2.4

Question 1

Description of autotrophic nutrition

Answer 1

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

Question 2

Description of photoautotrophic

Answer 2

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

Question 3

Description of chemoautotrophic

Answer 3

Uses chemical energy, from chemicals such as hydrogen sulphide, to combine inorganic substances into complex organic chemicals.

Question 4

Description of heterotrophic

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 synthesis their own organic chemicals.

Question 5

Description of holozoic nutrition

Answer 5

Absorption of organic matter followed by internal digestion of the organic
chemicals within the organism.

Question 6

Description of parasitic nutrition

Answer 6

Living in or on another host organism, whereby nourishment is obtained from a host organism, usually to the detriment / harm of the host; the host usually derives no benefit.

Question 7

Ectoparasites

Answer 7

Live on outside of a host organism

Question 8

Endoparasites

Answer 8

Live inside a host organism

Question 9

What is symbiosis/ mutualism

Answer 9

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

Question 10

How do photoautotrophs work

Answer 10

Carry out photosynthesis
Carbon dioxide + water —> glucose and oxygen
Uses energy from photons of light and transfers light energy into chemical energy

Question 11

Primary host

Answer 11

Where sexual reproduction occurs

Human

Question 12

Secondary host

Answer 12

Where larval/ intermediate forms of the parasite are found

Pig or cow

Question 13

Steps of a parasite taking over

Answer 13

1. Eggs released into the environment in faeces
2. Secondary host eat vegetation contaminated with tapeworm eggs
3. Eggs hatch and larvae burrow through gut wall - then carried by blood around the body
4. Larvae develop into cysts in muscle
5. Humans eat undercooked/raw meat and get infected
6. Scolex develops and attaches to wall of small intestine
7. Adults grow to 5 cm longer and can survive for many years

Question 14

Adaptations of the tapeworm

Answer 14

1. Head = scolex and is embedded in gut wall and has hooks and suckers to prevent it being dislodged by peristalsis
2. No digestive system or mouth - tapeworm only needs to absorb nutrients already digested
3. Flat body - large surface area for absorption of nutrients
4. Each proglottid covered in a thick cuticle thats resistant to action of digestive enzymes
5. Proglottids secrete mucus and enzyme inhibitors to reduce risk of digestion
6. Anaerobic respiration- no oxygen in gut lumen
7. Contains male and female reproductive organs - can self-fertilise
8. Each proglottid contains about 50,000 eggs - increasing chance of being infected by another host

Question 15

What kind of parasite are headlouse

Answer 15

Ectoparasite

Question 16

What does it mean that headlouse are obligate parasites

Answer 16

They have only live in human hair

Question 17

Obligate parasite

Answer 17

Has to live on a host plant to survive

Question 18

Question 19

Buccal cavity

Answer 19

Mechanical and chemical digestion
Lips, tongue and teeth work together
• receive food, cut and chew food, mix with saliva and form bolus
Salivary glands
• slightly acidic, contains salivary amylase

Question 20

Oesophagus

Answer 20

Straight narrow tube with muscular wall
Carries food to stomach by peristalsis
Epiglottis - closes to prevent food from entering the trachea and lungs

Question 21

Peristalsis in oesophagus

Answer 21

Waves of contraction of muscles in gut wall which push forward through the whole gut

Question 22

How does the stomach carry out chemical and mechanical digestion

Answer 22

Chemical
• action of enzymes and hydrochloric acid
Mechanical
• muscles contract and relax to mix food and gastric juice to increase surface area of particles

Question 23

What cells secrete pepsinogen

Answer 23

Xymogenic

Chief cells

Question 24

What is pepsinogen

Answer 24

Precursor of pepsin
Digestion of protein into polypeptides
Digestion of milk protein

Question 25

What cells secrete hydrochloric acid

Answer 25

Oxyntic cells

Question 26

Function of hydrochloric acid in the stomach

Answer 26

Provides optimum pH for enzymes Denature proteins Softens connective tissues in food Activates pepsin

Question 27

What cells secrete mucus in stomach

Answer 27

Goblet | Neck cells

Question 28

Why is mucus needed in stomach

Answer 28

Forms a barrier between stomach lining and gastric juice | Prevents self-digestion of stomach walls and glands

Question 29

What is the small intestine comprised of

Answer 29

Duodenum and ileum

Question 30

Duodenum

Answer 30

First part of small intestine Receives secretions from accessory organs (bile and pancreatic juice) Folded wall (VILLI)- increase SA for final stages of digestion and absorption Base of villi - intestinal glands- crypts of LieberKühn Brunner's Glands - secrete alkaline fluid and mucus to neutralise acid chyme from stomach

Question 31

Ileum

Answer 31

Where digestion completed Main site of absorption 5m long - takes long time to pass through ileum - increases time available for digestion and absorption Villi - increase SA - rich blood supply to remove products of digestion Most water absorbed in ileum

Question 32

Question 33

Large intestine

Answer 33

First part = caecum No role in human digestive system Appendix in caecum - no known role Undigested food and remaining water and minerals first pass into colon

Question 34

Colon

Answer 34

Main part of large intestine Absorbs rest fo water and mineral salts Vitamins produced by microorganisms in colon absorbed into blood Semi-solid mass of undigested food - faeces

Question 35

Rectum

Answer 35

Last part of large intestine | Muscular tube that temporarily stores faeces before eliminated from body

Question 36

Anus

Answer 36

Made from sphincter muscles | Control defaecation occurs

Question 37

Accessory organs | Liver

Answer 37

Liver • bile produced by breaking down haemoglobin • receives almost all products of digestion carried there by hepatic portal vein • store excess glucose as glycogen • remove amino groups and convert into urea • store vitamins

Question 38

Accessory organs | Gall bladder

Answer 38

Stores bile | Secreted into duodenum via bile duct

Question 39

Accessory organs | Pancreas

Answer 39

ENDOCRINE • secretes insulin and glucagon for control of blood glucose levels EXOCRINE • secretes pancreatic juice ( mix of enzymes, enzyme precursors, sodium hydrogen carbonate) which are carried by pancreatic ducts to duodenum

Question 40

What are the layers in the gut wall

Answer 40

``` Serosa Longitudal and circular muscle layers Submucose Muscularis mucosa Mucosa ```

Question 41

Serosa in gut wall

Answer 41

a layer of connective tissue carrying blood vessels, lymphatic vessels and nerves.

Question 42

Longitudinal and circular muscle layers in gut wall

Answer 42

Responsible for peristalsis

Question 43

Submucosa in gut wall

Answer 43

Generally carries the main arterioles and venules | Contain glands

Question 44

Muscularis mucosa in gut wall

Answer 44

Thin lager of muscle involved in moving the inner wall of the gut

Question 45

Mucosa in gut wall

Answer 45

covered by a layer of epithelial cells; some of these produce mucus and others are responsible for the final stages of digestion and absorption of nutrients.

Question 46

Question 47

How are duodenum and ileum adapted to increasing efficiency of digestion and absorption

Answer 47

Folds in wall to increase SA inner surface further folded into villi Surface of epithelial cells covering villi further folded into microvilli

Question 48

How has the villi adapted to increase the efficiency of digestion and absorption

Answer 48

* rich capillary network to absorb and remove products of digestion and maintain concentration gradient * lacteals - absorb products of fat digestion and maintain concentration gradient * thin - reduce diffusion distance * microvilli - increase SA * many mitochondria- ATP for active transport

Question 49

pH of mouth

Answer 49

Varies depending on food eaten | 6.5 - 7.5

Question 50

pH of stomach

Answer 50

Upper - 4.0-6.5 Lower - 1.5-4.0 Less acidic where food enters from oesophagus

Question 51

pH of duodenum

Answer 51

7.0-8.5 Start - acidic Brunner's glands secretions neutralise acid and increases pH

Question 52

pH of ileum

Answer 52

4.0-7.0 | Fatty acids and amino acids lower it

Question 53

pH of colon

Answer 53

4.0-7.0 | Varies on food and action of bacteria

Question 54

Digestion of starch

Answer 54

Digestion of it starts in mouth and duodenum Salivary and pancreatic amylase STARCH --------> MALTOSE digestion of disaccharides into monosaccharides takes place on surface of epithelial cells covering villi Enzymes embedded in cell membranes

Question 55

Digestion of protein

Answer 55

* Involves breaking long polypeptide chains into amino acids and dipeptides that can be absorbed * Some protease enzymes secreted as inactive precursors to prevent autolysis * begins in stomach * pepsinogen activated by HCl to form the endopeptidase enzyme = pepsin * in duodenum - trypsinogen activated by enterokinase to form trypsin (endopeptidase) * pancreas and intestinal glands secrete exopeptidase * final digestion of dipeptides into amino acids takes place through enzymes embedded in cell membrane of epithelial cells in ileum

Question 56

Endopeptidase

Answer 56

Hydrolyse peptide bonds between amino acids in the middle of a polypeptide chain Non-terminal peptide bonds PROTEIN ---> POLYPEPTIDES + PEPTIDES happens before digestion by an exopeptidase to increase rate of digestion of proteins

Question 57

Exopeptidase

Answer 57

Break peptide bonds between amino acids at the ends of peptide/polypeptide chains Terminal peptide bonds PEPTIDES ---> AMINO ACIDS + DIPEPTIDES wont hydrolyse a dipeptide

Question 58

Lipid absorption

Answer 58

Digested by lipases LIPID ---> FATTY ACIDS + GLYCEROL bile emulsified lipids by breaking large globules of fat into small droplets This increases SA for lipase action Also allows very small droplets of fat to be directly absorbed into blood stream

Question 59

How are glucose and amino acids absorbed into ileum by villi

Answer 59

Active transport Diffusion Co-transport Into capillaries Then carries in hepatic portal veins to liver Disaccharides and dipeptides absorbed into epithelial - digested intracellularly Amino acids and monosaccharides- pass into capillaries

Question 60

What is glucose used for after being absorbed

Answer 60

For energy release in respiration Some converted into glycogen in liver and muscles Excess stored in fat cells

Question 61

What is amino acids used for after being absorbed

Answer 61

For protein synthesis Excess cannot be stored - deaminated and converted to urea Remainder converted to carbohydrates and stored

Question 62

How are fatty acids and glycerol absorbed into ileum

Answer 62

Separately into epithelial cells Reassembled into triglycerides Some pass into lacteal then lymphatic system to blood stream opening at thoracic duct Some short-chain fatty acids diffuse directly into blood in capillaries

Question 63

What are lipids used for after being absorbed

Answer 63

Produce cell membranes and hormones | Excess stored as fat

Question 64

How is water absorbed in the digestive system

Answer 64

Most absorbed into bloodstream in ileum | Remainder of water and mineral salts and vitamins secreted by microorganisms in colon are absorbed by colon