The Secret of Life. A scientific inquiry into what it means… Quiz

Explore foundational scientific concepts about what distinguishes living things from non-living, tracing the journey from vitalism to molecular biology and uncovering how life is explained today.

1. What distinguishes living organisms from non-living matter according to modern biology?

   Which property is essential for distinguishing living organisms from non-living matter?

   1. Immobility
   2. Unchanging chemical structure
   3. Existence of a unique life force
   4. Ability to carry out metabolism

   Explanation: The ability to carry out metabolism—meaning chemical reactions that sustain life—is a core property of living things. The idea of a unique life force reflects outdated vitalism theories, not modern science. Unchanging chemical structure is not characteristic of living entities, as they undergo constant chemical changes. Immobility is not a distinguishing factor, since some living things (like plants) are immobile and some non-living things are too.

2. Vitalism was replaced by biochemical understanding in the 20th century.

   Why did the theory of vitalism fall out of favor in scientific circles during the 20th century?

   1. Scientists could not observe cells under microscopes
   2. Vitalism was proven to cause diseases
   3. New evidence supported the idea humans are unique among life forms
   4. Advancements in biochemistry explained life through chemical processes

   Explanation: The rise of biochemistry allowed scientists to explain life using chemical reactions, rendering the vitalism concept unnecessary. Vitalism was not associated with causing diseases, and microscopes had already enabled cell observation. The uniqueness of humans compared to other life forms is a separate question not related to vitalism's decline.

3. DNA's discovery clarified the basis of heredity.

   What major scientific discovery linked the storage and transmission of genetic information in living beings?

   1. Structure of DNA
   2. Law of gravity
   3. Discovery of chlorophyll
   4. Discovery of mitochondria

   Explanation: The discovery of DNA's structure revealed how genetic information is stored and transmitted in living organisms. Mitochondria are involved in energy production but not primary genetic storage. The law of gravity pertains to physics, not biology. Chlorophyll relates to photosynthesis, not inheritance of traits.

4. Irreversible thermodynamic processes in life.

   Why are living systems described as open systems in thermodynamics?

   1. They are sealed from external influence
   2. They exchange energy and matter with their surroundings
   3. They are always colder than their environment
   4. They do not undergo any chemical changes

   Explanation: Living systems are open because they constantly exchange energy and matter with their environments, essential for sustaining life. Being colder than surroundings or sealed off is incorrect; organisms require interaction with their environment. They also undergo frequent chemical reactions, making the last option false.

5. The origin of the life force concept.

   What was the main idea behind the concept of 'vitalism' in biology?

   1. Life began with the evolution of plants
   2. All living things are composed only of water
   3. Life is due to Earth's gravity
   4. A non-material essence is required for life

   Explanation: Vitalism asserted that living things possess a unique, non-material 'life force' absent in non-living matter. The other options do not accurately represent vitalism: water composition and gravity are not its basis, and vitalism does not specify the evolutionary timeline of plants.