Where Plant Mass Comes From

Start with Where Plant Mass Comes From so students know the equation, then use Stomata, Transpiration and Water Loss Data to apply it. The page 1 passage and table on the stomata sheet are the reference for the graph on page 2.

Count atoms in the photosynthesis equation to see where van Helmont's willow gained its mass. The directions on the page read: Read the text. Then count the atoms in the equation to complete the tally. An answer key is included.

Yes, both. We made it for 7th grade living things, and it works the same at home or at school. At home, a student can work through it alone and then go over it with you, which shows quickly what is solid and what needs another look. In class it works as independent practice, homework or a warm-up, and you can print one copy or a full set.

Van Helmont's willow gained about 164 pounds while the dried soil lost only about 2 ounces, so the soil was not the main source. The tree built its mass from water and from carbon dioxide in the air. Where Plant Mass Comes From has students count the atoms in the photosynthesis equation.

Stomata are tiny pores on the underside of a leaf, each surrounded by two guard cells. Open stomata let carbon dioxide in for photosynthesis and let water vapor out in transpiration.

Water vapor leaves through open stomata, and this loss is called transpiration. Stomata, Transpiration and Water Loss Data compares plants in shade, in sun and in sun with wind.