Bio 30 Final practice

review

🧪 Biology Final Exam Review Guide

📘 PART ONE: GENERAL BIOLOGY, CELLS & EVOLUTION

1. Biology and Life

• Biology is the study of living things.

• Life includes organisms that show all 6 characteristics of living things.

2. 6 Characteristics of Life

1. Made of cells (unicellular or multicellular)

2. Uses energy (metabolism)

3. Responds to environment (stimuli)

4. Grows and develops

5. Reproduces (asexually or sexually)

6. Maintains homeostasis (internal balance)

3. Prokaryotic vs. Eukaryotic Cells

4. Cell Parts and Functions

• Nucleus: Holds DNA (eukaryotes only)

• Ribosomes: Make proteins

• Mitochondria: Make energy (ATP)

• Chloroplast: Photosynthesis (plants only)

• Cell membrane: Controls what enters/leaves

• Cell wall: Structure/support (plants/bacteria)

5. Cell Membrane Structure

• Phospholipid bilayer: Heads = water-loving, tails = water-fearing

• Has proteins for transport, cholesterol for flexibility

6. Cell Membrane Transport

🔹 Passive Transport (no energy):

• Diffusion: Movement from high to low concentration

• Osmosis: Water moving through a membrane

• Facilitated diffusion: Uses protein channels

🔸 Active Transport (needs energy):

• Moves substances against the concentration gradient (low → high)

• Example: sodium-potassium pump

7. Photosynthesis & Cellular Respiration

8. Chloroplast and Mitochondria Diagrams

Know how to draw and label:

• Chloroplast: thylakoids, grana, stroma

• Mitochondria: inner membrane, outer membrane, matrix, cristae

9. Evidence for Evolution

• Fossils

• Anatomical structures (homologous = similar structure, different function)

• DNA comparisons

• Embryology

10. Micro vs. Macroevolution

• Microevolution: Small changes in a population over time (e.g., antibiotic resistance)

• Macroevolution: Big changes leading to new species (speciation)

11. Patterns of Evolution

• Co-evolution: Two species evolve together (e.g., bees & flowers)

• Convergent: Different species evolve similar traits (e.g., sharks & dolphins)

• Divergent: One species splits into many (e.g., Darwin’s finches)

12. 3 Domains & 6 Kingdoms

Domains:

1. Bacteria – Prokaryotic, common bacteria

2. Archaea – Prokaryotic, extreme environments

3. Eukarya – Eukaryotic (animals, plants, fungi, protists)

Kingdoms:

1. Bacteria – Unicellular, no nucleus

2. Archaea – Unicellular, extreme environments

3. Protista – Mostly unicellular, mixed traits

4. Fungi – Decomposers, chitin cell walls

5. Plantae – Photosynthetic, cellulose cell walls

6. Animalia – Multicellular consumers, no cell wall

13. Classification Systems

• Limitations: Linnaean system is based on physical traits, not DNA

• Value: Helps organize and understand relationships between organisms

🧬 PART TWO: MOLECULAR BIOLOGY & GENETICS

1. DNA & RNA Structure

• DNA: Double helix, bases = A, T, C, G

• RNA: Single strand, bases = A, U, C, G

• Nucleotide = sugar + phosphate + base

2. Base Pairing Rules

• A pairs with T (in DNA), A with U (in RNA)

• C pairs with G

3. DNA Replication

• Happens before cell division

• DNA unzips (enzyme = helicase)

• New bases added by DNA polymerase

• Makes two identical copies

4. Protein Synthesis

Step 1: Transcription (in nucleus)

• DNA → mRNA
  Step 2: Translation (in ribosome)

• mRNA → protein (using codon chart to find amino acids)

5. Mutations

• Point mutation = change in one base

  • Silent, missense, or nonsense

• Frameshift = insertion or deletion that shifts the reading frame

6. Meiosis & Errors

• Meiosis = forms gametes (sperm/egg)

• Errors can cause:

  • Nondisjunction (e.g., Down syndrome)

  • Chromosomal abnormalities

7. Karyotypes

• Picture of chromosomes

• Can determine sex (XX or XY)

• Can show disorders (extra or missing chromosomes)

8. Genetics – Punnett Squares

• Monohybrid cross (1 trait)

• Dihybrid cross (2 traits)

• Sex-linked traits (e.g., colorblindness)

9. Pedigrees

• Diagrams of inheritance in families

• Squares = males, circles = females

• Shaded = affected, half-shaded = carrier

10. CRISPR Technology

✅ Pros: Can treat genetic diseases, improve crops, powerful research tool
❌ Cons: Off-target effects, unequal access, long-term risks
⚖ Ethics: Designer babies, germline editing, consent issues

Theme 1: Life (Characteristics and Organization of Life)

1. List and briefly explain three characteristics that define living organisms.

• Growth – Living things grow and develop.

• Reproduction – Living things can make more of their own kind.

• Response to Stimuli – Living things react to their environment.

Theme 2: Cellular Energy and Transport

2. Differentiate between passive and active transport. Give one example of each.

• Passive transport moves substances from high to low concentration without using energy. Example: Oxygen entering a cell.

• Active transport moves substances from low to high concentration using energy. Example: Sodium-potassium pump.

3. A plant cell is placed in a hypotonic solution. Explain what happens and how this relates to osmoregulation.

Water enters the plant cell, making it swell and become turgid, but it does not burst because of the cell wall. This helps the plant maintain water balance (osmoregulation) and stay upright.

4. Explain the role of ATP in cellular activities.

ATP provides energy for cell functions like movement, transport, and building molecules. It's called the “energy currency” because cells spend it to do work.

5. Compare and contrast photosynthesis and cellular respiration.

6. Explain how photosynthesis and respiration are interdependent.

Photosynthesis makes glucose and oxygen, which are used in cellular respiration. Respiration makes CO₂ and water, which are used in photosynthesis. This cycle keeps life going and supports the ecosystem.

7. Compare facilitated diffusion and active transport.

8. Explain how the electron transport chain (ETC) generates ATP.

In the mitochondria, the ETC uses electrons from glucose to pump H⁺ ions across the membrane. These ions flow back through ATP synthase, making lots of ATP. Oxygen is needed at the end to make water and keep the chain moving.

(Diagram not shown here, but mitochondrion should label: matrix (Krebs cycle), inner membrane (ETC), and outer membrane)

Theme 3: Evolution

9. Define natural selection and describe how it leads to evolution.

Natural selection is when organisms with traits better suited to their environment survive and reproduce. Over time, these traits become more common, leading to evolution.

10. How is antibiotic resistance in bacteria an example of natural selection?

Mutations cause some bacteria to survive antibiotics. These resistant bacteria reproduce, spreading the resistance gene. The population evolves to become more resistant.

11. Why is genetic variation important in evolution?

It provides differences in traits. Some may help survival and reproduction, leading to natural selection. Without variation, evolution would slow down or stop.

12. What evidence supports evolution?

1. Fossils – Show changes over time
2. Embryology – Similar embryos show shared ancestry
3. Anatomy – Homologous structures show common origin
4. Molecular Evidence – Similar DNA shows relationships

13. Why are DNA similarities more reliable than physical traits for classifying organisms?

DNA gives direct info about genetic relationships, while physical traits can be affected by environment.
Example: Whales look like fish but DNA shows they are mammals.

Theme 4: Classification

14. What is binomial nomenclature, and why is it useful in biology?

It’s a two-part naming system (Genus species) used to name organisms. It helps scientists clearly identify and communicate about species around the world.

15. How can a pedigree chart show the mode of inheritance?

If a disorder is seen mostly in males and females are carriers, it is likely X-linked recessive. The pattern of shaded shapes shows how the trait is passed.

Theme 4 (continued): Classification

1. Describe one difference between the domains Bacteria and Archaea.

• Bacteria have peptidoglycan in their cell walls; Archaea do not. Archaea often live in extreme environments.

2. Name the five (or six) commonly accepted kingdoms of life and give one example organism from each.

3. Compare the characteristics that differentiate the three domains of life.

4. A newly discovered single-celled organism lacks a nucleus but thrives in extreme acidic environments. Predict its domain and kingdom and justify your answer.

• Domain: Archaea

• Kingdom: Archaea

• Justification: It’s prokaryotic (no nucleus) and survives extreme conditions, traits typical of Archaea.

5. Describe the difference between a phylogenetic tree and a cladogram.

• Phylogenetic tree shows evolutionary time and relationships based on common ancestry and genetic distance.

• Cladogram shows shared traits and branching order but not time.

Theme 5: DNA Structure and Function

6. Describe the structure of a DNA molecule.

DNA is a double helix made of nucleotides, which include a sugar, phosphate, and nitrogen base. Base pairs (A-T and C-G) are held by hydrogen bonds.

7. How do base pairing rules contribute to DNA replication accuracy?

The base pairing rules (A with T, C with G) ensure that the new strand matches the original exactly, reducing errors during replication.

8. Differentiate between the functions of DNA and RNA in living organisms.

• DNA stores genetic information in the nucleus.

• RNA carries messages (mRNA), helps build proteins (tRNA and rRNA), and works in the cytoplasm.

• DNA stays in the nucleus to stay protected.

9. Explain the significance of complementary base pairing during DNA replication and transcription.

It ensures that each new strand or RNA copy is accurate, which is key for correct gene expression and inheritance.

10. Describe the roles of enzymes in DNA replication and protein synthesis.

11. How does the semi-conservative nature of DNA replication ensure genetic continuity?

Each new DNA molecule has one original strand and one new strand, helping preserve the exact genetic code each time the cell divides.

Theme 6: Gene Expression and Regulation

12. Outline the steps of transcription and translation.

• Transcription (in nucleus):

  1. DNA is unzipped.

  2. RNA polymerase makes mRNA using base pairing rules.

  3. mRNA leaves the nucleus.

• Translation (in cytoplasm at ribosome):

  1. mRNA attaches to ribosome.

  2. tRNA brings amino acids.

  3. Amino acids join to make a protein.

13. Explain how mutations in a DNA sequence can affect the structure and function of a protein. Give an example.

A point mutation (like changing A to G) can change an amino acid in a protein, possibly making it nonfunctional.
Example: Sickle cell anemia – a mutation changes the shape of red blood cells.

Theme 7: Mendelian and Non-Mendelian Genetics

14. Explain the difference between genotype and phenotype.

• Genotype = genetic makeup (e.g., Aa)

• Phenotype = physical trait (e.g., tall)
  Example: Aa (heterozygous) results in tall if tall is dominant.

15. Describe incomplete dominance and codominance with examples.

Genetics – Punnett Square Problems

1. Widow’s Peak (W) x Straight Hairline (w)

Cross: Ww × ww

• Genotypic ratio: 2 Ww : 2 ww (1:1)

• Phenotypic ratio: 2 widow’s peak : 2 straight hairline (1:1)

2. Incomplete Dominance – Red (RR) × White (WW)

F1 Generation:

• Genotype: 100% RW

• Phenotype: 100% pink

F2 Generation: RW × RW

• Genotypic ratio: 1 RR : 2 RW : 1 WW

• Phenotypic ratio: 1 red : 2 pink : 1 white

3. Codominance – Blood Type AB × O (IᴬIᴮ × ii)

• Genotypes: 2 Iᴬi, 2 Iᴮi

• Blood types: 2 type A, 2 type B (50% A, 50% B)

4. Sex-linked – XᴄY × XᶜXᶜ

• Daughters: 1 carrier, 1 color blind

• Sons: 1 normal, 1 color blind

• 50% sons affected

5. Multiple Alleles – Ccᶜʰ × cᶜʰcᶜʰ

• Genotypes: 2 Ccᶜʰ, 2 cᶜʰcᶜʰ

• Phenotypes: 2 full color, 2 chinchilla (1:1)

6. Dihybrid Cross (BbEe × BbEe)

• Phenotypic ratio:

  • 9 black

  • 3 brown

  • 3 yellow

  • 1 yellow (ee)
    Epistasis: ee blocks pigment, so dog is yellow no matter the B gene.

7. Pedigree Problem – X-linked Recessive

Most likely inheritance: X-linked recessive

• Affects only males

• Passed by carrier females

Cross: Carrier female (XᴄX) × Normal male (XY)

• Daughters: 1 carrier, 1 normal

• Sons: 1 normal, 1 color blind

• Probability of affected son: 50%

If autosomal recessive: Both males and females would be equally likely to show the trait.

Theme 8: Biotechnology

1. What is CRISPR-Cas9 and what is it used for?

CRISPR-Cas9 is a tool that scientists use to edit genes by cutting DNA at a specific spot.
Ethical concern: It could be misused to edit human embryos or change traits like intelligence or appearance.

Stages of Merosis

• Merosis involves 2 nuclear divisions. Meiosis I kII:

→ Meiosis I reduces the Chromosome number trom diploid to haploid

24 →> 23

→ Meiosis II seperates double Stranded Chromosomos into Chromdids

→ 4 haploid cells produced in the end

Meiosis I :Prophase I

• Nuclear membrant dissolves

• Centrioles move to the poles, spindle fibers tormeo

• Chromosomes Come togetter in homologous pair called detradi

• Synapsis and crussing Over oxcur

MetaPhase I

• Homoglous Chromosomes attacn to spindle fibers and line up clong the contoric plate

Anaphase 1

- Homoylous chromosomes move towerds the poles

• Chromosomes # is now reduced by half

Telophase 1

•Chromosomes rechpoles and nucler membrane fams

→ doughter cells are not identical

Prophase I

"no replication ol chromosomes belore prophese II

•nuclear membrane dissolves, spindle farms

Metaphase II

• Sister Chromatids align on ematoral Plate still attoned cet centromere

• no pairing of chromosomes

Anaphase II

-Chromatids are broken apart at centromere regions and move to opposite poles

opposite poles

Telophase II

• nuclear membrane reforms

• division of cytoplasim occous

- 4 haploid daughter. cells are produced