Nutrition

Question 1

How do Unicellular organisms absorb nutrition?

Answer 1

Amoeba pseudopodia move around prey and enclose it in a food vacuole, enzymes are released and prey is digested. Products of digestion are absorbed into cytoplasm and undissolved waste is left behind.

Question 2

Name examples of multicellular organisms

Answer 2

• Hydra
• Earthworm
• Human

Question 3

Describe the Hydra’s gut

Answer 3

Undifferentiated sac-like gut with a single opening

Question 4

Describe the digestion of an Earthworm

Answer 4

Tube gut, has different openingsfor ingestion and egestion. it has specified regions for the digestion of different foods

Question 5

Describe the digestion of a human

Answer 5

Specialised regions of gut, the wall contains: muscle layers, sub-mucosa, mucosa and epithelium

Question 6

Define autrophic nutrition

Answer 6

Makes complex organic molecules from simple inorganic ones

Question 7

Define Heterotrophic nutrition

Answer 7

Consume complex organic food molecules

Question 8

Define Photoautotrophic nutrition

Answer 8

Uses light as a source of energy for synthesis of food

Question 9

Define Chemoautotrophic nutrition

Answer 9

Oxidise inorganic molecules to provide energy for the synthesis of food

Question 10

Define Saprophytic nutrition

Answer 10

External digestion of food using secretion of enzymes followed by absorption of the products of the products of digestion into the organism (eg. fungi)

Question 11

Define Holozoic nutrition

Answer 11

Internal disgestion of food, involves ingestion, absorption, assimilation and egestion

Question 12

What is the type of protease hydrolises peptide bonds?

Answer 12

Endopeptidases- hydrolise bonds between specific amino acids in the middle of polypeptide chains to form peptides

Question 13

What type of protease hydrolises peptide bonds at the end of peptides?

Answer 13

Exopeptideases

Question 14

Describe the Human digestive system, giving details of each part.

Answer 14

Buccal Cavity- mechanical digestion (teeth + tongue), tongue moves food to teeth to cut and grind, amylase is produced from salivary glands which breakes down starch and glucose into maltose.
Oesophagus- peristalic waves of muscle contraction push the bolus of food down to the stomach, mucus lubricates the way.
Stomach- gastric glands in mucosa produce gastric juice. Oxyntic produces HCl that kills bacteria and lowers pH to 2, the cheif cells produce pepsinogen the inactive precursor of the endopeptidase enzyme, peptin.
Liver- produces bile that emulsifies lipids to increase the surface area available for lipase enzymes to digest them. Neutrilises the stomach acid.
Gall bladder- stores bile before delivering to duodenum via bile duct.
Pancreas- produces enzymes that are transported to the duodenum via pancreatic duct.
Duodenum- further digestion occurs on the epithelial cells of the villi, sucrose digested into glucose and fructose by sucrase, maltose digested into alpha glucose by maltase, lactose digested into glucose and galactose.
Ileum- Amino acids are actively transported into the epithelial cells of the villi (facilitated diffusion to capillaries), glucose and other monosaccharudes move into epithelial cells, fatty acids and glycerol diffuse into epithelial cells and are reassembled into triglycerides and carried to the lymphathic system.
Rectum and Anus- waste products

Question 15

What’s the features of the serosa layer?

Answer 15

Tough outer coat of connective tissue

Question 16

What are the features of the muscle layers?

Answer 16

Longitudinal muscle contracts to shorten the gut and circular muscle contracts to reduce diameter. these waves of contraction called peristalsis force food along the gut.

Question 17

What are the feautures of the submucosa layer?

Answer 17

Contains blood and lymph vessels to remove digested food products

Question 18

What are the features of the mucosa layer?

Answer 18

Inner layer, secretes mucus for lubrication.

Question 19

What are the features of the epithelium layer?

Answer 19

Layers of cells in contact with food

Question 20

Describe the dentition of a Carniover

Answer 20

Canines- long and pointed to pierce flesh and kill prey
Incisors- upper and lower jaw to grip and tear flesh
Carnassial- act like shears, sliding to rip muscle from bone
Premolars and molars- have sharp cusps that cut and crush, the jaw muscles are strong and moves in a vertical plane to strongly clamp down to hold prey.

Question 21

Describe the Canrivore gut

Answer 21

• relatively short
• usually a large stomach for digestion of mostly protein diet
• small, useless caecum

Question 22

Describe the dentition of a Herbivore

Answer 22

Diastema- space where tongue can push food to the grinding cheek teeth
incisors- lower jaw and cut vegetation against the horny pad.
Canines- absent
Premolars and molars- fit together in an MW shape and jaw moves horizontal so the interlocking teeth can grind food. These teeth regrow throughout life as they are quickly warn down.

Question 23

Describe the NON-RUMINANTS Herbivore gut

Answer 23

• Very long gut for difficult process of cellulose digestion
• large caecum containing bacteria that produces cellulase for cellulose digestion.

Question 24

Describe the RUMINANTS herbivore gut

Answer 24

• grass is chewed and swallowed as cud
• cud enters the rumen, cellulose digesting bacteria produce cellulase to break it down into glucose and is absorbed into bloodstream
• cud enters the second chamber, the reticulum, the cud is regurgitated to be rechewed in mouth
• rechewed cud is swallowed and enters third chamber, the omasum, water is absorbed
• food enters the abomasum and protein is digested
• products of digestion are absorbed into blood stream in small intestine

Question 25

Name an ectoparasite

Answer 25

Head Louse (lives on the surface of an organism) it’s claws hold onto the hairs and they lay eggs which are glued to the base of hairs

Question 26

Name an endoparasite

Answer 26

The pork tapeworm (lives inside the organism) it absorbs the hosts nutrients

Question 27

Describe how a tapeworm lives in another organism

Answer 27

• They have thick cuticles that produce anti enzymes
• Scolex to attach to the gut wall
• Have a reduced gut and feeds by absorbing pre-digested nutrients through its cuticle
• Produces large numbers of eggs that pass out in the faeces to infect a secondary host