Rocket is at the jar before breakfast. "Raven! One bean has a white bump poking out!"
Raven brings the ruler. "What do you notice about where it comes from? Measure it."
"Two millimeters," Rocket says. "It is coming out of the scar end. Is it a root or a stem?"
"The root comes first," Raven says. "The radicle. Write it down." Nova hovers close, her light on the bump.
"Yesterday that seed got a no for growth," Nova says. "Today?"
Rocket grins. "Today it gets a yes. The bean was alive the whole time." Raven nods. "Resting is not the same as not living."
A seed holds a seed coat, one or two cotyledons and a single embryo. The cotyledons of a bean hold the food reserves.
Beans and lentils are dicots. Dicot seeds have two cotyledons, which is why a soaked bean splits into two halves.
Until the first leaves open and begin making food from light, the seedling lives on the food stored in the seed.
A seed can be dormant for months or years. Dormancy keeps seeds alive through bad conditions, and water can wake them.
The living-or-not test works everywhere. Bread rising in a kitchen is the work of living yeast cells, which you will meet next week.
Mold on an old leaf is living. A rusting nail changes color and crumbles, but it is not alive. It has no cells.
A cloud grows and moves and even responds to wind. It has no cells, uses no food and makes no offspring.
Your seed jar is the best test of all. A dry seed that looked like a pebble is now growing a root.
| Week review | True or false? |
|---|---|
| Living things show all eight characteristics, not just one or two. | ? |
| A seed that has not sprouted yet is not alive. | ? |
| The radicle becomes the root. | ? |
| New cells arise from existing cells. | ? |
| A rusting nail is alive because it changes. | ? |
Strong first week, biologist. Tomorrow is Nature Day: a family hunt for living and nonliving things outdoors.