Chapter 1

The Scientific Study of Life

1.1: Life’s levels of organization define the scope of biology

• Ecosystem-

– All the non-living physical factors- temperature, water, soil, etc. that affect organisms

• Community- organisms that interact

–

– All of the organisms that live in a rainforest or all of the organisms that live under a rock

1.1: Life’s levels of organization define the scope of biology

• Population-

– Under same influences

• Organism- a single individual living being

• Organ systems-

– Systems work together to form an organism

• Organs-

– Lungs and trachea are organs within the respiratory system

1.1: Life’s levels of organization define the scope of biology

• Tissues-

– Layers of these cells- make up an organ

• Cell-

– Each tissue has a specialized function, which is performed by the cells that compose it.

• Molecule-

– Structure of DNA

– It takes many molecules to make a cell

Figure 1.3

1 The biosphere

Population

Biosphere

Organism

Ecosystem

Community

Cell

8 Cells

6 Organs and organ systems

7 Tissues

10 Molecules

9 Organelles

50 µm

10 µm

1 µm

Atoms

Figure 1.3

1.2, 1.3: Scientists pose and test hypotheses to answer questions about

nature

• Observations

• Questions

• Hypotheses

• Predictions

• Tests

1.2, 1.3: Process of Science (cont.) Observations lead to questions

A testable hypothesis is generated

Scientists used deductive reasoning

Conduct a controlled experiment

Two parallel experiments:

Experimental

Differs from control by only one variable

Dependent vs. independent variables

Everything else is held constant

Control

1.2, 1.3: Process of Science (cont.)

• Reevaluate hypothesis

• Can only be supported or not supported

– Hypotheses must be testable and falsifiable, those that are not testable, such as those involving supernatural causes, lie outside the realm of science and would be addressed under the realm of philosophy or religion.

• Scientists

1.4: The diversity of Life can be arranged into three domains

• Domains-

• Include the once 5 kingdoms (now 6)

• 3 domains are

• Prokaryotes- lack nucleus and organelles

• Prokaryotes, but extremophiles

1.4: Archaea and Bacteria Kingdoms

• Originally the Monera kingdom

• Monera was

1.4: The diversity of Life can be arranged into three domains (cont.)

– Eukarya

• Made of

• Can be single celled or multicellular

1.4 Kingdoms

After domains, kingdoms are the next most-inclusive level

Domain Kingdoms

1. Bacteria Bacteria or Eubacteria

2. Archaea Archaeabacteria

2. Eukarya Protista, Animalia, Fungi and Plantae

1.4: Eukarya Kingdoms • Kingdom Protista-

– Nutritional mode • Some are autotrophic by • Some are heterotrophic by

– Some are single-celled (Euglena) – Some are multicellular (Algae) – Most diverse of all eukaryotic organisms and has been

• Kingdom Plantae- – Nutritional mode is autotrophic by photosynthesis

– Cell walls made of cellulose

1.4: Eukarya Kingdoms • Kingdom Animalia-

– Nutritional mode is hetertrophic by

– Multicellular

– Most animals are motile at some point in their life cycle

– Lack

• Kingdom Fungi- includes molds, yeasts and mushrooms

– Nutritional mode is heterotrophic by

– Cell walls are

– Multicellular

Figure 1.15

100 µm

0.5 µm

4 µm Bacteria are the most diverse

and widespread prokaryotes

and are now divided among multiple

kingdoms. Each of the rod-shaped

structures in this photo is a bacterial cell.

Protists (multiple kingdoms)

are unicellular eukaryotes and

their relatively simple multicellular relatives.Pictured here

is an assortment of protists inhabiting pond water.

Scientists are currently debating how to split the protists

into several kingdoms that better represent evolution and

diversity.

Kingdom Plantae consists of

multicellula eukaryotes that carry

out photosynthesis, the conversion

of light energy to food.

Many of the prokaryotes known

as archaea live in Earth‘s

extreme environments, such as salty lakes

and boiling hot springs. Domain Archaea

includes multiple kingdoms. The photo

shows a colony composed of many cells.

Kindom Fungi is defined in part by the

nutritional mode of its members, such

as this mushroom, which absorb

nutrientsafter decomposing organic

material.

Kindom Animalia consists of

multicellular eukaryotes that

ingest other organisms.

DOMAIN ARCHAEA

Species Genus Family Order Class Phylum Kingdom Domain

Mammalia

Ursus

ameri-

canus

(American

black bear)

Ursus

Ursidae

Carnivora

Chordata

Animalia

Eukarya

Figure 1.14

Did

King

Phillip

come

over for

good

sushi?

1.5: Unity in diversity: All forms of life have common features

• DNA is the basis of life’s variety

–Structure of DNA is the same- phosphate backbone, 4 nucleotides (A,T,G,C)

–Life’s variation is

1.5: Properties that distinguish life from non-life

Order

Example: Similar cells are grouped together to form tissues. Tissues are organized to form organs, etc.

Regulation

Organisms have the ability to

Growth and development

Organisms vary is their patterns of growth and development

1.5: Properties that distinguish life from non-life

Energy utilization

Response to the environment

Sweating when hot, growing extra hair in winter Reproduction

Organisms must be able to reproduce at all levels to maintain species

The capacity of a species to change over time and is a

unifying feature of life.

The Cell is the smallest unit that can perform all living functions!

Figure 1.2

(c) Response to the

environment

(a) Order

(d) Regulation

(g) Reproduction (f) Growth and

development

(b) Evolutionary

adaptation

(e) Energy

processing

1.6: Evolution explains the unity and diversity of life

• 1859, Charles Darwin published On the Origin of Species by Means of Natural Selection

Figure 1.18

1.6: Evolution explains the unity and diversity of life

• Members of a family are fundamentally similar because

• Evolution explained the diversity of organisms

–New species arise

1.6: Theory of Natural Selection

• Theory- widely accepted explanation that is broad in scope and supported by a large body of evidence.

• 3 requirements of natural selection:

– 1.

– 2. Elimination of individuals with certain traits

– 3.

1 Populations with varied inherited traits

2 Elimination of individuals with certain traits.

3 Reproduction of survivors.

4 Increasing frequency of traits that enhance

survival and reproductive success. Figure 1.21

1.6: The products of natural selection

• Are often exquisite adaptations of organisms to the special circumstances of their way of life and their environment

Figure 1.22

1.6: The products of natural selection

• Evolution of a new species results from

• Each species has its own special set of adaptations,

1.7: Living organisms and their environments form interconnecting webs

• Darwin’s theory of natural selection focuses on the response of organisms to interactions with the living and nonliving components of their environment- ecosystem level

1.7: Energy- one way trip through ecosystem

• Energy flows through an ecosystem

–Usually entering as

1.7: Nutrients are recycled within an ecosystem

• Atoms of carbon dioxide, oxygen, water and various minerals are the most basic chemicals that are necessary for life

– Flow from the air and soil to plants, to animals and back to the air and soil

• All of life depends on the ability of ecosystems to cycle chemical nutrients and shuttle energy appropriately.