Synapse: Gap between two neurons.

Brain: Forebrain (cerebrum - thinking, memory), Midbrain, Hindbrain (cerebellum - posture, balance; medulla - involuntary actions).

Spinal Cord: Reflex actions, connects brain to nerves.

Reflex Arc: Sensory neuron $\rightarrow$ Spinal cord $\rightarrow$ Motor neuron.

Endocrine System (Hormones):

Pituitary: Growth hormone.
Thyroid: Thyroxine (metabolism).
Pancreas: Insulin (blood sugar regulation).
Adrenal: Adrenaline (fight or flight).
Testes: Testosterone (male secondary sexual characteristics).
Ovaries: Estrogen, Progesterone (female secondary sexual characteristics, menstrual cycle).

Coordination in Plants:

Phytohormones: Auxins (growth), Gibberellins (stem growth), Cytokinins (cell division), Abscisic acid (growth inhibition), Ethylene (fruit ripening).
Tropisms: Directional movements (e.g., phototropism, geotropism, hydrotropism, chemotropism).

Reproduction: Process by which organisms produce new individuals of their own kind.
Asexual Reproduction: Single parent, no gamete fusion, genetically identical offspring.
- Fission: Binary (Amoeba), Multiple (Plasmodium).
- Fragmentation: Spirogyra.
- Regeneration: Planaria.
- Budding: Hydra, Yeast.
- Vegetative Propagation: Plants (roots, stems, leaves - e.g., layering, grafting).
- Spore Formation: Rhizopus.
Sexual Reproduction: Two parents, gamete fusion, genetic variation.
- Flowering Plants: Flower (sepals, petals, stamens - male, pistil/carpel - female), Pollination, Fertilization, Seed/Fruit formation.
- Humans:
  - Male: Testes (sperm, testosterone), vas deferens, urethra, penis.
  - Female: Ovaries (egg, estrogen, progesterone), oviduct/fallopian tube, uterus, vagina.
  - Fertilization: Fusion of sperm and egg, usually in fallopian tube.
  - Menstrual Cycle: Monthly cycle of egg release and uterine lining preparation.
Reproductive Health: STDs, contraception (condoms, pills, IUCDs, surgical methods).

Heredity: Transmission of traits from parents to offspring.
Variation: Differences among individuals of a species.
Genes: Units of heredity, segments of DNA.
Chromosomes: Thread-like structures in nucleus carrying genes.
Mendel's Laws:
- Law of Dominance: One allele (dominant) expresses over another (recessive).
- Law of Segregation: Alleles separate during gamete formation.
- Law of Independent Assortment: Genes for different traits assort independently.
Sex Determination: In humans, XX (female), XY (male). Father determines sex of child.
Evolution: Gradual change in living organisms over generations.
- Acquired Traits: Developed during lifetime, not inherit