CAPE Biology U2 Summary/Revision Notes

CAPE Biology U2 Summary/Revision Notes (By Dinell Motilal)

This syllabus consists of three modules:

MODULE 1: Bioenergetics and Conservation

1. Photosynthesis and ATP Synthesis (Pg 2 – 23)

   • 1.1: Structure of Dicotyledonous Leaf, Palisade Cell, and Chloroplast in Photosynthesis

   • 1.2: Process of Photophosphorylation

   • 1.3: Calvin Cycle and Light Independent Fixation of Carbon Dioxide

   • 1.4: Limiting Factors in Photosynthesis

2. Cellular Respiration and ATP Synthesis (Pg 24 – 38)

3. Energy Flow and Nutrient Cycling (Pg 39 – 52)

4. Ecological Systems, Biodiversity, and Conservation (Pg 53 – 65)

MODULE 2: Biosystems Maintenance

1. The Uptake and Transport of Water and Minerals (Pg 66 – 74)

2. Transport in the Phloem (Pg 75 – 81)

3. The Circulatory System of Mammals (Pg 82 – 99)

4. Homeostasis and Hormonal Action (Pg 100 – 112)

5. The Kidney, Excretion and Osmoregulation (Pg 113 – 129)

6. Nervous Coordination (Pg 130 – 148)

MODULE 3: Applications of Biology

1. Health and Disease (Pg 149 – 161)

2. Immunology (Pg 162 – 182)

3. Social and Preventative Medicine (Pg 183 – 207)

4. Substance Abuse (Pg 208 – 219)

MODULE 1

1. PHOTOSYNTHESIS AND ATP SYNTHESIS

1.1: Structure of a Dicotyledonous Leaf, Palisade Cell, and Chloroplast in Photosynthesis

• Plants as Autotrophs: They produce their own food through photosynthesis, harnessing light energy.

• Leaf Structure:

  • Broad, Thin Lamina: Maximizes light interception while minimizing diffusion distance for gas exchange.

  • Midrib: Supports the leaf structure and contains vascular tissue.

  • Network of Veins: Transport water, nutrients, and sugars.

• Photosynthesis Definition:

  • The process where producers take in inorganic molecules to produce organic substances (e.g., carbohydrates).

• ATP Definition: Adenosine triphosphate, functioning as energy currency in all organisms. Contains a nitrogenous base (adenine), a ribose sugar, and three phosphate groups (Pi). Energy is released when phosphate bonds are broken.

1.2: Process of Photophosphorylation

• Overall Photosynthesis Equation:

  • $ext{CO}<em>2 + ext{H}</em>2 ext{O} <br>ightarrow ext{C}<em>6 ext{H}</em>{12} ext{O}<em>6 + ext{O}</em>2$

• Chloroplast Functionality:

  • Chloroplasts contain chlorophyll, which captures light energy. Light is absorbed, splitting water molecules, generating ATP, and reducing NADP.

• Light-dependent and Independent Stages:

  • Light-dependent: Occurs in thylakoids, converting light energy into ATP and NADPH.

  • Light-independent (Calvin Cycle): Uses ATP and NADPH to fix carbon dioxide.

1.3: Calvin Cycle and Light Independent Fixation of Carbon Dioxide

• Calvin Cycle Steps:

  1. Carbon dioxide fixation: CO2 combines with ribulose bisphosphate (RuBP), catalyzed by RUBISCO, producing phosphoglyceric acid (PGA).

  2. Reduction: ATP and NADPH convert PGA into triose phosphate (TP).

  3. Regeneration: Some TP is recycled to regenerate RuBP, while others form glucose.

• Energy Requirement: It takes 6 Calvin cycles to produce 1 glucose molecule, requiring 18 ATP and 12 NADPH.

1.4: Limiting Factors in Photosynthesis

• Definition: Any factor present in lesser quantity than necessary limiting the rate of photosynthesis.

• Key Factors:

  • Light Intensity: Higher intensity increases photosynthesis rate until saturation is reached.

  • CO2 Concentration: Increasing concentrations boost the rate until plateauing.

  • Temperature: Affects enzymatic reactions; extremes can inhibit or denature enzymes.

2. CELLULAR RESPIRATION AND ATP SYNTHESIS

2.1: Glycolysis

• Definition: The metabolic process of breaking down glucose into pyruvate, producing ATP and NADH.

• Location: Cytosol of cells, occurs without oxygen.

• Overall Reaction: $ext{Glucose} <br>ightarrow 2 ext{Pyruvate} + 2 ext{ATP} + 2 ext{NADH}$

• Steps of Glycolysis:

  1. Glucose is phosphorylated to glucose-6-phosphate using 1 ATP.

  2. Isomerization to fructose-6-phosphate.

  3. Phosphorylation to fructose-1,6-bisphosphate using 1 ATP.

  4. Cleavage into two molecules of glyceraldehyde-3-phosphate (G3P).

  5. G3P is oxidized to 1,3-bisphosphoglycerate, producing NADH.

  6. ATP is generated via substrate-level phosphorylation.

  7. Dehydration forms phosphoenolpyruvate.

  8. Final conversion to pyruvate, generating another ATP.

2.2: Mitochondrial Structure and Function

• Outer Membrane: Composed of a phospholipid bilayer.

• Inner Membrane: Contains proteins of electron transport chain (ETC) and ATP synthase; site of ATP production.

• Matrix: Contains enzymes for Krebs cycle and mitochondrial DNA.

• Cristae: Infoldings that increase surface area for ATP production.

2.3: Fate of Pyruvate

• Aerobic Conditions: Converted to acetyl CoA (2C) before entering the Krebs cycle after losing a carbon (CO2).

• Anaerobic Conditions: Converted to lactate in animals, or ethanol and CO2 in yeast.

3. ENERGY FLOW AND NUTRIENT CYCLING

3.1: Energy Transfer Efficiency

• Ecosystem Definition: A community of living organisms and their environment interacting as a system.

• Trophic Levels: Levels of energy transfer from producers to top predators.

• Energy Transfer: Only about 10% of energy is transferred from one level to the next.

3.2: Biological Pyramids

• Types: Pyramids of numbers, biomass, and energy.

• Pyramid of Energy: Best representation of energy flow, with energy decreasing as moved up trophic levels.

4. ECOLOGICAL SYSTEMS, BIODIVERSITY, AND CONSERVATIONS

4.1: Ecosystems as Dynamic Systems

• Interactions: Between biotic (living) and abiotic (non-living) factors.

• Examples: Competition, predation, mutualism, commensalism, and parasitism.

4.2: Biodiversity Definition

• Components: Species diversity, genetic diversity, and ecosystem diversity.

4.3: Importance of Biodiversity

• Reasons to Maintain: Intrinsic ethical, direct economic, and indirect ecological services.

4.4: Species Diversity and Ecosystem Stability

• Stability Relationships: High species diversity leads to greater ecosystem stability and resilience.

4.5: Conservation Methods

• In Situ: Protecting species within their natural habitats (e.g., National Parks).

• Ex Situ: Conservation methods outside natural environments (e.g., zoos, seed banks).