nutrition and digestive system

• Nutrient Procurement and Processing

  1. Nutrient definition

  2. Autotrophs vs Heterotrophs

  3. Nutritional requirements of plants

  4. Absorption routes in plants

  5. Specialized absorptive structures

  6. Nutritional adaptation by plants

  7. Concept of calories from food

  8. Digestion and absorption in animals
• 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 can produce their own food
  • Obtain energy from sunlight or inorganic chemicals and convert it into organic compounds through photosynthesis or chemosynthesis
• Autotrophs


  • Plants
  • Chemosynthetic bacteria
• Heterotrophs


  • Organisms that cannot synthesize their own food and rely on other organisms for their energy and nutrient requirements
• Heterotrophs


  • Animals
  • Fungi
• Nutritional requirements of plants

  • Water
  • Carbon Dioxide (CO2)
  • Macronutrients
  • Micronutrients
• Macronutrients


  Required in relatively large amounts, typically present in plant tissues above 0.5% of the plant's dry weight
• Micronutrients


  Essential nutrients required in minute or trace amounts by plants
• Absorption routes in plants

  1. Symplast route

  2. Apoplast route
• Symplast route


  • Movement of water and minerals through the symplast (interconnected cytoplasmic continuum of plant cells)
  • Utilizes plasmodesmata (cytoplasmic channels connecting adjacent cells)
  • Reaches the endodermis and crosses the Casparian strip
  • Enters the xylem
• Apoplast route


  • Movement of water and minerals through the cell walls and intercellular spaces
  • Bypasses the endodermis
  • Enters the xylem
• Root hairs


  • Slender extensions of specialized epidermal cells that significantly increase the surface area for nutrient absorption
• Root nodules


  • Localized swellings on the roots of legumes, formed due to a symbiotic relationship with nitrogen-fixing bacteria
  • Bacteria convert atmospheric nitrogen into a form usable by the plant
  • Plant provides carbohydrates and other organic compounds to the bacteria
• Mycorrhizae


  • Mutually beneficial association between plant roots and certain types of fungi
  • Enhances nutrient uptake, particularly for less accessible minerals
  • Ectomycorrhizae and Endomycorrhizae (Arbuscular mycorrhizae)
• Symbiosis of plants and soil microbes

  • Nitrogen fixation by bacteria in root nodules
  • Phosphorus and nutrient acquisition by mycorrhizal fungi
• Symbiosis of plants and fungi

  • Mycorrhizal fungi enhance the plant's ability to absorb water and nutrients, especially phosphorus and other minerals
  • Plant supplies carbohydrates to the fungi
• Parasitism


  • Some plants obtain nutrients from other living organisms by parasitic relationships, using specialized structures like haustoria to extract water, minerals, and carbohydrates
• Parasitic plants


  • Mistletoe
  • Dodder
• Predation


  • Some carnivorous plants capture and digest small animals to acquire additional nutrients like nitrogen
• Carnivorous plants


  • Venus flytrap
  • Pitcher plant
• Calorie


  A unit of energy that indicates the amount of energy contained in food, specifically the amount of heat energy required to raise the temperature of 1 kg (2.2lb.) of water by 1oC (1.8oF)
• Parasitic plants


  Extract nutrients from the host plants they attach themselves to, often have specialized structures like haustoria to penetrate the host's tissues and extract water, minerals, and carbohydrates
• Parasitic plants


  • Mistletoe
  • Dodder
• Carnivorous plants


  Have specialized structures to attract, trap, and digest insects and other small organisms to obtain additional nutrients like nitrogen
• Carnivorous plants


  • Venus flytrap
  • Pitcher plant
• The greater the number of Calories in a quantity of food, the greater energy it contains
• Macronutrients


  Carbohydrates, proteins, and fats, which provide energy when metabolized
• Carbohydrates


  Provide approximately 4 calories per gram
• Proteins


  Provide approximately 4 calories per gram
• Fats


  Provide approximately 9 calories per gram
• Alcohol


  Provides approximately 7 calories per gram
• Essential amino acids


  Amino acids that cannot be synthesized by the human body and must be obtained from food
• Essential amino acids


  • Lysine
  • Tryptophan
  • Threonine
  • Methionine
  • Phenylalanine
  • Leucine
  • Isoleucine
  • Valine
• Essential fatty acids


  Fatty acids that are required for making special membrane lipids and cannot be synthesized by the body
• Vitamins


  Organic molecules required in small amounts for normal metabolism
• Fat-soluble vitamins


  • Vitamin A
  • Vitamin D
  • Vitamin E
  • Vitamin K
• Water-soluble vitamins


  • Vitamin B
  • Vitamin B2
  • Vitamin B3
  • Vitamin B12
  • Vitamin C
• Trace elements or minerals


  Inorganic nutrients needed by the body in minute amounts, forming part of enzymes, body tissues, and body fluids