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Life Science

Life Science . Chapter 2 Characteristics of Life. Bellwork. Think and write about the parts of the test you had difficulty with. Early Science. Spontaneous generation: Early scientists believed that living things could develop from non-living matter. Francesco Redi.

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Life Science

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  1. Life Science Chapter 2 Characteristics of Life

  2. Bellwork • Think and write about the parts of the test you had difficulty with.

  3. Early Science • Spontaneous generation: • Early scientists believed that living things could develop from non-living matter

  4. Francesco Redi • In the 17th century, Francesco conducted an experiment that disproved the theory of spontaneous generation

  5. Louis Pasteur • Following the invention of the microscope, scientists began to see the sudden appearance of “live beasts” on spoiled or decaying food. • The theory of spontaneous generation was reignited.

  6. Louis Pasteur • Pasteur conducted an experiment to prove the these “live beasts” were not spontaneous, but travelled through the air and onto other organisms where they begin to grow.

  7. “Life is a germ, and a germ is life” • Pasteur’s experiment: • One glassware with a swan shaped neck to expel microorganisms, filled with broth • One glassware with a broken top to allow organisms to easily enter the glassware, filled with broth • Pasteur boiled both glaswares and waited • That with the swan shaped neck did not develop microorganisms • That which was broken did develop microorganisms • This proved that microorganisms are not spontaneously generated, but are present and move through the air

  8. A.I. Oparin and Miller • A 20th century scientist, Oparinhypothesised that life may have begun during early Earth conditions with high heat, electricity, and extra oxygen • Stanley Miller tested this hypothesis by mixing hydrogen, methane, and ammonia with water vapor, and passed electricity through it. • He did produce some substances found in living things, but no organisms

  9. Miller Experiment

  10. Characteristics of life

  11. Characteristics of Life • Nonliving things may have one or more of the characteristics of life, but not all of the • All living things have all of the characteristics of life

  12. 1. Living things have cells • Cells build living things and also perform life functions living things need to thrive.

  13. 2. Reproduction • Most plants and animals reproduce through sexual reproduction: • Two parents produce offspring with characteristics of both parents • Some female fish will release eggs, which the male will fertilize with his sperm • Some plants have male and female parts on their flowers. A pollinating insect (such as a bee) will deliver sperm cells to the egg cells and a seed will develop

  14. Fish eggs

  15. Plant reproductive system

  16. Bellwork • Think about your weekend plans and write possibilities of scientific observations you could make.

  17. Reproduction • Asexual reproduction: reproduction that involves only one parent and in which the offspring is identical to the parent • Bacteria reproduce by dividing into two parts • Yeast reproduce by forming buds that break off

  18. Bacteria reproduction

  19. Yeast Reproduction

  20. 3. All living things grow and develop • Some living things grow and develop, some only do one or the other • Development can mean becoming more complex • A Newly conceived child is made of only a few cells, which will divide and develop into a baby. • Once born that baby will continue to develop • Give some examples of living things that grow and develop

  21. Living things respond to stimuli • Work with a partner next to you. • Complete the first two directions on the “try this” activity on page 33. • Make a hypothesis as to what would be your response to the last two stimuli. • Record your response after each. • Make a hypothesis as to why you respond the way you do to each stimulus.

  22. Bellwork 8-26 • Write about some Scientific observations you made this weekend. Don’t ask, “What if I didn’t make any.” ;-)

  23. 4. All living things respond to their environment • Anything that affects the activity of an organism is called a stimulus • The response can be an action, movement, or behavior change

  24. What stimulates you? • An alarm clock is a stimulus that wakes you up in the morning. • List 10 other stimuli that cause you to react during the day.

  25. 5. All things use energy • All living things need energy to survive • Some of the ways they obtain this energy is through: • Making food, breaking down food, moving material in and out of cells, and building cells • Some of these activities combine simple substances into more complex substances • Some break down complex substances into simpler substances an organism can use • The sum of all of these chemical processes in a living cell or organism is called Metabolism

  26. Chemical processes • Before metabolism can take place, living things must take in food or process their own • Plants process their own food through photosythesis: • They use water, carbon dioxide, and energy from the sun to make food

  27. Chemical processes continued • One-celled organisms can engulf their food • Fungi secret enzymes to break food down so they can absorb it • Sponges eat by filtering food from the water

  28. Metabolism • Once an organism has food, metabolism begins • The first step is digestion • Digestion breaks down the food into simpler substances • Some are used to build more complex substances, others are stored for energy

  29. Bellwork • Draw the diagram of the 5 characteristics of living things from memory

  30. Metabolism • Metabolism also includes respiration: • The process in which living things use gases to produce energy • Respiration for most living things includes oxygen. • Animals get energy from combining digested food with oxygen

  31. Byproducts • Respiration and digestion both produce byproducts that the living organism doesn’t need • We release carbon dioxide when we breathe out • Plants release oxygen and water • The process of releasing these byproducts is excretion • They are all used/recycled in some form

  32. Bellwork 8-28 • Given our lesson yesterday, can you think of another example of a byproduct? Discuss it in your bellwork.

  33. Recycled byproducts

  34. Homeostasis • To perform metabolism and other chemical activities, all living things must maintain homeostasis: • The ability to maintain a stable internal environment • When hot, we sweat to cool off • When cold, we shiver to generate heat

  35. The needs of living things • 1. Food • 2. Water • 3. Certain gases • 4. Space

  36. Needs of living things • Food: needed for energy and the raw materials needed to perform metabolism • Living things eat food that contain the chemicals and energy they need • This helps maintain balance

  37. Living things need water • You could live for a week or more without food, but you could only live for about 3 days without water.

  38. Water • Water serves many important needs • Dissolves many substances • Our blood, for example, is mostly water and dissolves the minerals and nutrients our bodies need and carries them throughout our bodies. • Tree sap, which is mostly water, also dissolves sugars and nutrients and carries them throughout the tree. • Frogs absorb water through their skin to serve the same purpose.

  39. Water

  40. Living things need energy • All living things produce energy through metabolism • All things use energy differently • A mushroom uses it to grow, a tree uses it to produce leaves, a bird uses it to build a nest. • What is the original source of the energy for all these living things?

  41. Living things need certain gases • Most living things need oxygen to survive (remember respiration!) • Land animals get this oxygen from the air • Aquatic animals get this oxygen from taking regular breaths above water, or using dissolved oxygen in the water

  42. Breathing oxygen

  43. Other Gases • Some species of bacteria live on gases like ammonia, sulfur dioxide, or methane that are poisonous to most other organisms

  44. Whatever process created Carlsbad and Lechuguilla is largely dormant now. So the team visits a more active and dangerous cavern: Cueva de Villa Luz in Mexico, which emits the toxic, rotten-egg smell of hydrogen sulfide from its entrance. Inside, explorers must wear respirators and carry poison-gas monitors to protect themselves from the hydrogen sulfide that reacts with water in the cave to form caustic sulfuric acid. Deep within, they discover "snottites," mucous-like stalactites of sulfur-eating bacteria that also drip sulfuric acid. Oddly enough, the noxious environment teems with microbes, spiders, insects, crabs, and fish—all thriving in complete darkness. As strange as it may seem, sulfuric acid produced by microbial life is the cause of about five percent of all limestone caves, including Cueva de Villa Luz, Carlsbad, and Lechuguilla. Sulfuric acid not only dissolves limestone, it leaves a distinctive chemical residue: gypsum. This process, which is ongoing now in Cueva de Villa Luz, was completed millions of years ago in Carlsbad and Lechuguilla, where microbial activity continues today at a very slow pace.

  45. Bellwork 8-29 • Give and example of each of the “needs of Living Things”

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