Plant Reproduction: Asexual and Sexual

Reproduction in Plants

• Plants reproduce via asexual and sexual methods.
• Asexual Reproduction: A single parent yields genetically identical offspring.
• Sexual Reproduction: Gamete (sex cell) fusion from two parents creates genetic variation in offspring.

Asexual Reproduction in Plants

• Runners: Horizontal stems that root (e.g., strawberries).
• Rhizomes: Underground stems that send out shoots and roots (e.g., ginger).
• Bulbs: Underground storage with fleshy leaves (e.g., onions).
• Tubers: Enlarged underground stems with buds (e.g., potatoes).
• Fragmentation: A parent plant separates into new plants.
• Grafting: Two plants join to grow as one.
• Budding: A bud from one plant grows on another.

Sexual Reproduction in Plants

• Flowers contain reproductive organs.
• Stamen: The male part, includes the anther (pollen producer) and filament (anther support).
• Pistil (or Carpel): The female part, includes the stigma (pollen receiver), style (connects stigma to ovary), and ovary (contains ovules).
• Pollination: Pollen moves from anther to stigma.
  • Self-pollination happens within the same flower/plant.
  • Cross-pollination happens between different plants of the same species.
• Fertilization: Pollen grain fuses with the ovule, forming a zygote.
• The ovule becomes a seed, and the ovary becomes a fruit.

Seed Dispersal

• Seeds disperse to reduce competition.
• Dispersal Methods:
  • Wind: Lightweight seeds with air dispersal structures (e.g., dandelion).
  • Water: Seeds float (e.g., coconut).
  • Animals: Seeds stick or are eaten (e.g., burrs, berries).
  • Mechanical: Seed pods burst (e.g., peas).

Reproduction in Humans

• Human reproduction is sexual and involves gamete fusion.
• The male system produces sperm, and the female system produces eggs (ova).

Male Reproductive System

• Testes: Produce sperm and testosterone.
• Epididymis: Stores and matures sperm.
• Vas Deferens: Transports sperm to the ejaculatory duct.
• Seminal Vesicles & Prostate Gland: Produce nourishing and protective fluids for sperm.
• Urethra: Carries sperm and urine.
• Penis: Delivers sperm.

Female Reproductive System

• Ovaries: Produce eggs, estrogen, and progesterone.
• Fallopian Tubes (Oviducts): Transport eggs to the uterus; fertilization occurs here.
• Uterus: Site of fertilized egg implantation and development.
• Cervix: Lower part of the uterus opening to the Vagina.
• Vagina: Receives sperm and serves as the birth canal.

Fertilization and Development

• Sperm deposited in the vagina during intercourse.
• Sperm travel through the cervix, uterus, and fallopian tubes.
• Fertilization: Zygote forms, divides, and becomes an embryo.
• The embryo implants in the uterine wall and develops into a fetus in nine months (gestation).

Ecosystems

• Ecosystem: Living organisms (biotic) interact with each other and their non-living environment (abiotic).
• Includes:
  • Producers: Autotrophs (e.g., plants) make their food via photosynthesis.
  • Consumers: Heterotrophs eat other organisms for energy.
  • Decomposers: Break down dead organisms, returning nutrients (e.g., bacteria, fungi).
  • Abiotic factors: Non-living components (e.g., sunlight, water, temperature, soil, air).

Food Chains and Food Webs

• Food Chain: A linear sequence where one organism eats another, transferring nutrients and energy.
• Food Web: An interconnected network of food chains.
• Trophic Levels: Position in a food chain/web (e.g., producers, primary consumers, secondary consumers).

Energy Flow

• Energy flows from producers to consumers.
• 10% of energy transfers between levels; the rest is lost as heat.
• Energy loss limits food chain length.

Nutrient Cycles

• Nutrients (carbon, nitrogen, water) cycle through ecosystems.
• Carbon Cycle: Involves photosynthesis, respiration, decomposition, and combustion.
• Nitrogen Cycle: Involves nitrogen fixation, nitrification, assimilation, and denitrification.
• Water Cycle: Involves evaporation, condensation, precipitation, and transpiration.

Endocrine System

• A gland network produces hormones that regulate bodily functions.
• Hormones are messengers traveling via the bloodstream.

Major Endocrine Glands

• Pituitary: Controls growth, metabolism, and reproduction. It's the master gland.
• Thyroid: Regulates metabolism.
• Adrenal: Regulates stress response, blood pressure, and electrolyte balance, producing epinephrine/adrenaline.
• Pancreas: Regulates blood sugar via insulin and glucagon.
• Ovaries (females): Produce estrogen/progesterone for the menstrual cycle and female characteristics.
• Testes (males): Produce testosterone for sperm and male characteristics.

Hormone Action

• Hormones bind to receptors, triggering a response.
• Steroid Hormones: Enter cells, bind to nuclear receptors, and affect gene expression.
• Protein Hormones: Bind to cell surface receptors and activate signaling pathways.

Diseases and First-Aid

Common Diseases

• Infectious: Caused by pathogens (e.g., flu, common cold, malaria).
• Non-Communicable Diseases: Not contagious (e.g., heart disease, diabetes, cancer).
• Deficiency: Lack of nutrients (e.g., scurvy from vitamin C deficiency, rickets from vitamin D deficiency).
• Genetic: Caused by gene/chromosome abnormalities (e.g., cystic fibrosis, sickle cell anemia).

First-Aid Principles

• First-aid steps are taken before medical help arrives.
• Principles:
  • Assess the scene: Ensure safety.
  • Check responsiveness: Determine consciousness and breathing.
  • Call for help: Dial emergency services.
  • Provide care: Address life-threatening issues first (e.g., airway obstruction, bleeding, CPR).

Common First-Aid Procedures

• CPR: For cardiac arrest, use chest compressions and rescue breaths.
• Heimlich Maneuver: Dislodge airway obstructions.
• Wound Care: Clean with soap/water, apply antiseptic, and bandage.
• Burn Treatment: Cool with water, sterile dressing, and no creams/ointments.
• Fracture Management: Immobilize the limb and seek medical help.
• Nosebleeds: Pinch the nose's soft part and lean forward.