Earth and Life Science: SSA Review

6th Grade – Earth Science

The Nature of Science

• Why is science always changing, and why is that a good thing?

  • Science is always changing because our understanding of the universe is constantly evolving as new evidence is discovered and new technologies are developed. This is a good thing because it allows us to refine our knowledge, correct errors, and gain a more accurate picture of the world around us.

Scientific Theories vs. Laws

• What is the difference between scientific theories and laws? Give an example of each. (p. 486)

  • Scientific Law: A scientific law is a statement that describes what always happens under certain conditions in nature. It is typically based on repeated experimental observations. For example, $Law\ of\ Gravity$. It describes the attraction between objects with mass.

  • Scientific Theory: A scientific theory is a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses. For example, $The\ Theory\ of\ Plate\ Tectonics$ explains the movement of the Earth's lithosphere.

Celestial Objects

• Arrange the following in order of smallest to largest: the Sun, Earth, the Moon, universe, galaxy, solar system. (p. 425, 464)

  • Moon, Earth, Sun, Solar System, Galaxy, Universe

Brightness of Stars

• What is the difference between the apparent and absolute brightness of stars? (p. 457)

  • Apparent Brightness: How bright a star appears to an observer on Earth. It depends on both the star's luminosity and its distance from Earth.

  • Absolute Brightness (Luminosity): The actual amount of light a star emits. It is a measure of intrinsic brightness, independent of distance.

• How do size and temperature affect the brightness of a star? (p. 457)

  • Size: Larger stars have a greater surface area, thus they emit more light and are brighter.

  • Temperature: Hotter stars emit more energy per unit area than cooler stars. The relationship is described by $Stefan-Boltzmann\ Law$, where luminosity is proportional to $T^4$.

Earth's Seasons

• What causes the Earth’s seasons? (p. 393)

  • Earth's seasons are caused by the tilt of Earth's axis of rotation (approximately $23.5$ degrees) with respect to its orbital plane around the sun. This tilt causes different hemispheres to receive more direct sunlight at different times of the year.

Earth's Tides

• What causes the Earth’s tides? (p. 406)

  • Tides are primarily caused by the gravitational pull of the Moon and, to a lesser extent, the Sun on the Earth's oceans. The Moon's gravity pulls the water on the side of the Earth closest to it, creating a bulge. A corresponding bulge occurs on the opposite side of the Earth due to inertia.

Lunar Phases

• What causes the phases of the Moon? (p. 402)

  • The phases of the Moon are caused by the changing relative positions of the Moon, Earth, and Sun. As the Moon orbits the Earth, we see different amounts of its illuminated surface.

Eclipses

• What causes solar and lunar eclipses? (p. 404)

  • Solar Eclipse: Occurs when the Moon passes between the Sun and Earth, blocking the Sun's light and casting a shadow on Earth.

  • Lunar Eclipse: Occurs when the Earth passes between the Sun and Moon, casting a shadow on the Moon and making it appear dimmer or reddish.

Solar Activity

• What are sunspots, prominences, and solar flares? (p. 436)

  • Sunspots: Darker, cooler areas on the Sun's surface caused by magnetic activity. Sunspots follow an $11$-year cycle.

  • Prominences: Large, bright, gaseous features extending outward from the Sun's surface, often looping back into the Sun. They are associated with magnetic field lines.

  • Solar Flares: Sudden releases of energy from the Sun, resulting in bursts of radiation across the electromagnetic spectrum. They can disrupt communications on Earth.

Weathering, Erosion, and Deposition

• What is the difference between weathering, erosion, and deposition? Give an example of how each one affects our beaches. (p. 151, 161)

  • Weathering: The breakdown of rocks, soils, and minerals through contact with the Earth's atmosphere, water, and biological organisms.

    • Beach Example: Waves crashing against cliffs cause the rock to break down into smaller sediments.

  • Erosion: The movement of weathered material by natural agents such as wind, water, or ice.

    • Beach Example: Waves carry sand particles away from the beach, reducing its size.

  • Deposition: The accumulation of eroded material in a new location.

    • Beach Example: Sand and sediment are deposited on the beach, building it up.

Physical vs. Chemical Weathering

• What is the difference between physical and chemical weathering? Give two examples of each.

  • Physical Weathering: The breakdown of rocks without changing their chemical composition.

    • Examples:

      • $Freeze-thaw\ cycle$: Water expands when it freezes, exerting pressure on surrounding rock.

      • $Abrasion$ : Rocks collide and wear each other down.

  • Chemical Weathering: The breakdown of rocks by changing their chemical composition.

    • Examples:

      • $Acid\ Rain$: Dissolves limestone.

      • $Oxidation$: Rusting of iron-rich rocks.

Rock Cycle

• Explain how rocks cycle between igneous, sedimentary, and, metamorphic. (p. 221-223, 228)

  • Igneous Rocks: Form from the cooling and solidification of magma or lava.

  • Sedimentary Rocks: Form from the accumulation and cementation of sediments.

  • Metamorphic Rocks: Form when existing rocks are changed by heat, pressure, or chemical reactions.

  • The rock cycle is a continuous process where rocks can transform from one type to another through various geological processes. For example, igneous rocks can be weathered and eroded into sediments, which then form sedimentary rocks. These sedimentary rocks can then be subjected to heat and pressure to become metamorphic rocks. Metamorphic rocks can then be melted to form magma, which cools to form igneous rocks, completing the cycle.

Continental Drift

• What evidence do we have of continental drift? (p. 248-249)

  • Fossil Evidence: Similar fossils found on different continents.

  • Geological Evidence: Matching rock formations and mountain ranges across continents, like the Appalachian Mountains and those in Europe.

  • Paleoclimatic Evidence: Evidence of past climates, such as glacial deposits found in unexpected locations.

  • Fit of the Continents: The apparent jigsaw-puzzle fit of continents like South America and Africa.

Law of Superposition

• What is the law of superposition? (p. 294)

  • In undisturbed sedimentary rock layers, the oldest layers are at the bottom and the youngest layers are at the top. This principle is fundamental for relative dating of geological strata.

Radioactive Dating

• How can we use radioactive dating to determine the age of rocks? (p. 298)

  • Radioactive dating uses the decay of radioactive isotopes (e.g., carbon-14, uranium-238) to determine the age of rocks and other materials. By measuring the ratio of the parent isotope to the daughter product, scientists can calculate how many half-lives have passed since the rock formed.

Plate Tectonics

• Explain the theory of plate tectonics. (p. 257)

  • The theory of plate tectonics states that the Earth's lithosphere is divided into several large and small plates that are constantly moving. These plates float on the semi-molten asthenosphere, and their interactions give rise to many geological phenomena.

Plate Tectonics and Geological Events

• Explain how plate tectonics result in earthquakes, volcanoes, and mountains. (p. 271-275)

  • Earthquakes: Occur when plates slide past each other along faults, releasing stored energy in the form of seismic waves.

  • Volcanoes: Form at subduction zones, where one plate slides beneath another, or at mid-ocean ridges, where plates are moving apart and magma rises to the surface.

  • Mountains: Formed by the collision of two continental plates, causing the crust to buckle and fold.

Weather vs. Climate

• What is the difference between weather and climate? (p. 129)

  • Weather: The short-term condition of the atmosphere at a specific location and time (e.g., temperature, precipitation, humidity, wind speed).

  • Climate: The long-term average of weather conditions in a region, typically over a period of 30 years or more.

Earth's Spheres

• Describe each of Earth’s five spheres. (p. 6)

  • Atmosphere: The layer of gases surrounding the Earth.

  • Hydrosphere: All the water on Earth, including oceans, lakes, rivers, and groundwater.

  • Geosphere: The solid Earth, including the crust, mantle, and core.

  • Biosphere: All living organisms on Earth and their environments.

  • Cryosphere: The frozen parts of Earth's system, including ice sheets, glaciers, and sea ice.

Wind Formation

• Explain how energy from the sun creates wind on Earth. (p. 59)

  • Solar energy heats the Earth's surface unevenly, causing differences in air temperature and pressure. Warm air rises, creating areas of low pressure, while cool air sinks, creating areas of high pressure. Wind is the movement of air from areas of high pressure to areas of low pressure.

7th Grade – Life Science

Levels of Organization

• List the following in order of smallest/simplest to largest/most complex: organs, tissues, cells, organ systems. (p. 88-89)

  • Cells, Tissues, Organs, Organ Systems

Cell Theory

• What are the three components of cell theory? (p. 52)

  • All living organisms are composed of one or more cells.

  • The cell is the basic unit of structure and function in living organisms.

  • All cells arise from pre-existing cells.

Plant vs. Animal Cells

• Which organelles are found in plant cells but not in animal cells? (p. 62, 65)

  • Cell wall, chloroplasts, large central vacuole

Organelle Functions

• Describe the functions of the following organelles: cell membrane, cytoplasm, nucleus, ribosome, mitochondria, chloroplast. (p. 63-65)

  • Cell Membrane: Regulates the movement of substances into and out of the cell.

  • Cytoplasm: The gel-like substance within the cell that contains the organelles.

  • Nucleus: Contains the cell's genetic material (DNA) and controls cell activities.

  • Ribosome: Synthesizes proteins.

  • Mitochondria: Produces energy (ATP) through cellular respiration.

  • Chloroplast: (Plant cells only) Carries out photosynthesis.

Body System Functions

• Describe the functions of the following body systems: digestive, respiratory, circulatory, reproductive, excretory, immune, nervous, musculoskeletal. (p. 90-93)

  • Digestive System: Breaks down food into nutrients that the body can absorb.

  • Respiratory System: Exchanges gases (oxygen and carbon dioxide) between the body and the environment.

  • Circulatory System: Transports blood, oxygen, nutrients, and waste products throughout the body.

  • Reproductive System: Enables the production of offspring.

  • Excretory System: Removes waste products from the body.

  • Immune System: Protects the body against disease.

  • Nervous System: Controls and coordinates body functions and responses.

  • Musculoskeletal System: Provides support, movement, and protection.

Body Systems Working Together

• Give two examples of multiple body systems working together. (p. 97-100)

  • Example 1: The respiratory and circulatory systems work together to deliver oxygen to cells and remove carbon dioxide. The respiratory system brings oxygen. The circulatory system transports oxygen to tissues and removes carbon dioxide waste.

  • Example 2: The digestive and circulatory systems work together to absorb and distribute nutrients from digested food. The digestive system breaks down food into nutrients, and the circulatory system transports these nutrients to cells throughout the body.

Domains of Life

• Describe the characteristics that differentiate the three domains: Bacteria, Archaea, and Eukarya. (p. 18, 27)

  • Bacteria: Prokaryotic cells (no nucleus), peptidoglycan in cell walls, diverse metabolic capabilities.

  • Archaea: Prokaryotic cells, lack peptidoglycan in cell walls, often found in extreme environments.

  • Eukarya: Eukaryotic cells (contain a nucleus and other membrane-bound organelles), more complex organization.

Kingdoms of Life

• Describe the characteristics that differentiate the four kingdoms: Animalia, Plantae, Fungi, and Protista. (p. 18, 27)

  • Animalia: Multicellular, heterotrophic (obtains nutrients by consuming other organisms), eukaryotic.

  • Plantae: Multicellular, autotrophic (produces its own food through photosynthesis), eukaryotic.

  • Fungi: Multicellular (mostly), heterotrophic (absorbs nutrients from organic matter), eukaryotic.

  • Protista: Mostly unicellular, eukaryotic, diverse modes of nutrition (autotrophic or heterotrophic).

Genetic Variation and Evolution

• Explain how genetic variation contributes to evolution. (p. 197)

  • Genetic variation provides the raw material for evolution. Differences in genes lead to different traits. These traits can be passed to offspring. Natural selection acts on these variations, favoring traits that enhance survival and reproduction, leading to adaptation and evolution.

Punnett Square

• Create and complete a Punnett square. Include the probability associated with each possible offspring. (p. 136-137)

  • A Punnett square is a diagram used to predict the genotypes and phenotypes of offspring based on the genotypes of their parents. For example:

  • Let's cross two heterozygous plants (Bb x Bb) where B is dominant for purple flowers and b is recessive for white flowers.

  • Punnett Square:

  	B	b
  B	BB	Bb
  b	Bb	bb

  • Genotypes:

    • BB: $25\%$

    • Bb: $50\%$

    • bb: $25\%$

  • Phenotypes:

    • Purple (BB or Bb): $75\%$

    • White (bb): $25\%$

Pedigree

• Create a pedigree. Include the probability of a certain phenotype for each person. (p. 141)

  • A pedigree is a diagram that shows the inheritance of a trait within a family. It uses symbols to represent individuals and their relationships. Shaded symbols typically indicate individuals expressing a particular phenotype. Probabilities can be calculated based on Mendelian genetics.

Mitosis vs. Meiosis

• Compare and contrast mitosis and meiosis. (p. 149)

  • Mitosis: Cell division that results in two identical daughter cells. Used for growth, repair, and asexual reproduction. Maintains the same number of chromosomes in the daughter cells.

  • Meiosis: Cell division that results in four genetically different daughter cells with half the number of chromosomes. Used for sexual reproduction.

Relationships Among Organisms

• Describe the following relationships among organisms: parasitism, mutualism, predation, competition, and commensalism. (p. 271-276)

  • Parasitism: One organism (the parasite) benefits, and the other organism (the host) is harmed.

  • Mutualism: Both organisms benefit.

  • Predation: One organism (the predator) kills and eats another organism (the prey).

  • Competition: Organisms compete for the same resources, such as food, water, or shelter.

  • Commensalism: One organism benefits, and the other organism is neither harmed nor benefitted.

Producers, Consumers, Decomposers, and the Carbon Cycle

• Describe the roles and relationships among producers, consumers, and decomposers and the carbon cycle. (p. 322)

  • Producers (Autotrophs): Organisms that produce their own food through photosynthesis (e.g., plants). They convert carbon dioxide into organic compounds.

  • Consumers (Heterotrophs): Organisms that obtain energy by consuming other organisms (e.g., animals). They release carbon dioxide through respiration.

  • Decomposers: Organisms that break down dead organic matter and release carbon back into the environment (e.g., bacteria and fungi).

  • Carbon Cycle: The continuous process by which carbon is exchanged among the atmosphere, biosphere, hydrosphere, and geosphere. Producers take in carbon dioxide, consumers eat producers (transferring carbon), and decomposers break down dead organisms (releasing carbon). Human activities, such as burning fossil fuels, can disrupt the carbon cycle.

Limiting Factors

• Give two examples of limiting factors and explain how they would affect an ecosystem. (p. 254)

  • Limiting Factors: Resources or environmental conditions that limit the growth, abundance, or distribution of organisms in an ecosystem.

    • Example 1: Water scarcity in a desert ecosystem limits the growth of plants, which in turn affects the animals that depend on those plants for food and shelter.

    • Example 2: Nutrient availability in a lake limits the growth of algae, which affects the entire food web.

Photosynthesis vs. Cellular Respiration

• Compare and contrast photosynthesis and cellular respiration. (Including reactants and products) (p. 306, 312)

  • Photosynthesis:

    • Reactants: Carbon dioxide and water.

    • Products: Glucose (sugar) and oxygen.

    • Equation: $6CO<em>2 + 6H</em>2O + Light\ Energy \rightarrow C<em>6H</em>{12}O<em>6 + 6O</em>2$

  • Cellular Respiration:

    • Reactants: Glucose (sugar) and oxygen.

    • Products: Carbon dioxide, water, and energy (ATP).

    • Equation: $C<em>6H</em>{12}O<em>6 + 6O</em>2 \rightarrow 6CO<em>2 + 6H</em>2O + Energy(ATP)$

  • Comparison: Photosynthesis uses carbon dioxide and water to produce glucose and oxygen, while cellular respiration uses glucose and oxygen to produce carbon dioxide, water, and energy. They are complementary processes.