An Introduction to the Science of Botany

Chapter 1

Why study botany?

• Botany permeates our everyday life.

Overgrazing in Africa

LEARNING OBJECTIVE 1

• Briefly describe the field of botany, and give short definitions of at least five subdisciplines of plant biology

KEY TERMS

• BOTANY The scientific study of plants; also called plant biology

Subdisciplines 1

• Plant molecular biology• Structures and functions of important

biological molecules (proteins, nucleic acids)

• Plant cell biology• Structures, functions, and life processes of

plant cells

Subdisciplines 2

• Plant physiology• How plants function (photosynthesis, mineral

nutrition)

• Plant genetics• Plant heredity and variation

Subdisciplines 3

• Plant ecology• Interrelationships among plants, and between

plants ands their environment

LEARNING OBJECTIVE 2

• Summarize and discuss the features of plants and other organisms that distinguish them from nonliving things

Levels of Biological Organization

BiosphereAtoms

Hydrogen OxygenMolecule

Water

MacromoleculeChloroplast

Organelle

Epidermis

Tissue

Cell

Organ

Organism

Population

Community

Ecosystem

Fig. 1-3, p. 9

Characteristics of Living Things 1

• Organization • Plants and other organisms are highly

organized with cells as their basic building blocks

• Energy• Plants and other organisms take in and use

energy

Plant Cells

-the basic functional and structural building block of living things

• PHOTOSYNTHESIS • Biological process that includes capture of

light energy and its transformation into chemical energy of organic molecules that are manufactured from carbon dioxide and water

CELLULAR RESPIRATION • Cellular process in which energy of organic

molecules is released for biological work• All living things get the energy they need to

live from a chemical reaction called respiration. This process needs glucose as a starting point.

• respiration and photosynthesis are opposites

Photosynthesis

• Importance of Photosynthesis

The process is as important for the humans and animals as it is for plants. Other than glucose, which is an important source of carbohydrates, even proteins, fats, and water-soluble sugars are the products of photosynthesis. We cannot produce these nutrients on our own, and hence have to depend directly on plants, or other animals (which feed on these plants) to derive them. Plants, being the only producers, have a crucial role to play in any food chain.

• Read more at Buzzle: http://www.buzzle.com/articles/photosynthesis-for-kids.html

Characteristics of Living Things 2

• Interaction with environment• Plants respond to stimuli in their environment

• Plants undergo growth and development • Reproduction

• Plants form new individuals by asexual or sexual reproduction

Root Growth and Gravity

Response to Stimuli

Germination

Asexual Reproduction

Characteristics of Living Things 3

• Heredity • DNA molecules transmit genetic information

from one generation to the next in plants and other organisms

• Evolution • Plants and other organisms evolve• Populations change or adapt to survive in

changing environments

Adaptation

KEY TERMS

• DEOXYRIBONUCLEIC ACID (DNA)• A nucleic acid present in a cell’s

chromosomes that contains genetic information

• EVOLUTION • Cumulative genetic changes in a population of

organisms from generation to generation• NATURAL SELECTION

• Mechanism of evolution (Charles Darwin)• Tendency of organisms that have favorable

adaptations to their environment to survive and become parents of next generation

LEARNING OBJECTIVE 3

• Distinguish among the six kingdoms and three domains, and give representative organisms for each

Euglena

Six-Kingdom Classification 1

1. Archaea

2. Bacteria

3. Protista• protozoa, algae, water molds, slime molds

Six-Kingdom Classification 2

4. Fungi• molds, yeasts

5. Animalia

6. Plantae

Three-Domain Classification

• Archaea• Kingdom archaea

• Bacteria• Kingdom bacteria

• Eukarya• All other kingdoms

Kingdoms and Domains

Three Domains:

Bacteria Archaea Eukarya

Six Kingdoms:

Bacteria Archaea Protista Plantae Animalia Fungi

Prokaryotes (lackmembrane-boundorganelles); unicellular;most are heterotrophic(obtain food by eating other organisms),but some arephotosynthetic orchemosynthetic

Prokaryotes;unicellular;microscopic; most live in extremeenvironments; differ in biochemistry and in cell wall structurefrom bacteria

Eukaryotes; mainlyunicellular or simplemulticellular; maybe heterotrophicor photosynthetic;include protozoa,algae, and slimemolds

Eukaryotes;multicellular;photosynthetic;life cycle withalternation ofgenerations; cell walls of cellulose

Eukaryotes;multicellular;heterotrophic; most move about by muscular contraction;nervous systemcoordinatesresponses to stimuli

Eukaryotes; mostmulticellular;heterotrophic;absorb nutrients;do not photo-synthesize;cell walls of chitin

Fig. 1-11, p. 14

KEY TERMS• KINGDOM

• A broad taxonomic category made up of related phyla; many biologists currently recognize six kingdoms of living organisms

• DOMAIN • A taxonomic category that includes one or

more kingdoms

Classification (Binomial System)

KEY TERMS

• SPECIES • A group of organisms with similar structural

and functional characteristics • In nature, they breed only with one another

and have a close common ancestry

LEARNING OBJECTIVE 4

• Summarize the main steps in the scientific method, and explain how science differs from many other human endeavors

The Scientific Method 1

1. Recognize a problem• or an unanswered question• Why plants shoots grow away from gravity

or toward sunlight, while roots grow into the soil in the direction of gravity?

2. Develop a hypothesis • to explain the problem

3. Design and perform an experiment• to test the hypothesis

The Scientific Method 1

2. Develop a hypothesis • to explain the problem

gravitropism 

Amyloplasts 

Statolith

3. Design and perform an experiment• to test the hypothesis

The Scientific Method 2

4. Analyze and interpret the data• to reach a conclusion

5. Share new knowledge• with the scientific community

KEY TERMS• HYPOTHESIS

• An educated guess (based on previous observations) that may be true and is testable by observation and experimentation

• THEORY • A widely accepted explanation supported by a

large body of observations and experiments

Assignment

1. What is prokaryotic and eukaryotic cells?

2. Define the following: paleobotany, bryology, agronomy, horticulture, forestry & economic botany.

3. What is gravitropism?

4. What is Amyloplasts and what is its role?

5. What is the function of Indole acetic acid in plant growth?

Deadline: next meeting

Use white intermediate paper.