Matric Notes Biology Class 9th Ch 4 Cells and Tissues Extra Short & Long Questions
Short Questions
- All animals and plants are made up of cells and cell products. Some organisms are unicellular and some are multicellular.
- Cells are the structural and functional units of living organisms.
- New cells arise from the pre-existing cells by cell division.
Differences between Simple and Compound tissues:
Simple tissues | Compound tissues |
They are composed of only one type of cells performing a common function | They are composed of more than one kind of cells and type of cells perform a common function |
These type of tissues usually cover the surface of external and internal organs | They are found in the vascular bundles |
Simple tissues are mainly concerned with growth and variety of functions | Compound tissues mainly involved in the process of conduction in plants |
The cells are packed tightly together. | They are scattered throughout the body. |
Example: Epidermal (in plants) tissues | Example: Xylem and phloem |
It also enables the cell to form separate compartments within the cell in which specialized metabolic processes such as photosynthesis and aerobic respiration can take place. Membranes also act as receptor site for the attachment of hormones, neurotransmitters and other chemicals. Thus, it controls the movement of materials passing through it. It allows only the passage of water and other small molecules such as gases and other small molecules such as glucose, amino acids, fatty acids, glycerol, and ions can diffuse slowly through them. So, maintaining equilibrium by this membrane while exchanging material is actually its innate property.
Endocytosis | Exocytosis |
Endocytosis is a process that brings macromolecules, large particles, and even small cells into the cell. | Exocytosis is the process by which materials packaged in vesicles are excreted from a cell. |
In endocytosis, the cell membrane invaginates (folds inward) and takes in the materials from the environment, forming a small vesicle | The initial event in this process is the binding of the vesicle membrane with the cell membrane. |
The vesicle separates from the plasma membrane and migrates with its contents to the cell’s interior. | The contents of the vesicle are released into the environment and the vesicle membrane is incorporated into the cell membrane. |
Example: Engulfment of bacteria by the white blood cells during defense mechanism | Example: The release of hormones out of the cell |
When a cell is surrounded by water or hypotonic solution, the water moves into the cell vacuole by osmosis. The vacuole increases in size and pushes the cell contents against the cell wall. This pressure which is exerted by the cytoplasm against the cell wall is known as turgor pressure and the phenomena is called turgidity. In turgid condition, the plant cell does not burst because the cell wall is strong and relatively inelastic.
Long Questions
The function of root hairs is to collect water and mineral nutrients present in the soil and take this solution up through the roots to the rest of the plant. To perform this function the root hair cells have specific adaptations.
- Root hairs are long and narrow in their shape that increases their surface area to absorb water and minerals efficiently.
- The cell sap of root hair has higher salt concentration than surrounding water to absorb water through its movement along the gradient.
- Xylem tissues support the overall structure of the plants because of the presence of two types of cells i.e. vessels and tracheids.
- Vessels cells are short, wide and have thick secondary cell walls. These cells are dead and hollow and join together to form long tubes.
- Tracheids are long, slender cells with overlapping ends. Water move upwards from tracheids to tracheids.
- Xylem tissue is responsible for the transport of water and dissolved substances from roots to upper parts. Due to the presence of lignin in the secondary walls of its cells, xylem tissue also provides support to the plant body.

- Collenchyma tissue is found in young stems where it provides strength to different parts of the plant. The cells of this tissue are living, elongated, and polygonal with tapering ends.
- Parenchyma tissues are thick walled dead cells. Walls of these cells are heavily filled with lignin which provides hardness and strength to the cell.
- Vessel cells are short and wide and have thick secondary cell walls. These cells are dead and hollow and join together to form long tubes.
- Tracheids are long, slender cells with overlapping ends. Water moves upward from tracheid to tracheid.
- Xylem tissue is responsible for the transport of water and dissolved substances from roots to the upper parts. Due to the presence of lignin in the secondary walls of its cells, xylem tissue also provides support to the plant body.
- In sieve tube cells, protoplasm has no nucleus and the end walls have small pores called sieve plates. The transport of food occurs through the cytoplasm of the sieve tube cells.
- Companion cells accompany the sieve tube cells. They regulate the movement of food through sieve tubes.


- The cell wall of Prokaryotes is composed of peptidoglycan (Murein). It is a single large molecule made of amino acids and sugar.
- The cell wall of fungi is made of chitin.
- The cell walls of protists are made of a variety of chemicals.


