Biology Spring Final Exam Review Answers

Biology Spring Final Exam Review Answers: A Comprehensive Guide

This comprehensive guide provides answers and explanations for common topics covered in a high school biology spring final exam. Remember, this is a general review and may not cover every specific question on your exam. Always consult your textbook, notes, and teacher's materials for the most accurate and relevant information.

Unit 1: The Chemistry of Life

1.1 Water and its Properties:

• Key Concepts: Polarity, hydrogen bonding, cohesion, adhesion, high specific heat, universal solvent.
• Review Questions & Answers:
  • Q: Explain why water is a polar molecule. A: Water (H₂O) is polar because the oxygen atom is more electronegative than the hydrogen atoms, creating a partial negative charge on the oxygen and partial positive charges on the hydrogens. This unequal distribution of charge creates a dipole moment.
  • Q: How do hydrogen bonds affect water's properties? A: Hydrogen bonds between water molecules contribute to water's high specific heat (resistance to temperature changes), high heat of vaporization (requires significant energy to change from liquid to gas), cohesion (water molecules sticking to each other), and adhesion (water molecules sticking to other substances). These properties are crucial for life.
  • Q: Why is water considered the "universal solvent"? A: Water's polarity allows it to dissolve many ionic and polar substances, making it an excellent solvent for many biological molecules.

1.2 Organic Molecules:

• Key Concepts: Carbohydrates, lipids, proteins, nucleic acids; monomers and polymers; dehydration synthesis and hydrolysis.
• Review Questions & Answers:
  • Q: What are the four major classes of organic molecules? A: Carbohydrates, lipids, proteins, and nucleic acids.
  • Q: Describe the process of dehydration synthesis. A: Dehydration synthesis is the process by which monomers are joined together to form polymers, with a water molecule being removed for each bond formed.
  • Q: What is the function of enzymes? A: Enzymes are proteins that act as biological catalysts, speeding up chemical reactions in living organisms. They do this by lowering the activation energy required for a reaction.
  • Q: What are the building blocks of proteins? A: Amino acids. There are 20 different amino acids that can be combined in various sequences to form a vast array of proteins.

Unit 2: Cell Biology

2.1 Cell Structure and Function:

• Key Concepts: Prokaryotic vs. eukaryotic cells; organelles (function and structure); cell membrane structure and function; cell transport (passive and active).
• Review Questions & Answers:
  • Q: What are the key differences between prokaryotic and eukaryotic cells? A: Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have a nucleus and membrane-bound organelles. Prokaryotes are generally smaller and simpler than eukaryotes.
  • Q: Describe the structure and function of the mitochondria. A: Mitochondria are the "powerhouses" of the cell, responsible for cellular respiration, the process of generating ATP (energy) from glucose. They have a double membrane structure, with the inner membrane folded into cristae to increase surface area.
  • Q: Explain the difference between passive and active transport. A: Passive transport moves substances across the cell membrane without requiring energy (e.g., diffusion, osmosis), while active transport requires energy (ATP) to move substances against their concentration gradient (e.g., sodium-potassium pump).
  • Q: What is the role of the cell membrane in maintaining homeostasis? A: The cell membrane acts as a selectively permeable barrier, regulating the passage of substances into and out of the cell to maintain a stable internal environment.

2.2 Cell Communication and Signaling:

• Key Concepts: Receptor proteins; signal transduction pathways; cell-to-cell communication.
• Review Questions & Answers:
  • Q: Explain how signal transduction pathways work. A: Signal transduction pathways involve a series of steps that relay a signal from the cell's exterior to its interior. A signal molecule binds to a receptor protein, triggering a cascade of events that ultimately lead to a cellular response.
  • Q: What are some examples of cell-to-cell communication methods? A: Examples include direct contact (gap junctions), local signaling (paracrine signaling), and long-distance signaling (endocrine signaling using hormones).

Unit 3: Cellular Energetics

3.1 Photosynthesis:

• Key Concepts: Light-dependent reactions; light-independent reactions (Calvin cycle); factors affecting photosynthesis.
• Review Questions & Answers:
  • Q: What are the products of the light-dependent reactions? A: ATP and NADPH.
  • Q: What is the role of chlorophyll in photosynthesis? A: Chlorophyll is a pigment that absorbs light energy, which is then used to power the light-dependent reactions of photosynthesis.
  • Q: Explain the Calvin cycle. A: The Calvin cycle is a series of reactions that use ATP and NADPH (from the light-dependent reactions) to convert carbon dioxide into glucose.

3.2 Cellular Respiration:

• Key Concepts: Glycolysis; Krebs cycle; electron transport chain; ATP production; anaerobic respiration (fermentation).
• Review Questions & Answers:
  • Q: What are the main stages of cellular respiration? A: Glycolysis, the Krebs cycle (citric acid cycle), and the electron transport chain.
  • Q: Where does glycolysis take place? A: In the cytoplasm.
  • Q: What is the net ATP production from cellular respiration? A: Approximately 36-38 ATP molecules per glucose molecule.
  • Q: What are the products of fermentation? A: Lactic acid (in animals) or ethanol and carbon dioxide (in yeast).

Unit 4: Genetics

4.1 Mendelian Genetics:

• Key Concepts: Genes, alleles; dominant and recessive alleles; genotype and phenotype; homozygous and heterozygous; Punnett squares; monohybrid and dihybrid crosses.
• Review Questions & Answers:
  • Q: Explain Mendel's Law of Segregation. A: Mendel's Law of Segregation states that during gamete formation, the two alleles for each gene separate, so each gamete receives only one allele.
  • Q: What is a Punnett square used for? A: A Punnett square is a diagram used to predict the genotypes and phenotypes of offspring from a genetic cross.
  • Q: Explain the difference between genotype and phenotype. A: Genotype refers to the genetic makeup of an organism (e.g., homozygous dominant, heterozygous), while phenotype refers to the observable traits of an organism (e.g., tall, short).

4.2 Molecular Genetics:

• Key Concepts: DNA structure; DNA replication; transcription; translation; genetic code; mutations.
• Review Questions & Answers:
  • Q: Describe the structure of DNA. A: DNA is a double helix made up of two strands of nucleotides. Each nucleotide consists of a deoxyribose sugar, a phosphate group, and one of four nitrogenous bases (adenine, guanine, cytosine, and thymine).
  • Q: What is the central dogma of molecular biology? A: The central dogma describes the flow of genetic information: DNA → RNA → protein.
  • Q: Explain the process of transcription. A: Transcription is the process by which the genetic information in DNA is copied into mRNA (messenger RNA).
  • Q: What is the role of tRNA in translation? A: Transfer RNA (tRNA) molecules carry amino acids to the ribosome during translation, where they are added to the growing polypeptide chain according to the mRNA sequence.

4.3 Genetic Technologies:

• Key Concepts: PCR; gel electrophoresis; gene cloning; genetic engineering; biotechnology applications.
• Review Questions & Answers:
  • Q: What is the purpose of PCR (polymerase chain reaction)? A: PCR is a technique used to amplify (make many copies of) a specific DNA sequence.
  • Q: How does gel electrophoresis separate DNA fragments? A: Gel electrophoresis separates DNA fragments based on their size and charge. Smaller fragments move faster through the gel than larger fragments.

Unit 5: Evolution and Ecology

5.1 Evolution:

• Key Concepts: Natural selection; adaptation; speciation; evidence for evolution; phylogenetic trees.
• Review Questions & Answers:
  • Q: Explain Darwin's theory of natural selection. A: Darwin's theory of natural selection states that organisms with traits better suited to their environment are more likely to survive and reproduce, passing on those advantageous traits to their offspring. This leads to changes in the genetic makeup of populations over time.
  • Q: What is speciation? A: Speciation is the formation of new and distinct species in the course of evolution.

5.2 Ecology:

• Key Concepts: Biotic and abiotic factors; population dynamics; community interactions; ecosystems; biomes; conservation biology.
• Review Questions & Answers:
  • Q: Define the term "ecosystem". A: An ecosystem is a community of living organisms (biotic factors) in conjunction with the nonliving components of their environment (abiotic factors), interacting as a system.
  • Q: Describe the different types of community interactions. A: Community interactions include predation, competition, parasitism, mutualism, and commensalism.
  • Q: What are some threats to biodiversity? A: Threats to biodiversity include habitat loss, climate change, pollution, invasive species, and overexploitation of resources.

This comprehensive review covers many key concepts in high school biology. Remember to consult your specific course materials and review any areas where you feel less confident. Good luck on your final exam!