5.2 Integrated Science: Biology, Chemistry, Physics & Earth Science

Integrated Science: Biology, Chemistry, Physics & Earth Science

The General Science component of the ACET spans four major scientific disciplines. Success requires a firm grasp of core vocabulary, foundational equations, biological structures, chemical reactions, physical laws, and Earth system processes.

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1. Biological Sciences

Cell Biology & Organelles

All living organisms are composed of cells—prokaryotes (lacking a membrane-bound nucleus, e.g., bacteria) or eukaryotes (containing membrane-bound organelles, e.g., plants, animals, fungi).

Bioenergetics: Photosynthesis vs. Respiration

• Photosynthesis Equation: $$6\text{CO}_2 + 6\text{H}_2\text{O} + \text{Light Energy} \xrightarrow{\text{Chlorophyll}} \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$$
• Cellular Respiration Equation: $$\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + 36\text{--}38\text{ ATP}$$ Respiration occurs in three stages: Glycolysis (cytoplasm, anaerobic, net 2 ATP), Krebs Cycle (mitochondrial matrix, 2 ATP), and Oxidative Phosphorylation / Electron Transport Chain (inner mitochondrial membrane, ~32–34 ATP).

Genetics & Inheritance

Gregor Mendel's Laws of Inheritance:

1. Monohybrid Cross ($Aa \times Aa$): Produces a 3:1 phenotypic ratio (Dominant : Recessive) and a 1:2:1 genotypic ratio ($1 AA : 2 Aa : 1 aa$).
2. Dihybrid Cross ($AaBb \times AaBb$): Produces a 9:3:3:1 phenotypic ratio.
3. Central Dogma: DNA $\xrightarrow{\text{Transcription}}$ RNA $\xrightarrow{\text{Translation}}$ Protein. DNA uses bases A, T, C, G; RNA replaces Thymine with Uracil (U).

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2. Chemical Sciences

Atomic Structure & Periodic Trends

• Subatomic Particles: Protons ($p^+$, $+1$ charge, mass $\approx 1\text{ amu}$), Neutrons ($n^0$, neutral, mass $\approx 1\text{ amu}$), Electrons ($e^-$, $-1$ charge, negligible mass).
• Atomic Number ($Z$): Number of protons (defines the element). Mass Number ($A$): Protons $+$ Neutrons.

Periodic Table Trends:
  Increase Electronegativity & Ionization Energy  --->
  +--------------------------------------------------+
  |                                                  | ^
  |                                                  | |
  |                                                  | |
  +--------------------------------------------------+
  Increase Atomic Radius <--- | Downward Increase v

• Electronegativity: The ability of an atom to attract shared electrons in a bond (Fluorine is the most electronegative element).
• Ionization Energy: Energy required to remove an electron from a gaseous atom.
• Atomic Radius: Distance from nucleus to valence shell; decreases across a period (left to right) and increases down a group.

Bonding & pH Scale

• Ionic Bonding: Transfer of electrons from a metal (cation) to a nonmetal (anion), e.g., $\text{NaCl}$.
• Covalent Bonding: Sharing of electron pairs between nonmetal atoms, e.g., $\text{H}_2\text{O}, \text{CO}_2$.
• pH Scale: Logarithmic scale measuring hydrogen ion concentration: $\text{pH} = -\log[\text{H}^+]$.
  • $\text{pH} < 7$: Acidic (higher $[\text{H}^+]$)
  • $\text{pH} = 7$: Neutral (pure water at $25^\circ\text{C}$)
  • $\text{pH} > 7$: Basic / Alkaline
  • Logarithmic Rule: A drop from pH 6 to pH 4 represents a 100-fold ($10^2$) increase in acidity ($[\text{H}^+]$).

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3. Physics & Mechanics

Classical Mechanics & Newton's Laws

1. First Law (Inertia): An object remains at rest or in uniform motion unless acted upon by a net external force.
2. Second Law ($F = ma$): Force equals mass times acceleration ($1\text{ N} = 1\text{ kg}\cdot\text{m/s}^2$).
3. Third Law (Action-Reaction): For every action, there is an equal and opposite reaction.

Work, Energy & Electricity

• Work: $W = F \cdot d \cdot \cos\theta$ (measured in Joules, $1\text{ J} = 1\text{ N}\cdot\text{m}$).
• Kinetic Energy: $KE = \frac{1}{2} m v^2$ | Potential Energy: $PE = m g h$.
• Law of Conservation of Energy: Total mechanical energy ($KE + PE$) remains constant in an isolated system without friction.
• Ohm's Law: $V = I R$, where $V$ is Voltage (Volts), $I$ is Current (Amperes), and $R$ is Resistance (Ohms $\Omega$).

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4. Earth & Atmospheric Science

Earth Structure & Plate Tectonics

Earth is divided into Crust, Mantle, Outer Core (liquid iron-nickel driving the magnetic field), and Inner Core (solid iron-nickel).

• Convergent Boundaries: Plates collide (subduction zones form deep trenches, volcanic arcs, and mountain ranges like the Himalayas).
• Divergent Boundaries: Plates separate (mid-ocean ridges, rift valleys).
• Transform Boundaries: Plates slide past each other horizontally (cause shallow earthquakes along fault lines like the Marikina Valley Fault System).

Atmospheric Layers & Weather Events

• Troposphere: Lowest layer containing 75% of atmospheric mass; all weather phenomena occur here.
• Stratosphere: Contains the Ozone Layer ($\text{O}_3$), which absorbs harmful ultraviolet (UV-B and UV-C) solar radiation.
• El Niño vs. La Niña: El Niño is the anomalous warming of sea surface temperatures in the central/eastern tropical Pacific, causing prolonged droughts in the Philippines. La Niña involves anomalous cooling, bringing heavy rainfall and flooding.