AP Board 8th Class Biology Notes Chapter 2 Cell: The Basic Unit of Life

Students can go through AP State Board 8th Class Biology Notes Chapter 2 Cell: The Basic Unit of Life to understand and remember the concept easily.

AP State Board Syllabus 8th Class Biology Notes Chapter 2 Cell: The Basic Unit of Life

→ All living organisms are made of cells.

→ Cells were first observed by Robert Hooke in 1665.

→ Antonie Van Leeuwenhoek was the first to see living bodies under the microscope which he had constructed himself.

→ The cell has 3 main parts:

  1. The Cell membrane,
  2. Cytoplasm,
  3. Nucleus.

→ Robert Brown discovered the nucleus in the orchid leaf.

→ Plant cells differ from those of animals in having an additional layer around the cell membrane termed cell wall.

→ The cell wall gives strength and rigidity to plants.

→ Cell exhibits a variety of shapes and sizes and numbers.

→ Single-celled animals are called unicellular organisms.

→ More than one cell is called a multicellular organism.

→ Basic functions in multi-cellular organisms are carried out by a variety of cells.

→ Cell: The smallest biological unit capable of carrying out all of the fundamental activities of life. The basic unit of structure and function of any living thing.

AP Board Solutions AP Board 8th Class Biology Notes Chapter 2 Cell: The Basic Unit of Life

→ Cell membrane: The thin, flexible layer that surrounds a cell and which controls all that enters and leaves the cell.

→ Cell Wall: Cells, the outermost non-living cellulose layer that surrounds the entire cell, including the cell membrane.

→ Cytoplasm: That part of a cell’s protoplasm that lies outside of its nucleus.

→ Nucleus: A spherical structure present at the center of the cell.

→ Unicellular: An organism composed of just one cell.

→ Multicellular: Organism formed by more than one cell.

→ Organ: All organisms are made of smaller particles called organs.

→ Organelles: The small functional structures of the cell.

→ Pseudopodia: False feet or the structures formed by the unicellular organisms to capture food or for locomotion.

→ Staining: Obtain color to the cells

→ Magnification: Expanding the size of the structure

→ Focusing: To visualize the object by light

→ Centriole: In animal cells, a structure outside the nucleus organizes the spindle fibers during cell reproduction.

AP Board Solutions AP Board 8th Class Biology Notes Chapter 2 Cell: The Basic Unit of Life

→ Contractile Vacuoles: Large sacs found ¡n the cells of certain protozoans that remove the water that has accumulated inside the cell by pumping it to the outside of the cell.

→ Food Vacuoles: The sacs where food particles are digested that are found in the cytoplasm of protozoan cells.

→ Micrometer: Hundred part of millimeter 1/100 mm

→ Nanometer: Thousand part of micrometer 1/1000 (urn)

→ Heterogeneous: Different state of features in a group

→ Teeming: Occupying the full of container

→ Stomata: Tiny pores on leaves

→ Contractile vacuole: A sac-like cell organelle that pumps fluid in a cyclic manner
AP Board 8th Class Biology Notes Chapter 2 Cell The Basic Unit of Life 1

→ Antonie Van Leeuwenhoek (1632-1723) in 1674 was the first human to see living bodies like bacteria, yeast, protozoa, Red Blood cells, and the teeming life in a drop of water. He prepared several types of magnifying glasses and used his lenses to study both living and non-living things using under a microscope.

→ Robert Brown (1773 – 1858):

  • Robert Brown was born in 1773. He made a significant contribution to our understanding of cells.
  • He was the first person to observe the “Nucleus” in the epidermis of orchid leaves.
  • He died in 1858.