Component 3 - Nutriton

Question 1

How do unicellular organisms consume food e.g amoeba

Answer 1

1. Amoeba pseudopodia move around prey and enclose it in a food vacuole
2. Enzymes are released from lysosomes that fuse with the food vacuole and the prey is digested
3. Products of digestion are absorbed into the cytoplasm and the undissolved waste is egested by exocytosis

Question 2

Describe the gut of a hydra - single food source

Answer 2

Undifferentiated, sac-like gut with a single opening

Question 3

Describe the gut of an earthworm - varied foods

Answer 3

A tube gut with different openings for ingestion and egestion and specialised regions for the digestion of different food

Question 4

Describe the gut of a Human - Omnivorous diet

Answer 4

Specialised regions of gut. The wall of the gut contains the
following layers

Question 5

List the different layers of the gut from the outside to the inside

Answer 5

1. Serosa
2. Longtitudinal Muscle
3. Circular Muscle
4. Sub Mucosa
5. Mucosa
6. Epithelium

Question 6

What is the Serosa layer

Answer 6

Tough outer coat of connective tissue

Question 7

What do the circular and longtitudinal mucles do

Answer 7

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

Question 8

What does the submuosa layer do

Answer 8

Contains blood and lymph vessels to remove digested food products

Question 9

What does the mucosa layer do

Answer 9

Inner layer that secretes mucus for lubrication. In some areas it secretes digestive juices; in others it absorbs products.

Question 10

What does the epithelium layer do

Answer 10

Layer of cells in contact with food

Question 11

What is autotrophic nutrition and what are the two types

Answer 11

makes complex organic molecules from simple inorganic ones
* Photoautotrophic
* Chemoautotrophic

Question 12

What is Photoautotrophic nutrition

Answer 12

Use light as a source of energy for synthesis of
food

Question 13

What is Chemoautotrophic nutrition

Answer 13

Oxidise inorganic molecules to provide energy for the synthesis of food

Question 14

What is Heterotrophic nutrition and what are the two types

Answer 14

consume complex organic food molecules
* Saprophytic
* Holozoic

Question 15

What is Saprophytic Nutrition

Answer 15

External digestion of food using secretion of enzymes followed by absorption of the products of digestion into the organism, e.g. fungi.

Question 16

What is Holozoic nutrition

Answer 16

internal digestion of food. Involves ingestion, absorption, assimilation and egestion

Question 17

What are the two types of proteases

Answer 17

Endopeptidase
Exopeptidase

Question 18

What do endopeptidases do

Answer 18

endopeptidases hydrolyse peptide bods between specific amino acids in the middle of the polypeptide chain to form shorter polypeptide chains

Question 19

What do exopeptidases do

Answer 19

Exopeptidases hydrolyse peptide bonds on the end of peptides, from the free amino end or the free carboxyl end

Question 20

What happens at the buccal cavity

Answer 20

Mechanical digestion
* The tongue moves food to the cutting
and grinding surfaces of the teeth
* The tongue rolls the food into a bolus which is swallowed

Chemical digestion
* Starch and glycogen into maltose by the enzyme amylase. Saliva moistens food and also maintains the pH for the enzyme

Question 21

What does the Oesophagus do

Answer 21

Peristaltic waves of muscle contraction push the bolus of food down to the stomach
Mucus lubricates the way

Question 22

What does the Stomach do

Answer 22

• Gastric glands in the mucosa produce gastric juice
• The Oxyntic cells produce hydrochloric acid (HCl) that kills bacteria and lowers the pH to 2
• The chief or peptic cells produce pepsinogen, the inactive precursor of the endopeptidase enzyme, pepsin
• This is activated by the HCl
• Goblet cells produce mucus to protect the stomach lining

Question 23

What does the Stomach do

Answer 23

• Gastric glands in the mucosa produce gastric juice
• The Oxyntic cells produce hydrochloric acid (HCl) that kills bacteria and lowers the pH to 2
• The chief or peptic cells produce pepsinogen, the inactive precursor of the endopeptidase enzyme, pepsin
• This is activated by the HCl
• Goblet cells produce mucus to protect the stomach lining
• Churns Food

Question 24

What does the Liver do

Answer 24

• Produces bile.
• Bile emulsifies lipids to increase the surface area available for lipase enzymes to digest them.
• It neutralises stomach acid to create a slightly alkaline pH in the duodenum for the pancreatic enzymes

Question 25

What does the Gall Bladder do

Answer 25

stores the bile before delivering it to the duodenum via the bile duct.

Question 26

What does the pancreas do

Answer 26

Produces enzymes that are transported to the duodenum via the pancreatic duct * Carbohydrase - pancreatic amylase * Protease – trypsinogen activated into the endopeptidase Trypsin by enterokinase in the duodenum * Pancreatic lipase enzymes digest triglycerides into monoglycerides and eventually glycerol and fatty acids

Question 27

What does the duodenum do

Answer 27

further digestion occurs on the epithelial cells of the villi. * Sucrose digested by sucrase into glucose and fructose. * Maltose digested by maltase into alpha glucose. * Lactose digested by lactase into glucose and galactose. * Further digestion of polypeptides by endopeptidases and exopeptidases.

Question 28

What is the structure of a villus

Answer 28

On the outside, there are columnar epithelial cells. On the inside, there are capilliaries and lacteals .

Question 29

What type of diet are carnivores adapted to

Answer 29

High Protein Lipid Energy diet

Question 30

What are the features of the dentition of Carnivores

Answer 30

* Incisors on upper and lower jaw grip and tear flesh * Canines – long and pointed to pierce flesh and seize and kill prey * Carnassial teeth - act like shears, sliding past each other to rip muscle from bone * Premolars and molars - have sharp cusps that cut and crush. The jaw has strong muscles and moves in a vertical plane to hold prey

Question 31

How is a carnivore's gut adapted to it's diet

Answer 31

* Relatively short gut * Usually a large stomach for digestion of mostly protein diet * Small caecum

Question 32

What diet is a herbivore adapted to

Answer 32

A high Cellulose diet

Question 33

What are the 2 types of Herbivores

Answer 33

* Ruminants * Non Ruminants

Question 34

How is a herbivore's dentition adapted to it's diet

Answer 34

* Incisors – on lower jaw and cut vegetation against a horny pad on the upper jaw. Canines absent or indistinguishable * Diastema – space where tongue can push food to the grinding cheek teeth * Premolars and molars – cheek teeth. Fit together. Jaw moves in a horizontal plane so teeth grind food. Teeth have open, unrestricted roots and so grow throughout life

Question 35

How is a non-ruminant gut adapted to it's diet

Answer 35

* Very long gut for the difficult process of cellulose digestion * Large caecum containing bacteria that produce cellulase for cellulose digestion

Question 36

What is the main example of a Ruminant Gut

Answer 36

A cow

Question 37

How is a cow's gut (ruminant) adapted to it's diet

Answer 37

1. Mouth - Grass is mixed with saliva and then chewed (forming cud) before being swallowed 2. Rumen - Cud enters the rumen. Bacteria produce cellulase, breaking down cellulose into glucose. This ferments into organic acids which are absorbed. Produces greenhouse gasses 3. Reticulum - Fermented cud enters the reticulum. The cud is regurgitated from here and the rumen back into the mouth to be rechewed 4. Omasum - Rechewed cud is swallowed and enters the Omasum Water absorption occurs here 5. Abomasum - Protein Digestion 6. Small Intestine - Digested products absorbed into the blood

Question 38

What is a Parasite

Answer 38

Live on or in a host organism, obtaining their nutrition from the host and harming the host

Question 39

What is an ectoparasite

Answer 39

Lives on the surface of another organism

Question 40

What is an Endoparasite

Answer 40

lives inside another organism

Question 41

What is an example of an ectoparasite and how is it adapted

Answer 41

The head louse feeds by sucking blood from the scalp of the host. * It has claws to hold onto the hairs. * Lays eggs which are glued to the base of hairs. * Transfer between hosts is by direct contact as it cannot jump, only crawl

Question 42

Give an example of an endoparasite and how it's adapted

Answer 42

The adult pork tapeworm (Taenia solium) lives in the gut of humans. 1. Primary host – a larval form develops in pigs. 2. Secondary host – infection of humans occurs when a person eats pork containing live larval forms (tapeworm cysts in muscle tissue). The gut is a hostile environment due to the presence of various secretions and peristalsis. The tapeworm has adapted to living in the gut as follows: * Thick cuticle produces anti-enzymes. * Scolex to attach to the gut wall. * Taenia solium has a reduced gut and feeds by absorbing pre-digested nutrients through its cuticle. * To increase the chances of infecting a secondary host, it produces large numbers of eggs that pass out in shit