Class 9 Biology Chapter 5 – Tissues, Organs & Organ Systems

In living organisms, the body is organized in a hierarchical manner to perform various functions efficiently. This chapter explores the levels of organization, starting from simple cells to complex organ systems. Students will learn how cells group to form tissues, tissues combine to create organs, and organs work together in organ systems to maintain life processes.

Key topics include:

• Levels of Organization – Understanding how life is structured from cells to systems.

• Organs and Organ in Plants – Exploring how plant organs like roots, stems, and leaves perform specific functions.

• Organs and Organ Systems in Humans – Studying human organs and their integration into organ systems for survival.

• Homeostasis – Learning how organisms maintain a stable internal environment despite external changes.

This chapter provides a clear insight into the functional organization of living beings, helping students understand the connection between structure and function in both plants and humans.

Class 9 Biology Chapter 5 MCQs

1. What is the primary function of the xylem tissue in a leaf?

(a) To transport sugars to other parts
(b) To transport water to parts of leaf
(c) To synthesize chlorophyll
(d) To control the opening and closing of stomata

2. Which structures are responsible for the transport of food in the plant body?

(a) Xylem tissue
(b) Palisade mesophyll
(c) Phloem tissue ✅
(d) Spongy mesophyll

3. What is the smallest level of biological organization?

(a) Cell
(b) Atom ✅
(c) Molecule
(d) Organelle

4. What is the highest level of organization in living things?

(a) Organ
(b) Organ system
(c) Organism ✅
(d) Tissue

5. What is the highest level of organization in living things?

(a) Organ
(b) Organ system
(c) Organism ✅
(d) Tissue

6. The respiratory system helps maintain homeostasis by:

(a) Digesting food
(b) Producing blood cells
(c) Expelling carbon dioxide ✅
(d) Controlling urine

Class 9 Biology Chapter 5 Short Questions

1. How does the human body maintain a stable internal temperature?

The human body maintains a stable internal temperature through the temperature-regulating center in the brain (hypothalamus). This process works as follows:

1. When body temperature rises:

   • The brain signals the sweat glands to release sweat.

   • Evaporation of sweat cools the body.

2. When body temperature drops:

   • The brain signals muscles to contract rapidly, causing shivering.

   • Shivering generates heat to raise body temperature.

This process of regulation ensures that the body remains at a normal, stable temperature, which is crucial for proper functioning of enzymes and metabolic processes.

2. Differentiate between Tissue and Organ:

• Tissue: Tissue ek aise group of similar cells ka collection hai jo milkar ek specific function perform karte hain. Example: muscle tissue jo movement me help karta hai, ya xylem aur phloem jo plants me water aur food transport karte hain.

• Organ: Organ ek structure hai jo different types of tissues se bana hota hai aur milkar complex functions perform karta hai. Example: stomach jo digestion me help karta hai, leaf jo photosynthesis karta hai, ya heart jo blood pump karta hai.

Summary: Tissue ek basic functional unit hai cells ke upar, jabki organ ek higher-level structure hai jo multiple tissues ke combined functions ko perform karta hai.

3. Give two examples of molecules formed from atoms.

Answer:

1. Water (H₂O): Water molecule is formed when two hydrogen atoms combine with one oxygen atom through covalent bonds. It is essential for all life processes.

2. Protein: Proteins are complex molecules formed from atoms of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. They are made up of smaller units called amino acids, which are joined together to perform functions like enzyme activity, structural support, and transport in the body.

4. What is homeostasis, and why is it important?

Answer:

Homeostasis is the ability of an organism to maintain a stable internal environment despite changes in the external environment. This includes regulating factors like temperature, water balance, pH, and blood glucose levels.

Importance of Homeostasis:

1. Ensures that cells function properly, as enzymes and metabolic processes work best under stable conditions.

2. Maintains overall health by preventing harmful fluctuations in body conditions.

3. Helps organisms adapt to changing environments without disrupting internal balance.

📥 Download Chapter 5 Notes – Tissues, Organs, and Organ Systems

Get Class 9 Biology Chapter 5 complete notes for the 2026 new syllabus, including:

• Levels of Organization

• Organs and Organs in Plants

• Organs and Organ Systems in Humans

• Homeostasis

• Important MCQs, Short & Long Questions

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