Study sheet: The Logic of Living Systems

📋 Course Outline

1. Biology and Its Historical Foundations
2. Functional Properties of Living Things
3. Structure and Biological Function
4. Levels of Biological Organization
5. Interactions and Biological Flows
6. Unity and Diversity of Life

📖 1. Biology and Its Historical Foundations

🔑 Key Concepts & Definitions

• Biology : the scientific field that studies organisms and living structures, and the term comes from the Greek bios, meaning life, and logos, meaning thought

📝 Essential Points

• Early milestones include:

  • 460 BC: birth of Hippocrates of Cos
  • 343 BC: Aristotle’s History of Animals
  • 1543: Vesalius’s anatomical dissections
  • 1665: Hooke’s observations of cells
  • 1669: Malpighi’s description of chick embryonic development
  • 1736: Linnaeus’s first use of the term biology

• Later milestones include:

  • 1774: Priestley’s discovery of dioxygen and respiration
  • 1828: Wöhler’s synthesis of urea
  • 1838: formulation of the cell theory
  • 1859: Darwin’s natural selection theory
  • 1865: Bernard’s homeostasis concept
  • 1897: Buchner’s discovery of enzymes and foundation of biochemistry
  • 1901: first Nobel Prize in Physiology or Medicine, awarded to Emil Adolf von Behring
  • 1902: chromosomal theory of heredity
  • 1927: Elton’s ecological niche theory
  • 1977: Woese’s complete phylogenetic tree of life

💡 Memory Hook

From Hippocrates and Aristotle to Hooke, Darwin, Bernard, and Woese

📖 2. Functional Properties of Living Things

🔑 Key Concepts & Definitions

• Living thing : autonomous, has a metabolism, can develop and reproduce, and interacts with its environment
• Metabolism : the set of chemical reactions that transform energy and matter obtained from the environment

★ Must-know

• The essential properties are: development and growth, metabolism, movement, autonomous reproduction, reception and appropriate response to information

Further detail

• Derived properties include:
  • evolution across generations
  • interaction with the external environment
  • regulated states of equilibrium
  • ordered organization

💡 Memory Hook

G-M-M-R-I: growth, metabolism, movement, reproduction, information

📖 3. Structure and Biological Function

🔑 Key Concepts & Definitions

• Cell : the most evident unit of life, consisting of cytoplasm surrounded by a plasma membrane

★ Must-know

• Enzymes are proteins that catalyze practically all reactions of living organisms, while coenzymes such as ATP act as metabolic intermediates.

• DNA is an informational molecule capable of replication and therefore plays a central role in reproduction.

Further detail

• Movement relies on muscle cells in animals and cytoskeletal proteins such as actin, myosin, and microtubules.

📌 The relationship between structure and function means that a biological structure’s organization enables a particular function, such as a sensory organ enabling information reception.

💡 Memory Hook

Biological structures enable specific functions

📖 4. Levels of Biological Organization

🔑 Key Concepts & Definitions

• Emergent property : a property of an organizational level produced by interactions among its constituents and not reducible to their simple sum
• Population : a set of individuals belonging to the same species that interact, particularly by reproducing, within a given territory
• Ecosystem : groups of living organisms of different species, called the biocenosis, and their relationships with the environment, called the biotope, within a given area
• Biosphere : the set of all living organisms on Earth and the relationships they form with biological and geological environments, or more simply the set of terrestrial ecosystems

📝 Essential Points

• From smallest to largest, the levels are:
  • molecular level
  • cellular level
  • organic level
  • organismal level
  • population level
  • ecosystem level
  • landscape level
  • biosphere level

💡 Memory Hook

Molecules → cells → organs → organisms → populations → ecosystems → biosphere

📖 5. Interactions and Biological Flows

★ Must-know

• Biological systems transmit flows of:
  • matter
  • energy
  • information

📌 An integrated approach considers interactions across all organizational levels, whereas a reductionist approach studies a biological problem precisely at one selected level.

Further detail

• The effect of increased atmospheric carbon dioxide concentration on photosynthesis in plants requires changes of scale between the atmosphere, the organism, and cellular processes.

💡 Memory Hook

Integrated systems exceed their parts, whereas reductionism isolates one level

📖 6. Unity and Diversity of Life

🔑 Key Concepts & Definitions

• Biodiversity : the diversity of nucleotide sequences, protein forms and functions, cell types, organisms, species, individuals within species, and population modes of functioning

★ Must-know

• All living things share molecules such as DNA and proteins, are made of cells, and interact within populations, while many multicellular organisms also share a common body plan.

• The unity of living things indicates that they are related and descend from common ancestors, a relationship represented by phylogenetic trees.

Further detail

• The complexity of living systems results from multiple organizational levels, associated constituents, interactions among constituents, and the diversity of these systems, making exhaustive study practically impossible.

💡 Memory Hook

Shared cellular foundations reveal unity, while variation produces biodiversity

📊 Synthesis Tables

Unity and diversity of life

Dimension	Unity	Diversity
Molecular	Shared DNA and proteins	Different nucleotide sequences and protein forms
Cellular	All living things are cellular	Different cell types
Organismal	Common body plans in many multicellular organisms	Different organisms and species
Population	Interactions within populations	Different population modes of functioning