Unit 2 (2.4) Flashcards
Adaptations for nutrition
Define autotrophic
Organism that produces its own food. Manufactures complex organic compounds from simpler inorganic molecules such as water and carbon dioxide.
Name the two types of autotrophic organisms
Photoautotrophic
Heterotrophic
What is a phototrophic organism?
An organism which obtains its nutrition through photosynthesis.
What is a chemoautotrophic organism?
An organism which obtains its nutrition through inorganic molecules, such as sulphur, in the absence of light
Define heterotrophic
An organism that cannot produce its own food. It obtains energy by feeding on organic compounds produced by other organisms.
What is a saprotroph?
An organism that feeds by extracellular digestion, eg. fungi
Describe extracellular digestion by saprotrophs
Releases enzymes which catalyse the breakdown of dead plant and animal material into simpler organic matter.
Absorbs the products of digestion
What is mechanical digestion?
Physically breaking down food into smaller pieces, increases SA for chemical digestion
Two types of digestion
Mechanical
Chemical
What does holozoic nutrition involve?
Ingestion, digestion, absorption, assimilation and egestion
What does the term holozoic mean?
Describes a heterotrophic organism that internally digests food substances
What is chemical digestion?
A type of digestion that involves breaking down large, insoluble molecules into smaller, soluble, molecules using enzymes
What is absorption?
The movement of useful substances into the blood stream.
What is egestion?
The removal of undigested waste material from the body.
How do unicellular organisms obtain nutrients?
-Ingestion via phagocytosis
-Intracellular digestion
- Products of digestion pass into cytoplasm by diffusion and active transport
-Undigested material removed by exocytosis
What is intracellular digestion?
Breaks down large, insoluble molecules into smaller, soluble molecules.
What is a hydra?
A small, multicellular, fresh water organism of the phylum Cnidaria
Structure of a Hydra?
-Basic, undifferentiated sac-like gut
-Single opening, surrounded by tentacles, serves as mouth and anus
- single gut cavity known as enteron
What is holozoic nutrition?
The internal digestion of food substances
Describe the shape of the gut in more complex organisms?
Tube-like with two openings, a mouth for ingestion and anus for egestion.`
What type of diet is the human gut adapted to?
An omnivorous diet consistent of plant and animal material.
What are the names of the different layers of the gut wall?
Epithelium
Mucosa
Submucosa
Muscle layer
Serosa
What is the epithelium?
A single layer of cells that line the gut wall
Structure of mucosa
Mucous membrane, contains glands that secrete digestive enzymes, mucus and an acid or alkaline liquid that provides an optimum pH.
Structure of submucosa
layer of connective tissue below the mucous membrane
Describe muscle layer
A layer of circular and longitudinal muscles beneath the submucosa.
Action of circular and longitudinal muscles in peristalsis
The contraction of circular muscle behind the bolus of food and the relaxation of the longitudinal gut muscle in front forces the food down.
What is the serosa?
Tough protective layer that surrounds the gut
What is the buccal cavity?
The oral cavity through which food enters the body
