IB Biology: C1.3-Tropic Responses in Plants

What qualitative data can be recorded about tropic responses?

• Early shoot growth, appearance of cotyledons, and appearance of the first true leaves

• Height of the plant

• Number of leaves produced

• Color of the flowers

How do most shoots of plants respond to light and gravity?

• They are negatively phototropic and positively gravitropic.

• They are positively phototropic and negatively gravitropic.

• They are indifferent to light and gravity.

• They grow equally towards light and gravity.

How do most roots of plants respond to gravity?

• They grow upwards, against the direction of gravity.

• They grow downwards, in the same direction as gravity.

• They grow sideways, horizontally to the ground.

• They do not respond to gravity at all.

What does a negative tropic response mean?

• A negative tropic response means the plant organ grows towards the stimulus.

• A negative tropic response means the plant organ grows away from the stimulus.

• A negative tropic response means the plant organ remains unchanged.

• A negative tropic response means the plant organ grows in a circular motion.

What does a positive tropic response mean?

• A positive tropic response means the plant organ grows towards the stimulus.

• A positive tropic response means the plant organ grows away from the stimulus.

• A positive tropic response means the plant organ remains stationary.

• A positive tropic response means the plant organ shrinks in size.

What is a tropic response in plants?

• A response to light that causes plants to grow towards it.

• The differential growth of plant parts in response to directional stimuli.

• A reaction to temperature changes in the environment.

• The process of photosynthesis in plants.

How can tropic response be measured?

• By measuring the angle of curvature towards or away from the stimulus of light, providing quantitative data.

• By observing the color change in the plant leaves.

• By counting the number of leaves that grow in a given time period.

• By measuring the height of the plant over time.