🔥 Register Your Interest For Our Primary/Secondary Science & Math Programmes

Register
Back to Home

How Undigested Food Changes In The Digestive System

Published By

Lim Zi Ai

PSLE Science Specialist | Secondary Math Specialist

Last Updated: December 11, 2025

Editorial Policy & Guidelines

Our content is meticulously crafted and reviewed by experts in the field of education, ensuring accuracy and relevance by referencing reliable sources aligned with the MOE syllabus in Singapore. Before publication and significant updates, we rigorously confirm the factual integrity, delivering well-informed articles grounded in scientific principles and teachings.

Table of contents

Just recently, a parent in our Parent Support Group asked us for help on a question on the amount of undigested food in the different organs of the digestive system.

Read Also

  1. Digestive System: What Happens In The Small & Large Intestines?
  2. Fungi & Bacteria: How Does Mould Grow On Cheese?
  3. Maris Stella High School (MSHS) P3 SA1 Examination Paper Analysis

As such, in today’s article, I’ll be sharing on the process of digestion and what the amount of undigested food at the end of each organ is.

 

Question:

Explanation

Part A – Mouth – Digestion starts here

  • Food first enters the mouth where it is broken down into smaller pieces and acted on by the saliva.
  • The amount of digested food increases, while the amount of undigested food DECREASES when the food is leaving the mouth (A).

Part B – Gullet– No digestion occurs here

  • The gullet contains muscles to push the food down to the stomach.
  • The amount of digested food remains the same and the amount of undigested food REMAINS THE SAME.

Part C – Stomach – Digestion continues to occur here

  • The stomach acts like a washing machine to churn and mix the undigested food with the stomach’s digestive juices for the food to be digested.
  • The food stays in the stomach for a couple of hours before it is released into the small intestine.
  • The amount of digested food increases and the amount of undigested food DECREASES.

Part D – Small Intestine – Digestion continues to occur and ends here

  • The small intestine has the largest amount of digestive juices and will most of the digestion of food is carried out here.
  • After the food that can be broken down has been digested, the digested food is then absorbed into the bloodstream through the walls of the small intestine.
  • The amount of digested food increases and the amount of undigested food DECREASES.

Hence, the answer for this MCQ is Option 2.

I hope that this article has helped to introduce the functions of the different parts of the digestive system and clarify where digestion takes place in the system!

Got Some Good Takeaways?

Check Out Our Heat Energy Masterclass

Learn More
About Lim Zi Ai

I really enjoyed the annotations that Ms. Zi Ai did on questions. It really helped me understand what the question is asking for.

7 comments

Leave your comment

Table of contents

🔥 Similar Articles

November 12, 2025

Rate: How Many Men Can Build 5 Boats In 1 Day?

Trisha Wong

PSLE Math Specialist

November 12, 2025

Solving Whole Numbers Questions Using The Model Method

Trisha Wong

PSLE Math Specialist