Core Science Concepts: Physics, Biology, Chemistry Review

Posted on Sep 27, 2025 in Chemistry

Physics Concepts and Kinematics

Fundamental Physics Concepts

• Force: A push or pull that changes the motion of an object.
  • Unit: Newton (N).
  • Example: Pushing a shopping cart.
• Velocity: Speed in a given direction.
  • Formula: v = d/t.
  • Example: 20 m/s east.
• Speed vs. Velocity:
  • Speed: How fast (scalar quantity, no direction).
  • Velocity: Speed with direction (vector quantity).
  • Example: Speed = 60 km/h, Velocity = 60 km/h north.
• Displacement: The straight-line distance and direction from start to finish.
  • Example: Walk 3 km east then 3 km west → distance = 6 km, displacement = 0.
• Acceleration: Rate of change of velocity.
  • Formula: a = (v₏ – v₊)/t.
  • Example: Car speeds 0 → 20 m/s in 10 s = 2 m/s².
• Inertia: Resistance of an object to a change in motion.
  • Example: You lurch forward when a car brakes suddenly.

Biology: Genetics and Cell Division

Core Biology Concepts

• DNA (Deoxyribonucleic Acid): Molecule carrying genetic instructions.
  • Structure: Double helix, bases pair A–T, C–G.
  • Example: DNA determines hair color.
• Chromosome: DNA tightly coiled into a structure.
  • Humans: 46 chromosomes (23 pairs).
  • Example: Chromosome 23 = sex chromosomes (XX, XY).
• Gene: A section of DNA coding for a protein or trait.
  • Example: Eye color gene.
• Allele: Different versions of a gene.
  • Example: Brown eye allele (B), blue eye allele (b).
• Genotype vs. Phenotype:
  • Genotype: The genetic makeup (letters, e.g., Bb).
  • Phenotype: The physical trait (e.g., black hair).
• Mitosis: Cell division producing 2 identical body cells.
  • Purpose: Growth and repair.
  • Example: Skin healing after a cut.
• Meiosis: Cell division producing 4 non-identical gametes (sex cells).
  • Purpose: Sexual reproduction, variation.
  • Example: Sperm and egg formation.
• Mutation: Change in DNA sequence.
  • Examples: Caused by radiation; can lead to diseases or useful traits (e.g., antibiotic resistance).
• Dominant vs. Recessive:
  • Dominant allele: Always shows if present (B = black hair).
  • Recessive allele: Only shows if 2 copies are present (bb = red hair).
• Homozygous vs. Heterozygous:
  • Homozygous: Same alleles (TT or tt).
  • Heterozygous: Different alleles (Tt).
• Codominance: Both alleles expressed equally.
  • Example: Blood group AB.

Physics Laws, Units, and Formulas

Standard Physics Units

• Force (F) = Newtons (N)
• Mass (m) = kilograms (kg)
• Acceleration (a) = m/s²
• Velocity (v) = m/s (speed in a direction)
• Distance (d) = metres (m) or kilometres (km)
• Time (t) = seconds (s) or hours (h)

Newton’s Three Laws of Motion

1. 1st Law (Inertia): An object stays still or keeps moving in the same direction unless an external force acts on it.
   ➡️ Example: A car keeps rolling unless brakes (a force) stop it.
2. 2nd Law: F = m × a
   • Force = Mass × Acceleration.
     ➡️ Example: A 1000 kg car accelerating at 2 m/s² needs a force of 2000 N.
3. 3rd Law: Every action has an equal and opposite reaction.
   ➡️ Example: You push the ground when running → the ground pushes you forward.

Essential Physics Formulas

• Speed / Velocity:

  v = d/t

  ➡️ Example: 100 m in 4 s → v = 100 ÷ 4 = 25 m/s.
• Acceleration:

  a = (v₏ – v₊)/t

  ➡️ Example: Car goes from 0 to 20 m/s in 10 s → a = (20 – 0)/10 = 2 m/s².
• Force:

  F = m × a

  ➡️ Example: Mass = 1000 kg, a = 3 m/s² → F = 3000 N.
• Average Speed:

  Average Speed = Total Distance / Total Time

Forces and Motion Principles

• Balanced forces → no movement or constant motion.
• Unbalanced forces → cause acceleration.
• Vectors → arrows showing size and direction of force.

Motion Graphs (Distance-Time, Velocity-Time)

• Distance–Time Graph: Slope = speed. Steeper slope = faster speed.
• Velocity–Time Graph: Slope = acceleration.

Science Worked Examples (Multiple Choice Review)

Q1: Unit of Force

• Answer: Newton (N)

Q2: Acceleration Definition

• Acceleration = rate of change in velocity.

Q3: Velocity Definition

• Velocity = rate of change in position (speed + direction).

Q4: Jackson’s Displacement Calculation

• Travels: 2 km north → 3 km east → 2 km south.
• North and south cancel (2 km each).
• Displacement = 3 km east.

Q5: Position–Time Graph Interpretation

• If the line is straight (diagonal), motion is constant speed.
• Answer: Constant velocity in the positive direction.

Q6: Net Force Calculation

If diagram shows → 60 N right vs 40 N left →
Net = 60 – 40 = 20 N right.

Q7: Average Speed of Truck Calculation

• Distance = 150 km (to Bendigo) + 150 km (return) = 300 km.
• Time = 3 h + 2 h = 5 h.
• Speed = 300 ÷ 5 = 60 km/h.

Q8: Loaded Car Braking Analysis

• More mass = more inertia = harder to stop.
• Answer: Car has greater mass → decelerates more slowly.

Q9: Acceleration Calculation (km/h to m/s²)

• Speed change: 60 → 100 km/h in 8 s.
• Change = 40 km/h.
  Convert: 40 ÷ 3.6 ≈ 11.1 m/s.
• Acceleration = 11.1 ÷ 8 ≈ 1.4 m/s².

Q10: Distance Calculation

• d = v × t = 90 × 2 = 180 km.

Q11: Variable Identification in v=d/t

• In formula v = d/t, V = velocity.

Q12: Forces on a Car at Rest

A car at rest still has forces (gravity down + ground up).

Answer: At least 2 forces acting.

Q13: Dependent Variable Definition

• Dependent variable = what is measured.

Q14: Hypothesis Definition

• Definition = a prediction that can be tested.

Q15: Periodic Table Groups

• Elements in the same group = same number of valence electrons.

Q16: Noble Gas Identification

• Answer: Neon (Ne).

Q17: Group 18 Characteristics

• Non-reactive, gases at room temperature, full outer shells.

Q18: Ionization Trend in Group 2

• As you go down → atoms bigger → easier to lose electrons → lower ionization energy.
• Answer: Decreases because radius increases.

Q19: Rows and Columns in Periodic Table

• Rows = Periods
• Columns = Groups

Q20: Compound Carrying Genetic Instructions

• DNA.

Q21: DNA Structure

• Watson & Crick = Double helix.

Q22: Gametes Formed By

• Meiosis.

Q23: Chromosomes in Fertilized Egg

• 23 (sperm) + 23 (egg) = 46.

Q24: Alternative Forms of Gene

• Alleles.

Q25: Phenotype of Tt

• Tall (T = dominant).

Q26: Genotype of Red Hair

• Must be bb (homozygous recessive).

Q27: Parents with Black Hair → Red-Haired Child

• Must both be heterozygous (Bb).

Q28: Mutation Not Correct Statement

• “All mutations are harmful” = FALSE.

Q29: DNA Stands For

• Deoxyribonucleic Acid.

Q30: Chromosomes for Boy

• XY.

Q31: Complementary Sequence of GATTACA

• G ↔ C, A ↔ T
• CTAATGT.

Q32: Type B Blood Genotype

• Iᴮ Iᴮ or Iᴮ i.

Physics Calculations and Solutions (Q1-Q7)

Q1: Velocity and Acceleration from Graph

(Assumes velocity–time graph provided in exam)

• a) Velocity of car after 10 s: If line shows car at 20 m/s at 10 s → Answer = 20 m/s
• b) Acceleration over 20 s: If car went from 0 → 40 m/s in 20 s:

  a = (v₏ – v₊)/t

  a = (40 – 0)/20 = 2 m/s²

Q2: Bus Forces Analysis

• a) Vector arrows (Forces acting on a moving bus):
  • Forward driving force (engine)
  • Backward air resistance
  • Backward friction
  • Downward gravity
  • Upward normal/support force
• b) Resistance forces slowing bus:
  • Friction
  • Air resistance
  • Gravity (if on a slope)

Q3: Cheetah Speed Calculation

v = d/t = 100 m ÷ 4 s = 25 m/s

Q4: Dolphin Speed Calculation (Unit Conversion)

• Distance = 2 km
• Time = 3 minutes = 0.05 h (3/60)

v = d/t = 2 ÷ 0.05 = 40 km/h

Q5: Plane Force and Acceleration

• a) Force calculation: F = m × a

  F = 54,000 × 16 = 864,000 N

• b) New acceleration with extra mass (4,095 kg):

  New mass = 54,000 + 4,095 = 58,095 kg.
  Force remains 864,000 N.

  a = F/m = 864,000 ÷ 58,095 ≈ 14.9 m/s²

• c) Needed force for safe takeoff (a = 16 m/s², m = 58,095 kg):

  F = 58,095 × 16 = 929,520 N

Q6: Lizard Acceleration Calculation

a = (10 – 2)/4 = 8/4 = 2 m/s²

Q7: Ferrari Final Velocity Calculation

v₏ = v₊ + a t

v₏ = 10 + (50 × 3) = 10 + 150 = 160 m/s

✅ That’s all the Physics short answers done and solved.

Chemistry Fundamentals

Atomic Structure Basics

• Atoms: Smallest unit of matter.
• Protons (p⁺): Positive charge, located in the nucleus.
• Neutrons (n⁰): Neutral charge, located in the nucleus.
• Electrons (e⁻): Negative charge, orbit in shells.
• Atomic number: Number of protons (also equals electrons in a neutral atom).
• Mass number: Protons + neutrons.
• Isotopes: Atoms of the same element with different numbers of neutrons.

The Periodic Table Structure

• Rows = Periods (increasing atomic number).
• Columns = Groups (same number of valence electrons → similar properties).

Periodic Table Group Characteristics

Group 1: Alkali Metals (Li, Na, K, Rb, Cs, Fr)

• 1 valence electron.
• Soft, highly reactive metals.
• React strongly with water → hydrogen gas + alkaline solution.
• Reactivity increases down the group.

Group 2: Alkaline Earth Metals (Be, Mg, Ca, Sr, Ba, Ra)

• 2 valence electrons.
• Less reactive than Group 1 but still reactive.
• Form +2 ions.
• Burn with characteristic flame colors.

Group 3–12: Transition Metals

• Strong, hard metals.
• Good conductors of heat and electricity.
• Often form colored compounds.
• Can have multiple oxidation states (e.g., Fe²⁺, Fe³⁺).

Group 13: Boron Group (B, Al, Ga, In, Tl)

• 3 valence electrons.
• Metals (except B).
• Form +3 ions.

Group 14: Carbon Group (C, Si, Ge, Sn, Pb)

• 4 valence electrons.
• Can form covalent bonds.
• Includes nonmetal (C), metalloids (Si, Ge), metals (Sn, Pb).

Group 15: Nitrogen Group (N, P, As, Sb, Bi)

• 5 valence electrons.
• Form –3 ions (in compounds).
• Includes nonmetals, metalloids, and metals.

Group 16: Oxygen Group (Chalcogens: O, S, Se, Te, Po)

• 6 valence electrons.
• Very reactive nonmetals (O, S).
• Tend to form –2 ions.

Group 17: Halogens (F, Cl, Br, I, At)

• 7 valence electrons.
• Very reactive nonmetals.
• Form salts with metals (e.g., NaCl).
• Reactivity decreases down the group.

Group 18: Noble Gases (He, Ne, Ar, Kr, Xe, Rn)

• Full outer shells.
• Very stable, non-reactive.
• Colorless, odorless gases.

Chemical Bonding Types

• Ionic bonding: Metal + nonmetal. Transfer of electrons.
  ➡️ Example: NaCl (Na gives 1 e⁻ to Cl).
• Covalent bonding: Nonmetal + nonmetal. Sharing of electrons.
  ➡️ Example: H₂O (O shares with H).

Law of Conservation of Mass

• Law: Mass is not created or destroyed in a chemical reaction.
• Total mass of reactants = total mass of products.

Balancing Chemical Equations

• The number of atoms on the left side must equal the number on the right side.
• Example:

  2H₂ + O₂ → 2H₂O

Collision Theory and Reaction Rates

• Particles must collide with enough energy (activation energy) and correct orientation.
• Factors affecting reaction rate:
  • ↑ Temperature → faster rate.
  • ↑ Concentration → more collisions.
  • ↑ Surface area → more exposed particles.
  • Catalysts → lower activation energy.

Chemistry and Scientific Method Worked Examples

Q8: Periodic Table Data Completion

Q9: Sodium Chloride (Na + Cl) Bonding

• a) Bond type: Ionic bond (metal + nonmetal).
• b) Electron behavior:
  • Sodium loses 1 electron → becomes Na⁺.
  • Chlorine gains 1 electron → becomes Cl⁻.
  • Opposite charges attract → ionic lattice forms.

Q10: Identifying Atomic Components

(General method based on a hypothetical diagram showing Oxygen, 8 protons):

• Atom: Oxygen
• Symbol: O
• Valency: 2 (needs 2 more for a full shell)
• Electrons: 8 (neutral atom)
• Bonding electrons: 6 (outer shell)
• Ion electrons: 10 (O²⁻ ion)

Q11: Plant Growth Experiment Design

• a) Experiment design:
  • Grow plants under different sunlight levels (none, partial, full).
  • Measure growth over time (e.g., height in cm).
  • Keep same soil, water, pot size, plant type, and temperature (controlled variables).
• b) Dependent variable = growth (height).
• c) Independent variable = amount of sunlight.
• d) Controlled variables = soil, water, plant type, pot size, temperature.

Q12: Reaction Rate Experiment Analysis

• a) Purpose: Test how acid concentration affects reaction rate.
• b) Fastest reaction = Tube with highest concentration.
• c) Justification: Highest concentration = more particle collisions = faster reaction rate (measured by temperature change).
• d) Dependent variable = temperature change (rate of reaction).
• e) Independent variable = concentration of HCl.

Advanced Biology Concepts: Genetics and Cells

DNA and Genes

• DNA (Deoxyribonucleic Acid): The molecule that carries genetic instructions for growth, development, function, and reproduction.
  • A ↔ T (Adenine–Thymine)
  • C ↔ G (Cytosine–Guanine)
  • Shape = double helix (twisted ladder).
  • Sides = sugar + phosphate backbone.
  • Rungs = base pairs.
• Gene: A segment of DNA that codes for a protein (trait).
• Alleles: Different versions of a gene (e.g., brown eyes vs. blue eyes).
• Chromosomes: Long strands of DNA wrapped around proteins. Humans have 46 (23 pairs).

Cell Division: Mitosis and Meiosis

• Mitosis:
  • Produces 2 identical cells (growth/repair).
  • Same chromosome number as parent (46 → 46).
• Meiosis:
  • Produces gametes (egg + sperm).
  • Halves chromosome number (46 → 23).
  • Fertilization restores full set: sperm (23) + egg (23) = zygote (46).

Genetic Mutations

• Mutation: A change in DNA sequence.
• Can be caused by: radiation, chemicals, DNA copying errors.
• Not all harmful → some are neutral, some beneficial (e.g., antibiotic resistance).

Key Genetics Terminology

• Genotype: The genetic makeup (letters, e.g., Tt, Bb).
• Phenotype: The physical expression (tall, black hair).
• Homozygous: Two of the same allele (TT or tt).
• Heterozygous: Two different alleles (Tt).
• Dominant allele: Shows in phenotype even if only one copy.
• Recessive allele: Only shows if two copies present.

Genetic Inheritance and Punnett Squares

• Punnett Square: Used to predict offspring genotypes.

➡️ Example: Tall (T) is dominant, short (t) is recessive. Cross Tt × Tt →

• Genotypes: 1 TT, 2 Tt, 1 tt.
• Phenotypes: 3 tall, 1 short.

Understanding Pedigree Charts

• Squares = males.
• Circles = females.
• Shaded = affected individuals.
• Half-shaded = carrier (heterozygous).
• Tracks how traits are inherited in families.

Codominance and Human Blood Groups

• Codominance: Both alleles are expressed equally.
  • Example: Blood group AB (Iᴮ + Iᴮ).
• Blood types:
  • A = Iᴮ Iᴮ or Iᴮ i
  • B = Iᴮ Iᴮ or Iᴮ i
  • AB = Iᴮ Iᴮ
  • O = ii
• Universal donor: O
• Universal recipient: AB

Biology Worked Examples (Q13-Q21)

Q13: Genotype Example

• Genotype = alleles.
  ➡️ Example: Bb (black hair).

Q14: Phenotype Example

• Phenotype = appearance.
  ➡️ Example: Black hair.

Q15: Complementary DNA Sequence

Given: ATCCGAATCGGTCATCC
Answer: TAGGCTTAGCCAGTAGG

Q16: Punnett Square (BB × rr)

Father = BB (black), Mother = rr (red).

• Genotype = 100% Br.
• Phenotype = 100% black hair (since B is dominant).

Q17: Punnett Square (Bb × bb, Brown vs. Blue Eyes)

• 50% Bb = brown eyes.
• 50% bb = blue eyes.

Q18: Pedigree Chart Analysis (Haemophilia)

• Affected = hh. Carrier = Hh. Normal = HH.
• Answers:
  • George: healthy male (XY), genotype = HH.
  • Arlene: carrier female, genotype = Hh.
  • Tom: affected male, genotype = hh.
  • Ann: normal female, genotype = HH.
  • Sandra: could be HH or Hh (requires more data).
  • Michael: affected (hh).

Q19–Q21: Blood Type Genetics

• Homozygous B = Iᴮ Iᴮ
• Heterozygous A = Iᴮ i
• Type O = ii
• Type A with O parent = Iᴮ i
• Type AB = Iᴮ Iᴮ
• Universal donor = O
• Universal recipient = AB

Q20: Dad = Iᴮ Iᴮ, Mum = ii → offspring all Iᴮ i = Type B.

Q21 (Paternity Test):

• Mark = O = ii
• Matthew = A = Iᴮ i
• Luke = AB = Iᴮ Iᴮ (Impossible since dad is O = ii).
  → Luke is not their child (lacks Iᴮ or Iᴮ allele from father).

Mitosis: Detailed Definition and Purpose

Mitosis = the type of cell division that produces two daughter cells that are genetically identical to the parent cell.

• Used for: growth, repair, and replacing old/damaged cells.
• Chromosome number stays the same (46 → 46 in humans).
• Key stages:
  • DNA is copied (replication).
  • Chromosomes line up in the cell middle.
  • Chromosomes split and move to opposite ends.
  • Cell divides → 2 identical cells.

➡️ Mitosis = “cloning division” → exact copies.

Meiosis: Detailed Definition and Purpose

Meiosis = the type of cell division that produces four gametes (sex cells: sperm/egg), each with half the number of chromosomes.

• Used for: sexual reproduction.
• Chromosome number is halved (46 → 23 in humans).
• Introduces genetic variation (different combinations).
• Steps:
  • DNA copied once.
  • Cell divides twice → 4 cells.
  • Each gamete = unique combination of genes.

➡️ Meiosis = “mixing division” → halves number and creates variation.

Fertilization Process

• Egg (23 chromosomes) + Sperm (23 chromosomes) = Zygote (46 chromosomes).
• Restores the full chromosome number.

Simple Inheritance Mechanisms

Dominant and Recessive Alleles

• Dominant allele (A): shows even if only one copy is present.
• Recessive allele (a): only shows if two copies (aa) are present.

➡️ Example: Brown eyes (B) vs. blue eyes (b)

• BB = brown
• Bb = brown (dominant shows)
• bb = blue

Homozygous vs. Heterozygous

• Homozygous: two of the same allele (AA, aa).
• Heterozygous: two different alleles (Aa).

Genotype vs. Phenotype

• Genotype = letters (Bb, tt, Iᴮ i).
• Phenotype = physical trait (brown eyes, short, type A blood).

Punnett Squares – Detailed Example

Example: Tall (T = dominant), short (t = recessive).

Cross Tt × Tt:

• Genotypes: 1 TT, 2 Tt, 1 tt.
• Phenotypes: 3 tall, 1 short.
• Ratio = 3:1.