The question asks to identify the scientist who first observed and described a live cell. This is a factual question from the history of biology, specifically cell biology. We need to recall the contributions of each scientist listed in the options.
Based on these historical facts, Antonie Van Leeuwenhoek is credited with the first observation and description of live cells.
Correct Option: D) Antonie Van Leeuwenhoek first observed and described live cells (animalcules) using his improved microscopes.
The question asks to identify the scientist credited with the discovery of the cell nucleus. This requires knowledge of fundamental discoveries in cell biology and the contributions of prominent scientists.
Robert Brown, a Scottish botanist, is widely credited with the discovery of the cell nucleus in 1831. He observed an opaque spot, which he termed the "nucleus," within the cells of orchids and other plants.
C) Robert Brown — Robert Brown discovered the nucleus of the cell in 1831 while studying orchid cells. He described it as a central, opaque body within the cell.
The question asks to identify the scientists who proposed the cell theory. We need to recall the key contributors to the development of this fundamental biological concept.
Correct Option: D) Schleiden and Schwann are universally recognized for proposing the cell theory, based on their observations that all plants and animals are made of cells.
The question asks to identify the scientist who first proposed the concept that new cells arise from pre-existing cells, encapsulated by the phrase "Omnis cellula-e cellula". This is a fundamental principle of modern cell theory.
C) Rudolf Virchow — In 1855, Rudolf Virchow, a German physician, made a significant contribution to cell theory by proposing that all cells arise from pre-existing cells (Omnis cellula-e cellula). This idea challenged the prevailing belief of spontaneous generation and became a cornerstone of modern biology, completing the cell theory.
The question asks to identify which statement is NOT a component 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.
D) Cells arise spontaneously from non-living matter. This statement represents the discredited theory of spontaneous generation, which was disproven and is directly contradicted by the modern cell theory's postulate that all cells arise from pre-existing cells.
The question asks to identify the structure that Theodore Schwann concluded is unique to plant cells. This requires knowledge of the contributions of Theodore Schwann to cell theory and the distinguishing features between plant and animal cells.
Correct Option: D) Cell wall
The cell wall is a rigid outer layer found in plant cells, fungi, algae, and bacteria, but it is absent in animal cells. Theodore Schwann specifically noted its presence in plant cells as a distinguishing feature.