Biology Semester Exam

Characteristics of Life

Factors that make organisms considered 'alive', including growth, reproduction, response to stimuli, metabolism, homeostasis, and cellular organization.

Homeostasis

The process by which living organisms maintain a stable internal environment despite external changes.

Covalent Bond

A type of chemical bond where atoms share pairs of electrons.

Non-polar Covalent Bond

A type of covalent bond between atoms with similar electronegativities, resulting in an even distribution of charge.

Polar Covalent Bond

A type of covalent bond where electrons are shared unequally between different atoms, creating a dipole.

Oxygen as a Polar Molecule

Oxygen is polar due to the difference in electronegativity between oxygen and hydrogen, causing a partial negative charge on oxygen.

Hydrogen Bonds in Water

Weak bonds that form between the hydrogen atom of one water molecule and the oxygen atom of another, contributing to water's unique properties.

Adhesion

The attraction between different substances, important for processes like water transport in plants.

Cohesion

The attraction between molecules of the same substance, important for water's surface tension and transport in organisms.

Thermal Properties of Water

High specific heat and boiling point, which regulate temperature in organisms and environments.

Ionic Bond Formation

A chemical bond formed by the transfer of electrons from one atom to another, resulting in oppositely charged ions.

Hydrophilic Substance

A substance that has an affinity for water and can dissolve or interact with it.

Hydrophobic Substance

A substance that repels water and does not dissolve in it.

Solubility of Hydrophilic and Hydrophobic Substances

Hydrophilic substances dissolve in water, while hydrophobic substances do not.

Example of Hydrophilic Substance

Glucose, which dissolves readily in water and is utilized in biological functions.

Example of Hydrophobic Substance

Lipids, such as fats and oils, that do not dissolve in water.

Cooling Effect of Water's Thermal Properties

Water absorbs heat during evaporation, providing a cooling effect crucial for temperature regulation.

Macromolecules

Four main types of biological molecules: carbohydrates, lipids, proteins, and nucleic acids.

Elements in Macromolecules

Carbohydrates (C, H, O), Lipids (C, H, O), Proteins (C, H, O, N, sometimes S), Nucleic Acids (C, H, O, N, P).

Biological Functions of Macromolecules

Carbohydrates provide energy; lipids store energy; proteins perform various functions including catalysis; nucleic acids store genetic information.

Enzymes

Biological catalysts that speed up chemical reactions without being consumed.

Word Equation for Hydrogen Peroxide Breakdown

2 H2O2 → 2 H2O + O2 (catalyzed by catalase).

Enzyme Specificity

Enzymes have specific active sites that only bind to specific substrates, ensuring that reactions occur properly.

Factors Affecting Enzyme Activity

Temperature, pH, substrate concentration, and enzyme concentration can all influence the rate of enzyme-catalyzed reactions.

Word Equation for Starch Breakdown by Amylase

Starch → Maltose.

Effect of Substrate Concentration on Enzyme Activity

Increasing substrate concentration generally increases the rate of reaction until reaching maximum velocity.

Effect of High Temperatures on Enzymes

High temperatures can denature enzymes, altering their shape and reducing their effectiveness.

Effect of Extreme pH on Enzymes

Extreme pH levels can denature enzymes, affecting their ability to function properly.

Optimum Conditions for Enzymes

The specific temperature and pH where an enzyme has the highest activity and performance.

Nucleic Acids Elements

Nucleic acids are composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus.

Structure of Nucleic Acids

Nucleotides are the building blocks, comprising a sugar, phosphate group, and nitrogenous base.

Biological Functions of Nucleic Acids

Store and transfer genetic information; direct protein synthesis.

Examples of Nucleic Acids

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

Cell Organelles and Functions

Organelles are specialized structures within cells, such as the nucleus (genetic information), mitochondria (energy production), etc.

Organelles in Animal and Plant Cells

Animal cells contain organelles like lysosomes and centrioles; plant cells contain chloroplasts and a cell wall.

Prokaryotic vs Eukaryotic Cells

Prokaryotic cells are simpler, lack a nucleus, and are generally smaller; eukaryotic cells are more complex, have a nucleus, and larger.

Specialized Cell Definition

Cells that have specific structures and functions tailored to their roles in an organism.

Specialization of Sperm Cells

Sperm cells have a streamlined shape and a flagellum for movement, allowing them to reach and fertilize an egg.

Specialization of Red Blood Cells

Red blood cells lack nuclei and are disk-shaped to maximize oxygen transport via hemoglobin.

Stem Cell Definition

Undifferentiated cells that can develop into various specialized cell types.

Differentiation Process

The process by which stem cells mature into specialized cells with distinct functions.

Types of Stem Cells

Embryonic stem cells (derived from early embryos) and adult stem cells (found in tissues).

Pluripotent vs Multipotent Stem Cells

Pluripotent stem cells can become any cell type; multipotent stem cells are limited to certain lineages.

Ethical Issues of Embryonic Stem Cells

Concerns arise regarding the moral status of embryos from which embryonic stem cells are derived.

iPSCs Definition

Induced pluripotent stem cells are created by reprogramming adult somatic cells to an embryonic-like state.

Role of Stem Cell Research

Facilitates advancements in regenerative medicine and understanding of developmental biology.

Therapeutic Uses of Stem Cells

Include treatments for conditions like leukemia, spinal cord injuries, and various degenerative diseases.

Cell Membrane Structure

A selectively permeable barrier consisting of a phospholipid bilayer with embedded proteins.

Diffusion Process

The movement of molecules from an area of higher concentration to an area of lower concentration.

Permeable Substances

Small, non-polar molecules (like oxygen and carbon dioxide) that can cross the cell membrane easily.

Osmosis Process

The diffusion of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Osmosis Effect on Red Blood Cells

Red blood cells can shrink or swell depending on the surrounding solution's osmolarity.

Osmosis Effect on Plant Cells

Plant cells can become turgid (firm) or plasmolyze (shrink) based on water movement.

Active Transport Process

The movement of molecules against their concentration gradient, requiring energy.

Energy Differences in Active vs Passive Transport

Active transport requires ATP to move substances, while passive transport occurs naturally without energy.

Factors Affecting Osmosis

Concentration gradients, temperature, and membrane permeability can all influence the rate of osmosis.

Word Equation for Aerobic Respiration

Glucose + Oxygen → Carbon Dioxide + Water + Energy.

Aerobic vs Anaerobic Respiration

Aerobic respiration requires oxygen, while anaerobic occurs without it and produces less energy.

Stages of Aerobic Respiration

Include glycolysis, the Krebs cycle, and the electron transport chain, taking place in the cytoplasm and mitochondria.

Stages of Anaerobic Respiration

Include glycolysis and fermentation, occurring in the cytoplasm.

Word Equation for Fermentation in Animals

Glucose → Lactic acid + Energy.

Word Equation for Fermentation in Plants

Glucose → Ethanol + Carbon Dioxide + Energy.

Muscle Fatigue

Occurs when muscles are not able to generate enough energy to continue prolonged activity.

Fermentation in Plants and Yeast

A process that converts sugars to alcohol or acids under anaerobic conditions.