A narrow safe zone
Our body works in only a small stretch of the pH scale.
How wide is the safe zone?
The pH scale runs from 0 to 14. Our body works only between pH 7.0 and pH 7.8.
What does that tell us?
What this lesson covers
The idea
Living organisms survive only within a narrow range of pH, and plants need a specific pH range for healthy growth; the human body works within pH 7.0 to 7.8.
How wide is the safe zone?
The pH scale runs from 0 to 14. Our body works only between pH 7.0 and pH 7.8.
What does that tell us?
- A small change in pH can upset the body
- The body works at any pH from 0 to 14
- Only strong acids matter to the body
Find the safe zone
Slide the marker. Find where the body can work, then slide outside it.
Living things are picky about pH
Living organisms can survive only in a narrow range of pH. Plants need a specific pH range for healthy growth. The human body works within pH 7.0 to 7.8.
You can test soil from different places with pH paper to find the pH that a plant needs.
- Living thing | What it needs
- Human body | pH 7.0 to 7.8
- A plant | a specific pH range for the soil
- Any living thing | a narrow pH range
Notes
Living organisms survive only within a narrow range of pH, and plants need a specific pH range for healthy growth; the human body works within pH 7.0 to 7.8.
Check yourself
The human body works within which pH range?
A body fluid has a pH of 7.4. Is it inside the body's range?
The pH of a body fluid falls far below 7.0. What happens?
How can you find the pH a plant needs for healthy growth?
- 0 to 14. That is the whole scale. The body works in only a small part of it.
- 1.0 to 3.0. That is far too acidic for the body.
- 7.0 to 7.8 — correct. Yes! A narrow range.
- Yes, it is between 7.0 and 7.8 — correct. Yes!
- No, it is below 7.0. 7.4 is more than 7.0.
- No, it is above 7.8. 7.4 is less than 7.8.
- Nothing, the body works at any pH. The body can work only in a narrow range.
- The body cannot work properly — correct. Yes! Living things survive only in a narrow pH range.
- The body works even better. Outside the range the body is in trouble.
- Taste the soil. Never taste soil or chemicals. Use pH paper.
- All plants need exactly the same pH. Each plant needs its own specific range.
- Test the soil in which it grows well with pH paper — correct. Yes! Soil pH matters to plants.