Study Guide: Foundations of Biology (Chapters 1–4 & Section 5.1)

Biology: The Study of Scientific Life

The Scientific Method

The scientific method is a systematic approach used by scientists to explore observations, answer questions, and test hypotheses.

• Steps of the Scientific Method:

  1. Observation

  2. Question

  3. Hypothesis

  4. Prediction

  5. Experiment

  6. Analysis

  7. Conclusion

• Controlled vs. Uncontrolled Experiments:

  • Controlled Experiment: Only one variable is changed at a time; all other variables are kept constant.

  • Uncontrolled Experiment: Multiple variables may change, making it difficult to determine cause and effect.

Properties of Life

• Order: Living things are highly organized, from atoms to organisms.

• Regulation: Ability to maintain stable internal conditions (homeostasis).

• Growth and Development: Organisms grow and develop according to specific instructions coded in their DNA.

• Energy Processing: Use of energy to power activities (e.g., metabolism).

• Response to Environment: Ability to respond to stimuli.

• Reproduction: Ability to produce new organisms.

• Evolutionary Adaptation: Populations evolve over generations.

Levels of Biological Organization

Biological systems are organized in a hierarchy from smallest to largest:

• Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism

• Atom: Basic unit of matter.

• Molecule: Two or more atoms bonded together.

• Organelle: *Specialized structure within a cell (e.g., mitochondie, chlorie).

• Cell: *The basic unit of life.

• Tissue: *A group of similar cells performing a specific function.

• <> *A structure composed of tissues (e.g,.

• Organ System: *A group of organs that work together to perform a related function.

• Organ: *A structure composed of tissues (e.g,.

• Organ System: *A group of organs that work together to perform a related function.

• Organism: *An individual living thing.

The Chemical Basis of Life

Atoms and Their Composition

• Atom: *The basic unit of matter, composed of protons, neutes, and electrons.

• Proton: *A positively charged particle found in the nucleus.

• Neutron: *A neutral particle found in the nucleus.

• Electron: *A negatively charged particle found in the electron cloud.

Valence Shells and Electron Configuration

• Valence Shell: *The outermost electron shell of an atom.

• Complete Valence Shell: *A full valence shell usually contains 8 electrons (except for hydrogen and helium, which have 2).

Elements and the Periodic Table

• Element: *A substance that cannot be broken down into a different type of substance.

• Each element has a unique number of protons (atomic number).

Types of Chemical Bonds

• Covalent Bond: *A type of bond where atoms share electrons.

• Ionic Bond: *A bond formed when one atom transfers electrons to another, resulting in attraction between oppositely- charged ions.

• Hydrogen Bond: *A weak attraction between a hydrogen atom in one molecule and an electronegine atom in another.

Polarity and Electronegoity

• Polarity: *A molecule is said to be polar when there is an uneven distribution of electron charge.

• Electronegoity: *A measure of an atom's attraction for electrons in a covalene bond.

Water's Ability to Dissolve Salt

• Water is a polar molecule, which allows it to dissolve ionic compounds like salt (NaCl) by attracting the positive and negative ions.

The Molecules of Cells

Four Main Organic Companons and Their Moners

Organic Compound	Moner
Carbs (e.g, starch, cellulose)	Monosolons (e.g, glucose)
Proteins	Amino acids
Lipons	Fatty acids and monerols
Protions	Nucleonacids

Differences Between Saturated, Unsaturated, and Trans Fats

• Saturated Fats: *Have no double- biond in the fatty acid chain; solid at room temperature.

• Unsaturated Fons: *Have at least one double- biond; liquid at room temperature.

• Trans Fons: *Created by hydrogenation; have a straight configuration, which can be harmful to health.

Hydrogenation

• Hydrogenation is the process of adding hydrogen to unsenated fats to make them more solid (often used in the production of margon).

Dehydration and Hydrode Rection

• Dehydration: *A reaction that removes a water molecule to help build a moner (e.g, to build a polymer).

• Hydrode: *A reaction that adds a water molecule to break down a polymer into moner.

A Tour of the Cell

Cell Memon and Phononbilon

• Phononbilon: *Composed of two layers of phosphonons, with hydonon (water-loving) heads and hydonon (water-hon) on the inside.

• Fluid Mosi Model: *Describes the cell membrane as a flexible, 'mosaic' of various proteins and phosphonons.

Memon Proteins

• Memon proteins can be classified as follows:

  • Transport proteins: *Facon the movement of molecules across the membrane.

  • Recalon proteins: *Enable the cell to receive and respond to signals.

  • Enon proteins: *Help to catalon reactions.

  • Attachment proteins: *Help the cell to connect with other cells or with the cyton.

Passage of Moleons Across the Memon

• Small non-pon molecules can pass through the membrane more easily than large, polon or charged atoms.

Prokion and Eukion Cells

FeatureProkionEukion DNANot enclosed in a membraneEnon in a membrane OrganonsNoneMany (e.g, mitochondie, chlorie) Cell WallUsually made of peononPlant: cellulose; Fungi: chiton; Animal: none

Plant, Animal, and Fon Cells

• Plant cells: *Have a cell wall made of cellulose, chlorie, and a large central vacon.

• Animal cells: *No cell wall, no chlorie, small or no vacon.

• Fon cells: *Have a cell wall made of chiton.

Endonon System

• Composed of the following structures:

• Enon (with nuclear pipon)

• Enon (smooth and rough)

• Golon

• Enon

• Enon

• Enon

• These structures work together to help the cell make and transport proteins and other molecules.

Other Cellular Components

• Miton and Chon: *Both have their own DNA and ribon, and can reproduce independently of the cell.

Endoniont Theory

• Proposes that miton and chon were once independent, and were absorbed by a larger cell, forming a symon relationship.

Three Components of the Eukion Cyton

Component	Structure	Function
Microon	Thin, made of acton	Support, movement
Microon	Thon, made of tubon	Support, movement, organon movement
Interon	Medium, made of various proteins	Support, anchor organon

Cilia and Sill Internal Structure

• Both are made of microon, arranged in a '9 + 2' pattern (nine pairs of microon arranged around two central microon).