Chapter 1

Biology: Exploring Life

1.1 The Characteristics of Life

•  Life exists almost everywhere on the planet Earth.

•  Earth possesses a great variety of diverse life forms.

•  All living things have certain characteristics in common.

Living Things:

•  Are organized •  Acquire materials and energy •  Reproduce •  Respond to stimuli •  Are homeostatic •  Grow and develop •  Have the capacity to adapt

1. Biosphere

2. Ecosystem

3. Community

4. Population

5. Organism

6. Organ system

7. Organ

8. Tissue

9. Cell

10. Organelle

11. Molecule Atom

Nucleus

Brain

Spinal cord

Nerve

1

2

3

4

6

5

7 8

9 10

11

Life’s Levels of Organization

–  Eukaryotic cells •  Contain

membrane-enclosed organelles, including a DNA-containing nucleus

–  Prokaryotic cells •  Lack such

organelles

Nucleus (contains DNA)

Eukar yotic cell

Prokar yotic cell

DNA (no nucleus)

Organelles

25,0

00 ×

What are living things? How do you know?

–  All organisms share a common set of features •  Order •  Regulation of internal conditions

•  Growth and development •  Energy use •  Response to environmental stimuli •  The ability to reproduce and evolve

The Classification of Living Things

•  Living organisms are assigned to groups based upon their similarities.

•  Systematics is the discipline of identifying and classifying organisms.

Domain Archaea

•  Archaea are unicellular prokaryotes.

•  Archaea can be found in environments that are too hostile for other life forms.

Domain Bacteria •  Bacteria are unicellular

prokaryotes.

•  Bacteria are found almost everywhere on the planet Earth.

•  Some bacteria cause disease but many are beneficial.

Representative Organisms

black bread mold yeast mushroom bracket fungus

sea star earthworm finch raccoon

moss fern pine tree

paramecium euglenoid slime mold dinoflagellate

Kingdom Organization T ype of Nutrition

Protista

Fungi

Plantae

Animalia

Absorb food

Ingest food

Complex single cell, some multicellular

Some unicellular, most multicellular filamentous forms with specialized complex cells

Multicellular form with specialized complex cells

Multicellular form with specialized complex cells

Absorb, photosynthesize, or ingest food

Photosynthesize food

nonwoody flowering plant

Protozoans, algae, water molds, and slime molds

Molds, yeasts, and mushrooms

Mosses, ferns, nonwoody and woody flowering plants

Invertebrates, fishes, reptiles, amphibians, birds, and mammals

Domain Eukarya The cells of all eukaryotes have a membrane-bound nucleus.

The Domain Eukarya consists of four Kingdoms: Protista, Fungi, Plantae and Animalia

Diversity of Life:

Living Things are categorized into

3 Domains : Eukarya

Archaea

Bacteria Within the Domain of the Eukarya, we distinguish 4 kingdoms:

Plantae

Fungi

Animalia

Protista

•  A Case Study from Ever yday Life –  Deductive

reasoning is used in testing hypotheses as follows

–  If a hypothesis is correct, and we test it, then we can expect a par ticular outcome

Observations

Question

Hypothesis # 1: Dead batteries

Hypothesis # 2: Burnt-out bulb

Prediction: Replacing batteries will fix problem

Prediction: Replacing bulb will fix problem

Test prediction Test prediction

Test falsifies hypothesis Test does not falsify hypothesis

The Scientific Method

Scientific Method Observations

Question

Hypothesis

Test supports hypothesis; make additional predictions

and test them

Test does not support hypothesis; revise

hypothesis or pose new one

Prediction

Test: experiment or

additional observation

Results / Data

Conclusion

–  Biology is connected to many impor tant issues in our lives

•  Environmental problems and solutions •  Genetic engineering •  Medicine