AP Bio Unit 1

What is water important for?

Maintaining homeostasis

How does water transport in animals?

Blood

How does water transport in plants?

Sap

Is water a polar or non-polar molecule?

Polar

What does it mean when a molecule is polar?

The partial charges on the poles attract to opposite charges on other molecules full ride

What does waters polarity allow it to do?

Hydrogen bond with:

Other water molecules

Other polar or charged molecules

What do waters chemical properties allow it to do?

Exhibit cohesion and adhesion

Have surface tension

Resist temperature changes

Act as an excellent solvent

What is surface tension?

Cohesion of water molecules at the surface of a body of water

What is capillary action?

Water adheres to the side of tubes that are lined with polar molecules and “crawls” up the tube

Why do plants use capillary action?

To pull water from the roots and into their vascular tissue to transport it and up to the leaves where photosynthesis occurs

When are hydrogen bonds strong?

When they are all together as a collective

What is high specific heat capacity?

Water resisting temperature changes because it takes a lot of energy to break all of the hydrogen bonds

When is high specific heat capacity useful for living organisms?

When they need to live in water

For organisms to maintain a constant internal temperature for homeostasis

Why is water an excellent solvent?

Because it is polar

What is a solvent?

Substance that dissolves other chemicals

What are ions?

Electrolytes

What happens when the solvent is held together by covalent bonds?

Water can create a shell around polar molecules that can not ionize

What is an atom?

The smallest stable unit of matter that has the characteristics of its specific element

What is the structure of an atom?

Nucleus with electron orbitals

Are protons charged?

Yes, they have a positive charge

Are neutrons charged?

No, they are neutral

Do electrons have a charge?

Yes, they are negatively charged

Where is the lower energy orbital?

Close to the nucleus

Where is the higher energy orbital?

Farther away from the nucleus

What are valence electrons?

Electrons found in the outermost orbital

How many electrons do most elements want in their valence shell? Why?

8

This makes them the most stable

What are non-neutral atoms called?

Ions

What charge does a cation have?

Positive charge

More protons than electrons

What charge does an anion have?

Negative charge

More electrons than protons

What are the two types of ions?

Cation

Anion

What are the elements of life?

Carbon

Hydrogen

Oxygen

Nitrogen

What do organisms use carbon for?

To produce every bio molecule

What happens when organisms die?

Decomposers recycle the carbon back into the environment

What will happen in carbon-depleted areas?

They will die

What do organisms use nitrogen for?

To produce proteins and nucleic acids

How is nitrogen recycled into the environment?

By decomposers

What will happen in nitrogen depleted areas?

They will die

What is phosphorus used for?

To build nucleic acids and certain types of lipids

What will happen in phosphorus depleted areas?

They will die because they cannot make nucleic acids or phospholipids

What is electronegativity?

The measurement of how strongly atoms attract bonding electrons to themselves

What is electronegativity determined by?

How many electrons are in the valance shell

(The closer to eight electrons they have, the more electronegative the element is)

What is the most electronegative element?

Fluorine

How electronegative is oxygen?

Less electronegative than fluorine, more electronegative than nitrogen

How electronegative is nitrogen?

Less electronegative than fluorine and oxygen but still a very electronegative element

What are covalent bonds?

Occurs when two atoms share an electron

Energy is stored here

When do polar molecules occur?

When there is an unequal sharing of electrons across a covalent bond

What overall charge does polar molecules have?

Neutral charge

What are hydrogen bonds?

Weak attraction between a hydrogen bonded to an oxygen, nitrogen, or fluorine and another O, N, or F

What determines a molecules overall shape?

How atoms are bonded together

What determines the function of a molecule?

The structure, shape and chemical properties