BIOL 1306 Chapter 1

🟦 CHAPTER 1 — Evolution, the Themes of Biology, and Scientific Inquiry

🎯 Big idea

Biology is the study of life, and one of the biggest ideas connecting all of biology is evolution.

Think:

Life changes over generations → populations become adapted → diversity of life results.


⭐ 1. What makes something “living”?

There isn’t just ONE characteristic.

Living organisms generally have:

  • Order — organized structures

  • Evolutionary adaptation — populations change over generations

  • Response to the environment

  • Regulation — maintaining internal conditions

  • Energy processing — obtaining and using energy

  • Growth and development

  • Reproduction

🧠 Don’t memorize this as a random list.

Think:

Living things are organized systems that use energy, maintain themselves, respond to their environment, grow, reproduce, and evolve.


⭐ 2. Levels of biological organization

Know the order:

Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ system → Organism → Population → Community → Ecosystem → Biosphere

Example:

Atom
↓
Water molecule
↓
Cell
↓
Heart tissue
↓
Heart
↓
Circulatory system
↓
Human
↓
Human population
↓
Community
↓
Ecosystem
↓
Biosphere

⭐ Most important:

Cell = smallest unit that can perform all the characteristics of life.


⭐ 3. Evolution

Evolution = change in the genetic composition of a population over generations.

Natural selection

Natural selection happens when:

  1. Individuals in a population vary.

  2. Some variations are heritable.

  3. More offspring are produced than can survive.

  4. Individuals with advantageous traits tend to leave more offspring.

  5. Those traits become more common.

🧠 Simple version:

Environment “selects” traits that help organisms survive/reproduce.

Important:

❌ Individual organisms don’t evolve during their lifetime.

✅ Populations evolve over generations.


⭐ 4. Three domains of life

Life is divided into:

Bacteria

Prokaryotic

Archaea

Prokaryotic

Eukarya

Eukaryotic

Remember:

Bacteria + Archaea = prokaryotes

Eukarya = eukaryotes


🔬 5. Scientific method

Know these:

Observation

Something you notice.

↓

Question

“What is happening?”

↓

Hypothesis

A testable explanation/prediction.

↓

Experiment

Test the hypothesis.

↓

Results

Collect data.

↓

Conclusion

Determine whether evidence supports the hypothesis.


⭐ Hypothesis vs theory

This is a BIG test question.

Hypothesis

A testable explanation for an observation.

Scientific theory

A well-supported explanation backed by a large body of evidence.

❌ Theory does NOT mean “just a guess.”


⭐ Independent vs dependent variables

You asked about this before, so memorize this:

Independent variable

What the researcher changes.

Dependent variable

What the researcher measures.

🧠 Think:

Independent = I change it.

Dependent = data depends on what I changed.


⭐ Control group

A control group gives you something to compare your experimental group against.

Example:

You test whether fertilizer makes plants grow faster.

  • Experimental group → fertilizer

  • Control group → no fertilizer


🟩 CHAPTER 1 MUST KNOW

⭐ Evolution
⭐ Natural selection
⭐ Characteristics of life
⭐ Levels of organization
⭐ Domains of life
⭐ Hypothesis vs theory
⭐ Independent vs dependent variable
⭐ Control group
⭐ Scientific method