Page 134 - Science Course 1 (Book 1)
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Mo4-L4: Key Concept Organizer
Directions: On each blank, write the term or phrase that correctly completes each sentence.
1. Changes in the environment that cause an organism to respond are called .
2. Environmental stimuli include , , and .
3. When a response results in plant growth toward or away from a stimulus, the response is called
a(n) .
4. A(n) tropism occurs when the growth is toward the stimulus.
5. Growth of a plant toward or away from light is called .
6. is a plant’s response to gravity.
7. Another response, , describes a plant’s response to touch.
8. Vines that coil around a nearby plant are demonstrating .
9. Flowering plants show a response to darkness called .
10. A short-day plant must have more than hours of darkness to flower.
11. A(n) plant does not seem to be affected by the number of
hours of darkness.
12. Plants that flower in early summer but not in late fall are called plants.
13. Stems grow away from gravity, and roots grow toward gravity. This describes .
14. A stem grows even when there is no light.
15. Roots growing away from a source of light are examples of tropism.
Mo4-L4: Key Concept Check
Directions: Circle the term or phrase that correctly completes each sentence.
1. Light, touch, or gravity that causes plant growth toward or away from a stimulus is a
(chemical hormone, tropism).
2. A plant’s tropism to light is called (phototropism, gravitropism).
3. Bending toward the light is a (positive, negative) tropism.
4. If a planter is turned so the plant bends away from the light, the plant will gradually (bend lower, straighten).
5. The plant’s stems (will, will not) continue to grow upward if the plant is placed in the dark.
6. Roots that grow (toward, away from) the Sun help anchor the plant in the soil.
7. Some plants respond to touch. This is called (thigmotropism, photoperiodism).
8. A higher level of a plant hormone called (gibberellins, auxin) on the dark side of the plant causes plant
cells found there to grow longer.
9. When plant cells on the dark side of a plant grow longer, the plant (bends, dies).
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