w9 gen bio

• Nutrient


  Any substance required for the growth and maintenance of an organism
• Types of organisms based on mode of nutrition

  • Autotrophs
  • Heterotrophs
• Autotrophs


  • Obtain energy from sunlight and chemicals to produce their own food
  • Examples: plants, chemosynthetic bacteria
• Heterotrophs


  • Cannot make their own food and obtain their energy from other organisms
  • Examples: animals, fungi
• Nutritional requirements of plants

  • Water
  • Carbon dioxide
• Water and carbon dioxide are the raw materials needed for photosynthesis, the process by which plants convert the energy from sunlight into chemical energy
• Macronutrients


  Nutrients normally required in amounts above 0.5% of the plant's dry weight
• Micronutrients


  Nutrients required in minute or trace amounts
• Examples of macronutrients

  • C, H, O, N, K, Ca, Mg, P, S
• Examples of micronutrients

  • Cl, Fe, B, Mn, Zn, Co, Mo
• Calorie


  A unit of energy that indicates the amount of energy contained in food
• The greater the number of Calories in a quantity of food, the greater energy it contains
• Carbohydrates


  • Serve as a major energy source for the cells in the body
  • Usually obtained from grains, cereals, bread, fruits, and vegetables
  • Contain 4 Calories per gram
• Proteins


  • Can be used as an energy source but the body mainly uses these as building materials for cell structures and as enzymes, hormones, parts of muscles, and bones
  • Come from dairy products, poultry, fish, meat, and grains
  • Contain 4 Calories per gram
• Fats


  • Used for building cell membranes, steroid hormones, and other cellular structures
  • Used to insulate nervous tissue, and also serve as an energy source
  • Contain certain fat-soluble vitamins that are important for good health
  • Obtained from oils, margarine, butter, fried foods, meat, and processed snack foods
  • Contain about 9 Calories per gram
• Essential nutrients


  Substances that animals can only get from the foods they eat because they could not be synthesized inside the body
• Essential nutrients


  • Essential amino acids
  • Essential fatty acids
  • Vitamins
  • Trace elements or minerals
• Essential amino acids


  • Needed for the synthesis of proteins and enzymes
  • Eight could not be synthesized by humans: lysine, tryptophan, threonine, methionine, phenylalanine, leucine, isoleucine, and valine
• Essential fatty acids


  • Used for making special membrane lipids
  • Example is linoleic acid in humans
• Vitamins


  • Organic molecules required in small amounts for normal metabolism
  • Examples include fat-soluble Vitamins A, D, E, K, and water-soluble Vitamins B, B2, B3, B12, C
• Trace elements or minerals


  • Inorganic nutrients needed by the body in minute amounts
  • Form part of enzymes, body tissues, and body fluids
  • Examples include iodine, cobalt, zinc, molybdenum, manganese, selenium
• Types of endocytosis


  • Phagocytosis
  • Pinocytosis
  • Receptor-mediated endocytosis
• Phagocytosis


  • Engulfment of organic fragments of big particles
  • Example: pseudopod formation in Amoeba
• Pinocytosis


  • Uptake of extracellular fluid by a cell using small vesicles derived from the plasma membrane
• Receptor-mediated endocytosis


  • Relies on membrane receptor recognition of specific solutes which are then taken up by the cell via receptor-coated pits
• Types of union of gametes

  • Isogamy
  • Heterogamy
• Isogamy


  • Fusion of similar gametes which are usually motile
• Heterogamy


  • Animal sperm and egg as examples
• Stages of the human digestive system

  • Ingestion
  • Digestion
  • Absorption
  • Elimination
• Ingestion


  • The act of eating or feeding; this is coupled with the mechanical breakdown of food into smaller pieces allowing for a greater surface area for chemical digestion
• Digestion


  • Breakdown of food into particles, then into nutrient molecules small enough to be absorbed; chemical digestion by enzymes involves breaking of chemical bonds through the addition of water, i.e., enzymatic hydrolysis
• Absorption


  • Passage of digested nutrients and fluid across the tube wall and into the body fluids; the cells take up (absorb) small molecules such as amino acids and simple sugars
• Elimination


  • The expulsion of the undigested and unabsorbed materials from the end of the gut