Cells and Tissue

This concept mainly deals with the ultrastructure and functions of the cells and tissues inside human bodies. Here the students will be introduced to a plant cell parts with its structure and animal cell parts. After reading the concept, students will be able to:

Know about cell organelles like plastids, ribosomes, cytoplasm etc.
Answer what is mitochondria.
Analyse the parts of a cell.
State what is a cell membrane and cell membrane functions.
Mention what is cell wall, and nucleus functions, and what is tissue.

Each concept is explained to class 4 students using descriptions, illustrations, and concept maps. After you go through a concept, assess your learning by solving the two printable worksheets given at the end of the page.

Download the worksheets and check your answers with the worksheet solutions for the concept of Cells and Tissues provided in PDF format.

Cells are the structural and functional units of the living body.
Tissues originate from cells. A tissue constitutes a group of cells.
Cells are of two types: (i) Animal cells and (ii) Plant cells.

Animal Cell:

Parts of an animal cell	Structure and functions
1. Cell Membrane	It is the thin lining that covers the cell.
2. Cytoplasm	A fluid-like substance inside the cell.
3. Nucleus	It is located at the centre of the cell and controls all activities of the cell.
4. Mitochondria	Numerous mitochondria are present in the cytoplasm. It produces energy to keep the cell active.
5. Ribosome	Ribosomes are present in large numbers in the cytoplasm. They help in protein synthesis.

Plant Cell:

Parts of a plant cell	Structure and functions
1. Cell Wall	It is the outermost covering of the plant cell. It is made up of waxy materials and protects the cell from external stress.
2. Cell Membrane	It is the thin lining that covers the cell.
3. Cytoplasm	It is the fluid-filled matrix that is present inside the cell.
4. Vacuoles	These are closed fluid-filled pouch-like structures present inside the cytoplasm.
5. Nucleus	It is located either in the centre of the cell or may shift to the sides. The nucleus controls all activities of the cell.
6. Plastid	Plastids are present in the cytoplasm of all plant cells. They store food and contain colourful pigments. Green plastids are called chloroplasts.
Plant cells also have ribosomes and mitochondria in the cytoplasm.

Characteristics of tissues:

Various types of tissues are present in the human body.
A tissue is made with a pack of cells that originate from the same source, i.e., structurally, they are similar and perform the same function.

Example:

Epithelial tissue, which makes our skin; muscle tissue which makes our body muscles.