Biology Chapter 1

Definition of a hypothesis

A testable, tentative explanation for an observation

can multiple hypotheses be proposed for one question

Yes

Purpose of a prediction

To translate a hypothesis into an if–then statement

what are the two requirements of a hypothesis

testable and falsifiable

what does testable mean?

it can be examined through observation or experiment

what does falsifiable mean?

it can be shown to be incorrect

definition of a variable

any factor that can change during an experiment

Definition of a control group

A group identical to the experimental group except for the variable being tested

Does rejecting one hypothesis confirm another

No

Direction of deductive reasoning

General → specific

Where deductive reasoning is used

Hypothesis‑based science

Direction of inductive reasoning

Specific → general

How scientists use inductive reasoning

Identify patterns in observations to form broader conclusions

Relationship between inductive and deductive reasoning

Science often uses both together

Goal of basic (“pure”) science

Expand knowledge for its own sake

Focus of basic science

Not aimed at immediate practical applications

Example of basic science

Studying DNA structure before knowing its applications

Goal of applied science

Use scientific knowledge to solve real‑world problems

Defining feature of applied science

The problem is usually defined ahead of time

Definition of biology

The science that studies life

Why viruses are not considered alive

They lack independent metabolism

Number of characteristics of life

Eight

Characteristic of life — Order

Organized, structured systems

Characteristic of life — Sensitivity/Response

Ability to react to stimuli

Characteristic of life — Reproduction

Ability to produce new individuals

Characteristic of life — Adaptation

Evolutionary changes that enhance survival

Characteristic of life — Growth and development

Regulated by genetic information

Characteristic of life — Regulation/Homeostasis

Maintaining internal balance

Characteristic of life — Energy processing

Acquiring and using energy

Characteristic of life — Evolution

Populations change over generations

What is the smallest level of biological organization?

smallest unit of matter; contains a nucleus and electrons

What is a molecule?

Two or more atoms bonded together; includes water, sugars, lipids, etc.

What is a macromolecule?

Large, complex molecule formed by polymerization of monomers

Example of a macromolecule and its function

DNA — contains instructions for the structure and function of living organisms

What are organelles?

Membrane‑bound aggregates of macromolecules inside cells

Function of mitochondria

Produce energy (ATP) for the cell

Function of chloroplasts

Convert sunlight into sugars in plants

Why are organelles important?

They perform essential functions that keep cells alive

What is a cell?

Smallest fundamental unit of structure and function in living organisms

Why are viruses not considered living?

Not made of cells and must invade host cells to reproduce

What are prokaryotic cells?

Cells with no membrane‑bound nucleus; usually single‑celled or colonial

What are eukaryotic cells?

Cells with membrane‑bound organelles and a nucleus; can be single‑celled or multicellular

What is a tissue?

Group of similar cells performing related functions

What is an organ?

Collection of tissues working together for a common function

What is an organ system?

Group of organs working together (e.g., circulatory system)

What is an organism?

An individual living entity (e.g., a tree, a microorganism)

What is a population?

All individuals of a species living in a specific area

What is a community?

All populations living together in an area (plants, animals, microbes)

What is an ecosystem?

A community plus its abiotic environment (soil, water, air)

What is the biosphere?

All ecosystems on Earth; includes land, water, and parts of the atmosphere

Why does biology have many subdisciplines?

Because life is broad and complex; biologists specialize to study specific biological questions.

What does molecular biology study?

Biological processes at the molecular level.

What does molecular biology focus on?

Interactions among DNA, RNA, proteins, and how these interactions are regulated.

What does biochemistry examine?

Chemical processes within and related to living organisms.

How does biochemistry relate to molecular biology?

They overlap heavily in studying molecular and chemical processes of life.

What does microbiology study?

Microorganisms, especially single‑celled organisms.

What are major sub‑areas of microbiology?

Microbial physiology, microbial ecology, microbial genetics.