NEET notes on Tissues

🌱 What Are Tissues? Definition: A tissue is a group of similar cells having similar structure and performing a specific function. Tissues are the next level of organization between cells and organs in multicellular organisms. Hierarchy of Organization: Cells ➡️ Tissues ➡️ Organs ➡️ Organ Systems ➡️ Organism 

  🌿 Plant Tissues Plant tissues are mainly of two types:

 

1. Meristematic Tissue

• Cells can divide throughout life — responsible for growth.
• Types:
  • Apical Meristem: Tip of roots & shoots (length growth)
  • Lateral Meristem: Width growth
  • Intercalary Meristem: At leaf bases (regrowth in grasses)

2. Permanent Tissue

Derived from meristematic cells that lost the ability to divide.

1. A) Simple Permanent Tissues

• Parenchyma: Thin-walled cells; photosynthesis & storage
• Collenchyma: Thick uneven walls; flexible support
• Sclerenchyma: Very thick walls; strong support

1. B) Complex Permanent Tissues

• Xylem: Transports water & minerals
• Phloem: Transports food from leaves

🐾 Animal Tissues Animal tissues are specialized cells working together for specific roles like protection, movement, transport, and communication. Main Types of Animal Tissues

1. Epithelial Tissue
   • Covers body surfaces and lines organs & cavities
   • Functions: protection, absorption, secretion
   • Types: Squamous, Cuboidal, Columnar, Stratified, Glandular
2. Connective Tissue
   • Binds and supports other tissues
   • Includes: Areolar, Adipose, Cartilage, Bone, Blood
3. Muscle Tissue
   • Enables movement
   • Types:
     • Skeletal: Voluntary movement
     • Smooth: Involuntary (organs)
     • Cardiac: Involuntary (heart)

1. Nervous Tissue
   • Specialized for communication via electrical signals
   • Made up of neurons
   • Coordinates body responses and regulation

🔍 Plant vs Animal Tissue — Quick Comparison

Feature	Plant Tissue	Animal Tissue
Cell Wall	Present	Absent
Growth	Throughout life (meristem)	Limited
Types of Tissues	Meristematic & Permanent	Epithelial, Connective, Muscle, Nervous
Functions	Support, transport, photosynthesis	Movement, protection, coordination
Vacuole	Large central vacuole	Small/absent

  📌 Main Points (Quick Revision) ✔ A tissue is a group of similar cells with a specific function. ✔ Plant tissues: Meristematic & Permanent. ✔ Permanent tissues include parenchyma, collenchyma, sclerenchyma, xylem, phloem. ✔ Animal tissues are epithelial, connective, muscular, and nervous. ✔ Epithelial protects; connective supports; muscle moves; nervous controls. ✔ Differences include cell wall, growth pattern, and functions.