**This Powerpoint specifically uses the Cambridge AS Level Biology Syllabus and covers all criteria for – Unit 14 Homeostasis in Plants
**
Students will be able to -

1 explain that stomata respond to changes in environmental
conditions by opening and closing and that regulation of
stomatal aperture balances the need for carbon dioxide
uptake by diffusion with the need to minimise water loss by
transpiration

2 explain that stomata have daily rhythms of opening and
closing

3 describe the structure and function of guard cells and explain
the mechanism by which they open and close stomata

4 describe the role of abscisic acid in the closure of stomata
during times of water stress, including the role of calcium ions
as a second messenger

**Every Powerpoint includes learning objectives, a starter and plenary, suitable activities and review questions with mark scheme. We also provide a FREE pdf version of the file so it can easily be printed for students as a handout or uploaded to the school VLE system
**
Bring your Cambridge AS Level Biology lessons to life with our expertly designed teaching resources. Each unit is tailored to the latest syllabus, offering ready-to-use lesson plans, engaging experiments, and visually clear notes that save hours of prep time. Whether you’re new to the course or refining your approach, The Science Shelf gives you everything you need to boost student understanding and exam success — all in one place.