Biology Terms and Definitions Overview

Cell Membrane

Made of phospholipids: hydrophilic heads ('water-loving') and hydrophobic tails ('water-hating'). Semi-permeable: allows small, uncharged molecules to pass; restricts large, charged ones.

Passive Transport

Movement of molecules without energy: includes diffusion and facilitated diffusion.

Active Transport

Requires energy (ATP); moves substances against the concentration gradient.

Osmosis

Movement of water across a membrane. Cells shrink in hypertonic and swell in hypotonic solutions.

Photosynthesis

Converts light energy into chemical energy (glucose); occurs in chloroplasts. Chlorophyll absorbs light; green light is least effective.

Cellular Respiration

Converts glucose + O₂ into CO₂ + H₂O + 36 ATP. Includes Glycolysis, Krebs Cycle, and ETC in mitochondria.

Aerobic Respiration

Occurs with oxygen; produces more ATP.

Anaerobic Respiration

Occurs without oxygen; produces less ATP; in humans → lactic acid.

Energy Flow (Ecology)

Energy moves from producers → primary → secondary → tertiary consumers. Only 10% of energy is transferred at each level.

Food Chains/Webs

Food webs are interconnected chains; decomposers are essential but often left out.

Mutualism

A symbiotic relationship where both organisms benefit.

Parasitism

A symbiotic relationship where one benefits and the other is harmed.

Commensalism

A symbiotic relationship where one benefits, the other is unaffected.

Central Dogma

Flow of genetic information: DNA → RNA → Protein.

DNA vs RNA

DNA: double-stranded, thymine, deoxyribose, nucleus. RNA: single-stranded, uracil, ribose, both nucleus and cytoplasm.

Transcription

DNA is transcribed into mRNA in the nucleus.

Translation

mRNA is translated into an amino acid sequence (protein) at the ribosome.

Mutations

Changes in DNA that can alter protein structure and function.

Punnett Squares

Tool to predict genetic outcomes; includes dominant/recessive, sex-linked, codominance, blood types.

Pedigrees

Charts used to determine inheritance patterns and genotypes.

Asexual Reproduction

Produces genetically identical offspring.

Sexual Reproduction

Increases genetic variation through combination of gametes.

Mitosis

Cell division for growth/repair; creates 2 identical cells.

Meiosis

Produces 4 unique haploid gametes for sexual reproduction.

Homologous Chromosomes

Chromosome pairs, one from each parent, that pair during meiosis.

Evolution

Genetic change in populations over time.

Natural Selection

Process where better-adapted organisms reproduce more successfully.

Adaptations

Traits that enhance survival and reproduction in specific environments.

Scientific Method

Includes hypothesis, variables, controls, and conclusions.

Independent Variable

The factor being tested or changed in an experiment.

Dependent Variable

The factor being measured or observed in response.

Controls

Constants in an experiment that ensure valid results.

Performance Task Review

Practice skills like transcription/translation, Punnett squares, pedigrees, mitosis/meiosis, experimental analysis, food webs.

Tips for Success

Study diagrams, review vocabulary, use mnemonics (e.g., IPMAT), practice experiment analysis.

DNA → RNA → Protein Practice

Transcribe DNA, predict amino acid sequence, assess mutation impacts on proteins.

Genetics Practice

Solve problems involving Punnett squares, sex-linked inheritance, blood types.

Pedigree Practice

Identify genotypes and predict affected offspring probabilities.

Mitosis vs Meiosis Practice

Identify stages in diagrams, explain outcomes and purposes of both processes.

Cell Cycle Practice

Understand interphase, mitosis, and how cancer relates to cell cycle errors.

Photosynthesis & Respiration Experiments

Use indicators like BTB to analyze plant gas exchange and metabolic activity.

Ecosystem Analysis

Identify roles in a food web, predict outcomes of disruptions, and describe energy/chemical flow.