Biology: Plant Tropisms and Hormones Worksheet

Question 1

Define tropism in your own words. Give one example of a tropism in a plant.

Accepted Answer

A tropism is a growth response of a plant toward or away from a stimulus. One example is phototropism, when a stem grows toward light.

Question 2

A houseplant on a windowsill begins bending toward the window. Identify the type of tropism and explain why this helps the plant.

Accepted Answer

This is positive phototropism because the plant is growing toward light. It helps the plant receive more light for photosynthesis.

Question 3

Plant roots usually grow downward into the soil. Identify the type of tropism shown and explain the advantage of this response.

Accepted Answer

The roots show positive gravitropism because they grow in the direction of gravity. This helps the plant anchor itself and absorb water and minerals from the soil.

Question 4

A vine wraps around a fence as it grows. What type of tropism is this, and what stimulus causes it?

Accepted Answer

This is thigmotropism. The stimulus is touch or contact with the fence.

Question 5

Auxin is a plant hormone that often causes cells in stems to lengthen. In a stem exposed to light from one side, auxin collects more on the shaded side. Explain how this causes the stem to bend toward the light.

Accepted Answer

Auxin causes cells on the shaded side of the stem to grow longer than cells on the lighted side. Because the shaded side grows faster, the stem bends toward the light.

Question 6

Match each plant hormone to its main role: auxin, gibberellin, cytokinin, ethylene, abscisic acid. Roles: helps fruit ripen, helps seeds germinate and stems grow, helps cells divide, helps plants close stomata during drought, helps stems bend toward light.

Accepted Answer

Auxin helps stems bend toward light. Gibberellin helps seeds germinate and stems grow. Cytokinin helps cells divide. Ethylene helps fruit ripen. Abscisic acid helps plants close stomata during drought.

Question 7

A farmer wants green bananas to ripen faster before selling them. Which plant hormone is most connected with fruit ripening, and how could it affect the bananas?

Accepted Answer

Ethylene is the hormone most connected with fruit ripening. Exposure to ethylene can speed up the ripening process, causing bananas to become softer and sweeter.

Question 8

During a dry week, a plant begins closing tiny openings on its leaves to reduce water loss. Name the openings and identify the hormone that helps control this drought response.

Accepted Answer

The tiny openings are called stomata. Abscisic acid helps control the closing of stomata during drought, which reduces water loss.

Question 9

A student places a germinating seed on its side in a clear container. After two days, the root curves downward and the shoot curves upward. Explain how this shows gravitropism.

Accepted Answer

The root shows positive gravitropism because it curves downward with gravity. The shoot shows negative gravitropism because it grows upward, away from gravity.

Question 10

Some plants grow roots toward areas with more water in the soil. What is this response called, and why is it useful?

Accepted Answer

This response is called hydrotropism. It is useful because it helps roots grow toward water, which the plant needs for survival and photosynthesis.

Question 11

A student claims, "Plants do not respond to their environment because they cannot move from place to place." Explain why this claim is incorrect using two examples from plant tropisms or hormones.

Accepted Answer

The claim is incorrect because plants can respond through growth and chemical signals. For example, stems can bend toward light by phototropism, and roots can grow downward by gravitropism. Plant hormones such as auxin help control some of these responses.

Question 12

Design a simple experiment to test phototropism in seedlings. Include the independent variable, one controlled variable, and what you would measure.

Accepted Answer

One experiment is to grow seedlings with light coming from one side and compare them with seedlings receiving light from above. The independent variable is the direction of the light. One controlled variable is the amount of water each seedling receives. I would measure the direction or angle of stem bending after several days.

Biology: Plant Tropisms and Hormones

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