- Anatomy- Study of internal structure of plant.
The Tissue-
- Tissue- It is a group of cells having a similar structure and function.
- A plant is made from different types of tissues mainly 2-
- Meristematic Tissue and
- Permanent Tissue
The Tissue System-
- The type of cells discussing based on type of tissue. Also the structure and function of tissue depending on location. On the basis of structure and function of tissue, there are 3 types of tissue system.
- These 3 types of tissue system are-
- Epidermal Tissue System,
- Fundamental or Ground Tissue System and
- Conducting or Vascular Tissue System.
This chapter focuses on the internal structure and functional organization of higher plants, which is called plant anatomy. Let’s break down the content, along with additional knowledge to enhance understanding and help tackle competitive exams:
1. Structural Similarities and Differences
- Plants and animals show both similarities and differences in their external morphology (structure).
- Internally, plants have distinct anatomical features, especially between groups like monocots (e.g., grass) and dicots (e.g., sunflower).
- Adaptations in structure help plants survive in diverse environments.
2. Basics of Plant Anatomy
- Cell → Tissue → Organ Hierarchy: Cells combine to form tissues, which then organize into organs (like roots, stems, and leaves).
- Study of internal plant structure = Anatomy.
3. Tissue Systems in Plants
Based on structure and location, plant tissues are categorized into:
- Epidermal Tissue System
- Outermost protective layer; includes epidermal cells, stomata, and appendages (trichomes and hairs).
- Functions:
- Cuticle: A waxy layer prevents water loss (absent in roots).
- Stomata: Openings for gas exchange and transpiration, controlled by guard cells.
- Monocots: Dumbbell-shaped guard cells.
- Dicots: Bean-shaped guard cells.
- Root Hairs: Unicellular, absorb water and minerals.
- Trichomes (on stems): Multicellular, reduce water loss and may secrete substances.
- Ground Tissue System
- Comprises all tissues except epidermis and vascular tissues.
- Includes parenchyma, collenchyma, and sclerenchyma.
- Parenchyma: Thin-walled cells; stores nutrients and performs photosynthesis.
- Collenchyma: Provides flexibility and support.
- Sclerenchyma: Thick-walled, provides mechanical strength.
- Specialized in leaves as mesophyll (photosynthesis zone).
- Vascular Tissue System
- Xylem and Phloem: Transport water, minerals, and food.
- Xylem = Water conduction.
- Phloem = Food translocation.
- Vascular Bundles:
- Open (Dicots): With cambium for secondary growth.
- Closed (Monocots): Without cambium; no secondary growth.
- Radial Bundles: Alternating xylem and phloem (in roots).
- Conjoint Bundles: Xylem and phloem side by side (in stems and leaves).
- Xylem and Phloem: Transport water, minerals, and food.
4. Anatomy of Specific Plant Parts
(a) Roots
- Dicot Root:
- Example: Sunflower root.
- Layers: Epiblema → Cortex → Endodermis → Pericycle → Vascular Bundles → Pith.
- Features:
- Fewer xylem bundles.
- Endodermis has Casparian strips (waterproof barriers).
- Lateral roots originate from pericycle.
- Undergoes secondary growth.
- Monocot Root:
- Example: Grass root.
- Similar to dicot root but:
- More xylem bundles (polyarch).
- Large, well-developed pith.
- No secondary growth.
(b) Stem
- Dicot Stem:
- Layers: Epidermis → Hypodermis → Cortex → Endodermis → Pericycle → Vascular Bundles → Pith.
- Features:
- Vascular bundles in a ring (unique to dicots).
- Open vascular bundles allow secondary growth.
- Monocot Stem:
- Features:
- Vascular bundles scattered (no ring).
- Closed vascular bundles, no secondary growth.
- Ground tissue is uniform.
- Features:
(c) Leaves
- Dicot Leaf (Dorsiventral):
- Structure: Epidermis → Mesophyll → Vascular Bundles.
- Features:
- Differentiated mesophyll (palisade + spongy parenchyma).
- More stomata on the lower epidermis.
- Monocot Leaf (Isobilateral):
- Features:
- Stomata on both surfaces.
- Mesophyll not differentiated.
- Bulliform cells: Help in leaf curling during water stress.
- Parallel venation.
- Features:
5. Secondary Growth (Dicots Only)
- Secondary growth involves the formation of new xylem and phloem from the cambium, increasing stem/root girth.
Key Differences Between Monocots and Dicots
| Feature | Dicots | Monocots |
|---|---|---|
| Vascular Bundles | Ring-shaped, open | Scattered, closed |
| Root Xylem | Few bundles (diarch/tetrarch) | Many bundles (polyarch) |
| Secondary Growth | Present | Absent |
| Leaf Venation | Reticulate | Parallel |
Competitive Insights
- Stomata:
- Guard cells control transpiration and photosynthesis efficiency.
- Found more on lower leaf surfaces in dicots.
- Vascular Bundles:
- Open bundles signify potential for secondary growth.
- Scattered bundles are a monocot hallmark.
- Bulliform Cells: Water stress adaptations in monocots.
- Casparian Strips: Regulate water and nutrient flow in roots.
Summary
Understanding plant anatomy is crucial for analyzing plant functions like transport, support, and photosynthesis. Knowledge of tissues and their arrangement aids in identifying monocots vs. dicots and understanding their adaptations.
These all are the notes of chapter 6 in biology. And important questions are below HERE. *#THANKS FOR VISITING, VISIT AGAIN#* 😊
1. What is the study of plant anatomy?
Answer:
The study of the internal structure of plants is called plant anatomy. It focuses on tissues, their arrangement, and functions.
2. What is a tissue?
Answer:
A tissue is a group of cells that have a similar structure and perform a specific function in the plant.
3. What are the main types of plant tissues?
Answer:
There are two main types of tissues:
- Meristematic tissue: Made of actively dividing cells.
- Permanent tissue: Made of mature cells that do not divide.
4. What is a tissue system?
Answer:
A tissue system is a group of tissues organized based on their structure and function. There are three main tissue systems:
- Epidermal Tissue System
- Ground Tissue System
- Vascular Tissue System
5. What is the function of the epidermal tissue system?
Answer:
The epidermal tissue system forms the outer protective covering of the plant. Its functions include:
- Preventing water loss with the cuticle (waxy layer).
- Allowing gas exchange through stomata.
- Absorbing water and minerals with root hairs.
6. What are stomata, and how do they differ in monocots and dicots?
Answer:
Stomata are small openings in the epidermis that allow gas exchange and transpiration.
- Monocots: Guard cells are dumbbell-shaped.
- Dicots: Guard cells are bean-shaped.
7. What is the ground tissue system?
Answer:
The ground tissue system includes all tissues except the epidermis and vascular tissues. It provides support, stores nutrients, and performs photosynthesis. It is made of three types of cells:
- Parenchyma: Stores food and helps in photosynthesis.
- Collenchyma: Provides flexibility and support.
- Sclerenchyma: Provides mechanical strength.
8. What is the vascular tissue system?
Answer:
The vascular tissue system transports water, minerals, and food in the plant. It consists of:
- Xylem: Conducts water and minerals.
- Phloem: Transports food.
9. What are vascular bundles, and how do they differ in monocots and dicots?
Answer:
Vascular bundles are arrangements of xylem and phloem in the plant.
- In dicots, vascular bundles are arranged in a ring and are open (allowing secondary growth).
- In monocots, vascular bundles are scattered and closed (no secondary growth).
10. What are the key differences between monocot and dicot roots?
Answer:
| Feature | Dicot Root | Monocot Root |
|---|---|---|
| Xylem Bundles | Fewer (diarch or tetrarch) | Many (polyarch) |
| Pith | Small or absent | Large and well-developed |
| Secondary Growth | Present | Absent |
11. What are the key differences between monocot and dicot stems?
Answer:
| Feature | Dicot Stem | Monocot Stem |
|---|---|---|
| Vascular Bundle Arrangement | Ring-shaped | Scattered |
| Secondary Growth | Present | Absent |
| Ground Tissue | Differentiated into regions | Uniform |
12. What is the structure of a dicot leaf?
Answer:
A dicot leaf has three main parts:
- Epidermis: Protective outer layer with stomata, mostly on the lower surface.
- Mesophyll: Differentiated into palisade (photosynthesis) and spongy parenchyma (gas exchange).
- Vascular Bundles: Reticulate venation.
13. How does a monocot leaf differ from a dicot leaf?
Answer:
- Monocot Leaf:
- Stomata are present on both surfaces.
- Mesophyll is not differentiated.
- Venation is parallel.
- Dicot Leaf:
- Stomata are mostly on the lower surface.
- Mesophyll has two layers: palisade and spongy.
- Venation is reticulate.
14. What is secondary growth, and where does it occur?
Answer:
Secondary growth is the increase in the girth of stems and roots due to the activity of the cambium. It occurs only in dicots and involves the formation of new xylem and phloem.
15. What are bulliform cells, and where are they found?
Answer:
Bulliform cells are large, thin-walled cells found in monocot leaves. They help the leaf curl during water stress to reduce water loss.
16. What is the Casparian strip, and what is its role?
Answer:
The Casparian strip is a waterproof barrier in the endodermis of roots. It regulates the flow of water and nutrients into the vascular bundle.
17. How can you distinguish monocot and dicot plants based on anatomical features?
Answer:
| Feature | Monocots | Dicots |
|---|---|---|
| Vascular Bundles | Scattered, closed | Ring-shaped, open |
| Leaf Venation | Parallel | Reticulate |
| Secondary Growth | Absent | Present |
| Root Xylem Bundles | Many (polyarch) | Few (diarch/tetrarch) |
18. What is the function of trichomes?
Answer:
Trichomes are hair-like structures on stems. They reduce water loss and may secrete substances for protection.
19. What are the main adaptations of stems in arid plants?
Answer:
In arid plants, stems:
- Become green and photosynthetic (e.g., Opuntia).
- Store water and nutrients.
- Help the plant survive in water-scarce environments.
20. Why are stomata more common on the lower surface of dicot leaves?
Answer:
Stomata are more common on the lower surface to reduce water loss through transpiration, as the lower side is less exposed to sunlight.