2.4 - Adaptations for nutrition

Question 1

What is obtained from nutrition and give the main 2 types?

Answer 1

Energy and matter
Autotrophic and heterotrophic

Question 2

What is Autotrophic nutrition?

Answer 2

Organisms which are able to manufacture complex organic compounds from simple inorganic molecules (produce there own food)

Question 3

What are photoautotrophic organisms? Give examples

Answer 3

Use light energy as the energy source and preform photosynthesis. Green plants, some Protoctista, some bacteria

Question 4

What are chemotrophic organisms? Give examples

Answer 4

Use energy from chemical reactions. All prokaryotes (less efficient than phototrophic)

Question 5

What are Heterotrophic organisms? Give examples

Answer 5

Cannot synthesise their own organic food, they consume complex organic molecules produced by autotrophs, (either eat autotrophs or organisms that have eaten autotrophs). All animals, some fungi, some Protoctista and some bacteria

Question 6

What are Saprotrophic organisms? Give examples

Answer 6

Derives energy and raw materials from the extracellular digestion of dead and decaying material. All fungi, some bacteria

Question 7

How does Extracellular digestion work in Saprotrophic organisms? (Saprotrophs don’t have specialised digestive system)

Answer 7

Saprotrophs feed by secreting enzymes such as proteases, amylases, lipases and cellulases on to the food material outside the body and the absorb the soluble products across the cell membrane by diffusion. They are important in the recycling of nutrients and decomposition of dead plant and animal material

Question 8

What are parasitic organisms? Give examples

Answer 8

Live on surface or in a living organism. Obtains nutrition from host, host always suffers harm and sometimes death.
Tapeworm, head lice.

Question 9

What are Holozoic organisms? Give examples

Answer 9

Ingest food, digest it and egest indigestible remains. Most animals (herbivores, carnivores, omnivores and detritivores)

Question 10

How does Holozoic nutrition work?

Answer 10

Food is processed inside the body, in a specialised digestive system. Digested material is absorbed into the body tissues and used by the cells

Question 11

What are the definitions of:
1) Carnivore
2) Herbivore
3) Omnivore
4) Detritivore

Answer 11

1) Eat other animals
2) Eat plants only
3) Eat plants and animals
4) Feeds on dead and decaying material

Question 12

How does nutrition work in Unicellular organisms?

Molecules cross ____ _______ by ______, ________ ______ or _____ _____
Large molecules and microbes enter by ________ into food _____. Food _____ and ______ fuse. ________ enzymes break down food. Products absorbed by ______. Remains ejected by ________

Answer 12

cell membrane
diffusion, facilitated diffusion, active transport
endocytosis
vacuoles (x2)
lysosome
Lysosomal
Cytoplasm
Exostosis

Question 13

How does nutrition work in multi-cellular organisms? (single body opening) e.g. Hydra

Diploblastic (comprised of 2 layers of cells, an _______ and an ________. It’s _______ with stinging cells _______ the prey and move it into mouth. Digestive enzymes (________ and _______) secreted into hollow body cavity for extracellular digestive. Products are absorbed into cells. Egestion of waste through _______. Hydra is radial symmetry

See NC1

Answer 13

ectoderm, endoderm
tentacles
paralyse
protease and lipase
mouth

Question 14

How does nutrition work in multi-cellular organisms? (two opening) e.g. Tube gut. What does it mean?

Organisms with a ____ and ____ end, also a left and a right (Bilateral symmetry). ________ tract has an anterior (front) and (posterior) rear. Ingestion is via _____, egestion via ____.

Answer 14

head and tail
Digestive
mouth
anus

Question 15

Why must food be digested?

Answer 15

Because 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 into molecules needed by body cells

Question 16

Where does digestion and absorption occur in a human and what it is?

Answer 16

The gut, a long, hollow, muscular tube. It allows movement of its contents in one direction only. Each section is specialised

See NC 2

Question 17

What are the 4 main functions of the gut?

Answer 17

Ingestion
Digestion
Absorption
Egestion

Question 18

How does the 4 main functions of the gut work?

Answer 18

Ingestion - taking in food by buccal cavity (mouth)
Digestion - breakdown of large insoluble food molecules into smaller soluble molecules that can then be absorbed into blood**
Absorption - passage of molecules and ions through the gut wall into the blood
Egestion - elimination of undigested food (waste not made by body e.g. cellulose)

Question 19

Describe and explain the 2 types of digestion?**

Answer 19

Mechanical digestion - cutting and crushing by teeth followed by rhythmical muscle contractions of the gut wall to increase the S.A over which enzymes can act
Chemical digestion - The breakdown of large insoluble molecules into small soluble molecules using enzymes (chemical bonds are broken)

Question 20

What are the functions of the parts of the digestive system?

1) Mouth
2) Oesophagus
3) Stomach
4) Duodenum
5) Ileum
6) Colon
7) Rectum
8) Anus

Answer 20

1) Ingestion, digestion of starch and glucose
2) Carriage of food to he stomach
3) Digestion of protein
4) Digestion of carbohydrates , fats and proteins
5) Digestion of carbs, fats, proteins, Absorption of digested food and water
6) Absorption of water
7) Storage of faeces
8) Egestion

Question 21

Throughout its length the gut wall consists of 5 tissue layers surrounding the lumen, what are they?

Answer 21

Serosa
Muscle (longitudinal and circular)
Sub-mucosa
Mucosa
Endothelium

See NC 3

Question 22

What is the serosa layer of the gut wall?

Answer 22

Tough connective tissue, the gut moves while processing food and the serosa reduces friction with other abdominal organs

See NC 3

Question 23

What is the muscle layer of the gut wall?

Answer 23

Inner circular muscles - make coordinated waves of contractions, peristalsis
Outer longitudinal muscles - after circular muscles contract longitudinal relax, pushing the food along

See NC 3

Question 24

What is the submucosa layer of the gut wall?

Answer 24

connective tissue contain blood and lymph vessels, which remove absorbed products of digestion, and nerves that co-ordinate peristalsis.

See NC 3

Question 25

What is the Mucosa layer of the gut wall?

Answer 25

The innermost layer and lines the gut wall. Its epithelium secretes mucus, lubricating and protecting the mucosa

See NC 3

Question 26

What is the epithelium layer of the gut wall?

Answer 26

outermost layer, in direct contact with the food in lumen, secretes substances into the lumen

See NC 3

Question 27

The absorption of nutrients by the gut _________ cells is only possible if the large molecules/ macromolecules (carbs, ____ and ________) are first broken down or digested into smaller products by means of _______. Diff _______ are required to carry out the digestion of different food substrates (more than 1 _____ needed for digestion of particular food)

Answer 27

epithelium
fats and proteins
enzymes

Question 28

How are carbohydrates digested?

Answer 28

Carbs which are polysaccharides are digested into disaccharides and then into monosaccharides by a group of enzymes called carbohydrase’s

Question 29

Give the name of the 4 carbohydrase’s their substrate and the products

Answer 29

Carbohydrase –> Substrate –> Product
Amylase –> Starch –> Maltose
Maltase –> Maltose –> Glucose
Sucrase –> Sucrose –> Glucose + Fructose
Lactase –> Lactose –> Glucose + Galactose

See NC 4

Question 30

How are proteins digested? (extremely large molecules)

Answer 30

Broken down into polypeptides, then dipeptides, and finally amino acids. Endopeptidases hydrolyse peptide bonds within the protein molecule to form shorter polypeptides. Then exopeptidases hydrolyse peptide bonds at the ends of the shorter polypeptides, releasing amino acids

See NC 5

Question 31

How is fat digested?

Answer 31

fats (triglycerides) are digested to fatty acids and monoglycerides by one enzyme, lipase

Question 32

What happen in the buccal cavity of the mammalian gut?

Answer 32

Mechanical digestion begins, food is mixed with saliva produced by salivary glands and chewed by teeth. Food’s S.A increases, giving enzymes more access.

Question 33

What does saliva cointain?

Answer 33

Amylase to begin digestion of starch and glycogen into maltose.
Mineral ions (HCO2- and CO32- ions) which make mouth slightly alkaline.
Mucus, lubricating the foods passage down oesophagus.

Question 34

What happens in the oesophagus in the mammalian gut?

Answer 34

Bolus is pushed down the oesophagus by localised contraction of circular muscles, this process is called peristalsis

See NC 6

Question 35

What happens in the stomach of the mammalian gut?

Answer 35

Ring of muscle or sphincter controls entry of food into stomach. Volume = 2dm3. Food is mixed with gastric juice secreted by glands in stomach wall (mucosa and epithelium). These secretions are produced in pits called gastric glands

Question 36

What are the names of the sphincter at entrance and exit of the stomach?

Answer 36

Entrance - cardiac sphincter
Exit - pyloric sphincter

Question 37

Gastric juice is secreted from glands in depressions in the mucosa, called gastric pits. Gastric juices contains peptides, HCL and mucus but what secretes them and why?

Answer 37

Chief or peptic cells, produce pepsinogen which is inactive enzyme, that’s activated by H+ ions (HCL)
to pepsin which hydrolyses protein to polypeptides
HCL secreted by oxyntic cells gives the stomach contents a pH of 2 (kills most bacteria in food).
Mucus secreted by goblet cells at top of gastric pit, eases movements of food and protects the gut from digestive enzymes.

See NC 7

Question 38

What is the small intestine divided into?

Answer 38

The duodenum
The Ileum

Question 39

What are the functions of the small intestine?

Answer 39

Chemical digestion and absorption

Question 40

The duodenum is the first 25cm of the small intestine and receives secretion from the liver and pancreas. Bile is made in the liver. It’s stored in the gall bladder then passes through the bile duct into the duodenum. What is bile?

Answer 40

Contains no enzymes
Contains salts which are important in emulsifying lipids present in food, by lowering there surface tension of lipids and breaking up large globules into smaller globules, which increases S.A. This makes digestion of lipids by lipase more efficient.
Bile is alkaline and neutralises the acid in food coming from stomach

Question 41

What is pancreatic juice?

Answer 41

secreted form the exocrine glands in the pancreas and enters the duodenum through the pancreatic duct.

Question 42

What enzymes does Pancreatic juice secrete?

Answer 42

Endopeptidases, which hydrolyse proteins to peptides
Amylase which breaks down remaining starch into glucose
Lipase, which hydrolyses lipids into fatty acids and glycerol

Question 43

The duodenum - The walls of the duodenum contain glands that secrete _____ _____ and
______ (Brunner’s glands). The _____ _____ helps to keep the contents of the small
intestine at the correct __ for enzyme action, and the mucus is for ________ and
________. Enzymes secreted by cells at the tips of the ____ (finger-like projections on the
inner surface of the duodenum) complete digestion:
Maltase _______ maltose into two glucose molecules.
Endopeptidases and exopeptidases complete the digestion of polypeptides to
______ ______

Answer 43

alkaline juice
mucus
alkaline juice
pH
lubrication and protection
villi
amino acids

Question 44

Th Ileum is adapted for absorption. What is it?

Answer 44

Very long, lining is folded to give large S.A.
On the folds are numerous finger-like projections called villi and their epithelial cells have microscopic projections called microvilli - (Increases S.A. for absorption)

Question 45

Why do epithelia cells contain large numbers of mitochondria?

Answer 45

As ATP is needed for the active transport of some of products of digestion (by active transport)

Question 46

Glucose and amino acids are absorbed across the epithelium of the villi by a combination of _______ and _____ ________. They pass into the _____ network that supplies each villus.

Answer 46

diffusion
active transport
capillary
See NC 8

Question 47

The large intestine is about 1.5m long and is divided into the ______, the ________ the ______ and the _____. Water and minerals are absorbed from the colon along with vitamins secreted by micro-organisms living in the colon. These bacteria are responsible for making vitamin K and folic acid.

Answer 47

caecum
appendix
colon
rectum

Question 48

What are lipids used for and what are they used to make?

Answer 48

Used for cell membranes and hormones. Excess are stored as fat. Fat is an energy store and an insulator

Question 49

What are amino acids used for and what are they used to make?

Answer 49

Absorbed for protein synthesis, excess cant be stored so are deaminated in the liver (the amino group is removed and converted into urea and the remainder to carbs and stored)

Question 50

What is glucose used for and what is it used to make?

Answer 50

is absorbed from blood by cells, for energy release in respiration. excess glucose is stored as fat

Question 51

_______ and amphibians swallow food whole soon as its caught, but, in mammals food is retained in the ______ whilst it is cut up and _____

Answer 51

Reptiles
Mouth
Chewed

Question 52

What do mammals have that separates the air path (nasal cavity) from the mouth?

Answer 52

A palate, (allows food to be retained in mouth and chew while breathing)

Question 53

Why is the gut of a carnivore short?

Answer 53

Eats only animals so its diet is mostly protein, hence short gut reflecting the ease at which protein is digested

Question 54

Why is the gut of a herbivore long?

Answer 54

Digestion of plant material is difficult, (isn’t readily digested) and a long gut allows enough time for digestion and absorption of nutrients

Question 55

Since food must be crushed, ground or sheared according to diet, mammals have evolved different types of teeth, specialised for different functions, to suit the diet. What are the four kinds of teeth in humans?

Answer 55

Incisors - Chisel shaped for biting and cutting
Canines - pointed for tearing
Premolars and molars - Flat for chewing and grinding

Question 56

Give the key points of dentation in herbivores?
Tounge
Incisors
Canines
Diastema
Jaw
Molars
Growth and rapare of teeth

Answer 56

Tounge wraps around grass, traps it against dental pad on upper jaw.
Incisors present on lower jaw
Canines used to slice through grass
Diastema - gap between front teeth and premolars, allows cheek and tounge to move grass to grinding surface at rear
Jaw moves in circular grinding action in a horizontal plane
Molars interlock
Teeth wear overtime exposing sharp enamel ridges
Teeth have open roots allowing for continuous growth

Question 57

Give the key points in dentation of carnivores
Incisors
Canine
Molars
Carnassial
Jaw movement

Answer 57

Sharp incisors to grip and tear
Canine teeth are large, curved, pierce and tear
Premolars and molars are fir cutting and crushing
Carnassial to shear muscle from bone
Powerful, well developed jaw muscles allow firm grip on prey, helps crush bone
Lower jaw moves vertically, can be opened wider than a herbivores jaw

Question 58

Ruminants have diet of mainly cellulose which is hard to digest. They have a specialised stomach or rumen in which mutualistic bacteria can live. Herbivores lack ability to produce cellulase. Ruminant provides a region of the gut for the bacteria to inhabit and in return the bacteria digests the cellulose for the herbivore. Why must this region of the gut be kept separate?

Answer 58

food can be kept there long enough for the bacteria to carry out the digestion of cellulose
The bacteria are isolated from the mammal’s own digestive juices so that they’re at the optimum pH for their activities and they are not killed by extremes of pH

Question 59

Describe the digestion of grass in a herbivore?

Answer 59

1) grass is cut by teeth, mixed with saliva, and the cud is formed and swallowed
2) In the rumen (1st stomach), cud is mixed with cellulose digesting bacteria to produce glucose. Glucose is fermented to form organic acids, which are absorbed into the blood, and provide energy for the cow. Waste products (CO2 and Methane) passed out
3) fermented cud passes to the next region, reticulum, before being regurgitated into the mouth and chewed again
4) Cud passes directly into 3rd stomach, the omasum, where water is reabsorbed
5) 4th (last) stomach, the abomasum, functions like a normal stomach and protein is digested
6) digested food passes to the small intestine, where the products of digestion are absorbed into the blood