Chapter 3: Defining Life and its Origins

Question 1

List and describe the seven properties of life

Answer 1

• display order
• harness and utilize energy
• reproduce
• respond to stimuli
• exhibit homeostasis
• growth + environment
• evolve

Question 2

Explain why viruses are not considered to be true living organisms.

Answer 2

They lack many of the properties associated with living organisms. Primarily, they lack the ability to reproduce without the aid of a host cell, and don’t use the typical cell- division approach to replication.

Question 3

Describe the characteristics of Earth that made it suitable for development of life.

Answer 3

-it lies within the habitable zone around the sun which allows water to exist in liquid state (a fundamental prereq for the development of life)

Question 4

reducing atmosphere

Answer 4

an atmospheric condition in which oxidation is prevented by removal of oxygen and other oxidising gases or vapours.

Question 5

deep-sea vents

Answer 5

life could have originated on the ocean floor at the site of deep sea vents, which today support a remarkable diversity of life

Question 6

extraterrestrials

Answer 6

key organic molecules required for life came from space

Question 7

Describe the impact of oxygenic photosynthesis on evolution of life.

Answer 7

oxygenic photosynthesis relies on the oxidation of water as the source of electrons which then releases oxygen, therefore, cyanobacteria could thrive anywhere there was sunlight

Question 8

Describe the endosymbiotic theory of the origin and evolution of mitochondria and
chloroplasts.

Answer 8

suggest that mitochondria and chloroplasts evolved from ingested prokaryotes; mitochondria from aerobic bacteria and chloroplasts from cyanobacteria