6 th Grade Science Review

1. 6th Grade Science Review Microorganisms Heat Light Sound

2. Microorganisms • Microorganisms can only be seen with a microscope. • 6 Kingdoms of Life: • Plant • Animal • Fungi • Protista • Eubacteria • Archaebacteria Microorganisms

3. Microorganisms - Bacteria Prokaryotes (no nucleus or organelles) Unicellular Live everywhere Need food and moisture to survive. Helpful: decomposers; fuel(methane); medicine production; foods (yogurt, cheese, sour cream, buttermilk, pickles, apple cider); digestive system. Harmful: diseases (strep, Lyme disease, blood poisoning, whooping cough, meningitis, tuberculosis, tetanus.)

4. Microorganisms - Protista • One-celled or multi-celled organisms with a nucleus and organelles; all live in moist surroundings. • Eukaryotes – they have a nucleus. • They can be heterotrophs (eat other things) or autotrophs (make their own food using sunlight). • Three categories: • Protozoan (animal-like) • Algae (plant-like) • Fungus-like

5. Microorganisms - Protozoan • Unicellular heterotrophs • Classified according to the way the move: • Flagellum – long, whip-like extensions • Cilia – hairlike structures • Pseudopods – cell extension filled with cytoplasm; “false foot.” • Ameba (Sarcodines) – Pseudopods, irregular shapes. • Paramecium (Ciliates) – Cilia; large and small nucleus. • Zooflagellates – Flagellum; can be parasites (Giardia). • Sporozoans – Parasites; flagellum/slime (Malaria).

6. Microorganisms - Algae Euglenoids – green; autotroph and heterotroph; unicellular; fresh water; flagellum; eye spot. Dinoflagellates – many colors; 2 flagella; unicellular; stiff shell-like plates; salt water. Diatoms – glass-like cell walls; salt/fresh water, provide oxygen; toothpaste, cleaners, pool filters, pesticides. Green Algae – uni-/multicellular; fresh/salt water or moist soils. Red Algae – multicellular ; ice cream, hair conditioners. Brown Algae – cool, rocky water; kelp; eaten for nutrients.

7. Microorganisms – Fungus-like Protists • Heterotrophs; cell walls; spores. • Water Molds and Downy Mildews • Live in water/moist places; attack and kill fish. • Slime Molds • Live in moist soil/decaying plants and trees; pseudopods.

8. Microorganisms - Fungi Unicellular (yeast) or multicellular (mushrooms). Eukaryotes Heterotrophs Helpful: decomposers; yeast – bread and wine; molds – cheeses; mushrooms; disease-fighting fungi used in antibiotics; some help plants grow larger and healthier. Harmful: some mushrooms are poisonous; diseases in crops- corn smut, wheat rust; diseases in humans – athlete’s foot, ringworm.

9. Sound - Waves Amplitude = the maximum distance the particles of the medium carrying the wave move away from the rest position. Wavelength = the distance between two corresponding parts of a wave (crest to crest, trough to trough). Frequency = the number of complete waves that pass through a given point in a certain amount of time.

10. Sound • Sound is a disturbance that travels through a medium as a longitudinal wave (Vibrations!) • Sound moves out in all directions from the source. • Intensity = the amount of energy the wave carries. • Loudness = describes what you actually hear (higher intensity = more energy= louder sound). • Pitch = how high or low the sound seems to a person. • Pitch is related to frequency (higher frequency = higher pitch).

11. Light - Reflection Light can be reflected, absorbed, or transmitted. Opaque material reflects or absorbs all of the light that strikes it. (You see this material). Transparent material transmits or lets in all light. Translucent material scatters light as it passes through. Reflection = light hits an image and the image bounces back. Law of reflection: the angle of reflection equals the angle of incidence. Concave mirror – real/virtual image, focal point; Convex mirror – virtual image, smaller, farther away.

12. Light - Refraction When light rays enter a new medium (such as water) at an angle, the change in speed causes them to bend or change direction. Prisms separate white light into all the colors of the visible spectrum. Red, orange, yellow, green, blue, (indigo), and violet = order from longest wavelength to shortest. Concave lens – thinner in center; virtual image. Convex lens – thick in center; image depends on focal point.

13. Light - Color • The color of an object is the color it reflects. • White reflects all colors; black absorbs all colors. • Primary colors of light: red, blue, green. • TV and computer screens. • Secondary colors: cyan, magenta, yellow. • Pigments – substances used to color other materials.

14. Heat Heat = the movement of thermal energy from a substance at a higher temperature to a lower temperature. (Hot  Cold). Conduction = Transfer of heat through direct contact (“Can Touch”). Convection = Transfer of heat through currents – water or air. (“Heat rises”). Radiation = Transfer of heat through electromagnetic waves. (Sun). Conductor = a material that conducts/transfers heat well (metal, water, glass). Insulator = a material that does not conduct heat well (plastic, wool, wood, styrofoam).