Bio 103 Exam 1 context

Energy

The capacity to do work.

Work

The transfer of energy that occurs when a force is applied to an object causing displacement.

Potential Energy

Stored energy resulting from an object's position, shape, or chemical bonds.

Kinetic Energy

The energy of motion or movement, which includes heat energy and light energy.

Heat

The transfer of thermal energy generated by the random movement of molecules or atoms from one body to another.

Photosynthesis

The process by which autotrophic organisms convert light energy from sunlight into energy-rich organic chemical energy, such as glucose.

Autotrophs

Organisms (self-feeders), such as plants, algae, and cyanobacteria, that capture and transform sunlight energy by photosynthesis.

Heterotrophs

Organisms that obtain energy by consuming other organisms rather than producing their own food.

Thylakoid

A coin-shaped membrane compartment inside chloroplasts that serves as the site for the light-dependent reactions of photosynthesis.

Chlorophyll

The primary pigment in chloroplasts that absorbs light energy (primarily blue and red wavelengths) and reflects green light.

Chemiosmosis

The process where ions (usually $\text{H}^+$) diffuse across a membrane through a transport protein down their concentration gradient to produce ATP.

Carbon Fixation

The process of converting inorganic carbon dioxide gas ($\text{CO}_2$) into organic molecules like glucose during the Calvin cycle.

Greenhouse Effect

A natural process where heat generated by solar radiation at Earth's surface is trapped in the atmosphere by greenhouse gases such as carbon dioxide and methane.

Carbon Footprint

A measure of the total amount of greenhouse carbon emissions an individual or activity is responsible for releasing into the atmosphere.

Macronutrients

Nutrients that organisms must ingest in large amounts to maintain health, including carbohydrates, proteins, and fats.

Micronutrients

Essential nutrients, including vitamins and minerals, that organisms must ingest in small amounts for proper cell growth and maintenance.

Digestion

The multi-step process of breaking down large food macromolecules into smaller subunit molecules through bond-breaking chemical reactions.

Essential Nutrients

Nutrients that cannot be synthesized by cellular machinery and must be obtained directly through diet, such as the 9 essential amino acids.

Malnutrition

A serious medical condition caused by a chronic deficiency of one or more essential macro- or micronutrients in the diet.

Catabolic Reactions

Metabolic chemical reactions that break down larger structures into smaller subunit molecules by breaking chemical bonds.

Anabolic Reactions

Metabolic chemical reactions that construct new, complex structures from smaller subunit building blocks.

Exergonic Reactions

Chemical reactions that result in a net release of energy into their surroundings.

Endergonic Reactions

Chemical reactions that require an input of net potential energy to proceed.

Enzyme

A protein molecule that acts as a biological catalyst to accelerate chemical reactions by lowering activation energy.

Substrate

The specific reactant molecule to which an enzyme binds and converts during a chemical reaction.

Active Site

The specific region or pocket on an enzyme where the substrate binds.

Activation Energy

The initial energy required for a chemical reaction to start.

Coenzyme

A small organic helper molecule, typically derived from vitamins, required to activate certain enzymes.

Cofactor

An inorganic mineral ion (such as zinc, iron, or copper) required to activate certain enzymes.

Lactase Persistence

The genetic trait that allows an adult human to continue producing the enzyme lactase and digesting lactose.

Cell Theory

The scientific theory stating that all living organisms are composed of cells, cells are the basic structural unit of life, and all cells derive from pre-existing cells.

Peptidoglycan

A rigid polymer of sugars and amino acids that forms bacterial cell walls, protecting bacteria from osmotic pressure.

Nucleus

The double-membrane-enclosed organelle in eukaryotic cells that houses genetic instructions in DNA.

Endoplasmic Reticulum

A membranous network in eukaryotic cells where proteins (rough ER) and lipids (smooth ER) are synthesized.

Golgi Apparatus

An organelle of stacked membrane sacs that modifies, sorts, and packages proteins received from the rough ER for distribution.

Mitochondria

Double-membrane eukaryotic organelles that perform aerobic respiration to extract energy from food and generate ATP.

Lysosomes

Eukaryotic organelles loaded with digestive enzymes that function as cell recycling centers to break down worn-out components.

Cytoskeleton

A network of protein fibers (microfilaments, intermediate filaments, microtubules) that supports cell shape, enables movement, and transports internal structures.

Endosymbiosis Theory

The evolutionary theory proposing that eukaryotic organelles like mitochondria and chloroplasts originated when ancestral prokaryotes engulfed free-living bacterial cells.

Phospholipid Bilayer

A two-layer sheet of amphipathic phospholipids with hydrophilic heads pointing outward and hydrophobic tails pointing inward, forming cell membranes.

Osmosis

The passive diffusion of water molecules across a semipermeable membrane from a region of lower solute concentration to higher solute concentration.

Hypotonic Solution

A solution with a lower solute concentration than the cell's interior, causing water to enter the cell and swell it.

Isotonic Solution

A solution with an equal solute concentration relative to the inside of a cell, resulting in no net water flow.

Hypertonic Solution

A solution with a higher solute concentration than the cell's interior, causing water to diffuse out of the cell and shrivel it.

Simple Diffusion

The unassisted passive movement of small, uncharged molecules directly across a membrane down their concentration gradient.

Facilitated Diffusion

The passive transport of large or charged molecules across a membrane down their concentration gradient using specific membrane proteins.

Active Transport

The energy-requiring process of pumping solutes across a cell membrane against their concentration gradient via transport proteins.

Antibiotic

A chemical agent that targets and stops the growth of bacteria without harming host eukaryotic cells.

Homeostasis

The process by which an organism maintains a stable internal environment despite external environmental shifts.

Atom

The basic building block of matter and the smallest unit of an element that retains its chemical properties.

Protons

Positively charged subatomic particles contained within the nucleus of an atom.

Electrons

Negatively charged subatomic particles with negligible mass located in shells surrounding an atomic nucleus.

Neutrons

Uncharged, neutral subatomic particles located within the nucleus of an atom.

Isotopes

Atoms of the same chemical element that have the same number of protons but different numbers of neutrons.

Ionic Bond

A chemical attraction between oppositely charged ions formed when one atom transfers electrons to another.

Covalent Bond

A strong chemical bond formed when two atoms share one or more pairs of valence electrons.

Polar Molecule

A molecule with an uneven distribution of electron charge, resulting in partial positive and partial negative poles.

Hydrogen Bond

A weak electrostatic bond formed between a partially positive hydrogen atom in a polar molecule and an electronegative atom in another polar molecule.

Cohesion

The property of water molecules sticking to other water molecules via hydrogen bonds, creating surface tension.

Adhesion

The property of water molecules clinging to other polar surfaces.

pH

A measure of the hydrogen ion ($\text{H}^+$) concentration in a solution, on a scale from 0 to 14.

Organic Molecules

Molecules that feature a carbon-based backbone and at least one carbon-hydrogen ($\text{C-H}$) bond.

Inorganic Molecules

Molecules lacking a carbon-based backbone and carbon-hydrogen ($\text{C-H}$) bonds.

Dehydration Reaction

A chemical reaction that synthesizes polymers by linking monomer subunits together and removing a water molecule.

Hydrolysis

A chemical reaction that breaks polymers down into monomer subunits by adding a water molecule.

Monosaccharide

The simple sugar monomer subunit of carbohydrates, such as glucose, fructose, or galactose.

Triglyceride

A fat molecule consisting of a glycerol head attached to three fatty acid tails, storing energy in carbon-hydrogen bonds.

Sterols

Lipids characterized by a rigid four-ring carbon structure, including cholesterol and steroid hormones like estrogen and testosterone.

Nucleotide

The monomer building block of nucleic acids, consisting of a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Scientific Hypothesis

A tentative, testable, and falsifiable explanation for a scientific observation or question.

Scientific Theory

An overarching explanation of the natural world supported by extensive scientific evidence and repeated testing without being disproved.

Peer Review

A process where scientific studies are critically evaluated by independent experts in the field before publication.

Control Group

The baseline experimental group that receives a control or placebo treatment to serve as a comparison standard.

Experimental Group

The group in an experiment that receives the active test treatment containing the independent variable.

Independent Variable

The single factor or condition intentionally changed or manipulated by researchers in an experiment.

Dependent Variable

The measured outcome or response variable collected in an experiment.

Placebo

An inactive control substance administered to isolate specific effects of an independent variable.

Statistical Significance

A statistical measure (such as a $p\text{-value} < 0.05$) indicating that observed experimental results are meaningful and unlikely due to chance.

Epidemiology

The scientific study of disease patterns, incidence, and health factors across human populations.

What is energy, and how is a calorie defined in physics and biology?

Energy is defined as the capacity to do work. A calorie (cal) is the amount of energy required to raise the temperature of $1\,\text{g}$ of water by $1\,^{\circ}\text{C}$.

How does $1\text{ Calorie}$ (capital 'C') relate to calories and kilocalories?

$1\text{ Calorie}$ is equal to $1000\text{ calories}$, or $1\text{ kilocalorie (kcal)}$.

What are the subunits and caloric values per gram for the four major biological macromolecules?

Carbohydrates break down into simple sugars ($4\text{ Calories/gram}$); Proteins break down into amino acids ($4\text{ Calories/gram}$); Fats break down into fatty acids and glycerol ($9\text{ Calories/gram}$); Nucleic acids break down into nucleotides (not a significant source of energy for cells).

What three major components contribute to daily caloric expenditure, and what percentage of energy does each consume?

Resting Metabolic Rate / Basal metabolism ($60\%$), Activity Thermogenesis / Physical activity ($30\%$), and Thermic Effect of Food / Digestion ($10\%$).

What is Nonexercise Activity Thermogenesis (NEAT), and what activities fall under this category?

NEAT refers to energy expended during non-exercise daily physical activities, such as yard work, shopping, standing, pacing, and walking a dog.

In what form and location do animals store short-term versus long-term dietary energy?

Short-term energy is stored as glycogen in muscle and liver cells. Long-term energy is stored as triglycerides in fat cells.

Which stored energy source is utilized first by the body during hunger or exercise?

Glycogen is used first. Stored fats (triglycerides) are used only after glycogen stores have been depleted.

What is the overall chemical equation for aerobic cellular respiration?

$\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP}$ (Glucose + Oxygen \rightarrow Carbon dioxide + Water + Energy ATP).

What occurs during Glycolysis, where does it take place, and what is its net ATP yield?

Glycolysis takes place in the cytoplasm. It breaks down glucose into two pyruvate molecules, producing NADH and a net yield of $2\text{ ATP}$.

What occurs during the Citric Acid Cycle, where does it take place, and what are its outputs?

It takes place in the mitochondrial matrix. Pyruvate is converted to acetyl-CoA and enters the cycle, producing \text{CO}_2, NADH, \text{FADH}_2, and $2\text{ ATP}$.

How do \text{NAD}^+ and NADH function as electron carriers in cellular respiration?

\text{NAD}^+ accepts high-energy electrons and a hydrogen proton from food molecules to become reduced to NADH, which then transfers those electrons to the electron transport chain.

What happens during the Electron Transport Chain stage of aerobic respiration?

High-energy electrons from NADH and \text{FADH}_2 move through protein complexes in the inner mitochondrial membrane to oxygen, powering the active pumping of protons (\text{H}^+) into the intermembrane space.

What is the final electron acceptor in aerobic respiration, and what product does it form?

Oxygen (\text{O}_2) is the final electron acceptor, combining with transported electrons and hydrogen protons (\text{H}^+) to form water (\text{H}_2\text{O}).

How does ATP Synthase synthesize ATP during chemiosmosis?

Protons (\text{H}^+) in the intermembrane space diffuse down their concentration gradient through ATP Synthase into the matrix, causing its subunit to rotate and catalyze the synthesis of ATP from ADP and \text{P}_i.

How much ATP is generated per glucose molecule by each stage of aerobic respiration?

Glycolysis produces $2\text{ ATP}$; Citric Acid Cycle produces $2\text{ ATP}$; Oxidative Phosphorylation (Electron Transport + Chemiosmosis) produces $26\text{--}28\text{ ATP}$ (yielding around $30\text{--}32\text{ ATP}$ or up to $36\text{ ATP}$ total).

What is brown fat, and how do its mitochondria differ in function from standard tissue mitochondria?

Brown fat is a specialized thermogenic fat tissue found in newborn babies and hibernating mammals. Its mitochondria convert energy directly into heat rather than ATP to warm the body.

Under what cellular conditions does fermentation occur, and what is its primary biological purpose?

Fermentation occurs in the cytoplasm when oxygen is absent (anaerobic conditions). Its primary purpose is to convert NADH back to \text{NAD}^+ so that glycolysis can continuously produce ATP.

What are the inputs, outputs, and net ATP yield of lactic acid fermentation?

Inputs: Glucose (\text{C}6\text{H}{12}\text{O}_6); Outputs: $2\text{ lactic acid}$ (\text{C}_3\text{H}_6\text{O}_3) molecules and $2\text{ ATP}$.

What are the products of alcoholic fermentation, and in what organisms does it commonly occur?

Products: Ethanol (alcohol), Carbon dioxide (\text{CO}_2), and $2\text{ ATP}$. It occurs in yeast and some bacteria.

Why are humans unable to survive strictly on fermentation?

Fermentation produces only $2\text{ ATP}$ per glucose molecule (via glycolysis), which is insufficient to power long-term human cellular functions.

How do photosynthesis and aerobic respiration form a continuous biological cycle?

Photosynthesis uses light energy, \text{CO}_2, and \text{H}_2\text{O} to produce glucose and \text{O}_2. Respiration uses glucose and \text{O}_2} to produce ATP, releasing \text{CO}_2 and \text{H}_2\text{O} as outputs that serve as inputs for photosynthesis.