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:
- The Cell membrane,
- Cytoplasm,
- 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.
→ 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.
→ 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
→ 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.