Basis of Life- Cells, Protoplasm and Tissues
Basis of Life- Cells, Protoplasm and Tissues MCQ Questions
1.
Who first observed and described a live cell using a microscope?
C.
Antonie Von Leeuwenhoek
ANSWER :
C. Antonie Von Leeuwenhoek
Approach
The question asks to identify the scientist who first observed and described a live cell using a microscope. This requires knowledge of the history of cell biology and the contributions of key scientists in this field.
Step-by-step
- Recall the history of microscopy and cell discovery: The invention of the microscope opened up a new world of microscopic organisms and structures.
- Identify key figures: Robert Hooke is known for coining the term "cell" after observing dead cork cells. However, the first observation of live cells is attributed to another scientist.
- Consider Antonie Von Leeuwenhoek's contributions: Antonie Von Leeuwenhoek was a pioneer in microscopy. He developed his own powerful single-lens microscopes and was the first to observe and describe various microorganisms, including bacteria, protozoa, and sperm cells, which were all living cells. He referred to them as "animalcules."
- Evaluate other options: Matthias Schleiden and Rudolf Virchow are associated with the development of the cell theory, which came later than the initial observations of cells.
Based on historical records, Antonie Von Leeuwenhoek is credited with the first observation and description of live cells.
Correct Option:
C) Antonie Von Leeuwenhoek — He is widely recognized as the first person to observe and describe live cells, including bacteria and protozoa, using his self-made microscopes in the late 17th century. He called these living organisms "animalcules."
Incorrect Options
- A) Matthias Schleiden — Matthias Schleiden was a German botanist who, in 1838, concluded that all plant tissues are composed of cells. He is a co-founder of the cell theory, but he did not discover the first live cells.
- B) Rudolf Virchow — Rudolf Virchow was a German physician who, in 1855, proposed the famous axiom "Omnis cellula e cellula," meaning "all cells arise from pre-existing cells." He made significant contributions to cell theory, but he was not the first to observe live cells.
- D) Robert Hooke — Robert Hooke, in 1665, observed thin slices of cork under a microscope and coined the term "cell" to describe the small, box-like compartments he saw. However, these were dead plant cells, and he did not observe live cells.
2.
Who coined the term 'cell' for the basic unit of life?
B.
Antonie Von Leeuwenhoek
Approach
The question asks to identify the scientist who first used the term 'cell' to describe the basic unit of life. This requires knowledge of the history of cell biology and the contributions of key scientists.
Step-by-step
- Recall the early discoveries in microscopy and biology.
- Identify the scientist who observed cork under a microscope and described its compartments.
- Connect this observation to the coining of the term 'cell'.
- Robert Hooke, in 1665, observed thin slices of cork through his self-designed microscope. He noticed small, box-like compartments that reminded him of the small rooms or 'cells' in a monastery. He published his observations in his book Micrographia.
Correct Option: C) Robert Hooke
Robert Hooke was the first to observe and coin the term "cell" in 1665. He did this while examining a thin slice of cork under his microscope, noting the small, empty, honey-comb like compartments.
Incorrect Options
- A) Robert Brown — Robert Brown is credited with discovering the nucleus in plant cells in 1831, not coining the term 'cell'.
- B) Antonie Von Leeuwenhoek — Antonie Von Leeuwenhoek is known for significantly improving the microscope and being the first to observe and describe single-celled organisms (which he called "animalcules"), bacteria, and blood cells. However, he did not coin the term 'cell'.
- D) Theodor Schwann — Theodor Schwann, along with Matthias Schleiden, is famous for formulating the cell theory, stating that all animals are composed of cells. He did not coin the term 'cell'.
3.
Who discovered the nucleus of the cell?
D.
Antonie Von Leeuwenhoek
Approach
The question asks to identify the scientist credited with the discovery of the cell nucleus. This requires knowledge of key historical figures in cell biology and their specific contributions.
Step-by-step
- Recall the major discoveries in cell biology and the scientists associated with them.
- Identify the scientist who first observed and described the nucleus within a cell.
- Compare this information with the given options.
Robert Brown, a Scottish botanist, is credited with the discovery of the cell nucleus in 1831. He observed a prominent opaque spot, which he termed the "nucleus," within the cells of orchids and other plants.
Correct Option: B) Robert Brown
Incorrect Options
- A) Robert Hooke: Robert Hooke was an English scientist who, in 1665, observed cork cells under a microscope and coined the term "cell" because the structures reminded him of small rooms. He did not discover the nucleus.
- C) George Palade: George Palade was a Romanian-American cell biologist who, in the 1950s, discovered ribosomes using electron microscopy. He was awarded the Nobel Prize in Physiology or Medicine in 1974 for his contributions to the organization of the cell.
- D) Antonie Van Leeuwenhoek: Antonie Van Leeuwenhoek was a Dutch scientist who is often called the "Father of Microbiology." In the late 17th century, he made significant improvements to the microscope and was the first to observe and describe single-celled organisms (which he called "animalcules"), bacteria, muscle fibers, and blood flow in capillaries. He did not discover the nucleus.
4.
Matthias Schleiden proposed in 1838 that:
A.
Cells arise from pre-existing cells
B.
All plants are composed of cells
C.
New cells form from abiotic materials
D.
All animals are composed of cells
ANSWER :
B. All plants are composed of cells
Approach
The question asks about a specific contribution made by Matthias Schleiden in 1838 to the field of biology, particularly related to cell theory. To answer this, one needs to recall the historical development of cell theory and the individual contributions of its key proponents.
Step-by-step
- Recall the pioneers of Cell Theory: The cell theory was primarily developed by Matthias Schleiden and Theodor Schwann.
- Identify Schleiden's specific contribution: Matthias Schleiden, a German botanist, studied a wide variety of plant tissues. In 1838, he concluded that all plants are composed of cells and that cells are the basic structural units of plants.
- Identify Schwann's specific contribution: Theodor Schwann, a German zoologist, extended Schleiden's observations to animals in 1839, stating that all animals are also composed of cells.
- Identify Virchow's specific contribution: Rudolf Virchow later added the third tenet of cell theory in 1855, stating that all cells arise from pre-existing cells (\( \text{Omnis cellula e cellula} \)).
- Compare with options: Based on these historical facts, Schleiden's contribution in 1838 specifically pertains to plants.
Correct Option: B) All plants are composed of cells
Incorrect Options
- A) Cells arise from pre-existing cells — This statement is part of the modern cell theory, but it was proposed by Rudolf Virchow in 1855, not by Matthias Schleiden in 1838.
- C) New cells form from abiotic materials — This idea is contrary to the established cell theory and the principle of biogenesis. It suggests spontaneous generation, which was disproven.
- D) All animals are composed of cells — This conclusion was drawn by Theodor Schwann in 1839, building upon Schleiden's work, but it was not Schleiden's original proposition in 1838.
5.
Rudolf Virchow (1855) contributed to cell theory by stating:
A.
Cells have a plasma membrane
B.
All living things are made of cells
C.
Omnis cellula-e cellula (all cells from pre-existing cells)
D.
Cells contain a nucleus
ANSWER :
C. Omnis cellula-e cellula (all cells from pre-existing cells)
Approach
This question tests knowledge about the history and development of cell theory, specifically Rudolf Virchow's contribution. Recall the key postulates of cell theory and the scientists associated with each.
Step-by-step
- Understanding Cell Theory: The cell theory is a fundamental concept in biology. It has three main tenets.
- Early Contributions: Matthias Schleiden (1838) proposed that all plants are made of cells, and Theodor Schwann (1839) extended this to animals, stating that all animals are made of cells and cell products. Together, they formulated the first two postulates of cell theory: (1) All living organisms are composed of one or more cells, and (2) The cell is the basic unit of structure and organization in organisms.
- Virchow's Contribution: The third postulate, concerning the origin of new cells, was added later. In 1855, Rudolf Virchow, a German physician, observed that cells divide to form new cells. He famously stated, "Omnis cellula-e cellula," which means "all cells arise from pre-existing cells." This crucial addition completed the modern cell theory.
Correct Option: C) Omnis cellula-e cellula (all cells from pre-existing cells)
This statement directly reflects Rudolf Virchow's significant contribution to cell theory, explaining how new cells are formed.
Incorrect Options
- A) Cells have a plasma membrane — While true, the discovery and detailed understanding of the plasma membrane came much later with advancements in microscopy and biochemical techniques, not specifically attributed as Virchow's primary contribution to cell theory.
- B) All living things are made of cells — This idea was primarily put forth by Schleiden and Schwann in the 1830s, forming the initial postulates of cell theory.
- D) Cells contain a nucleus — The nucleus was observed much earlier (e.g., Robert Brown described it in 1831), and its presence is a characteristic of eukaryotic cells, but stating this was not Virchow's specific contribution to the *theory* of cell origin.
6.
Which of the following is NOT part of the modern Cell Theory?
A.
All living organisms are made of cells
B.
Cells were spontaneously generated from abiotic matter
C.
All cells arise from pre-existing cells
D.
Cell is the basic structural and functional unit of life
ANSWER :
B. Cells were spontaneously generated from abiotic matter
Approach
The question asks to identify which statement is NOT a part of the modern Cell Theory. To answer this, we need to recall the main tenets of the modern Cell Theory and compare them with the given options.
Step-by-step
- Understand the Cell Theory: The Cell Theory is one of the fundamental principles of biology. It has evolved over time, with the modern version incorporating advancements in understanding.
- Recall the main tenets of modern Cell Theory: The three core principles of modern Cell Theory are:
- All known living things are made up of one or more cells.
- All living cells arise from pre-existing cells by division.
- The cell is the fundamental unit of structure and function in all known living organisms.
- Evaluate Option A: "All living organisms are made of cells." This statement directly aligns with the first tenet of modern Cell Theory.
- Evaluate Option B: "Cells were spontaneously generated from abiotic matter." This idea, known as spontaneous generation, was disproved by scientists like Louis Pasteur and is contrary to the modern Cell Theory, which states that all cells arise from pre-existing cells.
- Evaluate Option C: "All cells arise from pre-existing cells." This statement is the second core tenet of modern Cell Theory (often attributed to Rudolf Virchow's "Omnis cellula e cellula").
- Evaluate Option D: "Cell is the basic structural and functional unit of life." This statement is the third core tenet of modern Cell Theory.
- Identify the incorrect statement: Based on the evaluation, Option B is the statement that is NOT part of the modern Cell Theory.
Correct Option:
B) Cells were spontaneously generated from abiotic matter — This statement represents the discredited theory of spontaneous generation, which proposes that living organisms can arise from non-living matter. The modern Cell Theory explicitly states that all cells arise from pre-existing cells, refuting spontaneous generation.
Incorrect Options
- A) All living organisms are made of cells — This is a fundamental principle of the modern Cell Theory. It establishes the cell as the universal building block of life.
- C) All cells arise from pre-existing cells — This is another core tenet of the modern Cell Theory, emphasizing that cells do not spontaneously appear but rather reproduce from existing cells.
- D) Cell is the basic structural and functional unit of life — This is also a fundamental principle of the modern Cell Theory, highlighting the cell's role as the smallest entity capable of carrying out all life processes.
