What characteristics are common to all organisms?

Characteristics of Life:Living things…

• use energy,

• develop and grow,

• maintain organization and homeostasis,

• reproduce asexually or sexually,

• form populations that evolve,

• have DNA as the genetic code.

Why is water so important to life?

Extraordinary Properties of Water

• Cohesion– Water molecules stick

together

– Surface tension

• Adhesion– Water molecules cling

to other solids

– capillarity

Extraordinary Properties of Water

• High Specific Heat– Amount of heat that

must be absorbed for 1g to change 1o C for water = 1.00 cal/g/oC

Sp Heat of common liquids

Liquid SpHt (cal/g/oC)

Ammonia 1.23

Water 1.00

Eth alc 0.60

Acetone 0.53

Olive oil 0.47

Mercury 0.03

Extraordinary Properties of Water

• High Heat of Vaporization– (change from liquid to

gas)

– Quantity of heat a liquid must absorb for 1g to be converted to the gas state for water = 576 cal/g

Ht of Vap of some liquids

Liquid Ht Vap (cal/g)

Water at 37C 576

Ammonia 302

Eth alcohol 237

Acetone 125

Mercury 59

Extraordinary Properties of Water

Extraordinary Properties of Water

• Water is a versatile solvent– Ionic compounds

dissolve in water

– Covalent compounds rich in O or N dissolve in water

Extraordinary Properties of Water

• Adhesion and Cohesion

• High Specific Heat

• High Heat of Vaporization

• Expands when freezing

• Versatile Solvent

How does water do all this?What allows water to facilitate life at the

cellular and global level?

Hydrogen Bonds

• A weak force of attraction between the H on one molecule and a highly electronegative atom on another molecule

Extraordinary Properties of Water

• Versatile Solvent-------due to polarity

• Adhesion and Cohesion---due to H bonds

• High Specific Heat --------due to H bonds

• High Heat of Vap. ---------due to H bonds

• Expands when freezing ---due to H bonds