Plant Life Processes: quick revision, 12 bites

Plants Are Living Factories

Plants run life processes silently.

Plants are **living organisms** that carry out essential life processes to survive, grow, and reproduce. Unlike animals, they make their own food through **photosynthesis** and perform **respiration**, **transport**, and **excretion** to maintain life.

Takeaway. Plants perform all life processes, just like animals, but make their own food.

Photosynthesis: The Food Factory

Sunlight becomes food.

**Photosynthesis** is the process by which green plants use **sunlight**, **carbon dioxide**, and **water** to make **glucose** (food) and release **oxygen**. It occurs in the **chloroplasts** of leaf cells, which contain the green pigment **chlorophyll**.

Takeaway. Photosynthesis converts light energy into chemical energy stored as food.

Chlorophyll: The Green Trap

Green pigment captures sunlight.

**Chlorophyll** is the green pigment in chloroplasts that absorbs **sunlight** (mainly red and blue wavelengths) and converts it into chemical energy. Without chlorophyll, photosynthesis cannot occur.

Takeaway. Chlorophyll is the molecule that captures light energy for photosynthesis.

Steps of Photosynthesis

Light to sugar in steps.

Takeaway. Photosynthesis has two main stages: light-dependent and light-independent reactions.

Respiration in Plants

Plants breathe too.

**Respiration** in plants is the process of breaking down **glucose** to release **energy** for life activities. It occurs in **mitochondria** and happens **24 hours a day**, unlike photosynthesis which only occurs in light.

Takeaway. Respiration releases energy from food and occurs day and night.

Photosynthesis vs Respiration

Opposite but linked processes.

Takeaway. Photosynthesis stores energy; respiration releases it.

Transport in Plants

Water and food travel.

Plants have a **transport system** made of **xylem** and **phloem** tissues. **Xylem** carries water and minerals from roots to leaves. **Phloem** carries food (glucose) from leaves to other parts of the plant.

Takeaway. Xylem transports water; phloem transports food.

Transpiration: Water Loss

Leaves lose water vapor.

**Transpiration** is the loss of water vapor from leaves through **stomata**. It helps in **cooling** the plant and **pulling water** upward through xylem. Stomata are tiny pores mainly on the underside of leaves.

Takeaway. Transpiration drives water movement and cools the plant.

Excretion in Plants

Plants remove waste too.

Plants produce waste products like **oxygen** (from photosynthesis) and **carbon dioxide** (from respiration). Other wastes are stored in **vacuoles**, **leaves**, or **bark** and removed when leaves fall or bark sheds.

Takeaway. Plants excrete waste through gases, storage, and shedding.

Stomata: Tiny Gates

Pores control gas exchange.

**Stomata** are tiny openings on leaf surfaces that allow **gas exchange** (CO₂ in, O₂ out) and **transpiration**. They are controlled by **guard cells** that open and close the pore based on water and light conditions.

Takeaway. Stomata are regulated pores for gas exchange and water loss.

Plants Respire All the Time

Don't confuse day and night.

Takeaway. Respiration is continuous; photosynthesis needs light.

Remember the Equation

Balance the photosynthesis equation.

In exams, you may be asked to write the **balanced equation** for photosynthesis. Remember: **6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂** in the presence of light and chlorophyll.

Takeaway. Memorize the balanced photosynthesis equation.