Problem 9 - Biology Today and Tomorrow with Physiology

Question

Plants obtain carbon, hydrogen, and oxygen from _______ a. soil b. water c. air d. b and c

Step-by-Step Solution

Answer

d. b and c

Step 1: Understanding the Sources

Let's first understand where plants can obtain carbon, hydrogen, and oxygen. Plants take in carbon through carbon dioxide ( ext{CO}_2) from the air. Water ( ext{H}_2 ext{O}), which provides hydrogen and oxygen, is absorbed through the roots from the soil.

Step 2: Analyzing Each Option

- Option a, soil: Soil contains nutrients, but not typically carbon, hydrogen, or oxygen in a form that plants mainly utilize. - Option b, water: Provides hydrogen and oxygen when split during photosynthesis. - Option c, air: Contains carbon dioxide ( ext{CO}_2), which is used in photosynthesis. - Option d, b and c: Suggests both air and water are sources.

Step 3: Identifying the Correct Choice

From the analysis, plants obtain carbon from the air and hydrogen and oxygen from water. Therefore, the accurate choices for obtaining all three elements are options b and c.

Key Concepts

Photosynthesis

Photosynthesis is the remarkable process by which plants create their own energy. Through this natural phenomenon, plants capture light energy from the sun to convert carbon dioxide ( ext{CO}_2) from the air and water ( ext{H}_2 ext{O}) from the soil into glucose and oxygen. This process not only fuels the plant's activities but also releases oxygen into the atmosphere, which is vital for all aerobic living beings.

Key stages in photosynthesis include:

• Light Absorption: Chlorophyll, the green pigment in leaves, absorbs sunlight.
• Conversion: Light energy is transformed into chemical energy.
• Transformation: ext{CO}_2 and ext{H}_2 ext{O} are converted into glucose ( ext{C}_6 ext{H}_{12} ext{O}_6) and oxygen ( ext{O}_2).

The formula for photosynthesis is: \[6 ext{CO}_2 + 6 ext{H}_2 ext{O} + ext{light energy} \rightarrow ext{C}_6 ext{H}_{12} ext{O}_6 + 6 ext{O}_2\]This process is crucial for the survival of plants and plays a significant role in maintaining the balance of carbon and oxygen in the earth's atmosphere.

Water Absorption

Water absorption is an essential process for plants, as it provides not only the necessary hydrogen and oxygen for photosynthesis but also acts as a solvent for nutrients from the soil. The roots of a plant are adept at absorbing water, thanks to their extensive network of root hairs that increase the surface area.

Here's how it works:

• Water enters the plant through osmosis, moving from the soil into the root cells where the concentration of water is lower.
• The root's vascular system then transports the water upward through xylem vessels to the rest of the plant.
• This water also helps maintain plant structure and thermoregulation by evaporating through stomata in a process called transpiration.

Overall, water absorption is vital for the plant’s growth, health, and the ongoing cycle of photosynthesis.

Carbon Dioxide

Carbon dioxide ( ext{CO}_2) is a crucial component of photosynthesis, as it provides the carbon atoms that are essential for synthesizing glucose. Plants absorb ext{CO}_2 from the air through small openings on their leaves known as stomata.

Elements to consider include:

• The process of getting ext{CO}_2 from the air involves opening the stomata, which also allows for water vapor to escape—a trade-off that plants must manage.
• Once inside the leaf, ext{CO}_2 diffuses into individual cells, where it participates in the photosynthetic reaction.
• This intake of ext{CO}_2 is vital for plants to build energy-rich carbohydrates that fuel their growth and activities.

Proper ext{CO}_2 levels are important in the environment, as they influence photosynthetic rates and, consequently, plant productivity and health. Remember, the balance of ext{CO}_2 in the atmosphere is also crucial for the life of terrestrial ecosystems.