Chapter 1: Biology and the Tree of Life - pt.2

what does cell theory state?

all organisms are made of cells, and cells come from preexisting cells

what is the smallest organism?

bacteria

what is a cell?

highly organized compartment bounded by a thin, flexible structure called the plasma membrane

where did people originally think cells came from?

from spontaneous generation (abiogenesis) - animals from non-living sources

who proposed that cells come from preexisting cells?

Virchow (1858), after witnessing cell division under a microscope

what are two hypotheses about the origin of cells?

1) spontaneous generation

2) all cells come from preexisting cells

who tested spontaneous generation with experiments ?

Louis Pasture

who developed the theory of evolution by natural selection?

Charles Darwin and Alfred Russell Wallace

what is evolution ?

change in characteristics of a population over time

what are two key ideas of evolution?

1) species are related by common ancestry

2) characteristics of species can change from one generation to the next

what is natural selection ?

the process of evolution, where heritable traits are passed on to offspring

what are two conditions must be met for natural selection?

1) variation in heritable traits in a population

2) certain traits help individuals survive or reproduce more

what is population?

group of individuals of the same species living in the same are at the same time

What is artificial selection?

Changes in a population caused by humans selecting individuals to reproduce.

What is fitness?

The ability to produce viable offspring.

What is adaptation?

A trait that increases an individual’s fitness in a particular environment.