Biology- The Fundamental Unit of Life Flashcards
Who discovered cells and how?
Robert Hooke discovered cells by observing a thin slice of cork through a self-designed microscope in 1665.
Hooke called the boxes he observed ‘cells’ because they resembled the structure of a honeycomb.
What is the significance of Hooke’s observation?
It was the first time someone observed that living things consist of separate units, leading to the term ‘cell’ being used in biology today.
What are unicellular organisms?
Organisms that consist of a single cell, such as Amoeba, Chlamydomonas, Paramecium, and bacteria.
‘Uni’ means single.
What are multicellular organisms?
Organisms composed of many cells that group together to perform various functions, such as fungi, plants, and animals.
‘Multi’ means many.
What is the cell theory?
The cell theory states that all plants and animals are composed of cells and that the cell is the basic unit of life.
It was proposed by Schleiden and Schwann and later expanded by Virchow.
What are the three main features of a cell?
- Plasma membrane
- Nucleus
- Cytoplasm
What is the function of the plasma membrane?
It separates the cell contents from the external environment and is selectively permeable, allowing certain materials to enter or exit the cell.
What is diffusion?
The spontaneous movement of a substance from a region of high concentration to a region of low concentration.
What is osmosis?
The net diffusion of water across a selectively permeable membrane toward a higher solute concentration.
What happens in a hypotonic solution?
The cell gains water by osmosis and may swell up.
What happens in an isotonic solution?
There is no net movement of water across the cell membrane, and the cell remains the same size.
What happens in a hypertonic solution?
The cell loses water by osmosis and may shrink.
What is the function of cell organelles?
Each organelle performs a specific function necessary for the cell’s survival and operation.
What is the cell wall, and what is it made of?
A rigid outer covering found in plant cells, mainly composed of cellulose.
What is plasmolysis?
The shrinkage or contraction of the cell contents away from the cell wall when a living plant cell loses water through osmosis.
What is the nucleus?
The control center of the cell, containing chromosomes made of DNA that carry genetic information.
What is the difference between prokaryotic and eukaryotic cells?
Prokaryotic cells lack a defined nucleus and membrane-bound organelles, while eukaryotic cells have a nucleus and organelles.
What is cytoplasm?
The fluid content inside the plasma membrane that contains cell organelles.
Fill in the blank: The term ‘protoplasm’ was coined by _______.
Purkinje
True or False: All cells have the same organelles regardless of their function.
True
What is the cytoplasm?
The fluid content inside the plasma membrane that takes up very little stain and contains specialized cell organelles.
The cytoplasm is essential for cellular processes and organization.
What distinguishes prokaryotic cells from eukaryotic cells?
Prokaryotic cells lack a defined nuclear region and membrane-bound organelles, while eukaryotic cells have a nuclear membrane and membrane-enclosed organelles.
This distinction is crucial for understanding cellular complexity.
What role do membranes play in cells?
Membranes keep cell contents separate from the external environment and support various chemical activities.
Membrane-bound organelles are vital for compartmentalizing cellular functions.
What is the endoplasmic reticulum (ER)?
A large network of membrane-bound tubes and sheets, involved in the transport of materials and biochemical activities.
There are two types: rough ER (RER) and smooth ER (SER).
