Biol 1551 Sep 9^th lecture notes

 

Chapter 1 Introduction to the world of biology

 

1)      Biology – Scientific study of life

 

 

2)      Scope of biology- Different areas of biology focus on different levels of life organization. (Fig 1.1, p2)

 

Different levels of life organization

a.       Ecosystem – all living organisms and non living component in a given area 

b.      Community – all living organisms in a given area

c.       Population – group of individuals of one species in a given area

d.      Organism – an individual living thing

e.       Organ system – group of organs

f.        Organ

g.       Tissue

h.       Cell

i.         Molecule

 

(Biol 1551 will deal mainly with the cellular and molecular levels.)

 

 

3)      Diversity of living organisms – Classification

a.       Three domains

                                                               i.      Bacteria

                                                             ii.      Archaea

                                                            iii.      Eukarya

 

b.      Organims belonging to Bacteria and Archaea are also referred to as prokaryotes.  Organisms belonging to Eukarya are referred to as eukaryotes.  Eukaryotes can be distinguished from prokaryote by the presence of nucleus and cell organelles.

 

c.       Domain Eukarya composed of several kingdoms

                                                               i.      Kingdom Animalia – animals (multicellular organisms without cell wall)

                                                             ii.      Kingdom Plantae – plants (multicellular organisms with cell walls and photosynthetic ability (green))

                                                            iii.      Kingdom Fungi – fungus, mushrooms, molds (multicellular organisms with cell walls without photosynthetic ability (non-green), decomposer)

                                                           iv.      Protists (other kingdoms) – multiple kingdoms including multicellular and single cellular organisms

 

 

4)      Common features of living organisms

a.       all living organisms are made of cells

b.      they use DNA as genetic blueprints

 

5)      Evolution – Heritable changes that produced earth’s diversity of organims

 

Natural selection – evolutional theory proposed by Charles Darwin in mid-19^th century (Fig 1.6B, p9)

 

            Natural variation (heritable traits)

                                    ↓

            Selection pressure (can be negative or positive)

                                    ↓

            Reproduction of survivors

 

                  Adaptation – survival strategies of each species

 

 

6)      Web of life

 

Major players in the web of life

                  Plants – convert light energy to chemical energy by process of

photosynthesis – production of food

                                                            ↓

                        Animals – herbivores – eat plants

                                         carnivores – eat other animals including herbivores

                                                            ↓

Decomposers (Fungi, Protists, some animals) – breakdown organisms –        production of nutrient in soil

                                    ↓

Plants – utilize the nutrients produced by decomposers

                                                            ↓

                                                            ↓

 

If one of these components is missing, it will destroy the whole balance and leads to eventual destruction of ecosystem.