Guard Cells

Guard cells are specialized cells found in the epidermis of plant leaves and stems. They play a crucial role in the process of gas exchange and transpiration in plants. The main function of guard cells is to regulate the opening and closing of stomata, which are tiny pores on the surface of leaves and stems.

Structure of Guard Cells

Guard cells are bean-shaped cells that surround each stoma. They contain chloroplasts, which are the site of photosynthesis in plants. The inner side of each guard cell is thicker than the outer side, giving them a kidney or bean-like shape.

Function of Guard Cells

Guard cells regulate the opening and closing of stomata in response to environmental conditions. When the guard cells are turgid (swollen with water), they bow outwards, opening the stomatal pore and allowing for gas exchange. On the other hand, when the guard cells lose water and become flaccid, they close the stomatal pore to prevent excessive water loss through transpiration.

Regulation of Guard Cell Function

The opening and closing of stomata by the guard cells are regulated by various factors, including light, carbon dioxide concentration, humidity, and plant hormones such as abscisic acid. For example, in the presence of light, guard cells take up potassium ions, which leads to an increase in turgor pressure and the opening of stomata.

Study Guide

Describe the structure of guard cells and their location in plants.
Explain the role of guard cells in regulating the opening and closing of stomata.
Discuss the factors that influence the function of guard cells in controlling stomatal aperture.
Compare and contrast the behavior of guard cells in response to light and water availability.
Examine the relationship between guard cell function and the process of transpiration in plants.

By understanding the structure and function of guard cells, you can appreciate the vital role they play in the survival and growth of plants.

◂Science Worksheets and Study Guides Eighth Grade. The Movement of Ocean Water

Study Guide

The Movement of Ocean Water

Worksheet/Answer key

The Movement of Ocean Water

Worksheet/Answer key

The Movement of Ocean Water

Worksheet/Answer key

The Movement of Ocean Water

Vocabulary/Answer key

The Movement of Ocean Water

Vocabulary/Answer key

The Movement of Ocean Water

The resources above cover the following skills:

Earth/Space Science: Students will use scientific skills and processes to explain the chemical and physical interactions (i.e., natural forces and cycles, transfer of energy) of the environment, Earth, and the universe that occur over time.

Interactions of Hydrosphere and Atmosphere: Cite evidence to explain the relationship between the hydrosphere and atmosphere.

Identify and describe how the temperature and precipitation in a geographic area are affected by surface features and changes in atmospheric and ocean content: Relative location of mountains; Volcanic eruptions; Proximity to large bodies of water; Heat energy of ocean currents.

Interactions of Hydrosphere and Atmosphere: Recognize and describe the various factors that affect climate.

Identify and describe how the temperature and precipitation of an area are affected by surface and ocean features: Relative location of mountains; Proximity to large bodies of water; Warm and cold ocean currents.

Recognize and describe the global effects of volcanic eruptions, greenhouse gases, and El Nino.