II. Digestion & Nutrition

• Digestion - process by which the body breaks down food into smaller, absorbable components that can be used for energy, growth, and repair
• AUTOTROPH

  • Producer
  • organisms that use energy from the sun to produce food
• HETEROTROPH

  • Consumer
  • organisms that cannot make their own food; must obtain energy from outside sources
• PLANTS: DIGESTION AND NUTRITION

  A) Photosynthesis

  B) Root Absorption

  C) Transport

  D) Assimilation

  
• PLANTS: DIGESTION AND NUTRITION

  • Plants do not have a digestive system like animals. Instead, they rely on a combination of physical and chemical processes to break down nutrients and absorb them.
  • Root hairs increase the surface area for absorption.
  • Xylem - Pathway of water throughout plants. + From bottom to top.
  • Phloem - Pathway of nutrients and glucose produced during throughout plants. photosynthesis + From bottom to top and vice versa.
• PLANTS: DIGESTION AND NUTRITION

  Soil

  • Plays a crucial role in plant nutrition, providing a medium for plant growth and serving as a reservoir of essential nutrients.
  • Not only anchors plant but also supplies them with water, minerals, and other elements, necessary for growth and development.

  A) Roles of Soil

  
• Role of Soil Charge in Transport

  • Soil plays a critical role in the transport of minerals by influencing nutrient retention, availability, and uptake from the soil.
  • Only minerals that are dissolved in water in the spaces or pores among soil particles are available for uptakes by roots.
  • Low concentration to High concentration

  
• Plant Nutrients

  • Photosynthesis is major source of plant nutrition via the fixation of CO2 into sugar using solar energy
  • Also need Macronutrients – used in relatively large amounts.
  • Nine = C, O, H, N, K, Ca, Mg, P, and S.
  • Micronutrients – used in minute amounts.
  • Seven = Cl, Fe, Mn, Zn, B, Cu, and Mo.
  • Deficiency of any one can have severe effects on plant growth.
• Mineral Deficiencies in Plants

  • Mg - yellowing between the veins; leaves are raised and bumpy
  • N - Light yellow leaf
  • Zn - brown spots between the veins
  • K - brown spots at the tip
  • Cu - curled leaves
• Identifying Nutritional Requirements

  Hydroponics

  • A method of growing plants without soil, where nutrient-rich water is used to deliver essential minerals and nutrients directly to the plant roots
  • Allows plants to grow well if they are supplied with all the nutrients they need
• Special Nutritional Strategies

  Rhizobium

  • Plants need ammonia (NH3 ) or nitrate (NO3 ) to build amino acids
  • However, they lack the biochemical pathways necessary to convert N2 in the atmosphere into NH3 .
  • Symbiotic relationships have evolved between plants and nitrogen-fixing bacteria
  • Legumes form nodules that house the bacterium Rhizobium
• Special Nutritional Strategies

  Mycorrhizae

  • Symbiotic associations with mycorrhizal fungi are found in about 90% of vascular plants
  • Substantially expand the surface area available for nutrient uptake.
  • Play a significant role in enhancing phosphate transfer to the plant
  • Uptake of some micronutrients is also facilitated
• Hyphae

  • Network of the roots of fungi
  • Absorbs nutrients, water, and mineral to transfer to the plants
  • Plants:Roots ; Fungi:Hyphae
• Special Nutritional Strategies

  Carnivorous Plants

  • Often grow in acidic soils that lack nitrogen Prey is digested with enzymes secreted from specialized glands
  • Ex. Asian pitcher plant (Nepenthes)
  • Trap and digest small animals, primarily insects, to obtain adequate nitrogen supplies.
  • Ex. Venus Flytrap
  • Have modified leaves adapted for luring and trapping prey
  • Ex. Sundew (Drosera)
• Special Nutritional Strategies

  Parasitic Plants

  • May be photosynthetic or non-photosynthetic
  • At least 3,000 types of plants
  • Tap into the nutrient resources of other plants
  • Adaptations include structures that are inserted into the vascular tissue of the host plant so that nutrients can be siphoned into the parasite
  • Examples include dodder and Indian pipe
• DIGESTIVE SYSTEM

  • Includes all the organs, tissues, and cells involved in ingesting food and breaking it down into smaller components.
  • Contributes to homeostasis by providing body with nutrients needed to sustain life of cells.

  A) Absorbs

  B) Eliminates

  C) Ingest

  D) Breaks

  
• INCOMPLETE DIGESTIVE TRACT

  • An incomplete digestive tract has a single opening used as an entrance for food and exit for wastes.
  • Also known as a sac-like or blind digestive system

  A) Planarian

  
• COMPLETE DIGESTIVE TRACT

  • A complete digestive tract has two openings.

  A) Earthworm

  
• INGESTION

  • Process by which an organism takes in food or other substances into its body for various purposes, such as obtaining nutrients, energy, or even for defensive mechanisms
  • Heterotrophs are divided into three groups based on their food sources

  A) Herbivores

  B) Carnivores

  C) Omnivores

  
• ADAPTATIONS TO DIET (Dentition differs with mode of nutrition)

  Herbivores.

  • Eat only plants.
  • Incisors for clipping.
  • Premolars and molars for grinding.
  • Land snails and some insects are herbivores.
  • Koalas, which are mammals, eat only eucalyptus leaves.
  • Grazers, like horses, feed on grasses.
  • Ruminants, like cattle, goats, and sheep, have a four-chambered stomach which allows them to regurgitate solid material for complete digestion.

  
• ADAPTATIONS TO DIET (Dentition differs with mode of nutrition)

  Carnivores.

  • Eat only other animals.
  • Pointed incisors and enlarged canines.
  • Shear off pieces small enough to swallow.
  • Spiders and sea stars are carnivores.
  • Dogs, lions, and dolphins are carnivores.
  • The lion’s pointed canine teeth are used for killing, sharp incisors for scraping bones, and pointed molars for slicing flesh.

  
• ADAPTATION TO DIET (Dentition differs with mode of nutrition)

  Omnivores.

  • Variety of specializations to accommodate both vegetation and meat.
  • Clams and tube worms are invertebrate omnivores.
  • Humans, pigs, raccoons, and most bears are omnivores.
  • Dentition of the above is specialized to accommodate vegetable and meat diet.
  • Better ability to adapt to different food sources.

  
• INGESTION: Mouth and Teeth

  • Many vertebrates have teeth used for chewing or mastication

  Birds

  • Lack teeth
  • Break up food in a two-chambered stomach
  • Gizzard – muscular chamber that uses
  • ingested pebbles to pulverize food
• MECHANICAL DIGESTION - grinding, chewing, and swallowing of food (bolus)
• PARTIAL CHEMICAL DIGESTION - secretion of saliva and amylase by salivary glands
• CHEMICAL DIGESTION

  • enzyme-mediated and hydrolytic process of breaking large food molecules into smaller units enough for the body to absorb
  • occurs in the stomach and small intestine
• Absorption - The complete digestion and absorption of nutrients occurs in the small intestine.
• Duodenum - receives chyme and secretions from the liver, gallbladder, and pancreases
• Jejunum - site of nutrients being digested and absorbed
• Ileum - absorbs some nutrients; delivers unabsorbed material to the large intestine
• ELIMINATION

  • Feces composed of water, undigested and unabsorbed matter, and bacteria are formed in the large intestine.
  • These move through the colon, stored in the rectum, and eliminated in the anus.
• MONOGASTRIC DIGESTIVE SYSTEM

  • Example: Humans, dogs, etc.
  • Characteristics:

  1. Have a single-chambered stomach
  2. Digestion primarily occurs in the stomach, where gastric juices break down food.
  3. Nutrient absorption occurs in the small intestine.
• RUMINANT DIGESTIVE SYSTEM

  • Example: cows, sheep, and deer,
  • Characteristics:

  1. have a complex stomach with four compartments: rumen, reticulum, omasum, and abomasum.
  2. foregut fermentation, where microbes in the rumen break down fibrous plant material before it enters the true stomach (abomasum) for further digestion and absorption.
• NONRUMINANT DIGESTIVE SYSTEM

  • Example: horses, rabbits, guinea pigs, and elephants, etc.
  • Characteristics:

  1. single-chambered stomach, similar to that of humans.
  2. enlarged cecum and colon
  3. sites for microbial fermentation of fibrous plant materials • esults in the production of volatile fatty acids (VFAs), which can serve as an energy source for the animal.
  4. involves enzymatic breakdown of carbohydrates, proteins, and fats
• AVIAN DIGESTIVE SYSTEM

  • Example: birds
  • Characteristics: beak of birds is adapted for various feeding habits
• • The crop is a storage pouch that temporarily store ingested food before it moves to the stomach for digestion.
  • The proventriculus, also known as the glandular stomach, that secretes gastric juices and enzymes to initiate the chemical breakdown of food.
• • The gizzard is a muscular organ that acts as a powerful grinding chamber, breaking down tough food particles, such as seeds and grains, with the help of ingested grit (small, hard particles like stones).
  • The cloaca is the common chamber into which the digestive, urinary, and reproductive systems empty
• Magnesium is part of the Chlorophyll molecule
• Pepsinogen – breaking down of proteins into amino acids