Introduction to Biology: Understanding Life and its Organisms

2. Table of Contents – pages iii 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

3. Table of Contents – pages vii-xiii 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

4. 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 vii-xiii

5. 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 vii-xiii

6. Table of Contents – pages vii-xiii 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

7. Table of Contents – pages vii-xiii 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

8. Unit Overview – pages 472-473 Viruses, Bacteria, Protists, and Fungi Viruses and Bacteria Protists Fungi

9. Chapter Contents – page ix Chapter 19Protists 19.1:The World of Protists 19.1:Section Check 19.2:Algae: Plantlike Protists 19.2:Section Check 19.3:Slime Molds, Water Molds, and Downy Mildews 19.3:Section Check Chapter 19Summary Chapter 19Assessment

10. Chapter Intro-page 502 What You’ll Learn You will differentiate among the major groups of protists. You will recognize the ecological niches of protists. You will identify some human diseases and the protists responsible for them.

11. 19.1 Section Objectives – page 503 Section Objectives: • Identify the characteristics of Kingdom Protista. • Compare and contrast the four groups of protozoans.

12. Section 19.1 Summary – pages 503-509 What is a protist? • Kingdom Protista contains the most diverse organisms of all the kingdoms. • Protists may be unicellular or multicellular, microscopic or very large, and heterotrophic or autotrophic.

13. Section 19.1 Summary – pages 503-509 What is a protist? • The characteristic that all protists share is that, unlike bacteria, they are all eukaryotes, which means that most of their metabolic processes occur inside their membrane-bound organelles.

14. Section 19.1 Summary – pages 503-509 What is a protist? • Although there are no typical protists, some resemble animals in the way they get food. • The animal-like protists are called protozoa (proh tuh ZOH uh) (singular, protozoan). Protozoa

15. Section 19.1 Summary – pages 503-509 What is a protist? • Unlike animals, though, all protozoans are unicellular. Protozoa

16. Section 19.1 Summary – pages 503-509 What is a protist? • Other protists are plantlike autotrophs, using photosynthesis to make their food. • Plantlike protists are called algae (AL jee) (singular, alga). Algae

17. Section 19.1 Summary – pages 503-509 What is a protist? • Unlike plants, algae do not have organs such as roots, stems, and leaves. Algae

18. Section 19.1 Summary – pages 503-509 What is a protist? • Still other protists are more like fungi because they decompose dead organisms. Slime mold • However, unlike fungi, funguslike protists are able to move at some point in their life and do not have chitin in their cell walls.

19. Section 19.1 Summary – pages 503-509 What is a protist? • Some protists cause diseases, such as malaria and sleeping sickness, that result in millions of human deaths throughout the world every year. • Unicellular algae produce much of the oxygen in Earth’s atmosphere and are the basis of aquatic food chains.

20. Section 19.1 Summary – pages 503-509 What is a protist? • Slime molds and water molds decompose a significant amount of organic material, making the nutrients available to living organisms.

21. Section 19.1 Summary – pages 503-509 What is a protozoan? • Although a diverse group, all protozoans are unicellular heterotrophs that feed on other organisms or dead organic matter. • They usually reproduce asexually, but some also reproduce sexually.

22. Section 19.1 Summary – pages 503-509 Diversity of Protozoans • Many protozoans are grouped according to the way they move. • Some protozoans use cilia or flagella to move. • Others move and feed by sending out cytoplasm-containing extensions of their plasma membranes. • These extensions are called pseudopodia (sew duh POH dee uh).

23. Section 19.1 Summary – pages 503-509 Diversity of Protozoans • There are four main groups of protozoans: the amoebas (uh MEE buz), the flagellates, the ciliates, and the sporozoans (spor uh ZOH unz).

24. Section 19.1 Summary – pages 503-509 Amoebas: Shapeless protists • Amoebas have no cell wall and form pseudopodia to move and feed. Pseudopodia Cytoplasm Nucleus Food vacuole Contractile vacuole

25. Section 19.1 Summary – pages 503-509 Amoebas: Shapeless protists • As a pseudopod forms, the shape of the cell changes and the amoeba moves. Amoebas form pseudopodia around their food. Pseudopodia Cytoplasm Nucleus Food vacuole Contractile vacuole

26. Section 19.1 Summary – pages 503-509 Amoebas: Shapeless protists • Although most amoebas live in saltwater, there are freshwater ones that live in the ooze of ponds, in wet patches of moss, and even in moist soil. • Because freshwater amoebas live in hyoptonic environments, they constantly take in water. • Their contractile vacuoles collect and pump out excess water.

27. Section 19.1 Summary – pages 503-509 Amoebas: Shapeless protists • Two groupings of mostly marine amoebas, the foraminiferan and radiolarian have shells. Foraminiferan Radiolarian

28. Section 19.1 Summary – pages 503-509 Amoebas: Shapeless protists • Foraminiferans, which are abundant on the sea floor, have hard shells made of calcium carbonate.

29. Section 19.1 Summary – pages 503-509 Amoebas: Shapeless protists • Radiolarians have shells made of silica. • In addition, radiolarians are an important part of marine plankton—an assortment of microscopic organisms that float in the ocean’s photic zone and form the base of marine food chains.

30. Section 19.1 Summary – pages 503-509 Amoebas: Shapeless protists • Most amoebas commonly reproduce by asexual reproduction, in which a single parent produces one or more identical offspring by dividing into two cells. • When environmental conditions become unfavorable, some types of amoebas form cysts that can survive extreme conditions.

31. Section 19.1 Summary – pages 503-509 Flagellates: Protozoans with flagella • The phylum Zoomastigina consists of protists called flagellates, which have one or more flagella. Nucleus Chloroplast • Flagellated protists move by whipping their flagella from side to side. Mitochondrion Eyespot Flagellum Pellicle Contractile vacuole

32. Section 19.1 Summary – pages 503-509 Flagellates: Protozoans with flagella • Some flagellates are parasites that cause diseases in animals, such as African sleeping sickness in humans. • Other flagellates are helpful.

33. Section 19.1 Summary – pages 503-509 Ciliates: Protozoans with cilia Anal pore Cilia • The roughly 8000 members of the protist phylum Ciliophora, known as ciliates, use the cilia that cover their bodies to move. Oral groove Gullet • Ciliates live in every kind of aquatic habitat—from ponds and streams to oceans and sulfur springs. Contractile vacuole Micronucleus and macronucleus

34. Section 19.1 Summary – pages 503-509 A Paramecium Anal pore Cilia • Within a paramecium are many organelles and structures that are each adapted to carry out a distinct function. Oral groove Gullet Contractile vacuole Micronucleus and macronucleus

35. Section 19.1 Summary – pages 503-509 A Paramecium • A paramecium usually reproduces asexually by dividing crosswise and separating into two daughter cells. • Whenever their food supplies dwindle or their environmental conditions change, paramecia usually undergo a form of conjugation.

36. Section 19.1 Summary – pages 503-509 A Paramecium • In this complex process, two paramecia join and exchange genetic material. • Then they separate, and each divides asexually, passing on its new genetic composition.

37. Section 19.1 Summary – pages 503-509 Sporozoans: Parasitic protozoans • Protists in the phylum Sporozoa are often called sporozoans because most produce spores. • A spore is a reproductive cell that forms without fertilization and produces a new organism. Sporozoans

38. Section 19.1 Summary – pages 503-509 Sporozoans: Parasitic protozoans • All sporozoans are parasites. • They live as internal parasites in one or more hosts and have complex life cycles. • Plasmodium, members of the sporozoan genus, are organisms that cause the disease malaria in humans and other mammals and in birds.

39. Section 19.1 Summary – pages 503-509 Sporozoans and malaria • Throughout the world today, more than 300 million people have malaria, a serious disease that usually occurs in places that have tropical climates. • The Plasmodium that mosquitoes transmit to people cause human malaria. • The malaria-causing Plasmodium live in both humans and mosquitoes.

40. Section 19.1 Summary – pages 503-509 Sporozoans and malaria • The life cycle of Plasmodium involves two hosts—mosquitoes and humans.

41. Section 19.1 Summary – pages 503-509 Sporozoans and malaria Gut wall of mosquito Zygote Gametes Mosquito bites a new, uninfected person Mosquito feeds on infected person Sporozoites Human host

42. Section 1 Check Question 1 What characteristic do all protists share? (TX Obj 2; 8C) Answer They are all eukaryotes. Most of their metabolic processes occur inside their membrane-bound organelles.

43. Section 1 Check Question 2 What common function do pseudopodia, cilia, and flagella share in protozoans? (TX Obj 2; 8C) Answer These are all structures that protozoans use to move.

44. Section 1 Check Question 3 Which amoebas possess shells? (TX Obj 2; 8C) A. plasmodia B. paramecia C. zoomastigina D. foraminiferans

45. Section 1 Check The answer is D, foraminiferans.

46. Section 1 Check Question 4 Explain how a paramecium eats. (TX Obj 2; 8C)

47. Section 1 Check Anal pore Food moves into the paramecium’s gullet, becoming enclosed at the end in a food vacuole. Enzymes break down the food, and the nutrients diffuse into the cytoplasm. Cilia Oral groove Gullet Contractile vacuole Micronucleus and macronucleus

48. 19.2 Section Objectives – page 510 Section Objectives • Compare and contrast the variety of plantlike protists. • Explain the process of alternation of generations in algae.

49. Section 19.2 Summary – pages 510-516 What are algae? • Photosynthesizing protists are called algae. • All algae contain up to four kinds of chlorophyll as well as other photosynthetic pigments.

50. Section 19.2 Summary – pages 510-516 What are algae? • These pigments produce a variety of colors in algae, including purple, rusty-red, olive-brown, yellow, and golden-brown, and are a way of classifying algae into groups.