nutrition (C3)

Question 1

Tooth type ( incisors, canines, pre molars and molars) functions

Answer 1

Incisors: biting and cutting
Canines: tearing and ripping meat
pre molars and molars: grinding and chewing

Question 2

Teeth functions

Answer 2

mechanical digestion

increase SA for enzyme action

Question 3

Herbivore diet and adaptations

Answer 3

• cellulose based ( difficult to digest )

- teeth adapted for GRINDING to increase SA for bacterial cellulase enzyme action

Question 4

Herbivore structural dentition features

Answer 4

HORNY PAD: grass wraps around tongue pulling across hp on upper jaw
INCISORS: slice through plant material
DIASTEMA: middle gap for large grinding surface
MOLARS: interlocking M and W for grinding
LOOSE ARTICULATION: side to side circular grinding action

Question 5

Carnivore dentition features

Answer 5

SMALL SHARP INCISORS: grip and tear flesh from bone
LARGE CURVED CANIES: seize and hold prey
PRE/MOLARS: cutting and crushing food
CARNASSIALS: slide like blades and crush bone
POWERFUL VERTICAL JAW: open wide without dislocation and grip prey

Question 6

Ruminant herbivore examples and diet

Answer 6

cows, goats and sheep

much cellulose yet unable to digest as lack of enzyme cellulase, they have a four chambered stomach

Question 7

Ruminant adaptations

Answer 7

Rely on mutalistic (rumin) bacterium living in gut which secrete cellulase enzymes, live in stomach chamber rumen - glucose fermentation occurs, digest cellulose to beta glucose

Question 8

Ruminant cellulose digestion

Answer 8

1. grass chewed, mixed with saliva, swallowed
2. passes into RUMEN, churned, mixed with bacteria secreting cellulase. b glucose absorbed in blood for energy
3. undigested grass passes to RETICULUM to form CUD that’s regurgitated to mouth for more chewing
4. cud passes to OMASUM where waters absorbed into blood
5. in ABOMASUM (true stomach) bacteria are killed and digested proving source of PROTEIN for animal

Question 9

Non ruminant herbivore example

Answer 9

rabbits

Question 10

Non ruminant adaptations (2)

Answer 10

CAECUM enlarged accommodating cellulose digestion bacteria

REFECTION occurs where rabbit ingests faecal pellets so material passes gut twice increasing digestion efficency

Question 11

Types of nutrition and sub categories

Answer 11

autotrophic ( photoautotrophic and chemoautotrophic)

heterotrophic ( holozoic, saprotrophic, parasitic )

Question 12

Autotrophic nutrition definition

Answer 12

organisms that synthesisze their own complex organic molecules from simpler molecules using either light (photo) or chemical (chemo) energy

Question 13

Photoautotrophic definition and examples

Answer 13

organisms use energy for sunlight to carry out photosynthesis to make organic molecules ( glucose) from inorganic, c02 and water
e.g green plants, algae, some bacteria

Question 14

Chemoautotrophic definition and examples

Answer 14

organisms using energy from chemical reactions to synthesize organic molecules
e.g bacteria respiring in DEEP sea HYDROTHERMAL VENTS

Question 15

Heterotrophic nutrition definition and types

Answer 15

organisms ( consumers ) cannot produce own organic molecules and so consume complex organic molecules from other organisms, break this material down to smaller soluble molecules which then absorb and assimilate

• holozoic
• saprotrophic
• parasitic

Question 16

Holozoic definition and examples

Answer 16

organisms INGEST food, DIGEST it, ABSORB into bloodstream, ASSIMILATE and EGEST indigestible remains - INTRACELLULAR digestion
e.g mostly animals, also some protoctista such as amoeba
includes:
CARNIVORNS ( flesh eating )
HERBIVORES ( plant eating )
OMNIVORES ( ‘all eaters’ significant in natural diet)
DETRITIVORES ( decomposing, dead or fecal organic matter )

Question 17

Holozoic unicellular organism example

Answer 17

AMEOBA - obtains nutrients such as oxygen and glucose through cell MEMBRANE, take in large food molecules via ENDOCYTOSIS and indigestible remains egested by EXOCYTOSIS, digestion is intacellular

Question 18

Holozoic simple multicellular organisms example

Answer 18

HYDRA - undifferentiated digestive system, prey is digested, absorbed and indigestible remains egested through same mouth (single opening digestive system)

Question 19

Saprotrophic nutrition definition and example

Answer 19

feed on dead or decaying organic material and carry out extracellular digestion, enzymes are secreted onto food material outside body, then absorb soluble products of digestion via diffusion or active transport
e.g fungi, some bacteria

Question 20

Parasitic nutrition definition and examples

Answer 20

organisms that live on (ectoparasite) or in (endoparasite) another organism (host) and obtain nourishment at the expense of the host therefore often causing harm or death of host
e.g pork tapeworm, headlice

Question 21

What is the structure and the functions of the mammalian gut wall? number of layers?

Answer 21

• 5 layers; lumen mucosa, sub-mucosa, muscularis (inner-circular, outer-longitudinal), serosa
• thickness of layers varies in different regions of gut
• MUCOSA - lines the gut wall, INNER most layer with epithelium, EPITHELIUM secrets MUCUS, lubricating and protecting mucosa (some regions secretes digestive juices others is absorbs digested food)
• SUB-MUCOSA - connective tissue containing BLOOD and LYMPH VESSELS removing products of digestion, contains NERVES coordinating peristalsis
• MUSCULARIS - inner-circular and outer-longitudinal; coordinated waves of contraction (PERISTALSIS), pushing the BOLUS along alimentary canal
• SEROSA - OUTERMOST layer, TOUGH connective tissue PROTECTING gut wall, reduces FRICTION with other abdominal organs during peristalsis

Question 22

What are the regions of the digestive system (mouth to anus) and functions? x10

Answer 22

BUCCAL CAVITY - ingestion; mechanical digestion of food; crushing and chewing action of teeth, tongue assists chewing of food into bolus, chemical digestion of starch by salivary amylase secreted by salivary glands

OESOPHAGUS - carriage of food to stomach via peristalsis

STOMACH - mechanical digestion; contraction of muscles to churn food, secretion of hydrochloric acid, chemical digestion; of proteins by enzymes i.e. pepsin

LIVER - secretes bile via the gall bladder and bile duct which helps break down lipids/fats

DUODENUM - first section of small intestine; receives pancreatic juices from pancreas, bile from gall bladder, chemical digestion of carbohydrates, lipids and proteins

ILEUM - second section of small intestine; chemical digestion of carbohydrates, lipids and proteins, absorption of digested food

CAECUM - first section of large intestine; connects small intestine to colon

COLON - large intestine; absorption of water, mineral ions, vitamins

RECTUM - final region of L.I. storage of faeces

ANUS - site of egestion

Question 23

What are the roles of saliva and mucus in digestion?

Answer 23

SILIVA - watery secretion containing:
• AMYLASE; hydrolysing STARCH —–> MALTOSE
• BICARBONATE IONS creating an optimum ph for amylase enzyme (ph 7.8 - slightly alkaline)
• MUCUS which lubricates the food and gut wall

Question 24

What are the stages involved in starch digestion?

Answer 24

• CHEMICAL digestion of starch and glycogen begins in the BUCCAL cavity where salivary glands secrete SALIVARY AMYLASE (starch -> maltose)
• starch digestion stops in the stomach due to the acidic conditions
• digestion continues in the DUODENUM where pancreas secretes PANCREATIC AMYLASE via pancreatic DUCT (starch -> maltose)
• MALTOSE is hydrolysed further by MALTASE (on epithelial cell membranes) to ALPHA-GLUCOSE in the ileum

Question 25

What are the stages in digestion of lactose and sucrose?

Answer 25

chemical digestion of: | LACTOSE to glucose and galactose by LACTASE SUCROSE to glucose and fructose by SUCRASE

Question 26

Where are sites of production for carbohydrase's, gut regions where they function and usual pH levels?

Answer 26

site of production and regions: • buccal cavity (salivary glands) • pancreas (pancreatic glands) • epithelial cells of small intestine/duodenum, ileum ph. levels; • 7.8

Question 27

What are the stages in digestion of proteins?

Answer 27

proteases: 1. ENDOPEPTIDASE - hydrolyse (NON-TERMINAL) peptide bonds WITHIN the protein molecule and form peptides from polypeptide proteins e. g PEPSIN - STOMACH (ph2), optimal in acidic conditions, secreted by GASTRIC glands in stomach mucosa, secreted as INACTIVE PEPSINOGEN which is activated by HCl forming pepsin e. g TRYPSIN - DUODENUM (ph7/8), pancreatic secretion entering duodenum via pancreatic duct, duodenum secretes ENTEROKINASE to convert the pancreas secretion of inactive trypsinogen to trypsin 2. EXOPEPTIDASE - hydrolyse the TERMINAL bonds of the short peptides, from the free AMINO END end or the free CARBOXYL end, forming amino acids

Question 28

What is the role of bile? ph? made? stored? works? contains?

Answer 28

BILE is made in the LIVER, stored in the GALL BLADDER and passed through the bile DUCT into the DUODENUM • bile is ALKALINE and NEUTRALISES ACID in food from stomach creating optimum ph. for enzyme action on small intestine (ph7.8) • bile contains BILE SALTS (hydrophilic outer side and hydrophobic inner side) • EMULSIFY lipid globules in partially digested food, large GLOBULES are broken down into SMALLER EMULSIFIED DROPLETS - increasing surface area for lipase action

Question 29

What is the role of pancreatic lipase? secreted from to where?

Answer 29

pancreatic lipase secreted into in the duodenum of small intestine: hydrolysis of triglycerides to fatty acids and glycerol

Question 30

Where is final digestion and absorption of amino acids, glucose, fatty acids and glycerol?

Answer 30

* digestion on the MEMBRANES of EPITHELIAL cells covering the VILLI * absorption of AMINO ACIDS by ACTIVE transport into the EPITHELIAL cells and FACILITATED diffusion into the CAPILLARIES * absorption of GLUCOSE and other monosaccharides into epithelial cells by CO-TRANSPORT (with sodium ions) and then into capillaries by FACILITATED diffusion * GLUCOSE and AMINO ACIDS are transported via the HEPATIC PORTAL VEIN to the LIVER • FATTY ACIDS and GLYCEROL DIFFUSE into the epithelial cells, where they are reassembled into TRIGLYCERIDES - then pass into the LACTEAL and are carried via the lymphatic system to the blood