STD IX – BASIC BIOLOGY (Online)

1. BASIC BIOLOGY

THE CELL

Cell- The Unit of Life

Cell is called the fundamental and structural unit of life.

A cell consists of three parts: the cell membrane, the nucleus, and, between the two, the cytoplasm.

Within the cytoplasm lie intricate arrangements of fine fibres and hundreds or even thousands of minuscule but distinct structures called organelles.

A cell is capable of independent existence and can carry out all the functions which are necessary for a living being. A cell carries out nutrition, respiration, excretion, transportation, and reproduction.

Unicellular organisms are capable of independent existence. The cell functions include movement of substances across the cell membrane, cell division to make new cells, and protein synthesis.

We will learn more about the structure and functions of the cell in this chapter.

Structure Of A Cell

Cell Structure

The cell structure comprises individual components with specific functions essential to carry out life’s processes. These components include- cell wall, cell membrane, cytoplasm, nucleus, and cell organelles. Read on to explore more insights on cell structure and function.

Cell Membrane | Cell Wall | Cytoplasm | Nucleus | Cell Organelles | Nucleolus | Nuclear membrane | Chromosomes | Endoplasmic reticulum | Golgi Bodies | Ribosome | Mitochondria | Lysosomes | Chloroplast | Vacuoles

Protoplasm

Protoplasm is the living part of a cell that is surrounded by a plasma membrane. In some definitions, it is a general term for the cytoplasm, but for others, it also includes the nucleoplasm.

Differences between an Animal and a Plant cell.

Both animal and plant cells have mitochondria, but only plant cells have chloroplasts. Plants don’t get their sugar from eating food, so they need to make sugar from sunlight.

Both plant and animal cells have vacuoles. A plant cell contains a large, singular vacuole that is used for storage and maintaining the shape of the cell. In contrast, animal cells have many, smaller vacuoles.

Plant cells have a cell wall, as well as a cell membrane. In plants, the cell wall surrounds the cell membrane. Animal cells simply have a cell membrane, but no cell wall.

TISSUES

Plant Tissues

A group of cells, that are similar in structure and work together to achieve a particular function, forms a tissue.

Plant tissues are categorised broadly into three tissue systems:

Epidermis | Vascular | Ground

Plant tissues can also be divided differently into two types:

Meristematic | Permanent

 Animal Tissues

A tissue is a group of similar cells with a common origin that together perform a specific function.The word tissue takes its origin from a Latin word which means ‘weave’. In tissues, cells are woven together. Sometimes these tissues are bonded by a sticky substance that coat the cells.

Epithelial | Connective | Muscular | Nerve