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Bio 4 Themes:

Here's a breakdown of the four Big Ideas in AP Biology with a focus on the key concepts highlighted in the document:

Big Idea 1: Evolution Drives the Diversity and Unity of Life

• Evolutionary Mechanisms

• Genetic Variation

• Speciation and Extinction

• Common Ancestry and Phylogenetics

• Origin of Life

Big Idea 2: Biological Systems Utilize Free Energy and Molecular Building Blocks to Grow, Reproduce, and Maintain Dynamic Homeostasis

- Energy Capture and Utilization

- Autotrophic cells using photosynthesis and chemosynthesis to capture free energy.

- Cellular respiration and fermentation as processes for harvesting free energy from sugars.

- Interdependence of photosynthesis and respiration.

- Matter Exchange and Homeostasis

- Exchange of matter with the environment (e.g., water, carbon, oxygen).

- Role of surface-to-volume ratios in resource acquisition and waste elimination.

- Apoptosis in development and differentiation.

- Membrane Function and Selective Permeability

- Cell membranes maintaining internal environments distinct from external surroundings.

- Mechanisms of osmosis, diffusion, and active transport in maintaining homeostasis.

- Compartmentalization in eukaryotic cells for optimal chemical reactions.

- Feedback Mechanisms

- Negative and positive feedback loops in maintaining internal balance.

- Impact of environmental changes on biological responses and resource acquisition.

- Evolution of defense mechanisms against homeostasis disruptions.

- Coordination of Biological Events

- Regulation of developmental, physiological, and behavioral events.

- Role of timing and coordination in increasing fitness and survival.

### Big Idea 3: Living Systems Store, Retrieve, Transmit, and Respond to Information Essential to Life Processes

- Genetic Information and Continuity

- DNA replication ensuring high fidelity transmission of genetic information.

- Role of mutations and errors in introducing heritable variation.

- Impact of nucleotide sequence changes on protein structure and function.

- Gene Expression and Regulation

- Transcription and translation processes controlling cellular metabolism and phenotypes.

- Environmental and developmental signals modulating gene expression.

- Cell signaling pathways influencing gene expression and protein activity.

- Inheritance and Reproduction

- Mitosis and meiosis as mechanisms for genetic continuity and variation.

- Mendelian and non-Mendelian inheritance patterns.

- Ethical and social implications of understanding human genetics.

- Genetic Variation and Evolution

- Importance of genetic variation for species survival and evolution.

- Mechanisms introducing variation in sexually and asexually reproducing organisms.

- Horizontal gene transfer in bacteria and viruses contributing to genetic diversity.

- Information Processing and Behavior

- Role of sensory organs and nervous systems in processing external information.

- Behavioral responses increasing fitness and survival at the individual and population levels.

### Big Idea 4: Biological Systems Interact, and These Systems and Their Interactions Possess Complex Properties

- Systems Interactions and Emergent Properties

- Complex interactions at molecular, cellular, and ecosystem levels.

- Emergent properties resulting from interactions among system components.

- Robustness and flexibility of complex biological systems in responding to environmental changes.

- Molecular and Cellular Interactions

- Influence of molecular subcomponents on polymer properties.

- Coordination among organelles in maintaining cell function and growth.

- Specialization and differentiation driven by gene expression and external stimuli.

- Organismal Interactions

- Coordination among organs and systems ensuring organismal survival.

- Effects of environmental changes on organ responses and overall organism health.

- Ecosystem Dynamics

- Community structure changes in response to environmental conditions.

- Species interactions driving the movement of matter and energy in ecosystems.

- Competition, Cooperation, and Flexibility

- Competition and cooperation among cells and organisms influencing system efficiency.

- Coordination of organs and systems for effective resource use.

- Genetic variation providing flexibility for populations to adapt to environmental changes.

Experimental Design

• Hypothesis

  • Does light color affect plant growth?

• Null hypothesis:

  • Hypothesis that there is NO significant effect, difference, or trend (opposite of the alternative hypothesis)

    • i.e. Light color does not affect plant growth

• Alternative hypothesis:

  • Hypothesis that there is a SIGNIFICANT effect, difference, or trend

    • i.e. Light color does affect plant growth

• Variables

• Independent/Manipulated

  • The actual thing being changed and tested during the experiment

    • i.e. Light color

• Dependent/Responsive

  • The response to the independent variable; What will be measured to determine the effect of the independent variable

    • i.e. plant growth

• *Control

  • `Held constant through the experiment so they do not affect the outcome

    • i.e. Type of plant, amount of water, type of soil, temperature, light intensity, etc. kept the same

• Groups

  • Experimental- Receives the independent variable to test it

  • Control- Group that does not receive the independent variable in order to be able to compare the results of the experimental group

    • Positive: expect a result

      • i.e. normal full spectrum sunlight

    • Negative: expect no result—receive no treatment

      • i.e. No light

• Graphing- DRY MIX

  • Dependent, Manipulated, Responding, Independent

• Scatterplots

  • Qualitative data not manipulated variable or multiple trials

  • Typically include a trend line

• Line

  • To show change in the dependent variable over time or some continuum

• Box and Whisker

  • Compare variability of 2+ sets of data

• Interpreting Results

  • Error bars

    • **Represent +/- 2SEM (Standard error of the mean)

    • If error bars overlap -> not a significant difference between the means

    • If error bars do not overlap -> significant difference between the means

• Writing a conclusion

  • Claim- statement that responds to the question that was investigated

  • Evidence- Provide data from your evidence to support your claim

  • Reasoning- Explain how your data supports your claim

Properties of Water 💧

• Causes of Water’s Properties:

  1. Polarity

  • Caused by the UNEQUAL sharing of electrons in a COVALENT bond between hydrogen/oxygen → unequal distribution of charge in molecules with 2 partial NEGATIVE charges on oxygen + partial POSITIVE charges on hydrogen

  • 2 Types of bonds:

    • Covalent: Sharing of electrons

    • Ionic: Transfer of electrons

  • Hydrogen Bonds:

    • A strong attractive force between POLAR molecules (polar ± ends attracted)

      • i.e. Oxygen + Hydrogen; Nitrogen + Hydrogen

• 

• Properties of Water:

  • Cohesion: Water molecules stick to EACH OTHER → transport of water up roots

  • Adhesion: Water molecules stick to OTHER POLAR surfaces → stick to sides of tubes etc.

  • High Surface Tension: Difficult to stretch/break the surface of water → insects can glide across water surface

  • High Specific Heat- Ability to stabilize temperatures b/c requires a large amount of heat stored/lost to change its temperature

    • Moderates Temperatures: absorbs heat from the warmer air and releases heat to cooler air

  • High Heat of Vaporization: Water must absorb a high quantity of heat to transform from a liquid to gaseous state → Evaporative cooling: Heat released from surface as water evaporates contributes to temperature stability

  • Universal Solvent: Dissolves other polar substances (can be ionic)

  • Water’s Density- Water reaches its greatest density at 4 degrees Celcius—enables ice to float on top of water since water’s solid form is less dense than liquid

pH Level 🧪

• Water as a Solvent:

  • Polar water molecules separate ionic compounds into their constituent ions

  • Does NOT dissolve nonpolar substances (fats, oil)

  • MUST be polar, can be ionic but doesn’t have to be to dissolve in water (i.e. sugar)

    I. Hydrophilic - “water-loving” POLAR molecules that dissolve in water; polar regions attract water molecules = easily broken apart

    II. Hydrophobic - “water-hating” nonpolar molecules that DO NOT dissolve in water b/c not attracted to polar regions of water molcules

• Ionization: The formation of ions (charged atoms) by polar molecules in a solvent (dissolves other substances)

  • In liquid water hydrogen (H+) atom often jumps from the oxygen (O) atom it is COVALENTLY bonded to the oxygen atom it is HYDROGEN bonded

• Acids and Bases:

  • Water serves as BOTH an acid & base

    • Water dissociates and produces Hydronium (H30+) and Hydroxide (OH-) ions

    • In pure water, the number of hydrogen (H+) ions equal the number of hydroxide (OH-) ions

      • Both very REACTIVE can drastically impact cells—must control their concentrations

  • Acids- PRODUCES/donates (H+) ions/protons when dissolved

    • Acidic when (H+) > (OH-)

  • Bases- ACEEPTS (H+) ions/protons

    • Basic when (H+) < (OH-)

  • pH scale- measures the acidity/concentration of (H+) ions in a substance ranging from (0-14); LOGARITHMIC

    

    • Lower the pH = MORE acidic/(H+) ions; pH of 7 = neutral; Below 7 = acidic; Above 7 = basic

    • Each pH unit represents 10x difference; Ex. pH 3 1000x as acidic as pH 6 (10³)

    • *pH = -log10[H+]; Ex. H+ concentration = 10^-7 -log[10^-7] = -(-7) = 7 OR positive # of the exponent

    • *[OH-] and [H+] have a PRODUCT of 1.0 x 10^-14M; find one given another by dividing 10^-14 by the given/subtracting exponents

    • *pOH - OPPOSITE of pH scale—lower = basic, 7 = neutral, higher = acidic

  • Living Organisms and pH

    • Organisms attempt to maintain neutral pH level b/c enzymes can be denatured in pH changes

    • Buffers: weak acids/bases that are (H+)/(OH-) ion ACCEPTORS; living cells produce buffers to absorb excess (H+)/(OH-) and maintain neutral pH level

    • Ex. (H2CO3)Carbonic Acid ←→ (HCO3-)Bicarbonate + (H+) moves Right when too BASIC/Left when too ACIDIC

Tricky Practice Problems:

1. What is the pOH of a solution with a pH of 2

   • 10^-14/10^-2 = 10^-12 -log[10^-12] = 12

     OR 14 - 2 = 12

2. A liquid with a pH of 4 is how many times more concentrated in H+ than a liquid with a pH of 6?

   • 6 - 4 = 2; 10² = 100

3. The [H+] of a juice is 0.00010 M, find the pH

   • Count zeroes after 1; 1.0 × 10^-4 = 4

4. The greater the pOH the SMALLER the concentration of:

   • OH- remember pH/pOH scales OPPOSITE higher the pH/pOH = lesser the concentration of respective substances

Statistics and Standard Deviation 📊

• • Standard Deviation (x1- mean)² + (x2-mean)²…etc

    

    • Standard Error of the Mean

    

  • Variance