MODULE 1.1 - Origins and History of Animal Life

Spontaneous Generation

Disproven scientific theory stating that living organisms can develop directly from non-living matter

Big-Bang Model

The universe originated from a primeval fireball and has been expanding and cooling since its inception 10 to 20 billion years ago

Cosmic dust and gases

4.6 billion years ago, the sun and planets formed from a spherical cloud of ____, which collapsed under its own gravity

Oparin-Haldane Hypothesis

Proposed that simplest form of life arose gradually by the progressive assembly of small molecules into more complex organic molecules, and molecules capable of self-replication eventually would be produced, leading to assembly of living microorganisms

Water

Most abundant of all compounds in cells, forming 60% to 90% of most living organisms

Hydrogen Bonds

Form between adjacent water molecules that underlie properties that explain water’s essential role in living systems and their origin

High Specific Heat Capacity

1 calorie is required to elevate the temperature of 1 g of water 1° C

This energy is used to rupture some hydrogen bonds, as well as increase the kinetic energy and temperature of water

Greatly moderates environmental temperature changes, thereby protecting living organisms from extreme thermal fluctuation

Water has a higher thermal capacity than any other liquid except ammonia

True

Calorie

Amount of heat required to heat 1 g of water from 14.5° to 15.5° C

4.184 J

1 cal

High Heat of Vaporization

500 C is required to convert 1 g of liquid water to water vapor

All hydrogen bonds between water molecule and neighbors must be ruptured before the water molecule can escape the surface and enter the air

Cooling

Important for terrestrial animals (and plants) to expel excess heat

This is produced by evaporation of water

Density

Measure of how much mass is packed into a given space or volume

Water reaches the maximum of this value at 4° C while still a liquid, then becomes less with further cooling

Dense

Ice water is less ___ than liquid water, which is why ice floats rather than sinking to the bottoms of lakes and ponds

If it was the opposite, bodies of water would freeze solid from the bottom upward in winter and might not melt completely in summer

Ice water

In this condition, water molecules form an extensive, open, crystal-like network supported by hydrogen bonds that connect all molecules

The molecules in this lattice are farther apart, and thus less dense than in liquid water at 4° C

High Surface Tension