A1.1 - Water
Guiding Questions
- What physical and chemical properties of water make it essential for life?
- What are the challenges and opportunities of water as a habitat?
SL and HL Content
A1 - 1.1—Water as the medium for life
Students should appreciate that the first cells originated in water and that water remains the medium in which most processes of life occur.
Water & the Origin of Life
Life on Earth depends on water—no known life can exist without it.
The first cells originated in water, likely in the oceans.
Water shielded early life from harmful ultraviolet radiation.
The Earth initially lacked liquid water due to extreme heat.
As the planet cooled, water formed and the water cycle began.
Oceans provided the solvent necessary for the complex biochemical reactions that support life.
The cell membrane evolved to separate intracellular water (cytoplasm) from ocean water.
Syllabus Link: B2.1 – Membranes & Membrane Transport
