2.4 Adaptations For Nutrition

Question 1

What is the autotrophic mode of nutrition?

Answer 1

Synthesis of complex organic chemicals from inorganic substances using an energy source.

Question 2

What is the photoautotrophic mode of nutrition?

Answer 2

Uses light energy to combine inorganic substances into complex organic chemicals.

Question 3

What is the chemoautotrophic mode of nutrition?

Answer 3

Uses chemical energy to combine inorganic substances into complex organic chemicals.

Question 4

What is the heterotrophic mode of nutrition?

Answer 4

Cannot synthesise its own complex organic chemicals; it must digest organic chemicals produced by other organisms and use the products of digestion to synthesise their own organic chemicals.

Question 5

What is the saprotrophic/saprobiontic mode of nutrition?

Answer 5

Extracellular digestion of dead or decayed organic matter

Question 6

What is the holozoic mode of nutrition?

Answer 6

Absorption of organic matter followed by internal digestion of the organic chemicals within the organism.
- single celled organisms = intracellular digestion
- multicellular organisms = extracellular digestion due to digestive system

Question 7

What is the parasitic mode of nutrition?

Answer 7

Living in or on another host organism, whereby nourishment is obtained from a host organism, usually to the detriment of the host

Question 8

What is the mutualism mode of nutrition?

Answer 8

Many organisms live in / on other organisms in a relationship that provides benefit to both organisms.

Question 9

Describe how saprotrophic nutrition works

Answer 9

In saprotrophic nutrition, extracellular enzymes are secreted from the organism which then digest whatever the organisms are growing on. The products of digestion are then absorbed and used by the organisms as their sources of energy and raw materials.

Question 10

What is a parasite?

Answer 10

• organisms that live in (endoparasites) or on (ectoparasites) another organism
• they obtain nourishment at the expense of the host
• usually cause harm to the host.

Question 11

What adaptations of the tapeworm allow it to live in the digestive system of an animal?

Answer 11

• Scolex (head): has hooks and suckers to prevent it being dislodged in peristalsis
• No digestive system, absorbs nutrients
• Flat body: Increase SA
• Thick Cuticle: Resist action of digestive enzymes
• Anaerobic respiration: no oxygen in gut lumen

Question 12

How do single-celled holozoic organisms ingest and digest food?

Answer 12

Intracellular digestion: food particles are ingested through endocytosis and undigested food / waste products are expelled through exocytosis.

Question 13

How does digestion work in Hydra?

Answer 13

• Simple, sac-like gut.
• Digestion combines extracellular and intracellular processes.
• Large-scale digestion occurs in the gastrovascular cavity, breaking down food into fragments.
• Gut cavity digestion combines mechanical and chemical digestion.
• Phagocytosis absorbs fragments, pinocytosis absorbs large molecules.
• Intracellular digestion completes food breakdown within food vacuoles.

Question 14

What happens in the buccal cavity of humans?

Answer 14

• Lips, tongue, and teeth work together for food capture and reception.
• Food moves about mouth and is cut, grind, and chewed.
• Food is mixed with saliva for lubrication.
• Food forms into bolus for easier swallowing.
• Saliva contains salivary amylase enzyme. converting starch to maltose

Question 15

What are the different regions of the human gut and what are their functions?

Answer 15

• One opening for ingestion and a separate opening for egestion
• mechanical digestion by teeth, muscular action
• chemical digestion by acids
• chemical digestion by enzymes with different optimum pH.

Question 16

What occurs in the oesophagus?

Answer 16

Peristalsis:
- Circular muscles contract behind food
- Longitudal muscles push food along
- muscles contract and relax in waves

Question 17

What closes when you start to swallow?

Answer 17

The epiglottis

Question 18

What chemicals are found in gastric juice in the stomach and what do they do?

Answer 18

• pepsinogen (precursor of pepsin) = digests protein into polypeptides
• HCl = provides optimum pH for enzymes, denatures proteins and activates pepsin
• mucus = protects stomach walls from self digestion

Question 19

What are the two sections of the small intestine called?

Answer 19

Duodenum and Ileum

Question 20

What is the function of the Duodenum?

Answer 20

Receives secretions such as bile from liver and pancreatic juice.

Question 21

What are the adaptations of the duodenum?

Answer 21

• folded walls called villi to increase SA
• Base of villi are intestinal glands called the crypts of Lieberkühn
• Has Brunner’s glands that secrete alkaline fluid to neutralise acid chyme from stomach

Question 22

What is the function of the Ileum?

Answer 22

Where digestion is completed and the main site of absorption

Question 23

What is the function of the first section of the large intestine?

Answer 23

The ileum opens up into the caecum and then the appendix. Whilst this is the site of cellulose digestion in some animals, it actually has no known function in humans. Undigested food passes through to the colon.

Question 24

What is the function of the colon?

Answer 24

Where remaining water and mineral salts are absorbed leaving behind a semi solid mass that forms faeces

Question 25

What is the function of the rectum and the anus?

Answer 25

The rectums hold faeces until it's ready to be eliminated from the body through the anus

Question 26

What are the functions of the liver?

Answer 26

- Producing bile from haemoglobin - Storing excess glucose as glycogen - Removing amino groups from amino acids to make urea - Storing vitamins

Question 27

What are the two functions of the pancreas?

Answer 27

- ENDOCRINE: Secretes hormones insulin and glucagon to control blood glucose levels - EXOCRINE: Secretes pancreatic juice

Question 28

What are the different tissue layers of the alimentary canal and their functions?

Answer 28

- Serosa: Outermost layer carrying blood vessels, lymphatic vessels and nerves - Longitudinal and circular muscle layers: Peristalsis - Submucosa: carries main arterioles and venules - Muscularis mucosa: thin layer of muscle that moves inner wall of gut - Mucosa: Covered by epithelial cells it secretes mucus and is involved in final digestion and absorption

Question 29

What is the pH of the mouth?

Answer 29

6.5 - 7.5

Question 30

What is the pH of the upper stomach?

Answer 30

4 - 6.5

Question 31

What is the pH of the lower stomach?

Answer 31

1.5 - 4

Question 32

What is the pH of the duodenum?

Answer 32

7 - 8.5

Question 33

What is the pH of the ileum?

Answer 33

4 - 7

Question 34

What is the pH of the colon?

Answer 34

4 - 7

Question 35

What enzyme digests starch?

Answer 35

Amylase = Polysaccharide --> Disaccharide Sucrase/Maltase/Lactase = Disaccharide --> Monosaccharide

Question 36

What enzymes digest protein?

Answer 36

Pepsinogen secreted in stomach is activated by HCl and converted to Pepsin. Pepsin (endopeptidase) = Protein --> polypeptides + peptides In the duodenum trypsinogen is activated by enterokinase to form trypsin. Trypsin (exopeptidase) = Peptides --> amino acids + dipeptides

Question 37

What enzymes digest lipids?

Answer 37

Pancreas secretes lipase. Bile emulsifies lipids by breaking large globules into small droplets Lipase = Lipid --> Fatty acids + glycerol

Question 38

What are the different types of teeth and their functions?

Answer 38

- Incisors = biting and tearing flesh - Canines = gripping prey - Premolars and molars = grinding plant tissue or shearing flesh off bones

Question 39

How is the mouth of a herbivore adapted to its diet?

Answer 39

- No need for large biting force - strong masseter muscle for grinding - premolars and molars highly ridged for mechanical digestion - No incisors on upper jaw - Presence of diastema so the tongue can be used to divide the mouth into two

Question 40

How is the mouth of a carnivore adapted to its diet?

Answer 40

- Sharp incisors and canines for biting and gripping prey - Premolars and molars are called carnassial teeth and have single ridges that slide past each other to shear flesh from bone - Strong biting force needed

Question 41

How is a ruminant herbivore adapted to its diet?

Answer 41

The oesophagus has three chambers, containing bacteria and archaea that digest cellulose, produce fatty acids, proteins, and vitamins, and utilize them for animal consumption. Protein digestion starts in the abomasum, and ruminants regurgitate food after digestion to release more nutrients.