Bio Paper 2

• Homeostasis


  Maintenance of a stable internal environment despite external changes
• Importance of homeostasis


  • Ensures optimal conditions for enzyme action and cellular processes
  • Key to overall health and functionality of the organism
• Examples of homeostasis


  • Regulation of body temperature, blood glucose levels, and water balance
• Body temperature regulation


  1. Sweating and vasodilation to cool down

  2. Shivering and vasoconstriction to warm up
• Systems involved in homeostasis

  • Nervous and endocrine systems
• Nervous system


  Detects changes and coordinates immediate responses
• Endocrine system


  Regulates long-term changes through hormones
• Central Nervous System (CNS)


  Brain and spinal cord
• Peripheral Nervous System


  All other neural elements
• Functions of the nervous system

  • Detects stimuli from the environment
  • Processes information and coordinates appropriate responses
• Reflex actions


  Automatic and rapid responses to stimuli
• Reflex arc


  Pathway involving sensory neuron, relay neuron in the spinal cord, and motor neuron
• Example of reflex action


  • Pulling a hand away from a hot surface
• Endocrine system


  Comprises glands that secrete hormones into the bloodstream
• Hormones


  Act as chemical messengers affecting target organs
• Blood glucose regulation


  1. Insulin lowers blood glucose by facilitating its uptake into cells

  2. Glucagon increases blood glucose by stimulating the release of glucose from glycogen stores in the liver
• Type 1 Diabetes


  Insufficient insulin production
• Type 2 Diabetes


  Insulin resistance
• Treatments for diabetes


  • Insulin injections, dietary changes, and medications
• Reproductive hormones


  Regulate menstrual cycle and reproductive processes
• Key reproductive hormones


  Estrogen and progesterone
• Hormonal contraception methods


  • Birth control pills, patches, injections
• Hormonal contraception


  Prevent pregnancy by inhibiting ovulation or altering the uterine lining
• Infertility treatments


  • In Vitro Fertilization (IVF)
• Ethical considerations of manipulating hormonal levels
• Plant hormones


  Regulate plant growth and responses to environmental stimuli
• Tropisms


  • Phototropism: Growth towards light
  • Gravitropism: Growth in response to gravity
• Auxin


  Promotes cell elongation in response to light and gravity
• Commercial applications of plant hormones

  • Auxins used for rooting plant cuttings
  • Gibberellins promote stem elongation and fruit growth
  • Ethylene used to ripen fruits
• Plant hormones are widely used in agriculture and horticulture to improve crop yields and manage plant growth
• Asexual reproduction


  Single parent, genetically identical offspring
• Sexual reproduction


  Two parents, genetically diverse offspring
• Meiosis


  • Special cell division reducing chromosome number by half
  • Produces haploid gametes (sperm and eggs)
  • Introduces genetic variation through random assortment of chromosomes and crossing over
• DNA


  • Hereditary material in all living organisms
  • Structured as a double helix
  • Organized into chromosomes, segments called genes
• Genetic diagrams (Punnett squares)

  • Predict inheritance patterns
• Mutation


  • Changes in DNA introducing new genetic variants
  • Can be neutral, harmful, or beneficial
• Evolution


  Beneficial traits become more common over generations through natural selection
• Selective breeding


  Humans select parents with desirable traits to produce offspring with those traits
• Applications of selective breeding

  • Used in agriculture and animal breeding
• Genetic engineering


  Direct manipulation of an organism's DNA