AP Biology Natural Selection Unit

Chi-Square test

Categories - 1 = DF

Higher = reject

Lower = can’t reject

How did the first living things form?

Two lines of thinking

1. Organic molecules formed from inorganic things

2. organic molecules arrived on Earth from a meteor

Primordial Sourp Theory

UV radiation provided energy for inorganic atmospheric molecules to combine in just the right way to form organic molecules

First cell is similar to

Modern day archaea

Chemosynthesis

Chemical source of energy instead of sunlight

Endosymbiosis Theory

One prokaryotic cell engulfed others

• They stayed inside and eventually became organelles

Evidence for Endosymbiosis Theory

Mitochondria and chloroplast

• resemble bacteria

• have double membranes

• Have their own circular DNA

Why does all mitochondrial genes come from the mother?

The egg cell contains all the organelles needed

Descent with modification

benificial traits (adaptations) passed on to the next generation at a higher rate —> become more prominent in population over time

Causes for genetic variety

1. Mutations

2. Random mating

Outgroup

Species on cladogram least closely related to the other organism

Evolution from common anscestors support

1. Fossil records

2. Comparative Anatomy BETWEEN DIFFERENT SPECIES

3. DNA

Relative Dating

Older fossils found deeper than younger

Carbon - 14 Dating

Uses known half life decay of radioactive carbon to date fossils

Homologous Structures

Similar structures inherited by a common anscestor

Analogous Structures

Similar structures from similar environment, not a common anscestor

Vestigial Structure

“Leftover” structure

Divergence

One species giving rise to 2+ species due to adaptations to different environments

Convergence

Distantly related species developing similarities because they live in similar environments