Chapter 11 - Adaptations for Nutrition

Question 1

What is an autotrophic organism?

Answer 1

Organisms that make their own food from the simple inorganic raw materials, carbon dioxide and water (Photo and chemoautotrophs).

Question 2

What is a heterotrophic organism?

Answer 2

Organisms that can’t make their own food and consume complex organic molecules produced by autotrophs.

Question 3

What are the 3 types of heterotrophic organism?

Answer 3

• Saprotrophic, enzymes secreted for extracellular digestion.
• Parasitic, obtain their nutrients from another living organism.
• Holozoic, ingest food, digest it and egest the indigestible remains.

Question 4

Why must food be digested?

Answer 4

The molecules are…

• Insoluble and too big to cross membranes and be absorbed into the blood.
• Polymers and must be converted to monomers so they can be rebuilt up into molecules needed by body cells.

Question 5

What is the process that is propelled along the gut?

Answer 5

By peristalsis.

Question 6

what are the 4 main functions the human gut performs?

Answer 6

• Ingestion.
• Digestion.
• Absorbtion.
• Egestion.

Question 7

What are the main parts of the digestive system and what is their function?

Answer 7

• Mouth, ingestion.
• Oesophagus, carriage of food to stomach.
• Stomach, digestion of protein.
• Duodenum, digestion of fats, carbohydrates and proteins.
• Ileum, further digestion and absorption of digested food.
• Colon, absorption of water.
• Rectum, storage of faeces.
• Anus, egestion.

Question 8

What are the 4 tissue layers surrounding a cavity that the gull wall consists of?

Answer 8

• Serosa, outermost layer of tough connective tissue.
• Longitudinal and circular muscle, responsible for peristalsis.
• Submucosa, connective tissue.
• Mucosa, its epithelium secretes mucus, lubricates and protects.

Question 9

What is the role of mechanical digestion?

Answer 9

It increases the surface area of food over which enzymes may act to chemically digest the food.

Question 10

What is the general name given to protein digesting enzymes and what are the 2 main types?

Answer 10

Peptidases.

• Endopeptidases, hydrolyse peptide bonds within.
• Exopeptidases, hydrolyse peptide bonds at the ends.

Question 11

What prevents the food from leaving the stomach until fully digested?

Answer 11

The pyloric sphincter.

Question 12

What pits are found in the mucosa of the stomach that secrete gastric juices?

Answer 12

Gastric pits.

Question 13

What are the 3 types of cells in gastric pits and what’s their function?

Answer 13

• Chief cells, secrete ‘Pepsinogen’ (Inactive).
• Parietal/oxyntic cells, secretes Hydrochloric acid which activates pepsinogen, creates optimum pH for the enzyme and kills pathogenic bacteria.
• Goblet cells, secrete mucus which protects the lining pf the stomach.

Question 14

What is the function of the liver in the digestive process?

Answer 14

It produces bile containing bile salts, mucus and water. It is stored in the gall bladder and flows along the bile duct into the duodenum.

Question 15

What is the function of bile salts?

Answer 15

Emulsification of fats. It breaks fats into tiny droplets which increases surface area so that lipase can digest them more readily.

Question 16

What does saliva contain?

Answer 16

• Amylase, beginning starch digestion.
• Mucus, lubricating the foods passage.
• HCO3 and CO3 ions making it slightly alkali.

Question 17

What are the 2 regions of the small intestine?

Answer 17

Duodenum and the ileum.

Question 18

What enzymes does pancreatic juice contain?

Answer 18

• Endopeptidases.
• Trypsinogen (Protein).
• Amylase (Starch).
• Lipase (Lipids).

Question 19

In humans, why is the ileum adapted to absorption?

Answer 19

• It is very long (6m).
• The lining is folded and on top of these folds are villi and they have microvilli which provide a very large surface area for absorption.
• They have many mitochondria providing energy for active transport.

Question 20

Where do fat-soluble molecules get absorbed into?

Answer 20

The lacteal.

Question 21

How is glucose absorbed into the capillaries?

Answer 21

Na+ ions are actively transported out of the epithelial cells into the capillary which creates a concentration gradient. This then causes glucose to move into the epithelial cells by co-transport with sodium down a concentration gradient. Glucose the diffuses across the epithelial cell and then into the capillary by facilitated diffusion.

Question 22

What are lipids used for in the body?

Answer 22

They’re used in membranes and to make some hormones but excess is stored.

Question 23

What is glucose and amino acids used for in the body?

Answer 23

• Glucose, respired for energy or stored as glycogen.
• Amino acids, taken to body cells for protein synthesis. Any excess is deaminated in the liver and excreted as urea and stored as fats.

Question 24

What does the large intestine compromise of?

Answer 24

• Caecum.
• Appendix.
• Colon.
• Rectum.

Question 25

What in the caecum is secreted by mutualistic micro-organisms living there?

Answer 25

Vitamin K and folic acid.

Question 26

What is the dentition of herbivores like?

Answer 26

Incisors on the lower jaw only with a leather dental pad on the upper jaw. A gap (Diastema). Molars interlock. The lower jaw moves side to side and the teeth have open unrestricted roots so they continue t grow. It doesn’t need strong facial muscles as its prey is unlikely to escape.

Question 27

What is the dentition of carnivores like?

Answer 27

They have sharp bones to grip and tear muscle from bone. They have large canine teeth that are curved and pointed for piercing and seizing prey, for tearing muscle and killing.
Sharp molars that cut and crush. Carnassials that shear muscle of the bone. Lower jaw moves vertically to prevent dislocation.

Question 28

What is a ruminant?

Answer 28

A cud chewing herbivore possessing a ‘stomach’ divided into 4 chambers, the largest of which is the rumen, which contains mutualistic microbes.

Question 29

How does cellulose digestion take place in a ruminant?

Answer 29

• Grass is mixed with saliva to form cud which passes to the rumen.
• Bacteria in the rumen digest cellulose into glucose and the fermented grass passes to the reticulum where it is re-formed into cud and may be regurgitated for further chewing.
• Cud passes to omasum where water and organic acids are absorbed.
• Abomasum is where protein is digested and then it passes into the small intestine where the products of digestion are absorbed into the blood.

Question 30

What is a parasite?

Answer 30

They live in or on an organism of another species, the host, and obtain nourishment at the host’s expense., causing some degree of harm and often death.

Question 31

What is the structure of a pork tapeworm?

Answer 31

The head (Scolex) is made of hooks and suckers. Its body is a linear series of sections called proglottids.

Question 32

What is the the primary and secondary host for the pork tapeworm?

Answer 32

• Primary, the human.

- Secondary, the pig.

Question 33

What is the pork tapeworms life-cycle?

Answer 33

The pig becomes infected when its food is contaminated with human faeces. Humans are then infected by eating under-cooked, infected pork.

Question 34

What adaptations does the pork tapeworm have to enable it to survive in the humans digestive system.

Answer 34

-Suckers and a double row of curved hooks attaching it to the duodenum wall.
-Thick cuticle around the body, protecting it from the humans immune responses.
-The ability to make enzyme inhibitors preventing the host’s enzymes digesting it.
Large surface area to volume ratio so food is absorbed over it’s whole surface.
-No sensory organs, simple excretory and nervous systems but most of the body concerned with reproduction.
-It is a hermaphrodite, allowing vast numbers of eggs to be produced.
-Eggs have resistant shells and survive until being eaten by secondary host.

Question 35

What is the 3 stages in a head louses life cycle?

Answer 35

• Nits are empty eggs.
• After 1-2 weeks, eggs hatch into nymphs.
• Nymphs become adults after about 10 days and feed on blood which they suck from the scalp of the host.