Comprehensive Biology Regents Review Guide

Scientific Inquiry

● Observation: This involves gathering information using the senses (sight, smell, touch, taste, hearing) or specialized tools. ● Inference: This is a conclusion or logical interpretation based on the observations made. ● Hypothesis: A testable prediction that serves as a starting point for an investigation. It is usually formatted as an "If _____, then _____" statement. ● Variables: ● Independent Variable: The factor that is purposely changed or manipulated by the researcher. This is plotted on the $x$ -axis of a graph. ● Dependent Variable: The factor that is measured or observed to see how it responds to the independent variable. This is plotted on the $y$ -axis of a graph. ● Control Group: The group in an experiment that is kept under normal conditions and does not receive the experimental treatment; used as a benchmark for comparison. ● Experimental Group: The group in an experiment that receives the specific treatment or variable being tested. ● Characteristics of Good Experiments: ● Inclusion of a large sample size. ● Performance of repeated trials to ensure reliability. ● Testing of only one variable at a time. ● Utilization of accurate measurements. ● Subjecting results to being peer reviewed.

Characteristics of Life

All living things exhibit the following traits: ● They are made of cells. ● They reproduce to create offspring. ● They grow and develop over the course of their lives. ● They obtain and use energy. ● They respond to stimuli in their environment. ● They maintain homeostasis. ● They possess DNA as their genetic material. ● They evolve over time as a population.

Homeostasis

● Definition: The process of maintaining stable internal conditions despite changes in the external environment. ● Examples of Homeostatic Mechanisms: ● Sweating when the body temperature is too hot. ● Shivering when the body temperature is too cold. ● Blood sugar regulation to maintain energy levels.

Cell Theory

All living things are composed of one or more cells.
Cells are the basic unit of life, performing the essential functions of living organisms.
All cells come from pre-existing cells through cell division.

Cell Organelles and Functions

● Nucleus: Contains the cell's DNA and acts as the control center.

● Cell Membrane: Controls the movement of substances into and out of the cell.
● Cytoplasm: The jelly-like fluid that serves as the site for many chemical reactions within the cell. ● Ribosome: The site where proteins are made.

● Mitochondria: The "powerhouse" of the cell that produces energy in the form of $ATP$ .

● Chloroplast: Found in plant cells; the site of photosynthesis where light energy is converted into food.

● Vacuole: Used for the storage of water, nutrients, or waste products.

● Cell Wall: Provides structural support and protection; found in plants only.

Plant vs. Animal Cells

● Plant Cells: ● Possess a cell wall. ● Possess chloroplasts. ● Feature a single, large central vacuole. ● Animal Cells: ● Have no cell wall. ● Have no chloroplasts. ● Typically have smaller, multiple vacuoles.

Transport Across Membranes

● Diffusion: The passive movement of molecules from an area of high concentration to an area of low concentration.
● Osmosis: The specific diffusion of water molecules across a selectively permeable membrane.

● Active Transport: The movement of molecules from an area of low concentration to an area of high concentration. This process requires energy in the form of $ATP$ .

Photosynthesis

● Process: Plants use light energy to convert carbon dioxide and water into glucose and oxygen. ● Formula: $6CO_2 + 6H_2O + \text{Light} \rightarrow C_6H_{12}O_6 + 6O_2$ ● Location: Occurs within the chloroplasts. ● Reactants: Carbon dioxide, water, and sunlight. ● Products: Glucose and oxygen. ● Classification: Plants are producers, also known as autotrophs, because they make their own food.

Cellular Respiration

● Process: The process of breaking down food (glucose) to release energy ( $ATP$ ). ● Formula: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + ATP$ ● Location: Occurs mainly in the mitochondria. ● Purpose: To release stored energy from food for cellular use.

Comparison: Photosynthesis vs. Respiration

● Photosynthesis: ● Function: Stores energy. ● Location: Chloroplast. ● Glucose: Makes glucose. ● Respiration: ● Function: Releases energy. ● Location: Mitochondria. ● Glucose: Breaks down glucose.

DNA and Genetics

● DNA Structure: A double helix shape containing genetic information. ● DNA Base Pairing Rules: ● Adenine ( $A$ ) always pairs with Thymine ( $T$ ) ( $A \leftrightarrow T$ ). ● Cytosine ( $C$ ) always pairs with Guanine ( $G$ ) ( $C \leftrightarrow G$ ). ● Gene: A specific segment of DNA that codes for a particular trait. ● Chromosome: A structure made of coiled DNA.

Protein Synthesis

● Transcription: The process where $DNA$ is used as a template to create $mRNA$ ( $DNA \rightarrow mRNA$ ). ● Translation: The process where the $mRNA$ sequence is read to build a $Protein$ ( $mRNA \rightarrow \text{Protein}$ ). ● RNA Base Pairing Rules: ● Adenine ( $A$ ) pairs with Uracil ( $U$ ) ( $A \rightarrow U$ ). ● Thymine ( $T$ ) pairs with Adenine ( $A$ ) ( $T \rightarrow A$ ). ● Cytosine ( $C$ ) pairs with Guanine ( $G$ ) ( $C \rightarrow G$ ). ● Guanine ( $G$ ) pairs with Cytosine ( $C$ ) ( $G \rightarrow C$ ).

Mitosis

● Purpose: Growth, tissue repair, and asexual reproduction. ● Results: Two identical diploid cells. ● Stages (PMAT): ● Prophase ● Metaphase ● Anaphase ● Telophase

Meiosis

● Purpose: To produce gametes (sperm and egg cells) for sexual reproduction. ● Results: Four genetically different haploid cells.

Comparison: Mitosis vs. Meiosis

● Mitosis: ● Number of daughter cells: $2$ ● Genetic composition: Identical cells. ● Function: Growth. ● Chromosome count: Diploid. ● Meiosis: ● Number of daughter cells: $4$ ● Genetic composition: Different cells. ● Function: Reproduction. ● Chromosome count: Haploid.

Genetics Concepts

● Dominant: Represented by a capital letter (e.g., $A$ ); masks the recessive trait. ● Recessive: Represented by a lowercase letter (e.g., $a$ ); only expressed if no dominant allele is present. ● Genotype: The genetic makeup or allele combination of an organism. ● Examples: $AA$ (Homozygous Dominant), $Aa$ (Heterozygous), $aa$ (Homozygous Recessive). ● Phenotype: The physical appearance or observable traits of an organism.

Punnett Square Example ( $Aa \times Aa$ )

	A	a
A	AA	Aa
a	Aa	aa

● Genotype Ratio: $1\,AA : 2\,Aa : 1\,aa$ ● Phenotype Ratio: $3$ dominant traits : $1$ recessive trait

Evolution

● Natural Selection: The survival and reproduction of organisms with traits beneficial to their environment. ● Requirements for Natural Selection: ● Variation within the population. ● Competition for limited resources. ● Inheritance of traits from parents to offspring. ● Survival advantage (differential survival). ● Evidence for Evolution: ● Fossils (remains of past life). ● DNA similarities between different species. ● Embryology (similarities in early development). ● Comparative anatomy (similar body structures). ● Key Principle: Species with more genetic variation are better equipped to survive environmental changes.

Ecology

Ecology is a major topic on the Regents exam. ● Levels of Organization: $\text{Organism} \rightarrow \text{Population} \rightarrow \text{Community} \rightarrow \text{Ecosystem} \rightarrow \text{Biosphere}$ ● Biotic Factors: Living components of an ecosystem. ● Abiotic Factors: Nonliving components of an ecosystem. ● Examples include: Water, Temperature, and Sunlight.

Food Chains and Energy Flow

● Food Chain Example: $\text{Grass} \rightarrow \text{Rabbit} \rightarrow \text{Fox}$ ● Trophic Roles: ● Producer: An organism that makes its own food. ● Consumer: An organism that eats other organisms. ● Decomposer: An organism that breaks down dead organic matter. ● Examples: Bacteria, Fungi. ● Energy Pyramid Rule: Only approximately $10\%$ of energy is passed from one trophic level to the next. The remaining majority of energy is lost to the environment as heat.

Ecosystem Relationships

● Predator: An organism that hunts another for food. ● Prey: An organism that is hunted by a predator. ● Competition: Occurs when organisms fight for limited resources. ● Symbiosis: ● Mutualism: A relationship where both organisms benefit. ● Commensalism: A relationship where one organism benefits and the other is unaffected. ● Parasitism: A relationship where one organism benefits (parasite) and the other is harmed (host).

Human Impact and Biodiversity

● Key Impacts to Know: ● Pollution of the environment. ● Climate change. ● Habitat destruction. ● Introduction of invasive species. ● Biodiversity loss. ● Biodiversity: The variety of life in a particular habitat or ecosystem. ● Greater biodiversity results in more ecosystem stability and better chances for survival.

Virus Basics

● Viruses are not considered living organisms. ● They require host cells to reproduce. ● They contain genetic material in the form of DNA or RNA.

Regents Test-Day Tips

✅ Read every graph carefully. ✅ Pay close attention to units and labels on diagrams. ✅ Eliminate clearly wrong answers first to improve your odds. ✅ Extract information directly from provided diagrams. ✅ Know your vocabulary thoroughly. ✅ Practice using released exams available on the NYS Regents website.

Highest-Priority Topics to Study Tonight

Ecology
Genetics & Punnett Squares
Photosynthesis & Respiration
Mitosis vs. Meiosis
Cell Organelles
Central Dogma (DNA → RNA → Protein)
Experimental Design
Evolution & Natural Selection
Homeostasis
Graph/Data Analysis