#03 Independent Practice: Plant Response to Stimuli

Match the following forms of tropisms with the correct stimuli.

• Hydrotropism

• Gravity

• Thigmotropism

• Touch

• Geotropism/ Gravitropism

• Light

• Phototropism

• Water

If a plant grows toward a stimulus, the tropism is

• Positive

• Negative

If a plant grows away from a stimulus, the tropism is

• Positive

• Negative

The illustration below shows how the hormone auxin causes a plant

• Positive geotropism

• Negative hydrotropism

• Positive phototropism

• Negative thigmotropism

The image to the right shows the shoot system of a plant growing upwards against the force of gravity. This response would best be described as--

• positive geotropism

• negative thigmotropism

• positive thigmotropism

• negative geotropism

The roots of a plant in dry soil tend to grow towards soil that contains more moisture. This pattern of growth is known as --

• positive hydrotropism

• negative phototropism

• negative hydrotropism

• positive phototropism

When a plant grows in the shade, its stems tend to bend away from the shade because of the hormone auxin. This gives the plant a greater chance of absorbing the energy it needs to make its own food. The response shown by a plant growing this way is called --

• phototropism

• thigmotropism

• gravitropism

• hydrotropism

The bending and growth of a plant’s stems and roots is primarily directed by the actions of which of the following?

• Salts and minerals

• Auxin hormones

• Turgor pressure

• Chlorophyll

Touch-me-nots (Mimosa pudica) are plants that rapidly respond to touch. By affecting the turgor pressure in their cells, these plants can cause their leaves to quickly droop allowing them to defend themselves from herbivores animals. This rapid response to touch is known as -- A thigmonasty B phototropism C photonasty D gravitropism.

• thigmonasty

• phototropism

• photonasty

• gravitropism

In the late 19th century, Charles Darwin and his son performed a series of experiments on young grass seedlings to observe the plants' response to sunlight. They grouped the seedlings as shown in the list:

They removed the tips of on group of seedlings.

They placed opaque caps over the tips of the second group of seedlings.

They placed transparent caps over the tips of a third group of seedlings.

Based on the diagram, which statement BEST supports the results of the experiment?

• The direction of light is detected by cells on the shoot tips, and plants respond by producing chlorophyll.

• The direction of light is detected by cells on the roots, and plants respond by bending toward the light.

• The direction of light is detected by cells on the shoot tips, and plants respond by bending toward the light.

• The direction of light is detected by cells within the roots, and plants respond by bending in the direction of gravity.