Biology STAAR Review

Gideon’s Facts for the EOC

I. Endotherms and Ectotherms

  • Endotherms: Organisms that create their own heat; commonly referred to as warm-blooded.

  • Ectotherms: Organisms that use their environment to regulate body temperature; referred to as cold-blooded.

II. Tropisms

  • A. Thigmotropism: Movement of an organism in response to touch stimuli.

  • B. Phototropism: Movement of an organism in response to light stimuli.

  • C. Gravitropism: Movement of an organism in response to gravity.

III. Plant Responses to Environmental Conditions

  • The epidermis of a plant will close in dry conditions to avoid losing water, which is crucial for water conservation.

IV. Dendrograms and Cladograms

  • A dendrogram is a type of cladogram, which is a branching diagram showcasing evolutionary relationships.

V. Biological Macromolecules

  • Important elements associated with various macromolecules:
      - CHO: Carbohydrates
      - CHO: Lipids
      - CHON: Proteins
      - CHONPS: Nucleic Acids

  • Constituent elements:
      - A. Carbon (C)
      - B. Hydrogen (H)
      - C. Oxygen (O)
      - D. Nitrogen (N)
      - E. Phosphorus (P)
      - F. Sulfur (S)

VI. Enzymes

  • Enzymes are proteins that facilitate biochemical reactions and typically end in the suffix -ase.

VII. Sugars

  • Sugars conventionally end in the suffix -ose.

VIII. Nitrogen Acquisition in Animals

  • Animals can acquire nitrogen necessary for various biological processes by consuming other organisms, integrating nitrogen into their own metabolic pathways.

IX. DNA Structure

  • The sides of the DNA “ladder” are constituted of the sugar deoxyribose, which is essential for the structural integrity of DNA.

X. Cell Walls

  • Cell walls in plants are primarily made of cellulose, a type of carbohydrate crucial for providing structure and rigidity to plant cells.

XI. Solutions and Cell Response

  • Definitions:
      - Solvent: The liquid component in which solutes are dissolved; water serves as the universal solvent.
      - Solute: The substance that is dissolved in the solvent.

  • Types of solutions:
      - A. Isotonic Solution: The cell is in an environment with the same solute concentration as the cytoplasm, resulting in equal movement of water in and out of the cell.
      - B. Hypertonic Solution: The environment has a higher solute concentration than the cell, causing the cell to shrink due to water loss.
      - C. Hypotonic Solution: The environment has a lower solute concentration than the cell, resulting in water influx that can lead to cell swelling and possible lysis.

XII. Mutations

  • A. Frameshift Mutations: Result from insertions or deletions that alter the reading frame of the genetic code, leading to extensive changes in the resulting protein.
      - 1. Insertion: Addition of one or more nitrogenous bases into the DNA sequence.
      - 2. Deletion: Removal of one or more nitrogenous bases from the DNA sequence.

  • B. Point Mutations: Changes in a single nitrogenous base.
      - 1. Substitution: One base is replaced by another.
      - 2. Translocation: A segment of DNA is moved to a new position.

XIII. Alleles

  • Alleles are different forms of a gene represented as one letter (e.g., R or r).

XIV. Dihybrid Cross - Punnett Square

  • A. Parental Allele Contribution: In a dihybrid cross, parents randomly provide one allele of each gene, a method often visualized using the FOIL (First, Outer, Inner, Last) Method:
      - Example: For a genotype of RrDd, the gametes produced are RD, Rd, rD, and rd.

XV. Karyotypes

  • A karyotype is an organized profile of an individual’s chromosomes with homologous chromosomes depicted together.

  • A. Homologous Chromosomes: Chromosomes that are generally similar in size and shape, except for the sex chromosomes (X and Y).

XVI. Cell Organelles

  • A. Lysosome: Known as the cell’s cleanup crew, responsible for digesting macromolecules and breaking down waste materials.

  • B. Golgi Apparatus: Functions as the post office of the cell, packaging and shipping proteins and lipids for transport.

  • C. Endoplasmic Reticulum (ER): Synthesizes proteins (Rough ER contains ribosomes) and lipids (Smooth ER lacks ribosomes).

  • D. Centrioles: Structures that assist in dividing animal cells and form spindle fibers during Mitosis and Meiosis.

XVII. Cellular Respiration

  • A. Glycolysis: The metabolic pathway that breaks down glucose to produce a small amount of ATP (specifically 2 ATP molecules).

  • B. Krebs Cycle (Citric Acid Cycle): Produces a small amount of ATP (also yielding 2 ATP molecules).

  • C. Electron Transport Chain: Generates the majority of ATP (32 ATP molecules) through oxidative phosphorylation:
      - 1. Oxidative Phosphorylation: Utilizes energy from electrons that move through the electron transport chain to create a proton gradient, which facilitates ATP synthesis.

XVIII. ATP Energy

  • ATP energy is released when ATP loses one of its phosphate groups, converting it to ADP (adenosine diphosphate).

XIX. Cell Cycle

  • A. Nondisjunction: Occurs during meiosis when homologous chromosomes fail to separate properly, which can result in gametes with abnormal chromosome numbers.

XX. Hypotheses and Variables

  • A. Hypothesis: An if-then statement that proposes a testable explanation for an observation.

  • B. Independent Variable: The variable modified by the experimenter in order to observe an effect in an experiment.

XXI. Structural Comparisons

  • A. Homologous Structures: Physical structures in different organisms that share a common ancestry.
      - 1. Example: Structures like the forelimbs of mammals that are different in function but similar in structure.

  • B. Analogous Structures: Structures in different organisms that serve similar functions but evolved independently from different origins.
      - 1. Note: The prefix Anolagous highlights their different ancestral backgrounds.

  • C. Vestigial Structures: Remnants of more developed structures from ancestors that are now reduced or entirely non-functional.
      - 1. Definition: “Vest” indicates uselessness; therefore, vestigial structures are considered functionless in the current organism's context.

XXII. Methods of Evolution

  • A. Divergent Evolution: The process by which one species evolves into two or more different species, leading to speciation.

  • B. Convergent Evolution: When two unrelated species independently evolve similar traits due to similar environmental pressures.

  • C. Coevolution: The concurrent evolution of two or more closely interacting species, where evolutionary changes in one species influence adaptations in another.

XXIII. Punctuated Equilibrium

  • The sudden appearance of new organisms in the fossil record is indicative of punctuated equilibrium, a concept that suggests rapid evolution can occur in response to environmental changes, leading to increased biodiversity.

XXIV. DNA and RNA Directionality

  • In both DNA and RNA, the direction of synthesis and reading is always from 5' to 3' end.

XXV. Viral Life Cycles

  • A. Lytic Cycle: A type of viral reproduction where the virus immediately takes over the host cell to produce new viral particles, leading to cell lysis and release of viruses.

  • B. Lysogenic Cycle: A viral cycle where the virus integrates its genetic material into the host cell's DNA, replicating along with the host's genome and possibly triggering lysis later.

XXVI. Mechanisms of Evolution

  • A. Natural Selection: The process where organisms better adapted to their environment survive and reproduce more successfully.

  • B. Mutation: Random genetic changes that can alter phenotypic traits, potentially resulting in beneficial adaptations (e.g., from bright green to brown coloration in a population).

  • C. Genetic Drift: Random fluctuations in allele frequencies within a small population.
      - 1. Bottleneck Effect: A severe reduction in population size leading to decreased genetic variability.
      - 2. Founder Effect: When a new colony is established by a small number of individuals, resulting in a subset of the original population's genetic traits dominating.

  • D. Gene Flow: The transfer of alleles between populations, which can happen through migration and lead to changes in allele frequencies.

  • E. Sex and Genetic Shuffling: Mechanisms such as sexual reproduction and crossing over during meiosis introduce genetic variability in populations, creating new combinations of genes each generation.

XXVII. Zygote Formation

  • A zygote is a fertilized egg that results from the union of male and female gametes, marking the beginning of a new organism's development.