🔺🔥2.5 Adaptations For Nutrition Flashcards
1
Q
Define Autotroph
A
An organism that synthesis it’s own complex organic molecules using either light or chemical energy
2
Q
Define Heterotroph
A
An organism that obtains complex organic molecules from other organisms
3
Q
Define Saprotroph
A
An organism that derives energy and raw material for growth from the extra cellular digestion of dead or decaying material
4
Q
Define photoautorophic (An autotrophic organism)
A
Organisms use light as the energy source and perform photosynthesis, they are green plants some protoctista and some bacteria. This type of nutrition is described as holophytic
5
Q
Define Chemoautotrophic organisms
A
Use the energy from chemical reactions. (All prokaryotes)
Less efficient than photosynthesis
6
Q
What can’t heterotrophic organisms do?
A
Make their own food, they are consumers
7
Q
Name some examples of heterotrophs
A
Animals, fungi, some protoctista and some bacteria
8
Q
Who uses saprotrophic nutrition?
A
All fungi and some bacteria
9
Q
How do saprotrophic organisms gain energy (extracellular digestion)
A
- Secrets enzymes including proteases, Amalyses, lipases and cullulases on to food material outside the body
- This is extracellular digestion
10
Q
What don’t saprotrophic organisms have?
A
Don’t have a specialised digestive system
11
Q
How do saprotrophs obtain the digested nutrients?
A
Absorb soluble products of digestion across cell membrane by diffusion and active transport
12
Q
Define parasite
A
An organism that obtains nutrients form another living organism or host, to which is causes harm
13
Q
What is parasitic nutrition?
A
Obtaining nutrients from another living organism (host)
14
Q
What is an endoparasite?
A
A parasite which lives in the body of the host?
15
Q
What is an ecto parasite
A
Parasite that lives of the surface of a host
16
Q
Name examples of parasite
A
Tapeworm (taenia solium) Head lice (pediculus capitis)
17
Q
What is holozoic nutrition?
A
- nutrition used by most animals
- ingest food, digest it in a specialised digestive system
- digested material is absorbed into the body tissues and used by cells
18
Q
What are herbivores?
A
Animals that eat plant material only
19
Q
What are carnivores
A
Animals that eat other animals only
20
Q
What are omnivores
A
Animals that eat both plant and animal material
21
Q
What are detrivores
A
Animals that feed on dead and decaying matter
22
Q
What nutrition do animal like protoctista use? (E.g Amoeba)
A
Holozoic nutrition
Large SA:V ratio
:: Obtain nutrients through diffusion, facilitated diffusion or active transport across the cell membrane
23
Q
How do amoeba take in large molecules for nutrition?
A
Larger molecules and microbe by endocytosis, into food vacuoles
- these fuse with lysosomes
- contents digested by lysosomal enzymes have
24
Q
What happens to the products of digestion Inside an amoeba
A
Products of digestion are absorbed into the cytoplasm
Indigestible remains are egested by exocytosis
25
What happens to the pH of the contents of the food vacuole during digestion?
Changes from 7 to 2 to 7
| -resembling the oH changes of food on its passage through the mammalian gut
26
What is a hydra?
A multicellular organism with a single body opening(mouth) (more complex than an amoeba)
E.g sea anemones
27
What does a hydra comprise of
It is diploblastic :: comprises two layers of cells, an organism ectoderm and endoderm separates by a jelly layer
- cylindrical
- has tentacles at the top surrounding mouth
28
Where do hydra live?
Lives in fresh water, attached to leaves or twigs
29
How do hydra gain nutrients? (Capture)
When hungry it extends its tentacles and when small organisms brush against them, their stinging cells discharge and paralyse prey
-tentacle move prey through the mouth into hollow body cavity
30
What happens once the hydra has its prey in the hollow body cavity?
- endodermal cells secrete protease and lipase (not amalyse) and prey is digested extracellularly
- products of digested are absorbed into the cells
- indigestible remains are egested through mouth
31
What do the tentacles of hydra contain?
Photosynthesising protoctista
32
Basically describe the tube gut
Digestive system that is a tube with 2 openings at anterior and posterior e.g food ingested at mouth and indigestible waste is egested at the anus
33
HUMAN DIGESTIVE SYSTEM:
| Why must food be digested?
Because molecules are:
- insoluble and too big to cross membranes :: absorbed into the blood
- polymers must be converted to monomers so they can be rebuilt into molecules needed by body cells
34
Where do digestion and absorption occur(brief)
| -movement??
In the gut, a long, hollow, muscular tube.
| -allows movement of contents in one direction during peristalsis
35
Describe the process of peristalsis
1. Longitudinal muscles contract to push food forewords and then relax
2. Circular muscles contract behind the boules and then relax
3. Wave of contraction pushes boules down the gut
36
What are the 4 main functions of the gut
- ingestion
- digestion
- absorption
- egestion
37
What is ingestion?
Taking food into the body through the mouth
38
What is digestion
The breakdown of large insoluble molecules that are small enough to be absorbed in the blood
39
What is mechanical digestion?
| What is its benefit?
Cutting and crushing by teeth and muscle contractions of the gut wall.
-it increases the surface area over which enzymes can act
40
What is chemical digestion?
| What aids it?
Digestion by the secretion of enzymes
| -bile and stomach acid contribute to chemical digestion
41
What is absorption?
The passage of molecules and ions through the gut walk into the blood
42
What is egestion?
The elimination of waste not made by the body, including food hat can’t be digested e.g cellulose
43
What is the function of the mouth?
Ingestion
| Digestion of starch
44
What is the function of the oesophagus
Carriage of food to the stomach
45
What is the function of the stomach
Digestion of protein
46
What is the function of the duodenum
Digestion of carbohydrates, fats and proteins
47
What is the function of the ileum
Digestion of carbohydrates, fats and proteins
| Absorption of digested food
48
What is the function of the colon
Absorption of water
49
What is the function of the rectum
Storage of faeces
50
What is the function of the anus
Egestion
51
What is the general structure of the gut wall?
4 tissue layers surrounding a cavity, the lumen.
52
What are the 4 tissue layers called?
- serosa (outer)
- muscle
- submucosa
- mucosa(inner)
53
Describe the structure of the serosa in the gut
-Tough connective tissue, protecting the gut wall.
54
What is the purpose of the serosa in the gut
The gut moves while processing food and the serosa reduces the friction with other abdominal organs
55
What is the structure of the muscle layer in the gut
Comprises of two layers:
-inner circular muscles
-outer longitudinal muscles
(Responsible for making the co-ordinated waves for peristalsis)
56
Describe the purpose of the layers of muscles in the gut
Behind the boules circular muscles contract and longitudinal muscles relax, pushing the food along
57
Describe the structure of submucosa in the gut
Connective tissue containing blood and lymph vessels
58
What is the purpose of the submucosa in the gut?
Remove absorbed products of digestion, and nerves that co-ordinate peristalsis
59
Describe the structure of the mucosa in the gut
Innermost layer of gut wall
60
What is the structure of the mucosa in the gut
Epithelium secrets mucus lubricating and protecting the mucosa
Secrets digestive juices and in others, absorbs digested food
61
What are some examples of macromolecules
Carbohydrates, fats and proteins etc
62
How are carbohydrates digested (short)
-polysaccharides digested into disaccharides (by amalyse to produce maltose + maltose) and then monosaccharides (by maltase to produce glucose)
63
Name the different enzymes digesting different carbohydrates
Amalyse hydrolyses starch
Sucrase digests sucrose
Lactase digests lactose
64
What is the general name for a carbohydrate digesting enzyme?
Carbohydrase
65
How are proteins digested (short)
Digested into polypeptides (by protease and peptidase) then dipeptides and then amino acids.
66
What do endopeptidases hydrolyse?
Peptide bonds within the protein molecule (middle)
67
What do exopeptidases hydrolyse?
Peptide bonds at the ends of polypeptides
68
How are fats digested?
Digested to fatty acids and monoglycerides by lipase
69
What factors can reduce the ph in in the gut below 7
Acid secretion in the stomach and the production of amino acids and fatty acids in the ileum
70
What increases the pH above 7 in the gut?
Alkaline secretions in the duodenum increase the pH above 7
71
What is the buccal cavity?
| What occurs here?
Buccal cavity = mouth
| -where mechanical digestion begins as food is mixed with saliva by the tongue and chewed with teeth
72
Why is it vital to chew food?
Food surface area increase giving enzymes more access
73
What does saliva contain? Why is each constituent vital for digestion?
Watery solution containing:
- amalyse (starch—> maltose)
- HCO3 and CO3 ions (pH in mouth alkaline optimum for amalyse)
- mucus (lubricating the foods passage down oesophagus)
74
What is the purpose of the oesophagus
-no role but it does carry food to stomach
75
What tissue layers are present in the oesophagus?
```
Mucosa
Submucosa
Circular muscle
Longitudinal muscle
Serosa
```
76
Where is the cardiac sphincter (Ring of muscle) located?
At the junction with the oesophagus and stomach
77
Where is the pyloric sphincter locates?
Junction between stomach and duodenum
78
How is food kept in stomach?
How long for?
What is the volume of the stomach?
- kept in stomach by contraction of two sphincters (rings of muscle; cardiac and pyloric)
- May stay for several hours
- 2dm cubed
79
What happens to food in the stomach?
Stomach walls contract rhythmically and mix the food with gastric juice
80
Where is gastric juice secreted from?
-secreted from glands in the mucosa, called gastric pits
81
What is gastric juice formed from?
- peptidases (secreted by chief cells at the base of gastric put)
- pepsinogen (inactive enzyme)
- HCL (secreted by oxyntic cells)
- mucus (secreted by goblet cells, at the top of gastric pit)
82
What is the role of pepsinogen in gastic juice?
Inactive enzyme, activated by H+ ions to pepsin, an endopeptidase which hydrolyses protein to polypeptides
83
What is the role of HCL in gastric juice?
Lowers the pH of the stomach contents to pH2, the optimum for the enzymes and kills most bacteria in food
84
What is the role of the mucus in gastric acid?
Mucus forms a lining which protects the stomach wall from the enzymes and lubricates food
85
What enhances mechanical digestion in the stomach
Stomach wall has folds in its surface called rugae, and an oblique muscle at an angle to circular and longitudinal muscle, which provides extra contractions
86
What causes ‘heartburn’
When stomach contents move up into oesophagus, causing pain due to the acid on the oesophagus wall
87
Name the parts of a gastric pit
```
Goblet cells (secreting mucus)
Chief cell (secrets enzymes)
Oxyntic cell (secreted HCL)
Mature and immature mucus producing cells
Submucosa
```
88
What are the two regions of the small intestine?
Duodenum and ileum
89
What affect does the relaxation of the pyloric sphincter muscle (between stomach and duodenum) have on food passage?
Allows partially digested food into the duodenum
90
What is the duodenum?
First 25 cm of small intestine
| Receives secretions from the liver and pancreas
91
Where is bike made, stored and travel?
Made in the liver
Stored in the gall bladder
Passes through the bile duct into duodenum
92
What does bile contain?
- no enzymes
| - bile salts which are amphipathic (hydrophilic and phobic parts)
93
What is the role of the bile salts?
- They emulsify lipids in the food by lowering their surface tensions
- break up large globules increasing surface area, making lipase digestion more efficient.
94
What is the benefit of the bile being alkaline?
Neutralises the acid in food coming from the stomach, providing a suitable pH for enzymes in small intestine (7/8)
95
What secrets pancreatic juice?
| Where does pancreatic juice enter the duodenum?
- Secreted by islet cells, exocrine glands in the pancreas.
| - Enters duodenum through pancreatic duct
96
Why are exocrine glands?
Glands that secrete enzymes
97
What are endocrine glands?
Glands that secrete hormones
98
What is the function of the pancreatic secretion of sodium hydrogen carbonate in the small intestine?
Raises pH to make pancreatic juice slightly alkaline ::
- neutralises acid from the stomach
- provides the optimum pH for the pancreatic enzymes
99
What is the role of enzymes secreting (endopeptidases, trypsinogen, amylase and lipase) in the pancreatic secretion in the small intestine?
Endopeptidases= hydrolyse protein to peptides
Trypsinogen= inactive enzyme converted into the protease trypsin by the duodenal enzyme enterokinoase
Amylase= digests remaining starch to maltose
Lipase= hydrolyses lipids into fatty acids and monoglycerides
100
What are Pepsin and Trypsin secreted by?
| Why is this important?
Secreted by inactive precursors pepsinogen and trypsinogen
Important as this is why they don’t digest cells in which they are synthesised
101
What are the brunners glands?
Cells at the base of the crypts of Lieberkühn which secrete alkaline secretions
102
In the small intestine (ileum), what are on the villi?
Enzymes associates with the epithelial cells (secreted by cells at the villus tips such as endo/exopeptidases) which continue the digestion of polypeptides in the gut lumen
103
Why are the enzymes on the cell membranes of epithelial cells of the villi important?
dipeptides are digested to amino acids by enzymes on the cell membranes of epithelial cells
104
Where are disaccharides absorbed into in the small intestine?
Explain this xx
Into the epithelial cells of the villi
- carbohydrases in the cell membranes of epithelial cells digest disaccharides into monosaccharides
- :: final stage of digestion is intracellular
105
What 3 enzymes are in the cell membrane of epithelial cells in villi?
Maltase (maltose—> glucose + glucose)
Sucrase (sucrose—> glucose + fructose)
Lactase (lactose—> glucose and galactose)
106
How is the ileum well adapted for absorption?
- very long (approx 6m in humans with folded lining)
- on surface of folds are villi whose epithelial cells have microscopic projections called microvilli (large SA for absorption)
107
Name the 3 ways monosaccharides are absorbed in small intestine
1. Diffusion
2. Facilitated diffusion
3. Active transport
108
Why do epithelial cells have mitochondria?
Because active transport requires energy in the form of ATP
109
What are the main 2 components of epithelial cells on villi?
- microvilli
| - goblet cells
110
Name the tissue layers in the small intestine
Serosa
Longitudinal muscle
Circular muscle
Mucosa with villi (and villi have microvilli)
111
How are amino acids absorbed into the epithelial cells?
| Where do they go now?
- By active transport
- Travel as individual amino acids into the capillaries by facilitated diffusion
- water soluble so next dissolve into plasma
112
How does glucose pass into epithelial cells?
- by co-transport with sodium ions
- move into capillaries (sodium by active transport and Glucose by facilitated diffusion)
- dissolve into plasma
113
Why is some glucose actively transported into epithelium cells on the villi?
-diffusion and facilitated diffusion are slow and :: not all of it can be absorbed :: active transport prevents glucose leaving body in faeces
114
Where are fatty acids and monoglycerides absorbed into?
| How?
Absorbed into epithelial cells and lacteals
| By diffusion
115
What are lacteals
Parts of the lymphatic system which transport day soluble molecules to the left subclavian vein near the heart
116
How are minerals absorbed into the blood
Diffusion, facilitated diffusion and active transport, then dissolve in the plasma
117
Why are Vitamins B & C absorbed into the blood?
Because they are water soluble
118
Why are Vitamins A, D and E absorbed into lacteals?
Because they are fat soluble
119
What are lipids used for after being absorbed into the blood?
Used in membrane and to make some hormones, excess is stored
120
What is glucose used for after being absorbed into the blood?
Taken to body cells and respires for energy or stored as glycogen in the liver and muscle cells
-excess stored as fat
121
What are amino acids used for after being absorbed into the blood?
Takes to body cells for protein synthesis
- excess can’t be stored so liver deaminates the amino acids and converts NH2 groups to urea
- remaining AA are converted to carbohydrates for storage or fat conversion
122
How long is the large intestine?
| What parts make up the large intestine?
1. 5m long
| - the caecum, appendix, colon and rectum
123
What passes into the colon?
Undigested food, mucus, bacteria and dead cells
124
Why does the colon have a major role in water absorption?
It has villi (smaller value of larger villi compared to villi in the ileum)
125
What happens as material passes along the colon?
As it passes along water is absorbed and by the time it reaches the rectum the material is semi solid
126
What happens in the rectum
Food passes along rectum and is egested as faeces (defecation)
127
Describe the tissues in the colon wall
```
Serosa
Longitudinal muscle
Circular muscle
Submucosa
Mucosa with larger villi than small intestine
```
128
How do reptiles and amphibians ingest food?
Ingest food and swallow it whole
129
How do mammals ingest food (brief)
Retain food in the buccal cavity, while it is cut and chewed and then swallowed
130
Why is the palate separating nasal and mouth cavities vital in mammals (only found in mammals)
So food can be held in the mouth and chewed whilst breathing
131
What mostly comprises a carnivores diet?
| What adaptation reinforces this fact?
Eats only animals :/ high protein diet
- gut= 5x length of body
- small intestine is short compared to body showing ease at which proteins digested
132
Why is the small intestine of a herbivore relatively long in relation to its body?
Plant material is not readily digested :: a long gut allows enough time for digestion and absorption of nutrients
-gut= 10x length of body
133
How long is the gut in an omnivore?
Intermediate length
134
What are the 4 types of teeth in humans?
Incisors
Canines
Premolars
Molars
135
Why are humans teeth less specialised than carnivores or herbivores?
Humans are omnivores :: intermediate
136
Why do herbivores teeth have to be modified?
Because plant cell walls contain cellulose, lignin and sometimes silica which are tough to eat
137
Name the dentition parts of herbivores that i should know
```
Dental pad
Incisors
Canine
Diastema
Premolars
Molars
```
138
Where does a herbivore has incisors and canines?
On the lower jaw only, canine distinguishable from incisors in shape and size
139
How does the herbivore use the dental pad to aid grass digestion?
1. Wraps tongue around grass
2. Pulls it right across ‘dental pad’ on its upper jaw
3. Lower incisors and canines slice through it
140
What is the diastema featured in herbivores?
A gap separating the front teeth from the side teeth (premolars)
141
Why is the diastema needed
Allows room for the tongue and cheeks to move the grass to the large grinding surface of the cheek teeth or molars
142
How do the molars fit in the mouth?
Interlock like a W fitting into an M
143
How does the lower jaw move in a herbivore?
From side to side producing a circular grinding action in a horizontal plane
144
What happens to the teeth or herbivore over time?
| Why is this beneficial?
-grinding surfaces on the teeth become worn exposing shape edged enamel ridges (increasing efficiency of grinding)
145
Why are herbivores having open unrestricted roots a benefit
- Allow the teeth to continue to grow throughout the animals life
- replacing material worn down by chewing
146
Why does a herbivore not need strong muscles attached to its jaws?
Because it’s food is not likely to escape
147
Describe the skull of a herbivore
Relatively smooth
148
What adaptations are the teeth of a carnivore suited to?
Catching and killing prey, cutting or crushing bones and tearing meat
149
What is the purpose of incisors in a carnivore?
Sharp incisors grip and tear muscle from bone
150
Describe canine teeth in carnivore
Large, curved and pointed for piercing and seizing prey, tearing muscle and killing
151
What do the molars and premolars of carnivores have? Benefit?
Have cusps which are sharp point that cut and crush
152
What are carnassials?
Pair of large specialised cheek teeth in carnivores which slide past each other like scissor blades
(Sheer muscle off the bone)
153
Which direction does the lower jaw of a carnivore move? Benefit?
Moves vertically
| Open their jaws more widely than herbivores
154
Describe the jaw muscles in a carnivore
Well developed and powerful allowing carnivore to grip prey firmly and crush bone
155
Why are there protrusions on the skull of a carnivore?
Caused by the jaw muscles inserting into the bone
156
Define ruminant
A cud chewing herbivore possessing a ‘stomach’ divided into 4 chambers, the largest of which is called the rumen which contains mutualistic microbes
157
Name examples of ruminants
Cows and sheep
158
How do ruminants digest cellulose (cell wall material from their plant diet)
Rely on mutualistic microns living in their gut to secret enzymes e.g fungi, bacteria and protoctista which live in the rumen
159
Why do ruminants have to rely on mutualistic microbes to digest cellulose?
-animals don’t make cellulase and can’t digest B-glycosidic bonds in cellulose
160
Describe how grass becomes a source of energy for a ruminant
-grass cut by teeth and mixed with saliva to form w cud which is swallowed down oesophagus
-in rumen food mixes with microbes which secrete cellulase which digest cellulose to glucose
-mixture is fermented to organic acids that are absorbed into the blood and are now a source of energy for the cow
Glucose—> 2CH3COOH + CO2 + CH4
(Carbon dioxide and methane are waste products)
161
Describe the digestion of the fermented grass in the cow
- rumen—> reticulum and is reformed into cud
- regurgitated into mouth for further chewing (can be swallowed and regurgitated several times
- reticulum—> omasum where water and organic acids made from fermented glucose are absorbed into blood
- omasum—> abomasum where protein is digested by pepsin at pH2
- digested food passes into small intestine were products of digestion pass into blood
162
What are plants and animals parasitised by?
```
Bacteria
Fungi
Virus
Nematodes
Insects
(Humans also parasitised by tapeworm and mites)
```
163
What is a parasite that affects bacteria
Bacteriophages
164
What problems to parasites cause
Disease in humans, crops and domesticated animals
165
Why does the gut parasite pork tapeworm (taenia solium) survive?
1. It has no competition
| 2. It is an endoparasite and :: can’t be preyed upon
166
Describe the structure of the pork tapeworm (taenia solium)
- ribbon like (thin so allows hosts food to pass)
- up to 10m long
- anterior end=scolex
- body= linear series of sections called proglottids
167
Why is the scolex vital to the tapeworms survival?
The muscle carries suckers and hooks which attach to the duodenum wall
168
Name the pork tapeworms (taenia solium) hosts
Primary host= human
| Secondary host= pig
169
How are pigs/humans infected by pork tapeworm (taenia solium)
Pig= infected when it’s food is contaminated with human faeces
Human= eating undercooked, infected pork.
170
What challenges in humans does the tapeworm have to overcome? (5)
- lives surrounded by digestive juices and mucus
- peristalsis produces constant motion
- experience pH changes in passage to duodenum
- exposed to hosts immune system
- if host dies so does the parasite
171
Describe the pork tapeworm cycle (from pig to human and back)
1. Human eats meat infected with pork tapeworm
2. Adult tapeworm attach to duodenum via hooks on their scolex
3. Mature proglottids contain uterus with embryos
4. Terminal (dead) proglottids fall off tapeworm and are discharged with human faeces
5. Eggs and embryos from within proglottids remain alive in the ground
6. cycle only continuous of consumed by pig
172
Wha must the tapeworm do to survive the hostile environment?
- penetrate the host
- attach to the host
- protect itself against hosts immune system
- develop only organs essential for survival
- produce many eggs, giving high chance of transmission to secondary host
- have resistant stages whilst away from host
173
Name the structural modifications enabling tapeworm to live as a parasite
- suckers and double row of curved hooks attaching it to duodenum wall
- thick body covering (cuticle) protecting against hosts immune response
- produce enzyme inhibitors (prevent host digesting it)
- large SA:V ration so food absorbed over whole surface
- only have simple excretory and nervous system + complex reproductive system
- eggs have resistant shells + survive until eaten by secondary host (pig)
174
What effects can the pork tapeworm cause in humans?
Long term infection causes taeniasis
Symptoms include abdominal pains and weakness
Can be treated with drugs
175
Name an example of an ectoprasite
| Describe this
Pediculus (lice)
- wingless insects
- can’t fly and legs poorly adapted for jumping and waking
- if removed from human they die
176
Describe the life cycle of a headlouse
1. nuts are empty eggs (easily seen in hair)
2. After 1-2 weeks egg hatches into a nymph (like adult but smaller)
3. Nymphs become adults after 10 days and both feed of blood which they suck
177
Why is mating of the pork tapeworm impossible?
| How do they reproduce?
The gut only accommodated one tapeworm :: mating is impossible
Tape work is a hermaphrodite (male and female organs in each proglottids :: they fertilise their own eggs
178
Suggest why the pH in the Rumen May alter from its normal of 6.2?
Because a solution of carbon dioxide is produce when microbes respire
179
How do cows control its rumens pH
HCO3- and CO3- in saliva swallowed into the rumen raising pH
180
What is the point of the smooth muscle cells in the small intestine?
- moves villus to change material in contact with it
| - movement forces material from lacteals
181
Explain how the gut of a hervivore is adapted for nutrition
Herbivore gut has 4 chambers (including rumen)
Rumen contains mutualistic microbes that produce cellulase
Long gut allows longer time for digestion
Cud is regurgitated for extra chewing
