A class weighs the dry dirt in a pot at 5,000 grams and plants a seedling. Months later the plant has gained 900 grams and the dried dirt weighs 4,990 grams. What do these results support?

A student claims that plants build their bodies mostly out of the dirt they grow in. Which observation would give the strongest evidence against that claim?

A tall oak tree holds hundreds of kilograms of wood. Where did the material in all that wood chiefly come from?

Some farmers grow lettuce with the roots hanging in water that has no dirt in it at all. The lettuce still grows large, green leaves. What does this show?

A plant gets the material it grows with by eating food from the soil, the way an animal eats its meals.

A plant's leaves take in something from the air that becomes part of the plant's new material. What is it?

Sunlight gives a plant the energy it needs, and sunlight is also the material the plant's wood and leaves are built from.

What do a plant's roots chiefly take in from the ground so the plant can build new material?

Two identical pots of dry dirt are weighed. A bean seed is planted in one and nothing is planted in the other. Both are watered the same for two months. What result would be expected?

A gardener wants to test whether a plant needs air to keep gaining material. What should be kept the same for both plants in the test?

A healthy plant is sealed inside a clear box with fresh air locked out. It gets plenty of light and water but slowly stops gaining material. What claim does this best support?

Old trees have stood in the same forest for a hundred years, yet the ground around their trunks has not sunk into deep holes. What does this observation support?

A team wants to find out whether a potted plant's dirt is used up as the plant grows. What is the most useful measurement to take?

Sam waters a young tomato plant every day and it grows heavier week after week. Sam says the extra weight is all water. Why is that claim incomplete?

A gardener adds a scoop of powdered plant food to a pot. The plant grows better, but the pot's dirt still loses almost no weight. What does the weight result tell us?

A huge oak tree's wood is made mostly of material that was already stored inside the small acorn it grew from.

A greenhouse crew grows two identical tomato plants for a month. Both get the same light and fresh air, but only one is watered. The dry plant wilts and stops gaining weight. What does this result support?

A dead tree trunk that weighed 400 kilograms rots away completely over many years. The ground beneath it does not rise into a 400-kilogram mound. Where did most of that material go?

A class will weigh a pot's soil before planting and again months later. Why should they dry the soil before each weighing?

If a plant's new material came chiefly from the soil, the dry soil in its pot would lose about as much weight as the plant gains.