Lecture Notes

Introduction

• Presenter: Hanjun, Sector Science Tutor at Over Marks
• Session Date: Sunday Evening
• Topics Covered: Electrical systems, digestive system, transport system, human reproductive system
• Previous Topics: Term 1 and 2 topics available on YouTube
• Materials: Available via QR Code or Google Drive Link
• Incentive: Kahoot game with a prize at the end of the session

Electrical Systems

Main Components

1. Electrical Current

   • Flow of electrons in one direction
   • Analogy: River flow
   • Models: Conventional (positive to negative) and Electron flow (negative to positive)
   • Measurement: Amperes (A), device used is Ammeter (drawn in series)

2. Potential Difference (Voltage)

   • Energy to move a charge between two points
   • Measurement: Volts (V), device used is Voltmeter (connected across components)

3. Resistance

   • Opposition to current flow
   • Relationship: Inverse with current
   • Measurement: Ohms (Ω)
   • Types: Fixed resistor (constant resistance), Variable resistor (varies resistance)

Circuit Types

• Series Circuit

  • Single path for current
  • Total resistance is the sum of individual resistances
  • Current is the same throughout

• Parallel Circuit

  • Multiple paths for current
  • Total resistance can be calculated using a specific formula
  • Total voltage is supplied to each branch

Wiring in the Main Plug

• Three wires: Live (current and voltage), Neutral (current, no voltage), Earth (safety, no current/voltage)
• Electrical dangers: Damaged wires, wet conditions, overloading, short circuit
• Precautions: Proper wiring, use of fuses, circuit breakers

Digestive System

Main Nutrients

• Carbohydrates: Energy
• Proteins: Growth and repair
• Fats: Insulation and energy

Digestion Process

• Enzymes: Proteins that speed up reactions
• Types: Carbohydrases, Proteases, Lipases
• Specificity: Each enzyme acts on only one type of nutrient

Organs Involved

1. Mouth

   • Chewing increases surface area
   • Enzyme: Salivary amylase (carbohydrate digestion)

2. Esophagus

   • Peristalsis (muscle contractions)
   • No digestion

3. Stomach

   • Gastric juice with HCl and proteases
   • Protein digestion

4. Small Intestine

   • Main site of digestion
   • Enzymes: Amylase, protease, lipase
   • Bile assists in fat digestion

5. Large Intestine

   • Water reabsorption
   • No digestion

Transport System

Key Processes

• Diffusion: Movement from high to low concentration
• Osmosis: Movement of water through a partially permeable membrane from high to low water potential

Plant and Animal Cells in Solutions

• Hypertonic: Cell loses water
• Hypotonic: Cell gains water (animal cell may burst)
• Isotonic: No net movement

Blood Components

• Red Blood Cells: Transport oxygen
• White Blood Cells: Immune function
• Platelets: Blood clotting
• Plasma: Transport nutrients and waste

Blood Vessels

• Arteries: Carry blood away from heart, high pressure
• Veins: Carry blood towards heart, low pressure
• Capillaries: Exchange of substances

Plant Transport System

• Xylem: Transports water and minerals
• Phloem: Transports sucrose
• Arrangement: Xylem near the center, Phloem outside

Human Reproductive System

Female Reproductive System

• Organs and functions

Male Reproductive System

• Organs and functions

Puberty

• Physical changes in boys and girls

Menstrual Cycle

• Day 1-5: Menstruation
• Day 6-10: Repair of uterine lining
• Day 11-16: Fertile period

Birth Control Methods

• Condoms: Male and female versions
• Diaphragm: Female condom
• IUD: Blocks implantation
• Contraceptive Pill: Stops ovulation
• Permanent Methods: Vasectomy, Tubal ligation

STIs (Sexually Transmitted Infections)

• Gonorrhea: Bacterial
• Syphilis: Bacterial
• HIV: Viral, causes AIDS

Conclusion

• Summary of key points
• Encouragement to study for exams
• Reminder about the Kahoot game for notes prize