4th quarter biology reviewer

• Four key processes underlying development


  • Determination
  • Differentiation
  • Morphogenesis
  • Growth
• Determination


  Sets the developmental fate of a cell—what type of cell it will become—even before any characteristics of that cell type are observable
• Differentiation


  The process by which different types of cells arise from less specialized cells, leading to cells with specific structures and functions
• Morphogenesis


  The organization and spatial distribution of differentiated cells into the multicellular body and its organs
• Morphogenesis


  • Can occur by cell division, cell expansion (especially in plants), cell movements, and apoptosis (programmed cell death)
• Growth


  The increase in size of the body and its organs by cell division and cell expansion
• Growth


  • Can occur by an increase in the number of cells or by the enlargement of existing cells
  • Continues throughout the individual's life in some organisms, but reaches a more or less stable end point in others
• Essential features of human reproduction


  • Liberation of an ovum, or egg, at a specific time in the reproductive cycle
  • Internal fertilization of the ovum by spermatozoa, or sperm cells
  • Transport of the fertilized ovum to the uterus, or womb
  • Implantation of the blastocyst, the early embryo developed from the fertilized ovum, in the wall of the uterus
  • Formation of a placenta and maintenance of the unborn child during the entire period of gestation
  • Birth of the child and expulsion of the placenta
  • Suckling and care of the child, with an eventual return of the maternal organs to virtually their original state
• Nutrient


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


  • Autotrophs
  • Heterotrophs
• Autotrophs


  Organisms that obtain energy from sunlight and chemicals to produce their own food
• Autotrophs


  • Plants
  • Chemosynthetic bacteria
• Heterotrophs


  Organisms that cannot make their own food and obtain their energy from other organisms
• Heterotrophs


  • 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
• Essential nutrients or elements


  • Macronutrients
  • Micronutrients
• Macronutrients


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


  Required in minute or trace amounts
• Routes for absorption of water and minerals across plant roots


  • Symplast route
  • Apoplast route
• Symplast route


  Through plasmodesmata
• Apoplast route


  Along cell walls
• The water and minerals from the soil need to reach the conducting tissues of plants, specifically the xylem
• Calorie


  A unit of energy that indicates the amount of energy contained in food. It specifically refers to the amount of heat energy required to raise the temperature of 1 kg (2.2 lb.) of water by 1oC (1.8oF).
• The greater the number of Calories in a quantity of food, the greater energy it contains
• Nutritional requirements of animals


  • Carbohydrates
  • Proteins
  • Fats
  • Essential nutrients
• Carbohydrates


  Serve as a major energy source for the cells in the body. Usually obtained from grains, cereals, breads, fruits, and vegetables. On average, 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. Proteins come from dairy products, poultry, fish, meat, and grains. Like carbohydrates, contain 4 Calories per gram.
• Fats


  Used to build cell membranes, steroid hormones, and other cellular structures; also used to insulate nervous tissue, and also serve as an energy source. Fats also contain certain fat-soluble vitamins that are important for good health. Fats are obtained from oils, margarine, butter, fried foods, meat, and processed snack foods. They contain a higher amount of energy per gram than carbohydrates or proteins, about 9 Calories per gram.
• Essential nutrients


  • Essential amino acids
  • Essential fatty acids
  • Vitamins
• Essential amino acids


  Needed for synthesis of proteins and enzymes; among the 20 amino acids, 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; an example is linoleic acid in humans.
• Vitamins


  • Fat-soluble Vitamins A, D, E, K
  • Water-soluble Vitamins B, B2, B3, B12, C
• Main stages of food processing


  • 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


  Expulsion of the undigested and unabsorbed materials from the end of the gut.
• Organs involved in food processing in the human digestive system


  • Oral cavity
  • Pharynx
  • Esophagus
• Oral cavity


  Where food is initially chewed into shreds by the teeth, and mixed with saliva by the tongue. Saliva is secreted into the mouth by three pairs of salivary glands located above the upper jaw and below the lower jaw.