AP Biology Unit 1

Temperature moderation

Water has a high specific heat, allowing it to absorb great amounts of energy without increasing temperature at the same rate

Expansion upon freezing

H-bonds between water molecules spread out at low temperatures, making ice float on water

Versatile solvent

Water is the solvent of life and all biochemical reactions occur in aqueous solution

chnops

the six most abundant elements in living organisms on Earth: Carbon (C), Hydrogen (H), Nitrogen (N), Oxygen (O), Phosphorus (P), and Sulfur (S)which are essential for building macromolecules and supporting life.

Adhesion

Adhesion is when water molecules stick to other things due to their polar nature, allowing for capillary action and important biological processes.

Cohesion

Cohesion is when water molecules stick to each other because of hydrogen bonds.Water molecules are polar — one side is slightly negative (oxygen) and the other is slightly positive (hydrogens). Because of this, water molecules are attracted to each other and form hydrogen bonds.

How Do Plants Pull Up Water?

Roots absorb water from the soil. Water sticks to the xylem walls by adhesion. Water sticks to other water molecules above it because of Cohesion. Water evaporates from the leaves (known as transpiration). That evaporation creates a pull (like sucking through a straw), and because of cohesion and adhesion, the whole water column gets pulled up

acidic

A solution is acidic if it contains a lot of hydrogen ions (H+). If you dissolve an acid in water, it will release a lot of hydrogen ions.

basic

Bases do not release hydrogen ions when added to water. They release a lot of hydroxide ions (OH–).

carbon

is a versatile atom, meaning that it has the ability to bind not only with other carbons but also with a number of other elements including nitrogen, oxygen, and hydrogen

Lipids

The most common examples of lipids are triglycerides, phospholipids, and steroids.Lipids are important due to their non-polar structures, they function as structural components of cell membranes, sources of insulation, signalling molecules, and a means of energy storage.

Phospholipids

Phospholipids contain two fatty acid “tails” and one negatively charged phosphate “head”.The two fatty acid tails are hydrophobic. The reason for this is that fatty acid tails are non-polar, and non-polar substances don’t mix well with polar ones, such as water. The phosphate “head” of the lipid is hydrophilic, meaning that it does mix well with water since it carries a negative charge, and this charge draws it to the positively charged end of a water molecule. A phospholipid has both a hydrophilic region and a hydrophobic region which makes it is an amphipathic molecule.