Chapter 1 The study of life

Biology

The scientific study of life

Cell

The basic and smallest unit of life

Unicellular

organisms that consist of a single cell

Multicellular

organisms that consist of multiple cells

Tissue

A group of similar cells working together to perform a specific function.

Organ

A structure composed of different tissues that work together to perform a specific function in an organism.

Organ System

A group of organs that work together to perform a function.

Organism

An individual living thing

Metabolism

all the chemical reactions that occur in a cell or organism

Energy

capacity to do work

Homeostasis

maintenance of a relatively stable internal environment

Reproduction

process by which organisms produce offspring

Asexual Reproduction

Reproduction with 1 parent

Sexual Reproduction

Reproduction with 2 parents

Growth and Development

An organism increasing in size and/or undergoing changes in its lifetime

Stimulus

Change in organisms environment that causes response

Adaption

Inherited characteristic that helps organism survive and reproduce in its environment

Evolution

change in populations over generations

Natural Selection

Process in which individual with helpful traits are more likely to survive and reproduce

Photosynthesis

process by which plants and other organisms convert solar energy into chemical energy

Producer

an organism that makes its own organic food using light or chemical energy

Levels of Biological Organization

Atom → Molecule → Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem → Biosphere

Atom

smallest unit of an element

Molecule

1 or 2 more atoms chemically bonded together

Population

members of same species living in same area

Community

All populations of different species living in the same area

Ecosystem

community of nonliving environment around it

Biosphere

all regions of earth where life exists

Taxonomy

science of naming, describing, and classifying organisms

Systemics

study of evolutionary relationships among organisms

Classification of hierarchy

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

Species

most specific classification category

Domain

largest classification category

Bacteria

1 or 3 domains of life; generally unicellular and prokaryotic

Archaea

1 of 3 domains; organisms are unicellular and prokaryotic and are chemically different from bacteria

Eukarya

1 of 3 domains; organisms have eukaryotic cells with a nucleus

3 domains of life

Bacteria, Archaea, and Eukarya

Prokaryote

cell that does not have a nucleus

Eukaryote

cell that does have a nucleus

Domains containing eukaryotes

Eukarya

Binomial

two-part scientific name consisting of the genus and specific epithet

Scientific name

Genus name + specific epithet.

Scientific name capitalization The genus is capitalized; the specific epithet is lowercase

Observation

Gathering information using senses or scientific instruments

Question

Something a scientist wants to understand or explain

Hypothesis

A testable explanation for an observation.

Falsifiable

A hypothesis must be capable of being shown to be wrong by evidence

Prediction

What a scientist expects to happen if the hypothesis is correct

Experiment

test used to collect data and evaluate a hypothesis

Conclusion

decision about whether evidence supports a hypothesis

Inductive reasoning

Using specific observations to develop a general explanation or hypothesis

Indépendant Variable

The factor that the researcher changes or manipulates

Dependent Variable

The factor that the researcher measures

Control Group

The group that does not receive the experimental treatment and is used for comparison

Experimental Group

The group that receives the treatment being tested

Scientific theory

A broad explanation supported by a large body of evidence

Hypothesis vs. theory

A hypothesis is a specific, testable explanation; a theory is a broad explanation supported by extensive evidence

Climate Change

Changes in the normal cycles of Earth's climate, largely influenced by human activity

Global Warming

The increase in Earth's average temperature

Greenhouse Effect

The process in which gases in the atmosphere absorb and radiate heat back toward Earth

Biodiversity

The total number and relative abundance of species, genetic variation, and different ecosystems

Extinction

The death of a species or larger classification category

Emerging Disease

A disease that is relatively new to humans.

Examples of emerging diseases COVID-19, SARS, and avian influenza.

Reemerging Disease

A disease that has affected humans before but becomes a health concern again.

Main energy source for most life on earth

sun

Chemical cycling

Chemicals move between organisms and the environment and are eventually returned to producers

Energy flow in ecosystems

Energy flows from the Sun through producers and consumers and eventually leaves as heat.