food chain

Examples of food chain in the following topics:

• Food Chains and Food Webs

  • A food web describes the flow of energy and nutrients through an ecosystem, while a food chain is a linear path through a food web.
  • A single path of energy through a food web is called a food chain.
  • It is rare to find food chains that have more than four or five links because the loss of energy limits the length of food chains .
  • These are the trophic levels of a food chain in Lake Ontario.
  • Distinguish between food chains and food webs as models of energy flow in ecosystems

• Strategies for Acquiring Energy

  • It is important to understand how organisms acquire energy and how that energy is passed from one organism to another through food webs and their constituent food chains.
  • Food webs illustrate how energy flows directionally through ecosystems, including how efficiently organisms acquire it, use it, and how much remains for use by other organisms of the food web.
  • These ecosystems are often described by grazing food webs.
  • Heterotrophs function as consumers in the food chain; they obtain energy in the form of organic carbon by eating autotrophs or other heterotrophs.
  • Unlike autotrophs, heterotrophs are unable to synthesize their own food.

• Protists as Primary Producers, Food Sources, and Symbionts

  • Protists function as sources of food for organisms on land and sea.
  • Some protist species are essential components of the food chain and are generators of biomass.
  • Protists do not only create food sources for sea-dwelling organisms.
  • Virtually all aquatic organisms depend directly or indirectly on protists for food.

• Transferring of Energy between Trophic Levels

  • The low efficiency of energy transfer between trophic levels is usually the major factor that limits the length of food chains observed in a food web.
  • Incomplete ingestion refers to the fact that some consumers eat only a part of their food.
  • Thus, NPE measures how efficiently each trophic level uses and incorporates the energy from its food into biomass to fuel the next trophic level.
  • The inefficiency of energy use by warm-blooded animals has broad implications for the world's food supply.
  • This food web shows the interactions between organisms across trophic levels in the Lake Ontario ecosystem.

• Lipid Molecules

  • In a fatty acid chain, if there are only single bonds between neighboring carbons in the hydrocarbon chain, the fatty acid is said to be saturated.
  • In the food industry, oils are artificially hydrogenated to make them semi-solid and of a consistency desirable for many processed food products.
  • Many fast food restaurants have recently banned the use of trans fats, and food labels are required to display the trans fat content.
  • Saturated fatty acids have hydrocarbon chains connected by single bonds only.
  • A cis double bond causes a kink in the chain.

• Waxes

  • Waxes are a type of long chain nonpolar lipid.
  • Natural waxes are typically esters of fatty acids and long chain alcohols.
  • Plant waxes are derived from mixtures of long-chain hydrocarbons containing functional groups such as alkanes, fatty acids, alcohols, diols, ketones, and aldehydes.
  • Unlike most natural waxes, which are esters, synthetic waxes consist of long-chain hydrocarbons lacking functional groups.
  • They are also used in foods like chewing gum.

• Digestion and Absorption

  • Digestion is the mechanical and chemical break down of food into small organic fragments.
  • In chemical digestion, enzymes break down food into the small molecules the body can use.
  • The salivary enzyme amylase begins the breakdown of food starches into maltose, a disaccharide.
  • As the food travels through the esophagus to the stomach, no significant digestion of carbohydrates takes place.
  • The bile salts surround long-chain fatty acids and monoglycerides, forming tiny spheres called micelles.

• The Energy Cycle

  • But if plants make carbohydrate molecules, why would they need to break them down, especially when it has been shown that the gas organisms release as a "waste product" (CO2) acts as a substrate for the formation of more food in photosynthesis?
  • In addition, an organism can either make its own food or eat another organism; either way, the food still needs to be broken down.
  • Finally, in the process of breaking down food, called cellular respiration, heterotrophs release needed energy and produce "waste" in the form of CO2 gas.
  • Both processes use electron transport chains to capture the energy necessary to drive other reactions.

• Types and Functions of Proteins

  • Salivary amylase is an enzyme in the mouth that breaks down starch (a long carbohydrate chain) into amylose (a short chain of glucose molecules).
  • These long chains of amino acids are critically important for:
  • Sometimes these folded polypeptide chains are functional by themselves.
  • Other times they combine with additional polypeptide chains to form the final protein structure.
  • Enzymes are essential for digestion: the process of breaking larger food molecules down into subunits small enough to diffuse through a cell membrane and to be used by the cell.

• Carbohydrate Molecules

  • A long chain of monosaccharides linked by glycosidic bonds is known as a polysaccharide (poly- = "many").
  • The chain may be branched or unbranched, and it may contain different types of monosaccharides.
  • The starch in the seeds provides food for the embryo as it germinates while the starch that is consumed by humans is broken down by enzymes into smaller molecules, such as maltose and glucose.
  • Aldoses have a carbonyl group (indicated in green) at the end of the carbon chain, and ketoses have a carbonyl group in the middle of the carbon chain.
  • In cellulose, glucose monomers are linked in unbranched chains by β 1-4 glycosidic linkages.