1. Biology: Life Sciences 🧬

Biology covers the study of living organisms - from microscopic cells to complex ecosystems. The DOST-SEI exam focuses on molecular biology, genetics, and ecology.

Topic	Key Concepts	DOST Focus Areas
Cell Biology	Cell structure, organelles, membrane transport	Mitochondria function, osmosis, active transport
Genetics	DNA/RNA structure, replication, transcription, translation	Punnett squares, codominance, mutations
Evolution	Natural selection, adaptation, speciation	Evidence of evolution, Hardy-Weinberg
Ecology	Food webs, nutrient cycles, population dynamics	Energy flow, carbon/nitrogen cycle
Human Physiology	Organ systems, homeostasis, immune response	Nervous system, endocrine system

DNA & Genetics Quick Reference:

DNA Structure:

Double helix with sugar-phosphate backbone
Base pairing: A-T (2 bonds), G-C (3 bonds)
5' to 3' direction

Mendel's Laws:

Dominance: One allele masks the other
Segregation: Alleles separate during meiosis
Independent Assortment: Genes on different chromosomes sort independently

💡 DOST Bio Tip:

Know the central dogma of molecular biology: DNA → RNA → Protein. Transcription happens in the nucleus; translation happens in ribosomes!

2. Chemistry: Matter & Reactions ⚗️

Chemistry is the study of matter and its transformations. DOST-SEI covers atomic structure, chemical bonding, stoichiometry, and organic chemistry.

Topic	Key Concepts	Common Questions
Atomic Structure	Protons, neutrons, electrons, electron configuration	Identify element from config, predict properties
Chemical Bonding	Ionic, covalent, metallic bonds; Lewis structures	Predict bond type, draw structures
Stoichiometry	Mole concept, molar mass, limiting reagent	Calculate product mass, percent yield
Acids & Bases	pH, buffers, neutralization, titration	Calculate pH, identify acid/base
Organic Chemistry	Functional groups, hydrocarbons, nomenclature	Name compounds, predict reactions

Essential Chemistry Formulas:

Stoichiometry:

n = m / M (moles = mass / molar mass)
n = N / Nₐ (moles = particles / Avogadro's)
Avogadro's Number: 6.022 × 10²³

Acids & Bases:

pH = -log[H⁺]
pOH = -log[OH⁻]
pH + pOH = 14

Periodic Table Trends:

Atomic Radius: Decreases across period, increases down group
Ionization Energy: Increases across period, decreases down group
Electronegativity: Increases across period, decreases down group
Metallic Character: Decreases across period, increases down group

3. Physics: Motion & Energy 🚀

Physics explains how the universe works - from falling objects to electromagnetic waves. DOST-SEI focuses on mechanics, waves, electricity, and thermodynamics.

Topic	Key Formulas	Variables
Kinematics	v = v₀ + at, s = v₀t + ½at², v² = v₀² + 2as	v=velocity, a=acceleration, t=time, s=displacement
Newton's Laws	F = ma, F₁₂ = -F₂₁	F=force, m=mass, a=acceleration
Work & Energy	W = Fd, KE = ½mv², PE = mgh	W=work, KE=kinetic, PE=potential
Waves	v = fλ, f = 1/T	v=wave speed, f=frequency, λ=wavelength, T=period
Electricity	V = IR, P = IV = I²R	V=voltage, I=current, R=resistance, P=power

Newton's Three Laws:

Inertia: An object at rest stays at rest; object in motion stays in motion (unless acted upon by external force)
F = ma: Force equals mass times acceleration
Action-Reaction: For every action, there's an equal and opposite reaction

Free Fall Motion:

g = 9.8 m/s² (acceleration due to gravity)
Object falls faster as time increases
Air resistance eventually balances gravity (terminal velocity)

Conservation Laws:

Energy: Energy cannot be created or destroyed
Momentum: p = mv (conserved in collisions)
Charge: Total charge is constant

4. Earth & Space Science 🌍

Understanding our planet and the universe beyond. Topics include geology, meteorology, and astronomy.

Earth's Structure:

Crust: Thin outer layer (oceanic & continental)
Mantle: Thick layer of silicate rock
Outer Core: Liquid iron-nickel
Inner Core: Solid iron-nickel

Plate Tectonics:

Divergent: Plates move apart (mid-ocean ridges)
Convergent: Plates collide (mountains, trenches)
Transform: Plates slide past (earthquakes)

🌏 Philippine Context:

The Philippines is part of the Pacific Ring of Fire, located at the convergence of multiple tectonic plates. This explains our frequent earthquakes and active volcanoes!

5. Scientific Method & Laboratory 🔬

Understanding the scientific process is essential for all STEM scholars.

Steps of Scientific Method:

Observation: Notice something interesting
Question: Ask "why" or "how"
Hypothesis: Make an educated guess (testable)
Experiment: Test hypothesis with controlled variables
Data Analysis: Collect and interpret results
Conclusion: Accept or reject hypothesis

Variable Type	Definition	Example
Independent	Variable you change/control	Amount of fertilizer
Dependent	Variable you measure	Plant growth height
Controlled	Variables kept constant	Sunlight, water, pot size

6. Practice Questions 📝

Question 1: Genetics (Biology)

In pea plants, tall (T) is dominant over short (t). If a heterozygous tall plant is crossed with a short plant, what percentage of offspring will be short?

Solution: Tt × tt

Punnett Square: Tt, Tt, tt, tt

Phenotypes: 2 Tall : 2 Short

Answer: 50% short

Question 2: Stoichiometry (Chemistry)

How many moles are in 88 grams of CO₂? (C=12, O=16)

Solution:

Molar mass of CO₂ = 12 + (16 × 2) = 44 g/mol

n = m / M = 88 / 44 = 2 moles

Answer: 2 moles

Question 3: Kinematics (Physics)

A car accelerates from rest at 2 m/s². What is its velocity after 5 seconds?

Solution: Using v = v₀ + at

v = 0 + (2)(5) = 10 m/s

Answer: 10 m/s

Question 4: pH Calculation (Chemistry)

What is the pH of a solution with [H⁺] = 1 × 10⁻⁵ M?

Solution: pH = -log[H⁺]

pH = -log(10⁻⁵) = -(-5) = 5

Answer: pH = 5 (acidic solution)

Question 5: Work & Energy (Physics)

A 2 kg object is lifted 5 meters. How much potential energy does it gain? (g = 10 m/s²)

Solution: PE = mgh

PE = (2)(10)(5) = 100 J

Answer: 100 Joules

Science