(37) Biological Themes

Biological Themes

The Basis of Biological Principles and Concepts

Biology

The scientific study of life. It includes the study of living organisms, their structures, functions, relationships, and changes through time.

Biological Themes

Biologists use major biological themes. A ___ is a general idea that connects different concepts and topics in biology.

Five Biological Themes

1. Taxonomic classifications and orders drive the organization of life.

2. The diversity of life is exhibited through the transmission of genetic information.

3. All life forms on Earth are interdependent and interconnected.

4. Energy flow is needed to sustain and maintain life.

5. Diversity and variation among life forms are unified through evolution.

Theme 1

Taxonomic Classifications and Orders Drive the Organization of Life.

A. Taxonomic Hierarchy

B. Scientific Names

C. Classification and Evolution

Taxonomy

The branch of biology concerned with the identification, naming, and classification of organisms. There are millions of known species on Earth, and scientists continue to discover new organisms. Without a system of organization, it would be difficult to study and communicate about them

Taxonomic Hierarchy

• RANK: Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

• HUMAN CLASSIFICATION: Eukarya → Animalia → Chordata → Mammalia → Primates → Hominidae → Homo → Homo sapiens

Scientific Names

Scientists use binomial nomenclature, a system that gives each species a two-part scientific name: Genus + species. For humans, the Scientific name is Homo sapiens. Scientific names provide a standard way for scientists around the world to identify the same organism.

Classification and Evolution

Organisms that share common ancestors may have similar characteristics. Scientists use evidence such as body structures, fossils, DNA, embryonic development, and biochemical similarities to study these relationships.

Theme 2

The Diversity of Life Is Exhibited Through the Transmission of Genetic Information.

A. Genetic Information

B. Chromosomes

C. Heredity

D. Genetic Variation

Genetic Information

Information that helps determine the characteristics and biological functions of an organism. This information is stored in DNA, or deoxyribonucleic acid.

DNA → Genes → Traits

A gene is a segment of DNA that contains information used by cells. Genes contribute to characteristics or traits, such as blood type and some aspects of eye color and hair characteristics.

Chromosomes

DNA is organized into structures called ___. In humans, most body cells contain 46 ___, arranged in 23 pairs. One set comes from the mother and the other set comes from the father.

Heredity

Refers to the passing of genetic information from parents to their offspring. Offspring receive a combination of genetic information from both parents.

Genetic Variation

Refers to differences in genetic information among individuals of the same species. Variation can influence how organisms respond to their environment and can contribute to evolutionary change.

Theme 3

All Life Forms on Earth Are Interdependent and Interconnected.

A. Organisms and their environment

B. Example of interdependence

C. Food Chains and Food webs

Organisms and their environment

Organisms interact with both biotic and abiotic factors.

Biotic Factors

Living components: plants, animals, fungi, bacteria.

Abiotic Factors

Nonliving components: sunlight, water, air, temperature, soil, minerals

Example of interdependence

A flowering plant needs sunlight, water, carbon dioxide, and minerals. A bee may visit the plant to collect nectar. While doing so, the bee may transfer pollen from one flower to another, helping the plant reproduce. The bee, in turn, depends on plants for food

Food chains and Food webs

Shows how energy and food move from one organism to another. For example:

Grass → Grasshopper → Frog → Snake → Eagle

A food web is made of several connected food chains. Because organisms are interconnected, a major change in one population can affect other organisms.

Theme 4

Energy Flow Is Needed to Sustain and Maintain Life.

A. The sun as the main energy source

B. Producers

C. Consumers

D. Decomposers

E. Energy flow in an ecosystem

The sun as the main energy source

For most ecosystems, the ___. Plants, algae, and some bacteria capture light energy and convert it into chemical energy through photosynthesis.

Carbon dioxide + Water + Light Energy → Glucose + Oxyg

Autotrophs

Producers, or ___, make their own food. Examples include green plants, algae, and some bacteria.

Heterotrophs

Consumers, or ___, cannot make their own food and obtain energy by eating other organisms.

Herbivores

Animals that eat only plants, algae, and other photosynthesizing organisms for energy, such as cows

Carnivores

Organisms that get their energy and nutrition mainly by eating other animals, such as lions

Omnivores

An animal or organism that naturally eats both plants and animals

Decomposers

___, such as bacteria and fungi, break down dead organisms and organic waste. They help return nutrients to the environment.

Energy flow in an ecosystem

Sun → Producer → Primary Consumer → Secondary Consumer → Higher-Level Consumer

Energy flows from one level to another. Not all energy is transferred to the next level because organisms use energy for life processes and some is released as heat. Therefore, ecosystems need a continuous input of energy.

Important: Energy flows through an ecosystem, while nutrients are recycled.

Theme 5

Earth contains an enormous variety of organisms. This variety is called biological diversity or biodiversity. Organisms differ in structure, size, behavior, habitat, nutrition, reproduction, and genetic characteristics.

A. What is Evolution?

B. Variation

C. Natural Selection

D. Adaptation

E. Common Ancestry

What is Evolution

The change in inherited characteristics of populations over generations. ___ does not mean that an individual organism suddenly changes into another organism. Instead, populations change over many generations.

Variation

Individuals within the same species are not exactly alike. A population of birds, for example, may have differences in beak size, body size, feather color, and other characteristics. These differences are called ___.

Natural Selection

Is an important mechanism of evolution. Individuals with inherited characteristics that help them survive and reproduce in a particular environment may be more likely to pass those characteristics to their offspring.

Adaptation

Is an inherited characteristic that helps an organism survive and reproduce in its environment. Examples include thick fur in some cold-climate animals, specialized beaks in birds, and camouflage in some animals.

Common Ancestry

Evolution helps explain why different organisms share certain characteristics. Scientists use evidence from fossils, DNA, anatomy, embryology, and other biological evidence to study evolutionary relationships.

Connecting the Five Biological Themes

The five themes are not separate ideas. They work together to explain how life is organized, inherited, connected, powered, and changed through time.

1. Classification

2. Genetic Information

3. Interdependence

4. Energy flow

5. Evolution