DepEd MELC reviewer for Grade 9 Science, Quarter 1. Master the concepts, tables, and common-mistake warnings below.
1
The Respiratory System
Air path: nose → pharynx → larynx → trachea → bronchi → alveoli. Gas exchange (O₂ in, CO₂ out) happens in the alveoli.
2
The Circulatory System
| Vessel | Function |
|---|---|
| Arteries | Carry blood AWAY from heart |
| Veins | Carry blood TO the heart |
| Capillaries | Exchange gases/nutrients |
💡 Exam Hack
Arteries → Away from heart. The heart has 4 chambers: 2 atria (top), 2 ventricles (bottom).
3
Healthy Lifestyle
Avoid smoking, exercise regularly, and eat a balanced diet to keep both systems healthy.
4
Path of Blood
Body → right atrium → right ventricle → LUNGS → left atrium → left ventricle → body
💡 Exam Hack
The right side pumps to the lungs; the left side pumps to the body.
📌 Quick Recap — Master These
Before your test, make sure you can confidently do each of the following:
- Explain and apply The Respiratory System.
- Explain and apply The Circulatory System.
- Explain and apply Healthy Lifestyle.
- Explain and apply Path of Blood.
Re-read any section above where you hesitate, then try the worked example again without looking.