Biology Study Notes: Cells, Chemistry, and Biomolecules

A comprehensive set of Q&A flashcards covering cells, chemistry, biomolecules, metabolism, transport, signaling, organelles, and foundational biology concepts from the notes.

What are the Features of Life mentioned in the notes?

Living things are made up of one or more cells; require energy for growth, reproduction, and maintaining homeostasis; homeostasis involves keeping internal and external environments stable—chemically.

What are Producers (Autotrophs) and give an example?

Producers use energy from the sun to make food (e.g., plants).

What are Consumers?

Consumers eat other organisms to obtain energy (e.g., cows, humans).

What are Decomposers?

Decomposers break down dead organisms (e.g., fungi, bacteria).

How are Consumers further divided by trophic level?

Primary consumers (herbivores) eat plants; Secondary consumers (carnivores/omnivores) eat herbivores; Tertiary consumers (top predators) eat other carnivores.

What is the sequence of the Scientific Method?

Ask a question; do background research; formulate hypotheses and test them experimentally; analyze data; communicate results; revise based on new evidence.

What is the example given for the Scientific Method?

Testing which fertilizer helps plants grow fastest.

What are the limitations of Science mentioned in the notes?

Science cannot answer questions about meaning of life or personal beliefs; it relies on evidence, not opinions or biases.

What are the three statements of the Cell Theory?

All living organisms are made of one or more cells; the cell is the basic unit of life; all cells arise from pre-existing cells.

What are the general characteristics of cells?

Use energy (metabolism); contain genetic material (DNA); have a cell (plasma) membrane; contain cytoplasm; can communicate and interact with other cells.

What defines Prokaryotic cells?

No nucleus; DNA in the cytoplasm; no membrane-bound organelles; usually smaller and simpler.

What defines Eukaryotic cells?

Have a nucleus with DNA inside; contain membrane-bound organelles; larger and more complex.

Give an example of prokaryotic cells.

Bacteria and archaea.

Give an example of eukaryotic cells.

Human, plant, and fungal cells.

A notable fact about Human body cells vs. microbiota?

Only about 20% of the cells in the body are human; the rest are mostly bacteria (microbiota); gut bacteria assist digestion and immunity.

Name three common cell structures.

Plasma (cell) membrane, cytoplasm, and DNA.

What is the Plasma Membrane composed of?

Phospholipid bilayer with hydrophilic heads and hydrophobic tails; plus proteins, glycoproteins, and glycolipids for communication and transport.

What does selective permeability mean for the plasma membrane?

It allows small, nonpolar molecules to pass easily; other substances require transport proteins.

What is passive transport?

No energy required; moves substances down their concentration gradient (diffusion, osmosis, facilitated diffusion).

What is active transport?

Requires energy (ATP) to move substances against their concentration gradient (e.g., sodium-potassium pump).

What is the nucleus and its function?

Contains DNA; acts as the control center of the cell.

What are ribosomes and where are they found?

Sites of protein synthesis; found in the cytoplasm or on the rough endoplasmic reticulum.

What does the Rough Endoplasmic Reticulum do?

Has ribosomes; makes and processes proteins.

What does the Smooth Endoplasmic Reticulum do?

Synthesizes lipids and steroids.

What is the Golgi Apparatus responsible for?

Packages and ships proteins and lipids.

What do Lysosomes do?

Digest and recycle cellular waste and foreign material.

What is the mitochondrion's role?

Powerhouse of the cell; site of cellular respiration and ATP production.

What is the cytoskeleton?

Network of protein filaments for structure, support, and movement.

What are the three cytoskeleton components and their roles?

Microfilaments (actin) support movement and shape; Intermediate Filaments provide mechanical strength; Microtubules move chromosomes and serve as tracks for organelles.

What is ATP and why is it important?

Adenosine triphosphate; the cell’s energy currency used in metabolic processes.

What are the major metabolic pathways?

Anabolism (building up) and Catabolism (breaking down).

Describe the main steps of cellular respiration and ATP yield.

Glycolysis (cytoplasm) yields 2 ATP; Krebs Cycle (mitochondria) yields ~2 ATP; Electron Transport Chain (mitochondria) yields ~32 ATP; total ~36 ATP per glucose.

What is lactic acid fermentation?

When oxygen is low, muscles can produce lactic acid as a byproduct of anaerobic respiration.

What is osmosis?

Movement of water across a semi-permeable membrane following its concentration gradient.

Define isotonic, hypotonic, and hypertonic solutions.

Isotonic: equal solute inside and outside cell; cell stays same. Hypotonic: lower external solute; water enters and cell swells. Hypertonic: higher external solute; water leaves and cell shrinks.

What are Endocytosis and Exocytosis?

Endocytosis = bulk import of materials into the cell; Exocytosis = bulk export out of the cell.

What are Desmosomes, Gap Junctions, and Tight Junctions?

Desmosomes anchor cells for structural support; Gap Junctions allow cell-to-cell communication; Tight Junctions seal cells to prevent leaks.

What is plasmodesmata?

Plant cell equivalent of gap junctions, linking plant cells.

What is the ATP yield from glucose in aerobic respiration?

36 ATP per glucose.

What are the four main biomolecules?

Proteins, carbohydrates, lipids, and nucleic acids.

What are the four levels of protein structure?

Primary, Secondary, Tertiary, and Quaternary structures.

What is the difference between globular and fibrous proteins?

Globular proteins are soluble enzymes; fibrous proteins are insoluble structural proteins (e.g., collagen).

Give an example of a protein and a carbohydrate from the notes.

Protein: Hemoglobin; Carbohydrate: Glucose.

What are the main chemical energy sources in biology?

Carbohydrates and triglycerides; glucose is broken down to produce ATP.

What are some key properties of water?

Water is a solvent; has high heat capacity; participates in reactions (condensation/hydrolysis); polarity enables hydrogen bonding.

What is a free radical and what is an antioxidant example given?

Free radicals are unstable molecules that can damage cells; antioxidants neutralize them (e.g., vitamin C).

What is pH and why is it important in physiology?

pH measures hydrogen ion concentration; blood is about 7.4; deviations can cause acidosis/alkalosis; pure water is pH 7.

What are acids and bases with examples?

Acids donate H+ (e.g., HCl, H2SO4, acetic acid); bases accept H+ (e.g., household cleaners).

What are ionic and covalent bonds?

Ionic bonds result from transfer of electrons forming oppositely charged ions; covalent bonds involve sharing electrons.

What is the difference between nonpolar and polar covalent bonds?

Nonpolar covalent bonds share electrons equally; polar covalent bonds share electrons unequally, creating partial charges (e.g., H2O).

What are hydrogen bonds and why are they important?

Weaker bonds between polar molecules (e.g., between water molecules) that influence many properties of water and biomolecules.

What is the difference between elements, compounds, and mixtures?

Elements are pure substances of one type of atom; compounds are two or more elements chemically bonded; mixtures are physically combined substances with variable composition.

What is meant by homogeneous vs. heterogeneous mixtures?

Homogeneous mixtures have uniform composition (e.g., coffee); heterogeneous mixtures have non-uniform composition (e.g., oil and water).

How are compounds represented?

By chemical names, molecular formulas (e.g., H2O), and structural formulas/models showing atom connections.

What are ions and how do they form?

Atoms gain or lose electrons to form ions (cation = positive, anion = negative). Ionic bonds form between oppositely charged ions.

What is valence and why does it matter for bonding?

Valence electrons determine an element’s bonding behavior and ability to achieve a stable configuration.

What is the periodic table useful for?

Arranges elements by increasing atomic number and groups elements with similar chemical properties.

What is atomic structure and the key subatomic particles?

Protons and neutrons form the nucleus; electrons orbit the nucleus; atomic number = protons; mass number = protons + neutrons.

What is an isotope?

Atoms of the same element with the same number of protons but different numbers of neutrons.

What is carbon-14 dating used for?

Estimating the age of ancient artifacts and remains using the half-life of carbon-14.

What are double and triple covalent bonds?

Bonds where atoms share two or three pairs of electrons respectively, allowing multiple bonds.

What does a hydrogen bond contribute to in biology?

Contributes to water’s unique properties and stabilizes biomolecular structures.

What are the three main types of matter classification?

Elements, compounds, and mixtures; mixtures can be homogeneous or heterogeneous.

Why is compartmentalization important for eukaryotic cells?

It allows specialized environments and functions within organelles, supporting complex cellular processes.

How does the circulatory system interact with the respiratory system?

The circulatory system transports oxygen from the lungs to tissues and carries CO2 back to the lungs for exhalation.

Describe the pathway of a nerve impulse from receptor to effector.

A receptor detects a stimulus; signal travels via sensory neurons to the brain; brain processes and sends a response via motor neurons to effectors.

Trace the journey of a food molecule from ingestion to absorption.

Ingestion in the mouth; digestion with saliva; esophagus to stomach; small intestine for enzymatic digestion and nutrient absorption into blood.

What is the role of DNA in heredity?

DNA carries genetic instructions; passed from parents through egg and sperm to offspring.

How can mutations impact health and how is DNA repaired?

Mutations can disrupt vital genes; cells have repair enzymes that correct errors during replication.

What are the four main tissue types and a brief example of where each is found?

Epithelial (skin, gut lining); Connective (bone, blood); Muscle (skeletal, cardiac); Nervous (brain, nerves).

What are the primary defenses of the immune system?

Physical barriers, innate and adaptive immune responses; vaccines enhance adaptive immunity.

What are some ethical issues in health care and research mentioned?

Informed consent; beneficence; historical cases like HeLa cells, Tuskegee Study; importance of ethical guidelines.

What is endocytosis and give an example?

Bulk import of material into the cell; e.g., white blood cells engulfing bacteria.

What is exocytosis and give an example?

Bulk export of material out of the cell; e.g., secretion of hormones or neurotransmitters.

What is meant by homeostasis and feedback mechanisms in the body?

Maintenance of stable internal conditions; negative feedback detects deviations and initiates corrective responses.

What are autocrine, paracrine, and endocrine signaling?

Autocrine signals affect the signaling cell itself; paracrine signals affect nearby cells; endocrine signals travel through blood to distant cells.

What are ligand, receptor, and signal transduction?

Ligand is a signaling molecule; receptor receives the signal; signal transduction is the cascade of cellular responses leading to a reaction.

What happens to a cell in a hypotonic solution and why?

Water enters the cell, causing swelling or potential lysis due to lower external solute concentration.

What is the role of the plasma membrane in cell communication and transport?

It acts as a selectively permeable boundary, with embedded proteins functioning as channels, receptors, and pumps.