Plant Growth

In this lesson, students analyze how a plant’s structures allow it to capture the sun’s energy to transform water and carbon dioxide into oxygen and glucose, which it needs to grow and develop.

• Plants have both internal and external structures that allow them to complete the process of photosynthesis. 
• In photosynthesis, matter that is not food, such as air and water, is transformed into matter that is food (glucose). 
• In addition to chloroplasts, which are mostly found in the cells of a plant’s leaves, plant leaves also have pores called stomata that open and close to take in carbon dioxide from the environment and release oxygen.  
• Roots gather water and minerals from the soil. Photosynthesis requires inputs of energy from the sun, carbon dioxide, and water. Roots also hold the plant in the ground and withstand the forces of wind and moving water.
• The sun is the source of energy for plants. Through photosynthesis, plants capture the sun’s energy through their chloroplasts and convert it into chemical energy stored in glucose, which plants use to grow and develop.
  
  

• How do a plant’s leaves interact with the environment to support the process of photosynthesis?
• Why do plants have roots, and what is the role that roots play in photosynthesis?
• Why is glucose important for plants?
• How do plants use carbon dioxide to grow and develop?
• Why is water important for plants?
• Why is the sun important for plant growth and development?
• How is the cell able to get energy from food?
• What is the difference between nutrients that plants get from the soil, which they use for growth and develop, and food, which plants make through photosynthesis?
• Why do plants need air and water to survive?
• Why is the stem important?
  
  

Misconception: An organism is not a system.

Fact: Ecosystems are systems, made up of smaller interacting parts. Both the living and nonliving parts of an ecosystem influence the overall ecosystem.

Misconception: The organisms in an ecosystem are not part of a larger whole, but instead are just a collection of living things surviving independently of one another and their environment.

Fact: All organisms are systems because they are made up of structures that have a specific function to help the organism survive.

Ecosystem : a community of different organisms that depend on interacting with each other and their physical environment for survival

Function : the normal action of something or how something works

Inorganic :  anything that is not living and never was living (e.g., water and rocks)

Nutrients :  chemicals that organisms need for the growth and maintenance of cells

Organic :  anything that is living or was once living (e.g., fallen leaves and animal remains)

Organism :  a complete living thing

Photosynthesis :  the process of turning sunlight, carbon dioxide, and water into glucose and oxygen

Plant :  a living thing that captures energy from sunlight for growth and development

Soil :  a mixture of broken-down rocks, decaying organic matter, and other materials that plants use to grow

Structure :  the way in which parts are put together to form a whole

Plant Cells

Plant cells have cell walls in addition to a cell membrane. Cell walls are stiff fibers that help plants stay rigid and stand up. Animal cells lack cell walls, so they are less rigid. For this reason, animal cells can take many different shapes.

Plant cells have organelles called chloroplasts [klawr-uh-plasts]. Chloroplasts absorb energy from the sun to make their own food.

Chloroplasts contain a green pigment called chlorophyll. This pigment absorbs sunlight and gives plant cells their green color. The sunlight absorbed by the chloroplasts begins the process of photosynthesis. Photosynthesis uses the sun’s energy to convert carbon dioxide and water into a kind of sugar called glucose. Glucose holds stored chemical energy. Plants use glucose for growth and development.

Photosynthesis

Without sunlight, carbon dioxide, and water, plants would not be able to photosynthesize. During photosynthesis, plants transform matter that is not food, including air and water, into matter that is food, specifically glucose. Glucose contains chemical energy that allows the plant to grow and develop.

In addition to chloroplasts, which are found in the cells of a plant’s leaves, plants have other structures to perform photosynthesis. For example, leaves also have stomata, which are pores that open and close.

They take in carbon dioxide from the environment and release oxygen. This exchange of gasses in plants is called respiration. When plants take in carbon dioxide, not all of it is used for photosynthesis. Some of the carbon atoms become part of the plant as they are used for growth.

Plants also have roots to anchor the plant. Roots also gather water and minerals from the soil. Plants need different kinds of minerals, including nitrogen, phosphorus, and potassium. These nutrients help maintain the plants’ cells. The stems transport the water and minerals between the roots and the rest of the plant.

As the hands-on activity for this lesson, students figure out the connection between the phenomena of plant growth and development and environmental factors like nutrients. Students collect and analyze data from experiments they develop to analyze the influence of environmental factors on the height of plants and their structural appearance after 10 days of observations. Then, they use the data to construct an explanation for what a plant needs to grow and develop.