Honors Biology Midterm 2025 Study Guide PDF

Honors Biology Midterm 2025 Study Guide - COMPLETED BY CHATGPT Unit 1: NOS/Characteristics of Life What is a controlled experiment? A controlled experiment is an experiment where only one variable is changed at a time while all other variables are kept constant to isolate the effect of the indepen...

Honors Biology Midterm 2025 Study Guide - COMPLETED BY CHATGPT Unit 1: NOS/Characteristics of Life What is a controlled experiment? A controlled experiment is an experiment where only one variable is changed at a time while all other variables are kept constant to isolate the effect of the independent variable on the dependent variable. Experimental vs null hypothesis? Experimental hypothesis: A testable statement that predicts the outcome of the experiment. Null hypothesis: A statement that there is no effect or no relationship between variables, used as a baseline to compare results against. Control (positive, negative) vs experimental group? Control group: A group that does not receive the experimental treatment, used for comparison. ○ Positive control: A group that is exposed to a treatment that is known to produce a result. ○ Negative control: A group that is not exposed to the treatment and shows no effect. Experimental group: The group that is exposed to the variable being tested. Independent vs dependent variable? Independent variable: The variable that is deliberately changed or manipulated in the experiment. Dependent variable: The variable that is measured or observed in response to the changes in the independent variable. Role of constants? Constants are variables that are kept the same throughout the experiment to ensure that any observed effects are due to the manipulation of the independent variable. Explain the 8 characteristics of life. 1. Cellular organization: All living organisms are made up of one or more cells. 2. Metabolism: The sum of all chemical reactions within an organism. 3. Homeostasis: The ability to maintain a stable internal environment.  4. Growth and development: Organisms grow and develop following specific instructions coded in their DNA. 5. Reproduction: The ability to produce offspring. 6. Heredity: Passing genetic information from one generation to the next. 7. Response to stimuli: Organisms respond to environmental changes. 8. Adaptation through evolution: Organisms evolve over time to better survive in their environment. What are the levels of cellular organization? Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ system → Organism. Role of positive and negative feedback in homeostasis? Positive feedback amplifies a response to a stimulus (e.g., childbirth). Negative feedback counteracts a change to maintain stability (e.g., regulation of body temperature). What is evolution? Evolution is the change in the genetic composition of a population over successive generations. Natural selection? Adaptations? Fitness? Natural selection: The process by which organisms with favorable traits are more likely to survive and reproduce. Adaptations: Traits that increase an organism's ability to survive and reproduce. Fitness: An organism's ability to survive, reproduce, and pass on its genes. Do individuals or populations evolve? Populations evolve over time, not individuals. What is the role of the environment and random mutations on evolution? The environment determines which traits are advantageous for survival and reproduction. Random mutations introduce genetic variation that may result in beneficial adaptations or neutral changes. Unit 2: Biochemistry Part 1 Why do hydrogen bonds occur between water molecules? Hydrogen bonds occur because the hydrogen atom of one water molecule is attracted to the electronegative oxygen atom of another water molecule, due to water's polarity. Relationship between polarity and covalent bonds? Water molecules are polar because the oxygen atom is more electronegative than the hydrogen atoms, creating a partial negative charge on oxygen and partial positive charges on the hydrogens. What is the structure of a polar water molecule? A water molecule has a bent shape with one oxygen atom bonded to two hydrogen atoms. The oxygen end is slightly negative, and the hydrogen end is slightly positive. How does water’s polarity lead to the following intermolecular forces of attraction? Cohesion: Water molecules attract each other due to hydrogen bonding. Adhesion: Water molecules attract other substances. Capillarity: The movement of water up narrow tubes due to cohesion and adhesion. High specific heat/heat capacity: Water absorbs a large amount of heat before its temperature rises significantly. Density: Water is most dense at 4°C and becomes less dense when frozen (ice floats). Surface tension: Water’s surface is strong due to cohesion between water molecules. Universal solvent: Water can dissolve many substances due to its polarity. pH scale - hydrogen and hydroxide ions? pH measures the concentration of hydrogen ions (H⁺) in a solution. Acids release H⁺ ions, bases release hydroxide ions (OH⁻), and neutral solutions have equal H⁺ and OH⁻ concentrations. Acids, neutral, bases? Acids: pH < 7 (increase H⁺ concentration). Neutral: pH = 7 (equal H⁺ and OH⁻ concentrations). Bases: pH > 7 (increase OH⁻ concentration). Role of buffers in homeostasis? Buffers help maintain a stable pH by neutralizing excess acids or bases, preventing harmful pH fluctuations in biological systems. Unit 2: Biochemistry Part 2 Two reasons carbon is the GOAT? 1. Carbon has 4 valence electrons so it can form four covalent bonds, allowing it to create a diverse array of organic molecules. 2. Carbon atoms can bond with other carbon atoms to form chains and rings, making complex molecules like carbohydrates, proteins, and lipids. Dehydration synthesis vs hydrolysis reactions? Dehydration synthesis: Two monomers are joined together by removing a water molecule. Hydrolysis: A polymer is broken apart by adding water. Rules to ID macromolecules (proteins, lipids, carbs, nucleic acids). Proteins: Composed of amino acids, with peptide bonds. Lipids: Non-polar, composed of fatty acids and glycerol. Carbohydrates: Composed of sugar molecules (monosaccharides, disaccharides, polysaccharides). Nucleic acids: Composed of nucleotides (DNA and RNA). Functions of each class of macromolecules: Proteins: Enzymes, structure, transport, signaling. Lipids: Energy storage, cell membrane structure, insulation. Carbohydrates: Energy source, structural components. Nucleic acids: Genetic information storage and transmission (DNA/RNA). Enzymes: Reusable? Yes, enzymes are reusable. Specific? Yes, enzymes are highly specific to the substrates they act upon. Substrate/product/active site and enzyme/substrate complex? Substrate: The molecule an enzyme acts upon. Product: The result of the enzyme-catalyzed reaction. Active site: The region on the enzyme where the substrate binds. Enzyme/substrate complex: The temporary structure formed when the enzyme and substrate interact. Factors that affect the activity of enzymes; optimal/optimum enzyme activity? Temperature, pH, enzyme concentration, and substrate concentration all affect enzyme activity. Enzymes have an optimal temperature and pH range where they function best. Unit 3: Cells and Cellular Transport 4 minimum components required to be a cell?  Plasma membrane, cytoplasm, ribosomes, DNA. Prokaryotic vs eukaryotic cells? Prokaryotic: No membrane-bound nucleus, smaller (e.g., bacteria). Eukaryotic: Membrane-bound nucleus, larger, more complex (e.g., plant and animal cells). Plant vs animal cells - organelles in each? Plant cells: Chloroplasts, large central vacuole, cell wall. Animal cells: Lysosomes, centrioles, smaller vacuoles. Structure/function of organelles 1. Nucleus Function: The nucleus houses the cell's genetic material (DNA) and controls the cell's activities, including growth, metabolism, and protein synthesis. 2. Nuclear Envelope Function: The nuclear envelope is a double membrane that surrounds the nucleus, regulating the passage of materials (like RNA and proteins) into and out of the nucleus. 3. Nucleolus Function: The nucleolus is a region within the nucleus where ribosomal RNA (rRNA) is synthesized and ribosomes are partially assembled. 4. Plasma Membrane Function: The plasma membrane controls the movement of substances in and out of the cell and helps maintain the cell's homeostasis by regulating transport and communication with the external environment. 5. Cell Wall Function: The cell wall provides structural support, protection, and shape to the cell. It also helps resist turgor pressure in plant cells. 6. Cytoplasm Function: The cytoplasm is the gel-like substance within the cell that holds the organelles in place and provides a medium for chemical reactions to occur. 7. Cytoskeleton Function: The cytoskeleton is a network of protein filaments that provides mechanical support, helps maintain cell shape, and is involved in cell movement, division, and intracellular transport. 8. Centrioles Function: Centrioles help organize the microtubules during cell division (mitosis and meiosis) by forming spindle fibers that separate chromosomes. 9. Vesicle Function: Vesicles are membrane-bound sacs that transport materials within the cell or to the cell's surface for secretion or uptake. 10. Vacuole Function: Vacuoles are storage organelles that maintain turgor pressure in plant cells by storing water and other substances. In animal cells, smaller vacuoles are involved in storage and waste removal. 11. Lysosome Function: Lysosomes contain enzymes that break down waste, cellular debris, and foreign substances, and are involved in cellular digestion and recycling. 12. Rough Endoplasmic Reticulum (Rough ER) Function: The rough ER is studded with ribosomes and synthesizes proteins that are either secreted from the cell or incorporated into the cell membrane. 13. Smooth Endoplasmic Reticulum (Smooth ER) Function: The smooth ER synthesizes lipids, detoxifies certain chemicals, and stores calcium ions. 14. Ribosomes Function: Ribosomes are the sites of protein synthesis, where mRNA is translated into amino acid chains, forming proteins. 15. Golgi Apparatus (Golgi Body) Function: The Golgi apparatus modifies, sorts, and packages proteins and lipids for storage or transport out of the cell.. 16. Flagella and Cilia Function: Flagella and cilia are hair-like structures that help in cell movement or the movement of fluids and materials around the cell. Flagella are long and typically occur singly or in pairs, while cilia are short and more numerous. 17. Mitochondria Function: Mitochondria are the "powerhouses" of the cell. They generate ATP through cellular respiration, which is used as an energy source by the cell. 18. Chloroplast Function: Chloroplasts contain chlorophyll and are responsible for photosynthesis, converting sunlight into chemical energy stored in glucose. Plasma membrane transport Semi/selectively permeable: The plasma membrane allows some substances to pass but not others. Phospholipids: The basic structure of the plasma membrane with hydrophilic heads and hydrophobic tails. Passive vs active transport Passive: No energy required (e.g., diffusion, osmosis). Active: Requires energy (e.g., protein pumps, endocytosis). Unit 4: Bioenergetics Glucose and ATP as chemical energy ATP (adenosine triphosphate) is the energy currency of the cell, derived from glucose during cellular respiration. Chemical equation photosynthesis 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂. What occurs in light dependent reactions? In the thylakoid membranes, light energy splits water molecules, producing oxygen, and generates ATP and NADPH. What occurs in light independent reactions? Also known as the Calvin cycle, these reactions use ATP and NADPH to convert CO₂ into glucose. Chemical equation for cellular respiration C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP. What occurs in glycolysis? Glycolysis breaks down glucose into two molecules of pyruvate, producing a small amount of ATP and NADH. What occurs in Krebs cycle? The Krebs cycle (citric acid cycle) processes pyruvate to produce CO₂, ATP, NADH, and FADH₂. What occurs in ETC? In the electron transport chain, electrons are transferred, producing ATP and water as oxygen is reduced. Aerobic vs anaerobic respiration? Aerobic: Requires oxygen, produces more ATP. Anaerobic: Does not require oxygen, produces less ATP (e.g., fermentation). Purpose/function of glycolysis followed by fermentation? In the absence of oxygen, fermentation allows for the regeneration of NAD⁺ so glycolysis can continue producing ATP.