Biology - Digestion Flashcards
what are heterotrophs?
organisms that cannot make their own food
where does external digestion take place?
in a lumen or tract
where does internal digestion take place?
in a membrane-bound vesicle
how do unicellular organisms ingest food?
phagocytosis
where is food stored in unicellular organisms like amoeba?
food vacuoles
what are lysosomes?
they contain digestive enzymes and fuse with food vacuoles to digest nutrients
what is the “mouth” of the paramecium called?
cytopharynx
where do the needed nutrients diffuse to in paramecium and amoeba?
the cytoplasm
does the molecular composition of food change in the mouth when it is being chewed?
no….the surface area is increased
what kind of digestion do cnidarians (hydra) use?
both internal and external
what releases digestive enzymes in cnidarians?
endodermal cells lining the cavity
where is digestion completed in cnidarians?
intracellularly once food it engulfed by the gastrodermal cells
where is undigested food expelled in cnidarians?
the mouth
what digestive system do annelids have?
a one-way digestive tract
what is the crop of an annelids?
stores food
what is the gizzard of an annelids?
grinds the food
where is the dorsal fold of the annelids? what does it do?
in the intestine; it provides more SA; called the typholosole
what happens to soluble nutrients in annelids?
they diffuse into the blood from the small intestine
what do arthropods have in their digestive system that annelids don’t have?
jaw for chewing and salivary glands
trace the human digestive tract.
oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, anus
what happens in the oral cavity during digestion?
mechanical and chemical digestion of food
when is saliva secreted?
in response to a nervous reflex triggered by the presence of food
what enzyme in the mouth hydrolyzes starch to maltose?
salivary amylase
how is food moved through the esophagus?
peristalsis
what do the glands lining the stomach wall secrete in digestion?
mucus, pepsin and HCl
what does mucus do in the stomach?
protects the lining from acidic juices
what does pepsin do in digestion?
protein-hydrolyzing enzyme
what does HCl do in digestion?
kills bacteria, breaks food apart, and activates other enzymes
where does chyme go after the stomach?
through the pyloric sphincter to the duodenum of the small intestine
what are the 3 sections of the small intestine?
duodenum, jejunum and ileum
how does the small intestine maximize SA?
coiling and length and villi
what are lacteals? where are they located?
in the small intestine villi; they are vessels of the lymphatic system
what molecules pass through the villi and enter the capillary system?
monosaccharides and amino acids
what molecules are passes into the lacteals? why?
fatty acids and glycerol….to be converted into fat
what molecules are passively absorbed?
glucose and amino acids
where does most digestion in the small intestine take place?
duodenum
what do lipases digest?
fats
what do amino peptidases digest?
polypeptides
what does lactase do?
breaks down lactose
what causes discomfort for people who are lactose intolerant?
they lack lactase so bacteria metabolizes lactose instead
where is bile produced?
liver
where is bile stored?
gall bladder
does bile have enzymes?
no
what does bile do?
it emulsifies fats into small droplets
name 3 enzymes secreted from the pancreas and their functions:
amylase (carbs)
trypsin (protein)
lipase (fat)
what pH do pancreatic enzyme require?
not acidic….the bicarb juice neutralizes the chyme
what does the large intestine absorb?
water and salts
what holds feces?
the rectum
what plant example needs preformed molecules from the environment?
fungi
is the venus fly trap an autotroph or heterotroph?
autotroph because it photosynthesizes to make glucose; the flies are simply a nitrate source
