INTRODUCTION: Themes in the Study of Life

What is life?

"We recognize life by what living things do."

What do living things do? (properties of life)

• energy processing (eg. hummingbird will use nectar from flowers as a "fuel" to power its flight and other work)
• evolutionary adaption (eg. bowl shape of flowers allows bugs easy access to their organs to carry pollen from one flower to another)
• growth and development (inherited information carried by genes controls the pattern of growth and development)
• regulation (eg. regulation of blood helps maintain constant body temperature..)
• reproduction (organism reproduce their own kind --> a dolphin will have a baby dolphin)
• response to the environment (eg. a Venus flytrap will close its trap rapidly in response to the environmental stimulus of a damselfly landing on yhe open trap)
• order (structure)

Which are levels of biological organization?

1. The Biosphere - the entire portion of Earth inhabited by life
2. Ecosystems - all the organisms in the given area as well as the abiotic factors with which they interact (eg. grasslands, deserts...)
3. Communities - all the organisms that inhabit a particular area (eg. plants in a forest ecosystem)
4. Populations - all the individuals of a spicies living within the bounds of a specified area (eg. a population of white-tailed deer)
5. Organisms - individual living things
6. Organs and Organ Systems - specialized centers of body functions composed of several different types of tissues (organs)
7. Tissues - integrated groups of cellswith a common function, structure or both
8. Cells - fundamental units of structure and function
9. Organelles - any of several membrane-enclosed structures with specialized structures (eg. chloroplasts)
10. Molecules - chemical structures consisting of two or more small chemical units called atoms (eg. chlorophyll)

How do we classify life?

species..genus..family..order..class..phylum..kingdom..domain

eg. Ursus americanus (American black bear)..Ursus..Ursidae..Carnivora..Mammalia..Chordata..Animalia..Eukarya

Facts (in this chapter):

- Evolution is Biology's core theme! ("Nothing in biology makes sense except for the light of evolution.")

- Organism interact with their environments, exchanging matter and energy.

- Cells are organism's basic units of structure and function.

- Feedback mechanism regulate biological systems.

- Observations may be interesting but cannot be verified as evidence.

Summary:

Evolution (the process of change that has transformed life on Earth from its earliest beginnings to the diversity of organisms living today) is biology's core theme. It's the idea that makes sense of everything we know about living organisms. Scientists take evolution as explanation for diversity and suitability of organisms to their environment. The study of life extends from the microscopic scale of the molecules and cells that make up organisms to the global scale of the entire living planet (*look up: Which are levels of biological organization?).

Structure and function are correlated at all levels of biological organization.

Diversity is a hallmark of life. Biologists have identified and named 1.8 million species. The enormous variety of life is now classified in groups that are very closely related (*look up: How do we classify life?).

Scientists use two main forms of inquiry in their study of nature: discovery science and hypothesis-based science. Finally, science cannot address the possibility of supernatural phenomena because hypothesis must be testable and falsifiable, and observations and experimental results must be repeatable.

Key terms:

biology = ongoing inquiry about the nature of life

evolution = the process of change that has transformed life on Earth from its earliest beginnings to the diversity of organisms living today

reductionism = the reduction of complex systems to simpler components that are more managable to study

cell = organism's basic units of structure and function

system = a simply combination of components that function together

gene = a discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA/RNA (in some viruses)

DNA = deoxyribonucleic acid (DNA on YouTube)

genome = the entire "library" of genetic instructions that an organism inherits

inquiry = a search for information and explanation

hypothesis = tentativ answer to a well framed question