Energy in African Ecosystems and Macromolecules

Energy in African Ecosystems

  • Key players in ecosystems include wild dogs, hyenas, lions, cheetahs, caracals, servals, and various birds of prey like Ruppell's vulture and tawny eagle.
  • Food chain structure includes:
    • Trophic Levels:
    • Top-level predators (tertiary consumers)
    • Carnivores (secondary consumers)
    • Herbivores (primary consumers)
    • Plant life (primary producers)
  • Examples of organisms:
    • Producers: Acacia, star grass, bed out grass.
    • Primary Consumers: Wildebeest, Thompson's gazelle, impala, mouse, grasshopper, harvester ant, topi, warthog, hare.
    • Secondary Consumers: Carnivorous species that eat primary consumers, e.g. lions and hyenas.

Producer and Consumer Types

  • Producers (Autotrophs): Plants that perform photosynthesis to create carbohydrates.
  • Primary Consumers: Heterotrophs that only consume plants (herbivores).
  • Secondary Consumers: Species that consume both plants and animals (omnivores).
  • Tertiary Consumers: Heterotrophs eating animals only (carnivores).
  • Decomposers: Organisms that eat/breakdown dead and decaying matter.

Animal Dentition

  • Different types of teeth adapted to diet:
    • Incisors: For cutting; found in herbivores for grass.
    • Canines: Tearing meat; long canines in carnivores like lions.
    • Molars: Grinding food; flat molars in herbivores for chewing tough plant materials.
  • Snails possess the most teeth, with thousands in rows.

Teeth and Diet Types

  1. Carnivores (e.g. lions):
    • Adapted with sharp canines for gripping prey.
    • Carnassial teeth slice meat into chunks.
  2. Herbivores (e.g. zebras):
    • Use incisors for taking bites of grass; molars for prolonged chewing.
    • Longer intestines adapt to digesting plant matter.
  3. Omnivores (e.g. humans, chimpanzees):
    • Have varied teeth (incisors, canines, and molars) to process both plants and meat.

Digestive Differences Between Herbivores and Carnivores

  • Herbivores:
    • Longer small intestines for digesting plant material.
    • Larger cecum helps ferment plant matter.
  • Carnivores:
    • Shorter small intestines suited for meat digesting.
    • Smaller cecum.

Need for Food

  • Food is essential for:
    • Growth (biomass).
    • Energy for life processes.
    • Nutrients divided into macromolecules: carbohydrates, proteins, and lipids.

Macromolecules

  1. Carbohydrates:
    • Composed of C, H, O; used for energy and structure.
    • Building blocks: simple sugars (e.g., glucose).
    • Indicators for detection: Starch (iodine test), Sugar (Benedict's test).
  2. Proteins:
    • Composed of C, H, O, N; building blocks are amino acids.
    • Indicators: Biuret's reagent (turns purple).
  3. Lipids:
    • Composed of fats and oils; building blocks: fatty acids and glycerol.
    • Detection: Brown paper test (translucent spot).

Nitrogen Cycle

  • Essential for building proteins; nitrogen becomes available through bacteria.
  • Key processes include:
    • Nitrogen fixation, denitrification, and decomposition.
    • Lightning helps convert N₂ into nitrates, usable by plants.

Enzymes in Digestion

  • Enzymes are proteins that act as catalysts to facilitate chemical reactions in the body, essential for digestion and synthesis.
  • Each reaction requires a specific enzyme (Lock and Key model).
  • Influenced by temperature (optimum at 37°C for humans) and pH levels (e.g., salivary amylase in the mouth prefers pH = 7).

Enzyme Denaturation

  • Denaturation occurs under extreme temperatures or pH changes, leading to loss of enzyme function. Denatured enzymes cannot catalyze reactions effectively!