KS3 Biology — Bacteria in the Digestive System — Free Worksheet

🦠 Find out what bacteria are and why some are harmful while others are essential for life with this free KS3 Biology worksheet — no preparation required, just download and use. Bacteria are unicellular microorganisms, and while some cause disease, others such as gut flora are essential for digestion and health, and this taster resource introduces the basics for students aged 11–14.

📦 What's included:

3 questions, 13 marks:

Multiple choice — what bacteria are and their structure

Fill-in-the-blank — a passage using five key terms including unicellular, microorganism, cell wall, cytoplasm, and nucleus

Short answer — giving examples of helpful and harmful bacteria with explanations

Full answer key with detailed marking guidance included as a separate file.

🎬 Watch the free video lesson: https://www.youtube.com/watch?v=LUK9uywIB_g

👩‍🏫 Google Classroom ready — copy the link straight into your assignment. Print as many copies as your class needs.

🔓 This is a taster only. The full 100-mark worksheet goes deeper into the role of gut flora in the digestive system, how bacteria produce enzymes to digest food the body cannot break down alone, how gut bacteria compete with harmful pathogens to protect health, and what damages gut bacteria and how to restore it — available on its own, or as part of the Complete Lesson Pack with extension activities. Save £1 buying the pack (£3 + £3 = £6 separately, £5 together).

Price: Free