2.1 - Water - What does life require?

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Living Organisms can include what attributes?
- Growth
- Movement
- Reproduction
- Response to external environment stimuli
- Metabolism
Define: Metabolism

All of the chemical process that occur in cells, including the breakdown of substances to produce energy, the synthesis of substances necessary for life, and the excretion of waste generated by these processes.
What is homeostasis?

Roughly constant internal environment despite an ever changing external environment
The ability to maintain homeostasis requires:

-Complex feedback mechanisms between multiple sensory and physiological systems and is possible only in living organisms.
What is a requirement for lfe?

water
What are the 2 elements that what is made up of?
- hydrogen
- oxygen
Elements are the fundamental forms of _______ and are composed of _______ that cannot be broken down by normal physical means such as boiling.

Elements are the fundamental forms of MATTER and are composed of ATOMS that cannot be broken down by normal physical means such as boiling.
Atoms are the smallest units that have the properties of any given ________.

element.
Atoms are composed of subatomic particles called:
- protons
- neutrons
- electrons
Protons have a _____ electric charge

POSITIVE
Neutrons have a ________ electric charge

uncharged (0)
What makes up the nucleus of an atom?

protons and nuetrons
What gives an element their atomic number?

The number of PROTONS.

*All atoms of a particular element have the same number of protons.
Electrons have a _______ charge.

NEGATIVE
Where are the negatively charged electrons found in relation to the nucleus?

Outside in the nucleus in an electron cloud.
What are electrons attracted to?

positively charged nucleus.
To be considered a neutral atom what must happen?

There must be an equal number of electrons and protons.
Define ion:

Electrically charged atom
Water, like other molecules, consist of 2 or more _____ joined by ______ bonds.

Water, like other molecules, consist of 2 or more ATOMS joined by CHEMICAL bonds.
A substance that dissolves when mixed with another substance is called

Solute
When a solute is dissolved in a liquid (such as water) the liquid is called a

solvent
What makes water a good solvent?

It is polar.
Define: Polar

Different regions or poles of the molecule have different charges.
Define: Electronegative

The tendency to attract electrons to form a chemical bond.
Why is the water polar?

Oxygen is more attractive to electrons.
Electrons in a _______ molecule spend more time near the ______ of the oxygen atom than near the nuclei of the hydrogen atoms.
- water
- nucleus
When atoms of a molecule carry no partial charge they are said to be:

nonpolar
Hydrogen Bond

Is a weak chemical bond

Forms when a partially positive hydrogen bond atom is attracted to a partially negative atom.
Hydrophilic
- Water loving
- Ability to dissolve in water
Hydrophobic
- water-fearing
- -Do not contained charged atoms
- -They do not easily mix with water
Chemical reactions are facilitated by

water
Chemical Reactions - Define:

Changes in the chemical composition of substances.
Reactants - Define:

Any starting material in a chemical reaction.
What are the molecules formed as a result of a chemical reaction?

products
What is cohesion?

The tendency of like molecules to stick together.
Cohesion is much stronger in _____ than in most liquids because of the sheer number of hydrogen bonds.

Water
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