Bio 2

• Reproduction is a biological process where organisms produce another of their kind, improving their species and enhancing physical characteristics
• Reproduction can be asexual or sexual, with asexual reproduction not involving gametes or sex cells, observed in some plants and lower animals
• Sexual reproduction involves the union of gametes (sperm and egg cell) inside or outside the body, exhibited by higher organisms like humans
• In sexual reproduction, the sperm and egg fuse to create a fertilized egg (zygote) which becomes the embryo
• Plants and animals share similarities in reproduction, using color display for attraction, but differ in fertilization methods and physical interactions
• Animals exhibit sexual selection where males compete to copulate with females, aiding successful gene transfer to the next generation
• Plants and animals have different methods of fertilization, with animals requiring physical interaction and plants needing vectors like insects or birds
• Plants and animals have different ways of reproduction but share the main goal of extending their species
• Based on phylogenetic evidence, the primitive ancestor of plants and animals was likely a unicellular eukaryote
• During development, plant cells are positionally fixed while animal cells are motile, and plant body plans are regulated by the environment while animal body plans are determined by genes
• Most plants undergo alternation of generations, having sexual and asexual life cycles, while animal life cycles have one continuous multicellular stage after fertilization
• Plants produce spores before forming gametes during meiosis, while animals directly form gametes
• Plants develop through a longer period of morphogenesis than animals, growing continuously until death, while animals develop into a distinct body shape during adulthood
• Plants grow by increasing cell size, animals grow by increasing cell number
• Nutrition is the process of providing food necessary for health, survival, and growth of an organism
• Nutrients obtained from food provide energy for metabolic processes like growth, maintenance, reproduction, and immunity
• Organisms can be autotrophic, synthesizing their own nutrients, or heterotrophic, obtaining energy by digesting organic matter
• Photoautotrophic organisms use energy from the sun and inorganic substances to form organic food, while chemoautotrophic organisms use chemicals for survival
• Heterotrophic organisms cannot make their own food and obtain energy by digesting organic matter, classified into saprophytic, parasitic, and holozoic nutrition
• Saprophytic organisms obtain nutrients from dead organic matter by secreting digestive juices, like fungi and bacteria
• Parasitic organisms take food from another organism, either outside (ectoparasitism) or inside (endoparasitism) the host
• Holozoic nutrition involves ingesting solid or liquid food, digesting and absorbing it, subdivided based on the type of organic matter ingested
• The endocrine system is made up of glands that secrete hormones into the bloodstream.
• Gas exchange is an important biological process that allows organisms to survive by transferring different gases in opposite directions across a respiratory surface
• Different organisms have various ways of exchanging gases inside and outside their bodies, ranging from the simplest to the most complex respiratory systems
• Structures used for gas exchange in animals:

  • Cell membrane: used by unicellular organisms for gas exchange, where gases pass through via diffusion (e.g., bacteria)
  • Body surface / skin: covered with thin, moist epithelial cells allowing oxygen and carbon dioxide exchange (e.g., flatworms, frogs)
  • Gills: increase surface area for gas exchange in aquatic organisms, with convoluted outgrowths containing blood vessels (e.g., external gills in amphibians like axolotl, internal gills in fish)
  • Tracheal systems: composed of respiratory tubes carrying gases directly to cells for exchange, with openings at the body surface called spiracles (e.g., grasshoppers, cockroaches)
  • Lungs: complex respiratory organs in animals like humans
• Gas exchange in animals involves a system where oxygen diffuses into the blood from the respiratory surface, then transported to cells while carbon dioxide is absorbed into the bloodstream and released through the respiratory surface
• In plants, gas exchange mainly occurs in the leaves through specialized pores called stomata, controlled by guard cells that open and close the pores based on turgor pressure changes
• Roots and stems contribute to gas exchange in plants, with woody stems and mature roots having lenticels that provide a pathway for the direct exchange of gases between internal tissue and the atmosphere
• Plants and animals have circulatory systems to transport important particles and remove wastes, with plants using xylem and phloem for water, nutrients, and sugars transport, while animals have blood vessels and the heart to circulate blood carrying gases, nutrients, and wastes
• In animals, oxygen is taken into the bloodstream by combining with hemoglobin, while carbon dioxide is transported out of the body in the bloodstream after combining with hemoglobin
• Fluid regulation in plants involves processes like osmosis, transpiration, adhesion-cohesion property of water, and capillary action to regulate the amount of water entering and leaving the plant
• Fluid regulation in animals depends on their excretory systems and the concentration of water and mineral ions, with terrestrial and aquatic animals having different ways of regulating body fluids to maintain homeostasis
• Examples of pheromones include sex attractants, alarm pheromones, trail markers, and social bonding pheromones.
• Pheromones are chemical signals released by animals to communicate with others of their species.
• Endocrine cells release their products directly into the interstitial fluid or bloodstream to travel to target tissues where they bind with specific receptors on cell surfaces or inside cells.
• Hormones are chemical messengers produced by specialized cells called endocrine cells, which can be found throughout the body.
• Endocrine glands include the pituitary gland, thyroid gland, parathyroid gland, adrenal gland, pancreas, ovaries/testes, and pineal body.
• Higher forms of animals have complex forms of nervous control, while plants have parts that may be likened to certain nervous control mechanisms in animals
• Animals have a multifaceted and complex immune system capable of protecting them against invasive pathogens or disease-causing organisms