The Fundamental Unit of Life – Lecture Review

Twenty-eight question-and-answer flashcards covering key discoveries, cell structures, organelle functions, transport mechanisms, and cell division from the lecture notes on the fundamental unit of life.

Who discovered cells and in which material did he observe them in 1665?

Robert Hooke observed tiny compartments in a thin slice of cork, coining the term “cells.”

Which scientist first observed free-living cells in pond water in 1674?

Antonie van Leeuwenhoek.

Who discovered the cell nucleus and in what year?

Robert Brown in 1831.

Which scientist coined the term “protoplasm,” and when?

Johannes Purkinje in 1839.

Name the two biologists who proposed the original cell theory.

Matthias Schleiden (1838) and Theodor Schwann (1839).

Which scientist added the idea that “all cells arise from pre-existing cells” to the cell theory?

Rudolf Virchow in 1855.

Why is the cell called the structural and functional unit of life?

A cell is called the structural and functional unit of life because all living organisms are made up of cells, making cells the structural units. All life processes such as nutrition, respiration, excretion, and reproduction take place inside cells, making them the functional units as well. This shows that the cell is the smallest unit that can carry out all essential activities of life.

What is the main difference between unicellular and multicellular organisms?

Unicellular organisms consist of a single cell performing all life functions, whereas multicellular organisms have many specialized cells working together.

What term describes the outer boundary of a cell that controls substance movement?

The plasma membrane (cell membrane).

Why is the plasma membrane described as selectively permeable?

It permits the passage of some molecules while restricting others, regulating the cell’s internal environment.

Define diffusion in the context of cell transport.

The spontaneous movement of molecules from a region of higher concentration to a region of lower concentration.

What is osmosis?

The net diffusion of water through a selectively permeable membrane toward the side with higher solute concentration.

What happens to an animal cell placed in a hypotonic solution?

It gains water by osmosis and may swell or burst.

What is plasmolysis?

The shrinkage of the cytoplasm of a plant’s cell away from the cell membrane due to the loss of water.

State two key structural differences between prokaryotic and eukaryotic cells.

Prokaryotes lack a true nuclear membrane and membrane-bound organelles, whereas eukaryotes possess both.

What is the cytoplasm?

The fluid content inside the plasma membrane that contains the cell’s organelles.

Differentiate between rough and smooth endoplasmic reticulum (ER).

Rough ER has ribosomes and synthesizes proteins; smooth ER lacks ribosomes and synthesizes lipids/detoxifies poisons.

List two functions of the Golgi apparatus.

(1) Modifies, packages and transports lipids and proteins
(2) forms lysosomes

(3) forms vesicles to transport these materials

Why are lysosomes called “suicide bags” of the cell?

Lysosomes are called as the suicide bags of the cell because they contain powerful digestive enzymes which at time of cell damage , the lysosomes burst and digest the cell from within.

Which organelle is known as the powerhouse of the cell and why?

The mitochondrion, because it releases usable energy in the form of ATP during respiration.

Name the energy currency of the cell produced by mitochondria.

ATP (adenosine triphosphate).

Which two organelles contain their own DNA and ribosomes?

Mitochondria and plastids (e.g., chloroplasts).

Where in the cell are proteins synthesized?

On ribosomes, particularly those attached to the rough endoplasmic reticulum.

Name the two main types of plastids and give one function of each.

Chromoplasts (such as chloroplasts) carry out photosynthesis/contain pigments; leucoplasts store starch, oils, or proteins.

How do Amoebae obtain food from their surroundings?

By endocytosis—engulfing food particles with flexible extensions of the plasma membrane.

What is the primary role of vacuoles in mature plant cells?

They store cell sap, provide turgidity/rigidity, and accumulate important substances or wastes.

Which type of cell division produces genetically identical daughter cells for growth and repair?

Mitosis.

Why do cell walls enable plant, fungal, and bacterial cells to survive in hypotonic environments without bursting?

The rigid cellulose (or similar) wall resists internal pressure from water uptake, preventing the cell from rupturing.

What is the full form of DNA and RNA

Deoxyribonucleic acid and ribonucleic acid.