Nutrition

Question 1

2 main categories of nutrition and meaning

Answer 1

Autotrophic nutrition: Use of simple inorganic molecules to manufacture complex organic molecules
Heterotrophic nutrition: Complex organic molecules consumed and broken down for energy release

Question 2

2 subcategories of autotrophs

Answer 2

Photoautotrophs: Use light energy to convert simple inorganic molecules to complex organic molecules
Chemoautotrophs: Use energy from special respiration methods e.g oxidation of H2S to convert simple inorganic molecules to complex organic molecules

Question 3

2 subcategories of heterotrophs

Answer 3

Holozoic feeders: Food processed as it passes along the gut
Saprotrophs/ Saprobionts: Enzymes secreted onto food outside the body. Soluble products of digestion are absorbed by diff across cell membrane

Question 4

Examples of saprotrophs/ saprobionts

Answer 4

All fungi, some bacterium: Mucor

Question 5

What do saprotrophs/ saprobionts eat

Answer 5

Dead/ decaying matter

Question 6

Examples of holozoic feeders

Answer 6

Animals

Question 7

2 Types of holozoic feeders, meaning and examples

Answer 7

Simple organisms: Have only one type of food so undifferentiated gut e.g aphids
Advanced organisms: Varied diet so divided gut, each part specialised for a specific function e.g humans

Question 8

Parasites

Answer 8

Organisms that feed on or in another organism (the host)

Question 9

Mutualism/ symbiosis

Answer 9

Close association between members of 2 diff species
Both organisms benefit from the relationship

Question 10

Example of symbiosis and explain

Answer 10

Cellulose digesting bacteria in the gut of herbivores: The bacteria produce the enzyme to digest cellulose, in return bacteria gain digestive products and suitable conditions for growth.

Question 11

Key points about advanced organisms (holozoic feeders)

Answer 11

Gut divided
Each part specialised to carry out a specific function
Many different enzynes needed to complete the digestion of particular foods
Different parts have different pH to meet optimum of the enzymes that function there

Question 12

Explain digestion in unicellular organisms (holozoic) 4

Answer 12

Obtain nutrients via diff, FD, act trans or large molecules via endocytosis across cell mem
Vessicle containing molecules fuse with lysosomes so contents are digested
Digestion products absorbed into cytoplasm
Indigestable materials digested via exocytosis

Question 13

Structure of hydra 3

Answer 13

Multicellular organism
2 layers of cells: ectoderm and endoderm separated by a jelly layer containing a network of nerve fibres
Cylinder with tentacles ate head surrounding mouth

Question 14

Explain how hydra catch prey 3

Answer 14

Extend tenticles when small organisms brush
Stinging cells discharge barbwith venom to paralyze
Tenticles move prey through mouth into hollow body cavity

Question 15

Explain how hydra digest prey 3

Answer 15

Endodermal cells secrete protease and lipase, prey is digested extracellularly in the hollow cavity
Products of digestion absorbed into cells
Indigestible materials digested via mouth

Question 16

Ingestion

Answer 16

Large food particles taken into bucal cavity

Question 17

2 types of digestion

Answer 17

Mechanical: Muscular action which pounds food into semi solid state
Chemical: Break down of large insoluble molecules to small soluble via enzymes

Question 18

Absorption

Answer 18

Small soluble food molecules from small intestine to blood stream, then transported to cells

Question 19

Assimilation

Answer 19

Use of absorbed products of digestion by every cl in the body

Question 20

Egestion

Answer 20

Undigested food moves out body as faeces via colon, rectum, anus

Question 21

Sequence of whole digestion process 5

Answer 21

Ingestion
Digestion
Absorption
Assimilation
Egestion

Question 22

Excretion vs egestion

Answer 22

Removal of waste metabolic materials vs undigested food materials

Question 23

Tissue layers of gut 5

Answer 23

Serosa
Longitudinal muscle
Circular muscle
Sub Mucosa
Mucosa

Question 24

Serosa structure

Answer 24

Tough connective tissue, covered by squamous epithelium

Question 25

Serosa function

Answer 25

Protects wall of gut and reduces friction from other organs in the abdomen as gut moves during digestive process

Question 26

Muscle layer structure

Answer 26

Outer longitudinal muscle: Fibres running parallel to lumen Inner circular muscle: Fibres arranged in rings

Question 27

Function of muscle layer

Answer 27

Responsible for peristalsis

Question 28

Structure of submucosa

Answer 28

Contains blood and lymph vessels, contains rich network of nerve fibres

Question 29

Function of submucosa

Answer 29

Take away absorbed food products Coordinate muscular contractions involved in peristalsis

Question 30

Structure of mucosa 3

Answer 30

Lines gut wall Cells of mucosa stratified for protection Epithelial cells

Question 31

Function of mucosa

Answer 31

Secreted mucus to lubricate the passage of food and protect gut from damage Some regions secrete digestive juices Some regions absorb digested food

Question 32

How does gut length and specialisation relate to how advanced an organism is

Answer 32

In simple organisms that feed on one type of food the gut is short and undifferentiated vs more advanced organisms that feed on different foods with longer tube gut

Question 33

Describe the feeding of fungi 4

Answer 33

Growing tip of hyphae penetrates food secretes enzymes Enzymes diff out through cell wall onto the surface of the food (substrate) Enzymes digest food into soluble products Products absorbed into hyphae through cell wall via FD or act trans Soluble products transported within fungi, excess stored

Question 34

What type of feeders are parasites

Answer 34

holozoic feeders

Question 35

Incidences of mechanical digestion

Answer 35

Crushing action of teeth Action of stomach Peristaltic action of muscular layers in gut wall

Question 36

Function of mechanical digestion

Answer 36

Increases surface area of food over which enzymes may act to chemically digest the food

Question 37

2 types of proteases

Answer 37

Endopeptidase Exopeptidase

Question 38

Function of endopeptidase

Answer 38

Hydrolyses peptide bonds in the middle of the polypeptide chain

Question 39

Exopeptidases

Answer 39

Hydrolyses peptide bonds at terminal ends of polypeptide