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Questions and Answers
Who invented the microscope with a maximum of 30x magnification?
Who invented the microscope with a maximum of 30x magnification?
- Zacharias and Hans Janssen (correct)
- Ernst Ruska
- Anton van Leeuwenhoek
- Robert Hooke
Which scientist is known for observing cork and coining the term 'cells'?
Which scientist is known for observing cork and coining the term 'cells'?
- Anton van Leeuwenhoek
- Zacharias Janssen
- Ernst Ruska
- Robert Hooke (correct)
What significant contribution did Anton van Leeuwenhoek make to microscopy?
What significant contribution did Anton van Leeuwenhoek make to microscopy?
- Invented the first microscope
- Observed protozoa and bacteria (correct)
- Formulated the cell theory
- Developed the electron microscope
What does the term 'animalcules' refer to?
What does the term 'animalcules' refer to?
What year was the first prototype of the electron microscope built?
What year was the first prototype of the electron microscope built?
Which part of the microscope is responsible for holding the objectives?
Which part of the microscope is responsible for holding the objectives?
What feature allows modern electron microscopes to magnify objects up to 500,000 times?
What feature allows modern electron microscopes to magnify objects up to 500,000 times?
Which of the following is NOT a part of the mechanical parts of a microscope?
Which of the following is NOT a part of the mechanical parts of a microscope?
What is the function of the iris diaphragm in a microscope?
What is the function of the iris diaphragm in a microscope?
Which component of the microscope is used to tilt it for better viewing angles?
Which component of the microscope is used to tilt it for better viewing angles?
The total magnification of a microscope is calculated by multiplying which two elements?
The total magnification of a microscope is calculated by multiplying which two elements?
What was Matthias Schleiden's contribution to the cell theory?
What was Matthias Schleiden's contribution to the cell theory?
Which type of objective lens typically has a magnification of 40x?
Which type of objective lens typically has a magnification of 40x?
According to Rudolf Virchow, what is a key statement about cells?
According to Rudolf Virchow, what is a key statement about cells?
What does the condenser do in a microscope?
What does the condenser do in a microscope?
Which component directly allows the observer to view the specimen under a microscope?
Which component directly allows the observer to view the specimen under a microscope?
What is the size of the smallest cell in humans?
What is the size of the smallest cell in humans?
Which cell is the largest in humans?
Which cell is the largest in humans?
What shape do human red blood cells primarily have?
What shape do human red blood cells primarily have?
Which of the following cells can change shape to engulf microorganisms?
Which of the following cells can change shape to engulf microorganisms?
What is the length of the longest cell in humans?
What is the length of the longest cell in humans?
Which cell type is primarily branched to conduct impulses?
Which cell type is primarily branched to conduct impulses?
What is the primary reason for shape variation among different cells?
What is the primary reason for shape variation among different cells?
What is a feature of Euglena and Amoeba regarding cell shape?
What is a feature of Euglena and Amoeba regarding cell shape?
What is the primary function of cells in living organisms?
What is the primary function of cells in living organisms?
Who is credited with the observation of living cells, termed 'animalcules'?
Who is credited with the observation of living cells, termed 'animalcules'?
Which statement is NOT one of the main tenets of the cell theory?
Which statement is NOT one of the main tenets of the cell theory?
What did Rudolf Virchow contribute to the modern cell theory?
What did Rudolf Virchow contribute to the modern cell theory?
What unit is used to measure the size of a cell?
What unit is used to measure the size of a cell?
Which of the following scientists projected that plant cells are made of cells?
Which of the following scientists projected that plant cells are made of cells?
Which of the following describes the size of the smallest cell?
Which of the following describes the size of the smallest cell?
How do cells relate in terms of chemical composition and metabolic activity?
How do cells relate in terms of chemical composition and metabolic activity?
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Study Notes
Development of the Microscope
- In 1597, Zacharias and Hans Janssen invented the first microscope with a maximum magnification of 30x.
- Robert Hooke, through his microscope, discovered that cork consists of small, hollow compartments, naming them "cells" after the rooms in monasteries.
- Anton van Leeuwenhoek improved lens polishing techniques, resulting in higher magnifications, leading to the discovery of protozoa and bacteria, coining the term "animalcules" for single-celled organisms he observed.
Electron Microscopy
- Ernst Ruska and Max Knoll developed the first prototype of the electron microscope in 1931.
- Modern electron microscopes can magnify objects up to 500,000 times their actual size, enhancing resolution and detail.
Parts of the Microscope
- Mechanical Parts: Include body tube, revolving nosepiece, arm, stage, stage clips, base, and inclination joint; provide support and structure.
- Illuminating Parts: Comprise the mirror, condenser, and iris diaphragm; manage light direction and intensity on the specimen.
- Magnifying Parts: Eyepiece (ocular) and objectives; eyepiece magnifies the specimen, with various objective lenses (scanner 4x, low power 10x, high power 40x, oil immersion 100x) contributing to total magnification.
Cell Theory
- Formulated through the contributions of several scientists:
- Matthias Schleiden determined all plant parts are made of cells.
- Theodor Schwann stated that all animals are composed of cells, marking the first statement of cell theory: all living things are made of cells.
- Rudolf Virchow established that all cells arise from preexisting cells, completing the second statement of cell theory.
Tenets of the Modern Cell Theory
- All living organisms consist of one or more cells.
- Cells are the smallest functional unit of life.
- Cells arise only from preexisting cells.
- Cells transmit hereditary information during cell division.
- All cells share similar chemical compositions and metabolic activities.
Size and Shape of Cells
- Cells vary in size and shape; mycoplasma is the smallest cell at 0.1 µm, while the ostrich egg is the largest at 18 cm.
- In humans: sperm cell (5 µm) is the smallest, ovum cell (120 µm) is the largest, and nerve cell (1 m) is the longest.
- Cell shape is often specialized for function:
- Human red blood cells are circular and biconcave for easy movement through capillaries.
- Nerve cells are branched to transmit impulses effectively.
- Some cells, like white blood cells, can alter their shape to engulf microorganisms.
Contributors to Cell Theory
- Robert Hooke: Coined the term "cells" from his cork observations.
- Anton van Leeuwenhoek: First to observe living cells (animalcules).
- Matthias Schleiden: Identified cells as the building blocks of plants.
- Theodor Schwann: Expanded the theory to animals.
- Rudolf Virchow: Proposed that new cells come from existing cells.
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