Life Science Grade 8

1. Life Science Grade 8 Chapters 5, 18, 19, 22

2. Chapter 5 Heredity

3. What is Genetics? • Heredity: passing of traits from parents to offspring • Alleles: different forms a gene may have for a trait • Genetics: the study of how traits are inherited through the actions of alleles • Purebred- organism that always produces the same traits in its offspring

4. The Father of Genetics Gregor Mendel (Austrian Monk born in 1822) Experimented with garden peas • Quick germination • Quick growth • Easily observable traits

5. Mendel’s Experiments • Mendel cross-pollinated purebred tall plants with purebred short plants • He pollinated the plants himself! • Results: tall plants crossed with short plants produced tall plants • it seemed as though the short trait had “disappeared”

6. Dominant & Recessive Factors • Mendel called the tall plants “dominant” • The tall “covered up” the short • Dominant – tall • He called the form that disappeared "recessive” • Recessive- short What happened to the recessive (short) form?

7. Mendel’s Experiments • Next, Mendel allowed the tall plants to self-pollinate • Then, he collected the seeds from these tall plants & planted them • RESULT: for every 3 plants tall, there was 1 short plant (3:1 ratio) • He saw this 3:1 ratio often enough to know that the probability was great • He would get the same outcome each time

8. Using A Punnett Square Punnett Square: used to predict results Dominant Allele = Capital Letter (G) Recessive Allele = Lower Case (g)

9. Using a Punnett Square (con’t) • Homozygous- organism with two alleles that are identical for a trait (BB) (bb) • Heterozygous- organism with two alleles that are different for a trait (Bb)

10. Using A Punnett Square (con’t) • Genotype- genetic makeup • Phenotype- physical expression of the trait

11. Punnett Square Practice

12. Human Genetics Investigating Inherited Traits Lab!

13. Chapter 18 Life & The Environment

14. Living & Nonliving Environment • Biosphere- part of the earth that supports living organisms • Abiotic Factors- nonliving physical features of the environment (air, water, soil, light, temp.) • Biotic Factors- all of the living organisms in the environment (plants, animals, etc.)

16. Characteristics of Populations • Population Density: size of a population occupying an area of a specific size • Limiting Factor: any biotic or abiotic factor that restricts the number of individuals of a population • Carrying Capacity: largest number of individuals an environment can support & maintain for a period of time • Biotic Potential: number of individual each female of a population can produce under the best possible conditions

17. Predator-Prey Relationships • Predation: feeding of one organism on another

18. Symbiosis- any close relationship between 2 or more different species(can be positive, negative, or neither)

19. Flow of Energy • All energy is derived from the sun • Energy is transferred from the sun through all tropic levels Only about 10% of the energy available at each level is transferred to the next level.

20. Breakdown of the Energy Pyramid The level of the energy pyramid consists of: • Producer (produces its own food) • Primary Consumer (feeds on producers) • Secondary Consumer (feeds on primary consumer) • Tertiary Consumer (feeds on consumers)

21. Food Chain Terms • Producer: produces its own food • Herbivore: eats only plants • Carnivore: eats only meat • Omnivore: eats both plants & meat • Scavenger: feeds on dead remains of plant/animal • Decomposer: breaks down organisms & returns nutrients to the soil

22. Food Chain- animals that have a feeding relationship Reminders: food & energy are moving from one organism to another Arrows are drawn in the direction that energy flows Label the food chain above using “food chain terms”

23. Food Web- linking together of food chains

24. Hydrologic (Water) Cycle Evaporation from plants is called Transpiration

25. Nitrogen Cycle

26. Chapter 19 Ecosystems

27. How Ecosystems Change Ecological Succession- process of gradual change from one community of organisms to another

28. Primary Succession • Primary Succession- begins in a place that does not have soil • Lava flow, raised coral reef

29. Pioneer community- first community of organisms in this new environment • Hardy organisms that can survive drought, extreme heat & cold, and other harsh conditions

30. Secondary Succession • Secondary Succession- begins in a place that already has soil • Burned down forest, abandoned parking lot, demolished building

31. Climax Community- has reached the final stages of ecological succession • - May take hundreds or even thousands of years • - Complex food webs

32. BIOMES • Biome- large geographic areas with similar climates & ecosystems • Factors that Effect Biomes: • Temperature • Latitude • Elevation • Precipitation

33. TUNDRA • Cold, dry, treeless region • “Cold Desert” w/ little rain • Permafrost (permanently frozen soil) Popular Species: lichen, moss, grass, small shrubs, muskoxen, reindeer, mosquitoes, birds, lemmings, Arctic hares, caribou

34. TAIGA • Cold region of cone-bearing evergreens (pines, spruces, firs, hemlocks, cedars) • Shrubs & grasses (lichen, moss) Popular Species: plants from above, moose, black bears, lynx, wolves

35. TEMPERATE DECIDUOUS FOREST • You are here! (not at the mall) • Trees lose leaves every autumn • Beauty of Autumn • Good soil = lots of vegetation Popular Species: maple, oak, beech, birch, sycamore trees, deer, foxes, squirrels, mice, snakes, huge number of birds & insects

36. TROPICAL RAIN FOREST • Found near the equator • Abundant rainfall & high temperature & humidity • Unique plant & animal life • Lush, dense forest Popular Species: snakes, lizards, frogs, parrots, toucans, cockatoos, humming birds, ocelots, peccary, jaguars, orchids, ferns, mosses, bromeliads

37. Layers of Vegetation • Canopy- top of forest (leafy branches of trees) • Understory- shrub layer • Forest Floor (dark & moist)

38. GRASSLANDS • Dominated by grass • Little rainfall (more than desert or tundra) • Grasslands are found on nearly every continent Popular Species: kangaroos, wildebeests, zebras, meadowlarks, prairie chickens & dogs, bison wheat, oats, barley, rye, corn (harvested here)

39. DESERT • Driest biome on earth! • Less than 25 cm of rainfall yearly • Little plant life • Poor soil • Barren, Windblown Popular Species: whitetail deer (largest population in world), sagebrush, cacti, lizards, iguanas, tarantulas, roadrunner, coyote

40. Adaptations of Desert Plants & Animals • Adaptation- any characteristic an organism has that makes it better able to survive in its surroundings… adaptations are INHERITED

41. Chapter 22 Nutrients & Digestion

42. WHAT do you eat? • Breakfast: • Lunch: • Dinner: • Snacks:

43. WHY do you eat? • To obtain energy for your body to carry out cell development, growth, & repair

44. NUTRIENTS Nutrient- substances in foods that provide energy & materials for cell development, growth, and repair

45. Foods that contain the same nutrients belong to a food group

46. We have now moved toward the “My Plate” model…

47. Antioxidants Antioxidants- substances that prevent other chemicals from reacting with oxygen • fruits & vegetables are known to contain antioxidants that lower the risk of getting various diseases

49. Enzymes- Nature’s Chemists Enzyme (AKA: “CATALYST”) substance that speeds a chemical reaction (without raising the temperature) *enzymes are not changed by reactions