Biology

**7.1 Introduction to Natural Selection**

* **Evolution**: the __change in the genetic makeup__ of a population over time and is supported by multiple lines of evidence
* **Natural Selection:** the process by which organisms, having __adaptations suited for a particular environment__, having a __gr

AP Biology Review (Part Three)

## Chemistry of Life

**Elements**: Substances that cannot be broken down into simpler substances by chemical means

* 96% of the mass of all organisms are made mostly of oxygen (O), carbon (C), hydrogen (H), and nitrogen (N)
  * Calcium, phosphorus, potassium, sulfur, sodium, chlorine, magnesium pr

AP Biology Review (Part One)

**Translation: initiation, elongation, termination**

* Ribosome attaches to the mRNA, Ribosome holds everything in place while the tRNAs assist in assembling polypeptides

*Initiation*

* 3 binding sites: A site, P site, E site
  * mRNA shuffles through from A>P> E and as mRNA codons are read, the 

AP Biology Review (Part Two) 

### AP Daily 8.1 - Responses to Environment

*How do organisms respond to changes in their environment?*

* Organisms respond to changes in their environment through __behavio__r and __physiological__ mechanisms

*What is a stimulus?*

* Stimulus: an external or internal signal or combination of sig

AP Biology Review (Part Four)

Phospholipid bilayer - double layer – hydrophobic tails and hydrophilic heads (referred to as an “amphipathic” molecule) Fluid Mosiac Model of the Cell Membrane


1. Fluid–phospholipidsinthemembraneareismotion,changingplaces,switchingsides–unsaturated “tails” in the hydrophobic area increase fluidit