Biodiversity and Conservation

Unit 1: Biodiversity and Conservation

Core Concept: Biodiversity encompasses the variety of life at all levels of biological organization, from genes within individuals to complex species arrangements across the globe. It is vital for ecosystem health and human well-being.

Scales of Biodiversity:

• Genetic Diversity: The range of genes within a species or population, crucial for adaptation and long-term evolution.

• Ecosystem Diversity: The variety of ecosystems, habitats, communities, and ecological processes within a region or on Earth.

Ecosystem Services l

Ecosystems provide essential services categorized into four types:

• Provisioning Services: Tangible products from ecosystems.

  • Examples: Food, water, timber, fiber, medicinal plants. 4

• Regulating Services: Regulation of environmental conditions.

  • Examples: Climate regulation, flood control, carbon sequestration, pest and disease control. 4

• Supporting Services: Fundamental ecosystem processes.

  • Examples: Nutrient cycling, soil formation, primary production, biodiversity maintenance. 4

• Cultural Services: Non-material benefits from ecosystems.

  • Examples: Recreation, aesthetic value, spiritual experiences, educational opportunities. 4

Valuing these services is crucial for conservation and sustainable resource management.

2. Phylogenetics 3

Core Concept:Phylogenetic trees are visual representations of evolutionary relationships between organisms, showing divergence over time.

Key Components of a Phylogenetic Tree:

• Taxa (Tips): The groups of organisms being studied (species, genera, etc.). 3

• Branches: Represent evolutionary lineages and descent from ancestors. 3

• Root: Represents the most recent common ancestor (MRCA) of all taxa in the tree. 3

Monophyletic Groups and Nested Hierarchies 3 4

• Monophyletic Group (Clade): A group including a common ancestor and all of its descendants. These represent natural evolutionary groupings. 4

• Nested Monophyletic Groups: Occur when one monophyletic group is entirely contained within a larger one, reflecting hierarchical evolutionary relationships. 4

Using Parsimony to Evaluate Phylogenetic Trees 4

Princ of Parsimony: The most likely phylogenetic tree is the one that requires the fewest evolutionary changes to explain the observed data. 4

Process:

1. Evaluate different possible trees.

2. Count evolutionary changes for each trait on each tree.

3. Select the tree with the fewest changes (most parsimonious). 4

3. Phylogenetic Traits 4 5

Core Concept:Phylogenetic traits (character traits) are characteristics used to reconstruct evolutionary history and infer relationships. 4

Types of Traits:

• Genetic (DNA sequences)

• Morphological (physical features)

• Physiological (metabolic processes)

• Developmental

• Behavioral 5

Derived Traits: Modified forms of ancestral traits found in descendants, indicating shared recent ancestry. 5

Homology vs. Homoplasy 5 6

• Homology: Similarity due to shared ancestry. Used to build phylogenetic trees.

  • Example: Mammalian forelimb bone structure. 5

• Homoplasy: Similarity due to independent evolution (convergent evolution), often driven by similar environmental pressures. Can mislead phylogenetic reconstruction.

  • Example: Wings of birds and insects. 5

Mapping Traits 6

Involves tracing the distribution of traits across a phylogenetic tree to infer where evolutionary changes occurred. 6

Estimating Tree Reliability 6

Methods include Cladistic Methods (focusing on shared derived characters) and Phenetic Methods (grouping by overall similarity). 6

4. Evolution [pageCitation:7-9]

Core Concepts:

• Evolution: Change in the genetic makeup of a population over time. 7

• Genetic Variation: The raw material for evolution. 7

• Mutation: The source of new genetic variation. [pageCitation:7-8]

• Hardy-Weinberg Principle: States that allele and genotype frequencies remain constant in a large, randomly mating population if evolutionary influences are absent. Serves as a null hypothesis. 8

  • Conditions for Equilibrium: No mutations, random mating, large population size, no gene flow, no natural selection. 8

Common Misconceptions:

• Evolution is not goal-directed: It does not strive for perfection; it’s driven by environmental pressures. 8

• Evolution does not occur within individual organisms: It is a population-level process over generations. 8

• Evolution does not produce perfect solutions: Adaptations are compromises constrained by genetics and physics. 8

Acclimatization vs. Evolution:

• Acclimatization: Physiological or behavioral adjustments within an individual's lifetime (not heritable). 9

• Evolution: Heritable genetic changes in a population over generations. 9

Unit 2: Microbial Diversity 91. Genetic Drift 10 11

Core Concept:Genetic drift refers to random fluctuations in allele frequencies within a population due to chance events, not natural selection. 10 It is particularly impactful in small populations.

Key Characteristics and Effects:

• Randomness: Changes are unpredictable. 10

• Small Population Size: Drift is more pronounced. 10

• Reduced Genetic Variation: Decreases genetic diversity within a population. 10

• Allele Loss and Fixation: Alleles can be lost entirely or become fixed (100% frequency). 10

• Causes: Can be due to bottlenecks (drastic population reduction) or founder effects (small group establishing a new population). 11

Relationship to Other Evolutionary Forces:

• Natural Selection: Acts on adaptive traits; drift is random. 11

• Migration (Gene Flow): Introduces new genetic material, potentially counteracting drift. 11

2. Natural Selection 11 12

Core Concept:Natural selection is the primary driving force of evolution, favoring individuals with traits that enhance survival and reproduction in a specific environment. 11

Fitness: An organism's ability to survive and reproduce successfully. 11

Modes of Natural Selection:

• Directional Selection: Favors one extreme phenotype, shifting the population's trait distribution. 12

  • Example: Increase in beak size for seed cracking.

• Stabilizing Selection: Favors intermediate phenotypes, reducing variation. 12

  • Example: Human birth weight.

• Disruptive Selection: Favors both extreme phenotypes, potentially leading to subgroup diversification. 12 13

  • Example: Beak sizes for different seed types.

Sexual Selection 13

A form of natural selection where traits influence mate acquisition.

• Intrasexual Selection: Competition within the same sex (usually males) for mates. 13

  • Example: Male deer fighting.

• Intersexual Selection (Mate Choice): One sex (usually females) chooses mates based on specific traits. 13

  • Example: Peahens choosing males with elaborate tails.

3. Population Growth [pageCitation:13-16]Population Growth Models 14

• Exponential Growth: Population increases at a constant rate, assuming unlimited resources (J-shaped curve). 14

  • Equation: dN/dt=rNdN/dt=rN 14

  • rr = intrinsic rate of increase.

• Logistic Growth: Population growth slows as it approaches carrying capacity (S-shaped curve). 14

  • KK = Carrying Capacity: Maximum population size an environment can sustain. 14

  • Equation: dN/dt=rN((K−N)/K)dN/dt=rN((K−N)/K) 14

• Density-Independent Growth: Growth rate unaffected by population density, often due to external factors like weather. 15

Key Differences: Exponential growth assumes unlimited resources, logistic growth considers carrying capacity. Exponential growth is J-shaped, logistic is S-shaped. Density-independent growth is driven by external factors. 15

4. Survivorship [pageCitation:16-17]

Core Concept: A survivorship curve graphically represents the proportion of individuals surviving to each age. 16

Types of Survivorship Curves:

• Type I: High survival in early/middle life, rapid decline in old age (e.g., humans, elephants). 16

• Type II: Constant mortality rate throughout life (e.g., small birds, squirrels). 16

• Type III: High mortality early in life, higher survival for those who reach adulthood (e.g., frogs, fish, plants). 17

Life Tables: Records of survival and reproductive rates used to construct survivorship curves. 17

Unit 3: Metabolic Diversity 171. Essential Nutrients [pageCitation:17-20]

Definition:Essential nutrients are compounds an organism cannot synthesize and must obtain from its diet. 18

Importance of Animal Nutrition: Provides building blocks for biosynthesis, raw materials for ATP production, and essential minerals/vitamins. 18

Roles of Macronutrients in Animal Nutrition:

• Carbohydrates: Primary energy source, converted to glucose, aid digestion (fiber), energy storage. [pageCitation:18-19]

• Fats: Concentrated energy source, facilitate vitamin absorption, hormone production, satiety, flavor. 19

• Proteins: Built from amino acids; essential for tissue repair, enzymes, and metabolic processes. 19

Essential Nutrients: Include amino acids, fatty acids, vitamins, minerals, and choline. 19

Classification of Essential Plant Nutrients:

• Macronutrients: Required in large quantities (e.g., N, P, K). 19

• Micronutrients: Required in small quantities (e.g., Fe, Mn, Zn). 20

2. Photosynthesis [pageCitation:20-22]

Core Concept:Photosynthesis converts light energy, CO2CO2​, and H2OH2​O into glucose and O2O2​. 20

Light-Dependent Reactions: Occur in the thylakoid membrane. 20

1. PSII Activation: Light energy excites chlorophyll, initiating electron transport. 20

2. Water Splitting: H2OH2​O is split by PSII to replace lost electrons, releasing O2O2​. [pageCitation:20-21]

3. Electron Transport Chain (ETC): Electrons move through proteins, generating ATP and NADPH. 21

4. ATP and NADPH Production: Energy carriers for the Calvin cycle. 21

Calvin Cycle (Light-Independent Reactions):Occurs in the stroma. 21

• Role of RuBisCO: Enzyme that catalyzes carbon fixation (CO2CO2​ + RuBP). 21

• Requirements: ATP and NADPH from light reactions. 21

• Process: CO2CO2​ is fixed and converted into glucose. 21

3. C4 Photosynthesis [pageCitation:22-24]

Core Concept:C4 photosynthesis is an adaptation to minimize photorespiration in hot, dry environments, using spatial separation of carbon fixation. 22

Spatial Separation:

1. Initial Carbon Fixation (Mesophyll Cells):CO2CO2​ is captured by PEP carboxylase (PEPcase), which has high CO2CO2​ affinity and doesn't bind O2O2​. CO2CO2​ is fixed into a 4-carbon molecule (oxaloacetate, then malate). 22

2. Malate Transport: Malate moves to bundle sheath cells. [pageCitation:22-23]

3. Calvin Cycle (Bundle Sheath Cells): Malate releases CO2CO2​, which enters the Calvin cycle. 23

PEP Regeneration: Pyruvate is converted back to PEP in mesophyll cells. 23

Advantages of PEP Carboxylase: High CO2CO2​affinity, no oxygen binding (prevents photorespiration). [pageCitation:23-24]

4. CAM Photosynthesis [pageCitation:24-26]

Core Concept:CAM (Crassulacean Acid Metabolism) photosynthesis minimizes water loss in arid climates through temporal separation of CO2CO2​ uptake and the Calvin cycle. 24

Temporal Separation:

• Night: Stomata open, CO2CO2​ enters and is fixed by PEPcase into organic acids (stored in vacuoles). 25

• Day: Stomata close. Stored CO2CO2​ is released from organic acids and used in the Calvin cycle. 25

Advantages: Reduced water loss, efficient Calvin cycle at night. 26

The Role of ATP

ATP (Adenosine Triphosphate): The primary energy currency of the cell, powering cellular work and regulating biochemical pathways. 24Released via hydrolysis. Used in cellular respiration. 25

Unit 4: Endosymbiosis 261. Plant Cells [pageCitation:26-29]

Unique Characteristics:

• Cell Wall: Rigid outer layer providing structural support and protection. Primarily cellulose, hemicellulose, pectin, lignin. 27

• Plastids: Organelles with various functions (photosynthesis, storage). 27

• Central Vacuole: Large, fluid-filled sac for storage, waste management, turgor pressure, and homeostasis. [pageCitation:27-28]

• Totipotency: The ability of a single plant cell to develop into a whole plant. 28

Plant Tissue Systems:

• Dermal Tissue: Outer protective covering. 28

• Ground Tissue: Photosynthesis, storage, support. 28

• Vascular Tissue: Transport of water, minerals, sugars. 28

2. Chloroplasts and Leucoplasts [pageCitation:28-30]

• Chloroplasts: Site of photosynthesis, containing chlorophyll in thylakoids. Essential for plants to produce their own food. 29

• Leucoplasts: Plastids involved in storage (starch, oils, proteins), typically found in non-photosynthetic tissues. [pageCitation:29-30]

3. Plant Nutrition [pageCitation:30-33]

Essential Nutrients: Required for growth and survival, obtained from air, water, and soil. Classified as macronutrients and micronutrients. 30

Nutrient Sources:

• Air: Carbon (CO2CO2​), Oxygen (O2O2​). 30

• Water: Hydrogen (H2OH2​O). 30

• Soil: Remaining 13 essential nutrients. 30

Macronutrients: Required in larger quantities.

• C, H, O: Building blocks of organic molecules. 30

• N: Proteins, nucleic acids, chlorophyll; promotes leaf/stem growth. 30

• P: Nucleic acids, ATP, phospholipids; crucial for root/flower development. [pageCitation:30-31]

• K: Enzyme activation, water regulation, translocation; enhances vigor. 31

• Ca: Cell wall strength, enzyme regulation, signaling. 31

• Mg: Chlorophyll component, enzyme activation, protein synthesis. 31

• S: Component of amino acids and vitamins. 31

Micronutrients: Required in smaller quantities (e.g., Fe, Mn, Zn, Cu, B, Mo, Cl). Often function as enzyme cofactors. 31

Iron Deficiency: Symptoms typically appear first in new leaves due to high demand. 33

4. Symbiosis [pageCitation:32-33]

Core Concept:Symbiosis involves mutually beneficial relationships between different organisms, often crucial for nutrient acquisition. 32

Mycorrhizal Symbiosis: Between plants and soil fungi.

• Plant Benefit: Enhanced nutrient uptake (especially phosphorus). 32

• Fungal Benefit: Access to sugars from the plant. 32

• Overcoming Zone of Depletion: Fungal hyphae extend root reach for nutrients. 33

Plant Nutrient Acquisition Mechanisms:

1. Direct Acquisition: Active transport from soil into root cells. 33

2. Acquisition via Barter: Symbiotic exchange with mycorrhizae. 33

Unit 5: Plant Adaptation to Life on Land 341. Plant Tissues [pageCitation:34-36]

Plant tissues are groups of cells with specific functions, classified into three systems:

• Dermal Tissue System: Outer protective covering (epidermis, periderm). Protects against water loss, injury, and pathogens. [pageCitation:34-35]

• Ground Tissue System: Bulk of the plant body; performs photosynthesis, storage, and support. Composed of parenchyma, collenchyma, and sclerenchyma cells. 35

  • Parenchyma: Versatile, performs photosynthesis, storage, secretion. 35

  • Collenchyma: Flexible support, especially in growing regions. 35

  • Sclerenchyma: Strong, rigid support; cells are dead at maturity with thick, lignified walls. 35

• Vascular Tissue System: Transport network (xylem and phloem). 36

Permanent Tissue: Cells that have differentiated and lost the ability to divide. 36

2. Meristems and Growth [pageCitation:36-38]

Core Concept:Meristems are plant tissues containing undifferentiated cells capable of continuous division, enabling plant growth. 36

Types of Growth:

• Indeterminate Growth: Continuous growth throughout life (roots, stems). Enabled by apical meristems. 36

• Determinate Growth: Growth stops at a certain size (leaves, flowers, fruits). 37

Types of Meristems:

• Apical Meristems: Located at root and shoot tips; responsible for primary growth(lengthening). 37

• Intercalary Meristems: At the base of leaves/nodes in some monocots; facilitate regrowth. 37

Primary Growth: Increases plant length, occurs via apical meristems, forming primary tissues (dermal, ground, vascular). [pageCitation:37-38]

3. Secondary Growth [pageCitation:38-40]

Core Concept:Secondary growth increases the girth (width) of stems and roots, primarily in woody plants. Driven by lateral meristems. 38

Lateral Meristems:

• Vascular Cambium: Produces secondary xylem (wood) and secondary phloem. 39

• Cork Cambium: Produces cork cells (outer bark) for protection. 39

Comparison of Primary vs. Secondary Growth:

4. Vascular Tissue [pageCitation:40-42]

Core Concept: The vascular tissue system is the plant’s transport network, consisting of xylem and phloem. 40

• Xylem: Transports water and minerals from roots to shoots; provides support. Composed of tracheids and vessel elements (mostly dead at maturity). 41

• Phloem: Transports sugars and nutrients from leaves to other plant parts. Composed of sieve tube elements, companion cells, phloem parenchyma, and fibers (living cells at maturity). 41

Direction of Transport:

• Xylem: Unidirectional (roots to shoots). 41

• Phloem: Bidirectional (source to sink). [pageCitation:41-42]

Unit 6: Gas Exchange in Plants and Animals 421. Vascular Transport [pageCitation:42-43]

Cohesion-Tension Theory: Explains passive water movement in xylem from roots to leaves. 42

• Cohesion: Water molecules stick together via hydrogen bonds, forming a continuous column. 42

• Tension (Transpirational Pull): Water evaporation from leaves creates a negative pressure that pulls water up the xylem. 42

• Process: Water enters roots via osmosis, moves through tracheids via pits, and is pulled up the xylem column. [pageCitation:42-43]

Stomatal Regulation: Stomata (pores on leaf surface) control transpiration rates by opening and closing in response to environmental factors (light, CO2CO2​, water availability). 43

2. Water Conservation [pageCitation:43-45]

Plant Water Conservation Strategies:

• Stomata Closure: Reduces water loss when water is scarce. 44

• Wilting: Reduces exposed surface area to minimize transpiration. 44

Roles of Cell Types:

• Parenchyma Cells: Store water, contributing to drought resilience. 44

• Companion Cells: Support sieve tube elements, ensuring efficient nutrient transport vital for water regulation. 44

• Sclerenchyma Cells: Provide structural integrity and support, helping maintain plant form during drought. [pageCitation:44-45]

3. Phloem [pageCitation:45-47]

Core Concept:Phloem is the vascular tissue for transporting organic substances (sugars, amino acids) throughout the plant. 45

Key Cell Types:

• Sieve Tube Elements: Primary conducting cells, forming tubes with sieve plates for efficient flow. [pageCitation:45-46]

• Companion Cells: Provide metabolic support to sieve tube elements. 46

• Phloem Fibres: Provide structural support. 46

• Phloem Parenchyma: Involved in storage and lateral transport. 46

4. Xylem [pageCitation:47-48]

Core Concept:Xylem transports water and minerals from roots to the rest of the plant. 47

Key Components:

• Tracheids: Elongated cells with tapered ends and pits for water movement. 47

• Vessel Elements: Shorter, wider cells forming continuous vessels with perforations for faster water transport. [pageCitation:47-48]

Water Transport Efficiency: Vessel elements allow faster transport than tracheids due to continuous tube formation. 48

Unit 7: Community Ecology, Ecosystem Ecology, Climate Change 491. Community Ecology [pageCitation:49-51]

Community Structure: Composition and organization of a biological community, defined by species present, their numbers, and interactions. 49

• Key Attributes: Species composition, relative abundance, species interactions. 50

Types of Biotic Interactions:

• Competition: Organisms vying for limited resources (intraspecific or interspecific). 50

• Predation: One organism consumes another. 50

• Symbiosis: Close interactions:

  • Mutualistic: Both benefit (e.g., pollination). 50

  • Commensalistic: One benefits, other unaffected (e.g., barnacles on whale). 51

  • Parasitic: One benefits (parasite), other harmed (host). 51

Secondary Succession: Ecological recovery after disturbance where soil remains intact (e.g., after fires, abandoned fields). Proceeds faster than primary succession. 51

2. Population Ecology [pageCitation:51-54]

Core Concept: Study of groups of individuals of the same species, focusing on factors affecting size, density, distribution, and growth rate. 51

Factors Influencing Population Size: Birth rate, death rate, immigration, emigration. 52

• Equation: Population Change = (Births + Immigration) - (Deaths + Emigration) 52

Demography: Study of population characteristics and their changes over time. 52

Density-Dependent Factors: Affect populations differently based on density. Intensify with increasing density. [pageCitation:52-53]

• Examples: Competition for resources, disease transmission. 53

Density-Independent Factors: Affect populations regardless of density. Often abiotic. 53

• Examples: Natural disasters (storms, droughts), climate. 53

3. Species Interactions [pageCitation:53-56]

Core Concept: Environmental factors (biotic and abiotic) shape species' distribution, abundance, and evolution. 53

Abiotic Factors: Non-living physical and chemical elements (rainfall, temperature, pH, sunlight, nutrients). [pageCitation:53-54]

Habitat: The natural environment or home of an organism. 54

Logistic Growth and Carrying Capacity (K):Population growth slows as it approaches K, the maximum sustainable population size, due to density-dependent factors. [pageCitation:54-55]

Competition: Occurs when resources are limited.

• Intraspecific Competition: Between individuals of the same species. 54

• Interspecific Competition: Between individuals of different species. 55

Summary of Species Interaction Outcomes:

55

4. Ecosystem Dynamics [pageCitation:56-58]

Core Concept: Interactions between organisms and their environment, including energy flow and processes driving change. 56

Key Components:

• Producers (Autotrophs): Convert light energy to chemical energy (photosynthesis). Base of food webs. 56

• Consumers (Heterotrophs): Obtain energy by consuming other organisms (primary, secondary, tertiary). 56

• Biotic Factors: Living organisms and their interactions. 56

Energy Flow and Trophic Levels: Energy flows from producers upwards; energy is lost at each level (thermodynamics). 57

Niche Concept:

• Fundamental Niche: Theoretical range of resources/conditions. 57

• Realized Niche: Actual range occupied, limited by interactions. 57

Competitive Exclusion Principle: Two species cannot occupy the same niche indefinitely; one will outcompete the other. 57

Ecological Succession: Gradual change in ecosystem species structure over time. 57

Unit 8: Plant Structure and Function 581. Vascular Tissue and Water Transport [pageCitation:58-59]

Overview of Vascular Tissue: Plant's circulatory system (xylem and phloem) for transporting water, minerals, and sugars. 58

• Xylem: Transports water and minerals; composed of tracheids and vessel elements. 58

• Phloem: Transports sugars; composed of sieve tube elements and companion cells. 58

Cohesion-Tension Theory: Explains passive water transport via xylem properties and transpiration pull. 59

• Mechanism: Transpiration creates tension, pulling water up due to cohesion (water-water attraction) and adhesion (water-xylem wall attraction). 59

2. Photosynthesis and Sugar Transport [pageCitation:59-61]

Photosynthesis: Converts light energy to chemical energy (glucose) in two stages: 59

• Light Reactions: Occur in thylakoids; convert light energy to ATP and NADPH, releasing O2O2​. 60

• Calvin Cycle: Occurs in stroma; uses ATP and NADPH to fix CO2CO2​ into glucose. 60

Stomata: Pores regulating gas exchange (CO2CO2​in, O2O2​ out) and water loss. Balancing these is critical. [pageCitation:60-61]

Sugar Transport: Sugars are transported via phloem from source (leaves) to sink (roots, etc.). Used for immediate energy or stored. 61

Relationship Between Photosynthesis and Respiration: Photosynthesis produces glucose, which respiration breaks down to generate ATP for plant energy needs. 61

3. Nutrient Acquisition and Transport [pageCitation:61-63]

Essential Nutrients: Elements plants cannot synthesize, obtained from air, water, and soil. 61

Nutrient Sources:

• Air: CO2CO2​ (carbon fixation), O2O2​ (respiration). 62

• Soil: Mineral nutrients (macronutrients and micronutrients). 62

• Water: Solvent for nutrients, provides Hydrogen (H2OH2​O). 62

Acquisition:

• Nutrients are absorbed with water by roots. 63

• Absorbed minerals transported via xylem to shoots. 63

4. Plant Tissues and Growth [pageCitation:63-65]

Plant Body Systems:

• Shoot System: Stems, leaves, flowers (photosynthesis, reproduction). 64

• Root System: Anchors plant, absorbs water and nutrients. 64

Plant Tissue Types:

• Dermal Tissue: Outer protective layer. 64

• Ground Tissue: Photosynthesis, storage, support (parenchyma, collenchyma, sclerenchyma). 64

• Vascular Tissue: Transport (xylem and phloem). Xylem cells (tracheids) have pits for water movement. [pageCitation:64-65]

Primary and Secondary Growth:

• Primary Growth: Lengthening of roots and shoots via apical meristems. 65

• Secondary Growth: Thickening of stems and roots via lateral meristems (vascular cambium, cork cambium). 65

Pith: Central tissue in stems/roots, involved in storage and support. 65

Unit 9: Plant Reproduction and Adaptation 651. Alternation of Generations [pageCitation:65-68]

Core Concept: Plants alternate between a haploid gametophyte (produces gametes) and a diploid sporophyte (produces spores) generation. [pageCitation:65-66]

The Two Phases:

• Sporophyte (2n): Diploid phase, produces haploid spores via meiosis. 66

• Gametophyte (n): Haploid phase, produces haploid gametes via mitosis. 66

Life Cycle Steps: Meiosis (sporophyte) -> Spores -> Gametophytes (mitosis) -> Gametes -> Fertilization (zygote) -> Embryo -> Sporophyte. 67

Roles:

• Spores: Dispersal, start of gametophyte generation. 67

• Gametophytes: Produce gametes for sexual reproduction. 67

Variation in Dominance: Sporophyte dominant in most vascular plants; gametophyte dominant in bryophytes (mosses). 68

2. Seed Development and Dispersal [pageCitation:68-71]

Overview: Plant reproduction involves alternation of generations. 68

Spores and Gametophytes: Spores facilitate dispersal; gametophytes produce gametes. [pageCitation:68-69]

Seed Development: A seed is a dispersal unit containing an embryo and food supply within a protective coat. 69

• Embryo: The young plant within the seed. 70

• Double Fertilization (Angiosperms): One sperm fertilizes the egg (embryo), another fertilizes polar nuclei (endosperm). 69

• Seed and Fruit Development: Ovule becomes seed coat; ovary becomes fruit. 70

Heterospory: Production of two types of spores (microspores for male gametophytes, megaspores for female gametophytes). Precondition for seed evolution. 70

Mutualistic Pollination: Pollinators (e.g., insects) benefit from nectar/pollen; plants benefit from pollen transfer. 71

3. Terrestrial Adaptations [pageCitation:71-74]

Transition to Land: Required adaptations for:

1. Structural Support: To withstand gravity. 71

2. Desiccation Prevention: Minimize water loss. 71

3. Water and Nutrient Uptake: From soil. 71

4. Reproductive Strategies: Suitable for land. 71

Ancestry: Land plants share a common ancestor with Charophyceae green algae. Land plants are embryophytes (protect embryo). 72

Water Transport and Turgor Pressure:

• Importance: Nutrient distribution, cell turgor (rigidity), photosynthesis reactant. 72

• Transpiration: Water evaporation from leaves pulls water up xylem (cohesion-tension). [pageCitation:72-73]

• Recovery from Wilting: Rehydration restores turgor pressure. 73

Reproduction on Land:

• Spore Protection: Tough sporopolleninlayer prevents desiccation. 73

• Gametophyte: Multicellular, haploid (n) structure producing gametes via mitosis. [pageCitation:73-74]

4. Photosynthetic Adaptations [pageCitation:74-76]

Core Concept: Adaptations like C4 and CAM photosynthesis minimize photorespiration and water loss, enhancing carbon fixation. 74

C4 Photosynthesis: Spatial separation of initial carbon fixation (mesophyll cells) and Calvin cycle (bundle sheath cells). Increases CO2CO2​concentration around RuBisCO. [pageCitation:74-75]

CAM Photosynthesis: Temporal separation; stomata open at night for CO2CO2​ uptake (stored as organic acids), Calvin cycle occurs during the day. Minimizes water loss. 75

C4 vs. CAM:

75

Light-Dependent Reactions: Convert light energy to ATP and NADPH via electron transport chains, driven by chlorophyll. [pageCitation:75-76]

Unit 10: Animal Nutrition and Digestion 761. Nutritional Processes [pageCitation:76-80]

Core Concept: Nutrition involves ingestion, digestion, absorption, and elimination. 76

• Digestion: Breakdown of complex food into absorbable units. 76

• Absorption: Uptake of nutrients into cells/bloodstream. 76

Macronutrient Digestion:

• Carbohydrates: Salivary amylase (mouth) -> pancreatic amylase (small intestine) -> monosaccharides (via maltase, sucrase, lactase). 77

• Proteins: Pepsin (stomach) -> peptides -> amino acids (via trypsin, etc. in small intestine). 77

• Lipids: Emulsified by bile (liver/gallbladder); broken down by lipases into fatty acids and monoglycerides (small intestine). Reassembled into chylomicrons for transport. [pageCitation:77-78]

Vitamin Absorption:

• Water-Soluble: Directly absorbed into blood. 78

• Fat-Soluble: Absorbed via lipid pathways (into chylomicrons). 78

Energy Release from ATP: Hydrolysis of ATP releases energy for cellular work. 79

Glycogen Breakdown (Glycogenolysis): Stored glucose is broken down to glucose when energy is needed. 79

Homeostasis: Maintenance of a stable internal environment. 79

2. Lipid and Protein Digestion [pageCitation:80-81]

Lipid Digestion: Primarily by pancreatic lipases, which break down emulsified lipids into fatty acids and monoglycerides. These are absorbed, reassembled into chylomicrons, and transported via the lymphatic system. 80

Protein Digestion: Begins with pepsin in the stomach, then further breakdown into amino acids by enzymes like trypsin in the small intestine. Amino acids are absorbed into the bloodstream. 81

3. Plant Macronutrients [pageCitation:81-83]

Essential Elements: Indispensable for plant growth, development, and reproduction. Obtained from air, water, and soil. Categorized as macronutrients and micronutrients. 81

Nutrients from Air and Water:

• Carbon (C): From CO2CO2​; basis of organic molecules. 81

• Hydrogen (H): From H2OH2​O; structure and energy transfer. 82

• Oxygen (O): From air and water; respiration and metabolism. 82

Primary Macronutrients (NPK): Nitrogen (N), Phosphorus (P), Potassium (K) are needed in large amounts and often deficient in soils. 82

• Nitrogen (N): Proteins, nucleic acids, chlorophyll; promotes growth. 82

• Phosphorus (P): ATP, nucleic acids, phospholipids; crucial for roots, flowers. 82

• Potassium (K): Regulates stomata, enzyme function, transport; enhances vigor. 82

• Sulfur (S): Amino acids, vitamins; enzyme function. [pageCitation:82-83]

Essential Elements Summary: Plants require ~17 essential elements, classified by quantity needed. 84

4. Waste Elimination [pageCitation:83-84]

Core Concept: Removal of undigested food and metabolic byproducts to maintain homeostasis. 83

Process in Digestive System:

1. Waste enters the colon.

2. Water is reabsorbed, solidifying feces.

3. Intestinal flora aid movement.

4. Rectum stores feces.

5. Peristalsis moves waste.

6. Elimination through the anus. 83

Macronutrients (Plants): Required in large quantities for structure, metabolism, physiology. 84

Micronutrients (Plants): Required in small quantities, but crucial for plant health and development. 84

Unit 11: Ecology and Species Interactions 851. Abiotic and Biotic Factors [pageCitation:85-86]

Abiotic Factors: Non-living physical and chemical elements of an ecosystem (e.g., rainfall, temperature, pH, sunlight, nutrients). 85

Biotic Factors: All living organisms and their interactions within an ecosystem (plants, animals, fungi, bacteria). 85

Species Interactions: Relationships between different species that shape communities and populations. Can be positive, negative, or neutral. 86

Trophic Dynamics and Food Webs: Study of energy and nutrient flow through feeding relationships. Food webs show complex interactions. 86

Trophic Levels: An organism's position in a food chain/web. 86

Foundation and Dominant Species:

• Foundation Species: Have the greatest impact on community structure (e.g., trees, corals). 86

• Dominant Species: Most abundant or have highest biomass, exert strong influence. [pageCitation:86-87]

Top-Down vs. Bottom-Up Control:

• Bottom-Up: Nutrient availability influences higher trophic levels. 87

• Top-Down: Top predators influence lower trophic levels. 87

Ecological Pyramids: Biomass or energy decreases significantly at higher trophic levels due to energy loss. 87

2. Species Interactions [pageCitation:87-90]

Core Concept: Diverse relationships between species shaping communities, driving evolution, and influencing natural selection. 87

Categories: Consumer-resource interactions, competition, symbiotic interactions. 88

Consumer-Resource Interactions:

• Predation: Predator kills and eats prey. Predator benefits, prey harmed. 88

• Herbivory: Herbivore consumes plants. Herbivore benefits, plant harmed. 88

• Parasitism: Parasite lives on/in host, obtains nutrients at host's expense. Parasite benefits, host harmed. [pageCitation:88-89]

Competition: Occurs when resources are limited (intraspecific or interspecific). Both species harmed. 89

• Interspecific Competition Outcomes:Resource partitioning, character displacement. 89

Symbiotic Interactions: Close, long-term interactions.

• Mutualism: Both species benefit. [pageCitation:89-90]

• Commensalism: One benefits, other unaffected. 90

• Parasitism: (Also considered here due to close interaction). 90

3. Mycorrhizae [pageCitation:90-92]

Core Concept:Mycorrhizae are symbiotic relationships between plant roots and fungi, crucial for nutrient/water uptake. Approx. 80% of vascular plants rely on them. 90

The Exchange: Plants provide sugars; fungi provide mineral nutrients (e.g., phosphorus) and water. [pageCitation:90-91]

Fungal Benefits: Sugars and a habitat. 91

How Mycorrhizae Enhance Uptake: Fungal hyphae extend root reach, accessing nutrients beyond the zone of depletion. 91

Transport: Nutrients and water absorbed are transported via xylem. [pageCitation:91-92]

Recovery from Water Stress: Rehydration restores turgor pressure via water absorption and transport. 92

4. Ecological Succession [pageCitation:92-93]

Core Concept: Gradual change in species structure of an ecological community over time, leading to a more stable ecosystem. 92

Primary Succession: Begins in lifeless areas with no soil (e.g., lava flows). Pioneer species (lichens) form soil, paving the way for others. [pageCitation:92-93]

Secondary Succession: Occurs in areas with existing soil after disturbance (e.g., fire, floods). Proceeds faster than primary succession. 93

Keystone and Dominant Species:

• Dominant Species: Most abundant or highest biomass, exert strong influence. 93

• Keystone Species: Have a disproportionately large impact relative to abundance, significantly altering ecosystem structure. 93

5. Population Growth Models [pageCitation:93-94]

Core Concept: Mathematical tools predicting population size changes over time. 93

Exponential Growth: Describes growth under ideal conditions with unlimited resources. 94

• Equation: dN/dt=rN

• r = intrinsic rate of increase. Low rr values mean slow growth even exponentially. 94

Carrying Capacity (K) and Environmental Constraints: Limited resources (food, water, shelter) determine K, the maximum sustainable population size. 94