SNS - Biology - Digestion Flashcards
1
Q
Unicellular Organisms
Amoeba
A
- Phagocytosis to form food vaculoes.
- Lysosomes fuse with these, releasing digestive enzymes
- Simpler molecules formed diffuse into the cytoplasm and unusable end products are subsequently eliminated from the vacuole
2
Q
Unicellular Organisms
Paramecium
A
- Cila sweep food into the oral groove and cytopharynx
- Food vacuole forms at lower end of cytophaynx
- Eventually breaks of into the cytoplasm and progresses towards the anterior end of the cell
- Enzymes are secreted into the vacuole and the products diffuse into the cytoplasm
- Solid wastes are expelled at the anal pore
3
Q
Invertebrates
Cnidarians
A
- Hydra use intracellular and extracellular digestion
- Tenticles bring food to the mouth (ingestion) and release the particles into cup-like sac.
- Endodermal cells lining this gastrovascular cavity secrete enzymes into it
- Thus digestion is principally extracellular, however once food is reduced to small fragments, are engulfed by gastrodermal cells and digestion completed intracellularly
- Undigested food expelled via the mouth
4
Q
Invertebrates
Annelids
A
- One-way digestive tract with mouth and anus
- Different parts specialised for different functions
- Soluble nutrients diffuse via walls of small intestine into the blood
5
Q
Invertebrates
Arthropods
A
Insects have digesitve systems similar to those of the earthworm
They also have a jaw for chewing and salivary glands which aid digestion
6
Q
Invertebrates
- Crop
- Gizzard
- Typholosole
A
- Stores food
- Grinds food
- Large dorsal fold of intestine to increase surface area for digestion and absorption
7
Q
Humans
Mouth
A
- Mechnical digestion
- Chemical digestion - amylase - converts starch to maltose
8
Q
Humans
Stomach
A
- Mucous - protects stomach lining
- Pepsin - hydorlysis proteins
- HCl - breakdown of food, activates enzymes such as pepsin
Chyme produced passes into duodenum of small intestine via pyloric sphincter
9
Q
Humans
Small Intestine
Villi
A
- Contain capillaries and lacteals (vessels of lymphatic system)
- AAs and monosaccharides pass via villi walls into capillary system
- Large FAs and glycerol pass into lacteals and are then reconverted into fats
- Some nutrients actively absorbed (eg glucose, AAs) others passively absorbed
10
Q
Humans
Small Intestine
A
- Duodenum - site of most dgestion in small intestine
- Jejunum
- Ileum
11
Q
Humans
Small Intestine
Enzymes
A
- Lipases - fats
- Aminopeptidases - polypeptides
- Disaccharidases - maltose, lactose, sucrose
12
Q
Humans
Liver
A
- Produces bile which is stored in gallbladder
- Emulsifies fats, breaking down larger globules into small droplets increasing surface area for action of pancreatic lipase
13
Q
Humans
Pancreas
A
- Has exocrine function which produces enzymes such as amylase (carbs), trypsin (proteins) and lipase
- Secretes bicarbonate-rich juice which neutralises acidic chyme - pancreatic enzymes act optimally at this higher pH
14
Q
Humans
Large Intestine
A
- Absorption salts and water not already absorbed by small intestine
- Rectum provides transient storage of faeces
15
Q
Plants and Fungi
Intracellular Digestion
A
- Plants store insoluble polymers, lipids, starches and proteins in cells
- Broken down when required by enzyme hydrolysis
- Products can be used in storage cell itself or diffuse to others
