Module 4 – Cell Structure & Function: History, Theory, and Characteristics

25 Q&A flashcards review the lecture’s key points: definitions of unicellular/multicellular, milestones in microscope history, contributors to cell theory, the three tenets of cell theory, cellular life functions, and the complexity of unicellular versus multicellular life.

What do we call organisms made of a single cell?

Unicellular organisms.

What term describes organisms composed of many cells?

Multicellular organisms.

Approximately how many cells make up the human body?

About 37 trillion (37,000,000,000,000) cells.

Who built the first compound microscope in 1595?

Hans and Zacharias (Zechariah) Jansen.

Which scientist coined the word “cell” after observing cork under a microscope?

Robert Hooke.

What did Robert Hooke actually observe in cork slices?

The remaining cell walls of dead plant cells.

Which Dutch scientist used simple microscopes to study living pond organisms and later bacteria (1683)?

Anton van Leeuwenhoek.

Which botanist identified the nucleus in plant cells in 1833?

Robert Brown.

Who concluded that all plant tissues are composed of cells?

Matthias Schleiden (1838).

Who concluded that all animal tissues are composed of cells?

Theodor Schwann (1839).

Which physician stated that all cells arise from pre-existing cells, opposing spontaneous generation?

Rudolf Virchow (1855).

List the three core statements of modern cell theory.

1) All living organisms are composed of cells. 2) The cell is the basic unit of structure and function in living things. 3) All cells arise from pre-existing cells.

What branch of biology specifically studies cells?

Cytology.

Define ingestion in cellular terms.

The ability of a cell to take in nutrients.

What is absorption?

Bringing dissolved materials into the cell.

What cellular process breaks food into simpler forms, often via hydrolysis?

Digestion.

Which process releases energy from broken-down food molecules?

Respiration.

How is homeostasis defined for a cell?

Maintaining internal stability or regulation.

What is synthesis (or biosynthesis) in a cell?

Combining simple compounds into more complex molecules.

Differentiate secretion and excretion.

Secretion releases useful biosynthesized substances; excretion removes soluble metabolic waste.

What is egestion?

Removal of insoluble, undigested waste from the cell.

In cell physiology, what does irritability mean?

The ability to respond to stimuli.

Why are unicellular organisms considered highly complex despite being single-celled?

Because one cell must perform all life functions that multicellular organisms divide among many specialized cells.

What improvement of the 1500s–1600s first allowed scientists to study cells?

The development of more powerful compound microscopes.

Which experiment by Pasteur (1859) ultimately disproved spontaneous generation, supporting Virchow's view?

The swan-neck flask experiment demonstrating that microorganisms come from existing life, not spontaneous generation.