Living Things and the Origin of Life

What makes something living? What are the characteristics of living things?

Living things:

  1. Use materials and energy
  2. Grow and develop
  3. Respond to stimuli and their environment
  4. Display homeostasis, which means maintaining a constant internal environment
  5. Reproduce & pass on traits to offspring
  6. Adapt, and the species evolve (slowly)
  7. Are made of cells or is a cell
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Healthy Pond Ecosystem with Living Organisms – Source: Rutgers University

The best way to understand these living characteristics criteria is to think about ourselves.

Imagine a human baby named Moo. Like other babies, Moo eats, drinks, and sleeps. This satisfies the first bullet point: Use materials and energy. Moo then grows bigger, learns how to walk and talk, and goes to school. He grows and develops. When his mother calls for him to wake up for school, Moo groggily rolls over in his bed. He responds to stimuli. When Moo is sick with the flu, his immune system  is battling against the virus and is helping maintain a constant internal environment.

Eventually, Moo grows up, goes to college, gets a job, and gets married to his high school sweetheart. They have a baby named Moo Jr., Moo’s offspring whom he has passed down his traits to.

In general, humans adapt to their environments, and over generations, the species evolve.

And, of course, Mr. Moo and his son are made of cells.

And, Just for fun 😀

Test your knowledge on <Living Things>

Questions:

Living or Nonliving?

  1. Bacteria
  2. T-shirt
  3. Computer
  4. Tissue Paper
  5. Virus
  6. Feces

Scroll down to the very bottom of the page for the answers to these questions.

Flashcards:

https://quizlet.com/114151189/flashcards/embed

Take a test with these flashcards:

https://quizlet.com/114151189/test/embed

The flashcards are from courtesy of Quizlet members, Llamaking and daretobe. Thank you!

 

The Origin of Life 

Life started about 3 billion years ago from a common origin.

How do we know that all life has a common origin?

  1. DNA: All organisms’ DNA sequences are related.
  2. Chemistry: All organisms’ cells have similar basic chemistry.
  3. Biological Processes: All organisms’ fundamental processes are very similar to one another.

Famous Biologists & The Discovery of the Cell

A cell is the smallest unit of life.

Cells were not seen until microscopes were invented in the 17th century.

Below are famous scientists who paved way for new discoveries in biology:

Scientist Discovery Year
Robert Hooke ·         First person to see a cell through his microscope

·         Observed the structure of dead cork

1655
Antonie van Leeuwenhook ·         First person to observe living cells (bacteria)

·         Built over 200 microscopes

1676
Matthias Schleiden & Theodor Schwann ·         Created the Cell Theory: Cells are the universal building blocks of all living tissues 1838
Charles Darwin ·         Theory of Evolution

·         All species are derived from other earlier species by selection of the fittest

1838

 

Louis Pasteur ·         Performed experiment to test if life can be spontaneously created

·         Answer: No, all cells arise from pre-existing cells

1860

Answers:

  1. Living
  2. Nonliving
  3. Nonliving
  4. Nonliving
  5. Nonliving
  6. Both nonliving and living 🙂 This one is tricky. Feces contain bacteria, unwanted dead and undigested material, etc.