insects are examples of protostomes.
Section 25.1 Summary – pages 673 - 679 Formation of mesoderm • In other animals, such as sea stars, fishes, toads, snakes, birds, and humans, the mouth does not develop from the gastrula’s opening.
Section 25.1 Summary – pages 673 - 679 Formation of mesoderm • An animal whose mouth developed not from the opening, but from cells elsewhere on the gastrula is called a deuterostome.
Section 25.1 Summary – pages 673 - 679 Formation of mesoderm • Scientists hypothesize that protostome animals were the first to appear in evolutionary history, and that deuterostomes followed at a later time. • Determining whether an animal is a protostome or deuterostome can help biologists identify its group.
Section 25.1 Summary – pages 673 - 679 Cell differentiation in Animal Development • The fertilized eggs of most animals follow a similar pattern of development. From one fertilized egg cell, many divisions occur until a fluid-filled ball of cells forms. • The ball folds inward and continues to develop.
Section 25.1 Summary – pages 673 - 679 Sperm cells Cell Differentiation in Animal Development Fertilization Egg cell Formation of mesoderm First cell division Endoderm Mesoderm Ectoderm Gastrulation Additional cell divisions Formation of a blastula
Section 25.1 Summary – pages 673 - 679 Growth and development • Most animal embryos continue to develop over time, becoming juveniles that look like smaller versions of the adult animal. • In some animals, such as insects and echinoderms, the embryo develops inside an egg into an intermediate stage called a larva (plural larvae).
Section 25.1 Summary – pages 673 - 679 Growth and development
Section 25.1 Summary – pages 673 - 679 Growth and development • A larva often bears little resemblance to the adult animal. • Inside the egg, the larva is surrounded by a membrane formed right after fertilization. • When the egg hatches, the larva breaks through this fertilization membrane.
Section 25.1 Summary – pages 673 - 679 Adult animals • Once the juvenile or larval stage has passed, most animals continue to grow and develop into adults. • This growth and development may take just a few days in some insects, or up to fourteen years in some mammals. • Eventually the adult animals reach sexual maturity, mate, and the cycle begins again.
Section 1 Check Question 1 Which of the following is NOT a characteristic of animals? A. eukaryotic B. multicellular C. heterotrophic D. prokaryotic The answer is D.
Section 1 Check Question 2 Sessile animals _______. A. live only underground B. are autotrophs C. are permanently attached to a surface D. live only on land
Section 1 Check The answer is C. Sessile animals are permanently attached to a surface.
Section 1 Check Question 3 Ingestion is another word for _______. A. digestion B. physically responding to a light stimulus C. breathing D. eating
Section 1 Check The answer is D,eating.
Section 1 Check Question 4 Which of the following is NOT true of animal fertilization? A. occurs when a sperm cell penetrates an egg cell B. forms a haploid zygote
Section 1 Check Question 4 Which of the following is NOT true of animal fertilization? C. forms a diploid zygote D. may be internal or external The answer is B, forms a haploid zygote.
Section 1 Check Question 5 When a zygote divides by mitosis and cell division to form two cells, the process is called _______. A. cleavage B. fertilization C. ingestion D. gastrulation
Section 1 Check The answer is A, cleavage. Cleavage
25.2 Section Objectives – page 680 Section Objectives: • Compare and contrast radial and bilateral symmetry with asymmetry. • Trace the phylogeny of animal body plans. • Distinguish among the body plans of acoelomate, pseudocoelomate, and coelomate animals.
Section 25.2 Summary – pages 680 - 685 What is symmetry • Symmetry isa term that describes the arrangement of body structures. • Different kinds of symmetry enable animals to move about in different ways.
Section 25.2 Summary – pages 680 - 685 Asymmetry • An animal that is irregular in shape has no symmetry or an asymmetrical body plan. • Animals with no symmetry often are sessile organisms that do not move from place to place. • Most adult sponges do not move about.
Section 25.2 Summary – pages 680 - 685 Asymmetry • The bodies of most sponges consist of two layers of cells. • Unlike all other animals, a sponge’s embryonic development does not include the formation of an endoderm and mesoderm, or a gastrula stage.
Section 25.2 Summary – pages 680 - 685 Radial symmetry • Animals with radial symmetry can be divided along any plane, through a central axis, into roughly equal halves.
Section 25.2 Summary – pages 680 - 685 Radial symmetry • Radial symmetry is an adaptation that enables an animal to detect and capture prey coming toward it from any direction.