Life Functions

1. Life Functions

2. Objectives • Analyze the processes by which organisms representative of the following groups accomplish essential life functions including: • Unicellular protists, annelid worms, insects, amphibians, mammals, nonvascular plants, seed plants • Transport, excretion, respiration, regulation, nutrition, synthesis, reproduction, and growth and development.

3. Life Functions • Transport : how organisms deliver what they need to cells and move wastes from cells to organs of excretion. • Excretion: how organisms get rid of their waste and balance their fluids (pH, salt concentration, water). • Respiration: How organisms get oxygen from the environments and release carbon dioxide back to the environment and how plants exchange gases. • Regulation: how organisms control body processes—hormones, nervous system. • Nutrition: how organism break down and absorb foods. • Reproduction: sexual versus asexual, eggs, seeds, spores, placental, types of fertilization. • Growth and Development: metamorphosis, development in egg or in uterus, growth from seed or spore.

4. Life Functions Protists

5. Life Functions of Protists • The methods of transport, excretion, and gas exchange used by protists are generally the same at those used by cells in general: • Diffusion/osmosis • Active transport • Facilitated diffusion • Vesicular transport (endocytosis, exocytosis)

6. Life Functions of Protists • Nutrition • Animal-like protists: • Flagellates and Ciliates • Ingest food via endocytosis • Digestion is intracellular (within the cell) • Undigested materials are eliminated by exocytosis • Nonmotile (Sporozoans) are parasites that feed off the cells and fluids of their hosts. • Plant-like protists are photosynthetic autotrophs and make their own food.

7. Life Functions of Protists • Reproduction • Most protists reproduce asexually by cell division (fission). • Some may produce sexually.

8. Life Functions Animals

9. Life Functions: Animals • Transport • Complex animals have tissues that are several cell layers thick. • Making exchange of materials directly with the environment impossible. • Oxygen and nutrients must be transported to these body cells by a circulatory system.

10. Life Functions: Animals There are two types of circulatory systems. • Open circulatory system • In an open circulatory system, a heart pumps fluids containing oxygen and nutrients through a series of vessels out into the body cavity. • The fluid washes across the body’s tissues, supplying them with oxygen and nutrients. • The fluid collects in open spaces in the animal’s body and flows back to the heart.

11. Life Functions: Animals Open Circulatory System

12. Life Functions: Animals • Closed circulatory system • In a closed circulatory system, a heart pumps blood through a system of blood vessels. • The blood vessels provide a network that allows blood flow from the heart to all of the body’s cells and back again. • The blood remains in the vessels and does not come in direct contact with the body’s tissues. • Materials pass into and out of the blood by diffusing through the walls of the blood vessels.

13. Life Functions: Animals Closed Circulatory System

14. Life Functions Annelid Worms

15. Life Functions of Annelids • Segmented worms have a closed circulatory system. • Blood carrying oxygen to and carbon dioxide from body cells flows through vessels to reach all parts of the body. • The earthworm circulatory system consists of enlarged blood vessels that are heavily muscled. • When these muscles contract, they help pump blood through the system.

16. Life Functions of Annelids Earthworm Circulatory System

17. Life Functions of Annelids • Excretion • In each segment of the worm is a pair of excretory tubules called nephridia that remove wastes from the blood and fluid in the body cavity. • The nephridia lead to exterior pores through which the wastes are discharged.

18. Life Functions of Annelids Earthworm Excretory System

19. Life Functions of Annelids • Respiration • Annelids that live in water breathe through gills. • A gill is an organ specialized for exchange of gases under water. • Annelids that live on land exchange oxygen and carbon dioxide through their moist skin.

20. Life Functions of Annelids • Regulation (Nervous Control) • An earthworm has a system of nerve fibers in each segment. • The nerve fibers are coordinated by a simple brain that lies above the mouth. • The earthworm also has a nerve cord that runs along its belly.

21. Life Functions of Annelids Earthworm Nervous System nerve cord brain

22. Life Functions of Annelids • Nutrition • Segmented worms have a complete internal digestive tract that runs the length of the body. • Food taken in by the mouth passes into the esophagus. • The food then moves through the crop, where it can be stored. • After that it moves through the gizzard where it is ground into smaller pieces. • Extracellular chemical digestion and absorption occurs along the intestine.

23. Life Functions of Annelids Earthworm Digestive System intestine esophagus pharynx mouth gizzard crop

24. Life Functions of Annelids • Reproduction • Most segmented worms are hermaphrodites, • Each individual contains both sexes. • Mating occurs when two worms join head to tail, exchanging sperm. • Later during egg laying, the clitellum (a thickened glandular ring) on each worm secretes a mucous cocoon. • Eggs are laid within the cocoon and fertilized externally with stored sperm as the worm withdraws from the cocoon.

25. Life Functions of Annelids Mating Earthworms

26. Life Functions Insects

27. Life Functions of Insects • Transport • Nutrients and other materials are transported through the body of a grasshopper by an open circulatory system. • A long blood vessel with a series of muscular “hearts” runs along the grasshopper’s back. Blood is pumped out of the open system and bathes the body tissues directly before returning to the heart.

28. Life Functions of Insects

29. Life Functions of Insects • Excretion • Insects have an excretory system that is composed of units called Malpighian tubules. • Malpighian tubules are slender, fingerlike extensions from the arthropod’s gut that are bathed by blood. • Water and small particles in the blood move through the tubules and into the gut. Metabolic wastes remain in the gut until they exit through the anus.

30. Life Functions of Insects • Malpighian Tubules (ant)

31. Life Functions of Insects • Respiration • The majority of terrestrial arthropods respire through a network of fine tubes called trachea. • Air enters the arthropod’s body through abdominal pores called spiracles and passes into the tracheae, delivering oxygen throughout the body. • Valves that control the flow of air through the spiracles and prevent water loss were a key adaptation for the first arthropods that invaded land more than 400 million years ago.

32. Life Functions of Insects • Tracheal system of a beetle

33. Life Functions of Insects • Grasshopper respiratory and circulatory systems.

34. Life Functions of Insects • Regulation (nervous system) • Senses • Insects have acute senses to detect movement, sound and chemicals. • Antennae detect touch and chemicals in the environment. They may also be used in communication. • Sensory hairs on the body may detect vibrations in the environment. • Eyes, simple or compound, are used to detect light or movement.

35. Life Functions of Insects • Regulation (nervous system) • Insects have a well developed nervous system that processes information coming from the sense organs. • It consists of: • A double nerve cord along belly. • A brain in the head.

36. Life Functions of Insects • Grasshopper nervous system

37. Life Functions of Insects • Nutrition • Insects have a complete digestive system with: • Mouth • Stomach • Intestine • Anus • Various glands that produce digestive enzymes • Mouthparts vary and are adapted for holding, chewing, sucking, or biting various foods.

38. Life Functions of Insects • Insect mouthparts

39. Life Functions of Insects • Anatomy of a Grasshopper

40. Life Functions of Insects • Reproduction • Most insect species have separate males and females and reproduce sexually. • Fertilization is usually internal. • Some species, including bees, ants and wasps, exhibit parthenogenesis, a form of asexual reproduction in which a new individual develops from an unfertilized egg.

41. Life Functions of Insects • Growth and Development Insect Life Cycle • The life cycles of most insects are complex, and often several molts are required before the adult stage is reached. • During the last molt, the young insect undergoes a dramatic physical change called metamorphosis.

42. Life Functions of Insects • Growth and Development Complete Metamorphosis • Almost all insect species undergo “complete” metamorphosis. • In complete metamorphosis, the wingless, wormlike larva encloses itself within a protective capsule called a chrysalis. Here, it passes through a pupa stage, in which it changes into an adult. • A complete metamorphosis is a complex life cycle. The larvae can, however, exploit different habitats and food sources than adults.

43. Life Functions of Insects • Complete Metamorphosis

44. Life Functions of Insects • Complete Metamorphosis

45. Life Functions of Insects • Growth and Development Incomplete Metamorphosis • A smaller number of species develop into adults in a much less dramatic incomplete metamorphosis. • In these species, the egg hatches into a juvenile, or nymph, that looks like a small, wingless adult. • After several molts, the nymph develops into an adult.

46. Life Functions of Insects • Incomplete Metamorphosis

47. Life Functions of Insects • Incomplete Metamorphosis

48. Life Functions Vertebrates

49. Life Functions of Vertebrates • Transport • The vertebrate circulatory system is closed and consists of the following parts: • Heart • Blood • Blood vessels

50. Life Functions of Vertebrates • Heart • Pumps blood through lungs and body systems. • Has two types of chambers. • Atria—receive blood returning to the heart from body systems. • Ventricles—pump blood out of the heart to body systems.