NYS Living Environment Regents Exhaustive Study Guide

Foundational Concepts in Scientific Inquiry

• Observation: Defined as what is seen or measured through sensory input or scientific instrumentation.

• Inference: A logical conclusion or interpretation derived from observations or existing evidence.

• Hypothesis: An untested prediction regarding a natural phenomenon. A well-constructed hypothesis must state both cause and effect, typically formatted as an "If-then" statement.

• Theory: A comprehensive and broad explanation of natural events that is reinforced by a significant body of strong evidence.

• Controlled Experiment: A scientific procedure that compares results between two or more groups to isolate the effects of a specific variable.     * Experimental Group: The group subjected to the variable being tested (e.g., a group receiving a new drug).     * Control Group: The "normal" group used for comparison. It must be identical to the experimental group in every aspect except for the treatment being tested (e.g., receives no drug, the original drug, or a placebo).     * Placebo: A fake treatment, such as a sugar pill, administered to the control group to ensure subjects do not know which group they are in, thereby maintaining the integrity of the experiment.     * Independent Variable: The variable that the researcher intentionally changes or tests (e.g., the new drug). In graphical representations, the independent variable is always plotted on the $X$ axis.     * Dependent Variable: The variable that is measured at the conclusion of the experiment to determine results (e.g., patient recovery). Chronicling the outcome, the dependent variable is always plotted on the $Y$ axis.

• Criteria for a Valid Experiment:     * Repeatability: The experiment can be replicated by other researchers with the same results.     * Large Sample Size: Includes a significant number of test subjects to ensure statistical reliability.     * Duration: Performed over extended periods of time to observe long-term effects.     * Single Variable: Tests only one independent variable at a time.     * Peer Review: The study is examined by several independent scientists to verify accuracy and methodology.     * Hypothesis Independence: The results do not have to support the initial hypothesis; a scientist's prediction is allowed to be incorrect.     * Objectivity: The experiment and its conclusions must be fair, unbiased, and strictly separate fact from opinion.

Characteristics of Living Things and Life Functions

• Homeostasis: All living organisms must maintain a stable internal environment. Failure to maintain homeostasis results in disease or death.

• Metabolism: The sum of all life processes and chemical reactions occurring within an organism.

• Basic Life Functions: To maintain homeostasis, organisms perform nutrition, excretion, transport, respiration, growth, synthesis, and regulation.

• Nutrition:     * Autotrophs: Organisms that can manufacture their own food.     * Heterotrophs: Organisms that must consume other organisms for energy.     * Photosynthesis: Process carried out by plants, alga, and blue-green bacteria (autotrophs). It converts radiant energy from the sun into chemical energy stored in the bonds of sugar molecules. This occurs primarily within the chloroplasts of plant cells.     * Stomates: Small openings in plant leaves used for gas exchange.     * Guard Cells: Specialized cells that open and close the stomates.

• Respiration: The process of obtaining energy by breaking the chemical bonds of sugar molecules. The released energy is utilized to produce $ATP$ (Adenosine Triphosphate).     * Aerobic Respiration: Requires oxygen ($O_2$) and produces a significantly higher yield of $ATP$ per sugar molecule.     * Anaerobic Respiration: Occurs without oxygen and yields less energy. In humans, this process produces lactic acid, cause of the "burn" felt in muscles during strenuous exercise.     * Environmental Cycle: Photosynthesis and Aerobic Respiration are opposite reactions and are critical for cycling oxygen, carbon, hydrogen, and water through the biosphere.

Cell Transport and Regulation

• Diffusion: The passive movement of molecules from an area of high concentration to an area of low concentration. This process requires zero energy.

• Active Transport: The movement of molecules from low concentration to high concentration (against the concentration gradient). This process requires the expenditure of cellular energy.

• Osmosis: The diffusion of water across a membrane.     * If water diffuses into a cell, the cell swells and may burst.     * If a cell is placed in salt water, it loses water and shrivels.

• Regulation: The coordination and control of various life functions.     * Stimulus: A change in the internal or external environment that triggers a response.     * Neuron: A specialized nerve cell.     * Impulse: An electrical signal transmitted by nerves.     * Neurotransmitters: Chemical substances that facilitate the transmission of impulses.     * Hormone: Chemical signals secreted by glands. Examples include insulin, adrenaline, testosterone, and estrogen.     * Receptor Molecules: Proteins located on the cell membrane surface that receive signals from the nervous and endocrine systems, allowing cells to communicate.

Biochemistry and Cell Theory

• Elemental Composition: The four most common elements in living organisms are Carbon, Hydrogen, Oxygen, and Nitrogen ($CHON$).

• Organic Compounds: Molecules containing both Carbon and Hydrogen (e.g., Glucose: $C_6H_{12}O_6$). These are generally larger and more complex than inorganic molecules (e.g., $H_2O$, $CO_2$, $NO_3$).

• Carbohydrates: Sugars and starches made from simple sugars like glucose. Their primary function is to supply energy.

• Lipids: Fats, oils, and waxes composed of fatty acids and glycerol. These are used for long-term energy storage.

• Proteins: Composed of amino acids. They are considered the most important organic molecules as they form hormones and various body/cell structures.     * Protein Shape: The specific shape and fit of a protein determine its function.     * Protein Functions: 1) Enzymes, 2) Receptor molecules on cell membranes, 3) Antibodies, 4) Hormones.

• Enzymes: Biological catalysts that alter the rate of chemical reactions using a "lock and key" model (one enzyme fits one specific molecule).     * Denaturation: High temperatures can cause enzymes to lose their shape, rendering them non-functional. This is why high fevers are dangerous.

• pH Scale: Measures the strength of acids and bases.     * Acid: $pH$ range of $0 - 6.9$.     * Base: $pH$ range of $7.1 - 14$.     * Neutral: $pH$ of $7$ (e.g., water).

• Cells: The basic structural and functional unit of life. All living things (excluding viruses) are comprised of cells.     * Organelles: Components include cell membrane, cell wall, nucleus, chloroplast, cytoplasm, ribosome, vacuole, and mitochondria.     * Cell Membrane: Composed of lipids and proteins; exhibits selective permeability (allowing small molecules like water and oxygen to pass while requiring active transport for large molecules like starch or protein).     * Cell Wall Note: ALL cells have a cell membrane. Plants, fungi, bacteria, and protists also have cell walls for protection. The animal kingdom is the only group that completely lacks cell walls.

• Classification:     * Evolutionary History: The primary basis for classification.     * Kingdoms: Large groups including fungi, bacteria, protists, animals, and plants.     * Species: A group able to successfully reproduce among its members.     * Scientific Name: Comprised of the Genus and species.

Human Body Systems and Homeostasis

• Organization Levels: Cells $\rightarrow$ Tissues $\rightarrow$ Organs (heart, lungs, kidney) $\rightarrow$ Organ Systems (digestive, nervous).

• Specialization/Differentiation: The process where cells develop specific roles because only certain genes in the nucleus are "turned on" or active.

• Digestive System: A one-way passage (mouth, stomach, intestines) that breaks down food mechanically and chemically. Movement is achieved via peristalsis (muscular contractions). Undigested food is eliminated as solid waste (not the same as excretion).

• Circulatory/Transport System: Moves nutrients, water, hormones, and wastes.     * Red Blood Cells: Transport oxygen.     * White Blood Cells: Fight disease.     * Plasma: Fluid portion of blood transporting non-oxygen substances.     * Platelets: Responsible for blood clotting.

• Immune System: Shields the body from pathogens (viruses, bacteria, parasites).     * Antigens: Substances that trigger an immune response.     * Antibodies: Proteins made by white blood cells that attack specific antigens based on shape.     * Vaccines: Injections of dead or weakened pathogens to stimulate antibody production. They are preventative, not cures.     * Antibiotics: Drugs used to stop bacterial infections; ineffective against viruses.     * Blood Types: Type $O$ is the universal donor; Type $AB$ is the universal acceptor.

• Respiratory System: Provides oxygen for chemical respiration and removes $CO_2$.     * Diaphragm: The primary muscle for breathing.     * Breathing Rate: Controlled by the build-up of $CO_2$ in the blood.     * Alveoli: Microscopic sacs surrounded by capillaries where gas exchange occurs.

• Excretory System: Removes metabolic wastes including salt, water, urea, and $CO_2$.     * Lungs: Excrete $CO_2$ and water.     * Skin: Excretes sweat.     * Kidneys: Filter waste from blood and reabsorb nutrients.     * Liver: Filters toxins and dead red blood cells.

• Skeletal/Muscle System: Bones, marrow, cartilage, tendons, and ligaments. Muscles only pull and must function in pairs.

• Nervous System: Regulates the body via the brain (cerebrum, cerebellum, medulla) and spinal cord (reflexes).

• Endocrine System: Uses hormones for regulation; effects are slower but longer-lasting than the nervous system.     * Pancreas: Produces insulin and glucagon for blood sugar control.     * Adrenal Glands: Produce adrenaline under stress.     * Sex Hormones: Testosterone (male), Estrogen and Progesterone (female).     * Negative Feedback: The mechanism that controls hormone levels.

Reproduction and Genetics

• Asexual Reproduction: Fast and easy, but results in no genetic variety; offspring are clones.

• Sexual Reproduction: Provides genetic variety, but requires more time, effort, and risk.

• Mitosis: Asexual process involving one division resulting in two identical, diploid ($2n$) cells. Used for growth and healing in large organisms.

• Meiosis: Sexual process where one cell divides twice to create four different haploid ($n$) cells (gametes). This separates homologous pairs so offspring receive one chromosome of each pair from each parent.

• Fertilization: Occurs in the fallopian tube. The resulting cell is a zygote ($2n$).

• Development: Occurs in the uterus. Initial cell division without growth is called cleavage. Differentiation follows, creating vulnerable embryos.

• Genetics Principles:     * Chromosomes: Humans have $46$ chromosomes ($23$ pairs).     * Genes: Each gene codes for a specific protein ($1 \text{ gene} = 1 \text{ protein}$).     * DNA: Made of bases Adenine, Thymine, Cytosine, and Guanine ($ATCG$). Base pairs are $A-T$ and $C-G$.     * RNA: Uses Uracil instead of Thymine ($A-U$, $C-G$). It carries the genetic code to ribosomes for protein synthesis.     * Mutations: Changes in DNA. They can only be passed to offspring if they occur in reproductive cells (sperm or egg).

• Genetic Technology:     * Selective Breeding: Choosing parents for desired traits.     * Genetic Engineering/Gene Splicing: Inserting genes from one organism into another. Example: Human insulin genes inserted into bacteria to produce medicine for diabetics.     * Karyotyping and DNA Fingerprinting: Used to diagnose and treat genetic diseases.

Evolution and Ecology

• Evolution: The theory that modern species evolved from earlier species and share common ancestors.

• Natural Selection (Darwin): Mechanism involving overproduction, competition, and survival of the "fit" (those adapted to reproduce).     * Fitness: Does not necessarily mean physical strength.     * Variations: Must exist via sexual reproduction or mutation before environmental changes occur.

• Speciation: Usually requires geographic isolation leading to reproductive isolation.

• Ecology Concepts:     * Energy Flow: Sun $\rightarrow$ Producers (Autotrophs) $\rightarrow$ Consumers (Heterotrophs). Most energy is lost as heat at each trophic level.     * Carrying Capacity: The maximum population size an ecosystem can support based on limiting factors (food, water, etc.).     * Niche: An organism's role. Competition usually prevents two species from occupying the same niche simultaneously.     * Ecological Succession: The process of change in the species structure of an ecological community over time.

• Human Impact:     * Primary Cause: Increasing human population.     * Biodiversity: Variety of life; high diversity leads to stable ecosystems. Loss of biodiversity reduces resources for food and medicine.     * Ecological Problems: Acid rain, habitat loss (deforestation), global warming, ozone layer depletion, and introduced (invasive) species.     * Solutions: Recycling, conservation, using solar power, biological controls (instead of pesticides), and crop rotation.