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Biology component 3 > Adaptations for nutrition > Flashcards

Adaptations for nutrition Flashcards

1
Q

What does autotrophic mean

A
  • make own food from simple inorganic raw materials
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2
Q

What is photoautotrophic

A
  • use light energy to perform photosynthesis
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3
Q

Give examples with photoautrophic organisms

A
  • green plants
  • protoctista
  • some bacteria
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4
Q

What does chemoautotriophic mean

A
  • use energy from chemical reactions
  • inclue prokaryotes
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5
Q

What does heterotrophic mean

A
  • consume complex organic molecules produced by autotrophs
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6
Q

what does saprotrophic mean

A
  • feed on dead or decaying matter by secreting enzymes extracellularly and then absorbing the products
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7
Q

What does parasitic mean and what are the two types

A
  • obtain nutrition from another living organism called the host over a long period of time whilst causing it harm
  • endoparasities live within the hosts body eg tapeworm
  • ectoparasities live on the surface - human head louse
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8
Q

What does holozoic mean

A
  • form of nutrition used by most animals where they ingest and then digest food absorbing nutrients
  • they possess a specialised digestive system
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9
Q

What types of holozoic organisms contain a speicalised digestive system

A
  • herbivores - plant
  • carnivores - animal
  • omnivores - plant and animal
  • detritivores - dead or decaying material
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10
Q

Describe the nutrition in unicellular organisms giving an example

A
  • protoctista such as amoema are holozoic hetertrophs
  • they absorb nutrients directly through their cell membrane by diffusion ingesting leager molecules by endocytosis and fluids by pinocytosis into food vacuoles
  • lysosomes fuse with the vacoules and release digestive enzymes
  • nutrients are absorbed through the membrane of the food vacoule and waste is egested by exocytosis
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11
Q

Describe the nutrition in a hydra

A
  • single opening
  • lives in fresh water
  • tentacles paralyse prey and move it into the hollow body cavity through the mouth
  • protease and lipase enzyme digest the food extracellularly and the products are absorbed before the indigestible remains are egested back out through the mouth
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12
Q

Describe the nutrition of more developed multicellular organisms

A
  • possess a tube gut
  • ingesting at one end
  • egesting at the other
  • most advanced posessing specialised regions
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13
Q

Describe what the gut does

A
  • long hollow muscular tube which food passes along by peristalsis
  • different regions of the gut are specialised to perform four main functions
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14
Q

What is peristalsis

A

the wave of coordinate contraction and relaxation of smooth mucles in the gut

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15
Q

What is hydrolysis

A

the reaction involving the chemical addition of water to break the bond formed during condensation

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16
Q

What is ingestion

A

taking food into the body via the mouth bringing it into contact with the digestive surface

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17
Q

What is digestion

A
  • results in large biological molecules being hydrolysed to smaller molecules that can be absorbed across cell membranes
  • begins with mechanical digestion in the mouth involving teeth which breaks large food pieces into smaller pieces
  • it is then completed by enzymes
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18
Q

What is absorption

A

passage of nutrient molecules through the wall of the gut into the blood

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19
Q

What is egestion

A

elimination of undigested material eg cellulose fibre

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20
Q

What are the four layers of the gut wall

A
  • serosa
  • muscle
  • submucose
  • mucosa
21
Q

What is the function of the serosa

A
  • outermost layer consisting of tough connective tissue which protects the gut and reduces friction from other abdominal organs
22
Q

Describe the function of muscle in the gut wall

A
  • consists of two layers circular and longitudinal smooth muscles whcih contract in a coordinated fashion to push food along by peristalsis
23
Q

Describe the function of the submucosa

A
  • connective tissue containing blood and lymph vessels to take away the absorbed products of digestion
  • nerves are also present whcih co ordinate muscular contractions
24
Q

What is the function of the mucosa

A
  • innermost layer lining the gut it secretes mucus lubrication and protection from enzymes)
  • depending upon the region it secretes enzymes and absrobs digested food and nutrients
25
Q

Where does carbohydrate digestion start

A
  • hydrolysis of starch in the mouth by salivary amylase
26
Q

Where does protein digestion start

A
  • begins in the stomach by action of pepsin
27
Q

Describe the digestion of carbohydrates

A
  • amylase hydrolyses starch to maltose and then maltase hydrolyses maltose to glucose
  • sucrase hydrolyses sucrose to glucose and fructose
  • lactase hydrolyses lactose to glucose and galactose
28
Q

Describe the digestion of proteins

A
  • proteins are digested into polypeptides, dipepteides and eventually amino acids
  • enzymes involved are peptidases names according to where they break the peptide bonds
29
Q

Descibe digestion of fats

A
  • fats are emulsified by bile then hydrolyses to fatty acids and glyceol by lipase
30
Q

Describe the function of the mouth / buccal cavity in digestion

A
  • where digestion begins
  • teeth mecahnically digest food the tongue mixes this with saliva rolls it into a bolus for swallowing
  • saliva contains enzyme amylase and mucus which lubricates the food
  • enzyme amylase initiates starch digestion
31
Q

What is the role of the oesophagus during digestion

A

oesophagus muscles contract to move the food toward the stomach via peritalsis

32
Q

What is emulsification

A

large fat droplet are broken into smaller droplets which increases the surface area for lipase action

33
Q

Describe the role of the stomach during digestion

A
  • food is digested for about four hours by muscular action from the stomach walls and gastric juice whcih contains hydrochloric acid and pepsin
  • pepsin is an endopeptidase that is secreted in an inactive form pepsinogen and activated by H+ ions this prevents pre digestion the acidic pH of around 2 also kills bacteria
  • mucus is produced by goblet cells in the gastric pits which lubricated food and protects the lining
34
Q

Describe the role of the duodenum in digestion

A
  • first part of the small intestine recieving secretions from the liver and pancreas
  • bile contains bile salts neutralising the acidic food from the stomach and emulsifies fat
  • pancreatic juice is slightly alkaline due to presecnce of sodium hydrogen carbonate and is secreted by islet cells in the pancreae entering the duodenum via the pancreatic duct
  • it contains endopeptidases and trypsinogen ( which is inactive and converted to the active form trypsin by enterokinase) amylase and lipase
  • brunners glands at the base of the crypts produce alklaine secretions also neutralise acidic food from the stomach
  • the mucose of the small intesting is heavily folded to form villi the duodenum endopeptidases and exopeptidases are secreted by cells at the tips of the villi and peptidases bound to epitherlial cells complete the digestion to amino acids
  • maltase, lactase and sucrease are also bound to epitherlial cells complete the digestion of carbohydates
35
Q

Describe the role of the ileum in digesttion

A
  • second part of the small intestine responsible for the absorption of digested food
  • villi and microvilli increase the surface area for absorption by diffusion, facilitated diffusion, co transport and active transport and for action of membrane bound enzymes
  • glucose enters the epitherlial cells by co transport and active transport and facitilitate diffuction into capillary of the villi
  • amino acids enter by active transport into epitherlial cells and then by facilitated diffusion into capillary of the villi
  • fatty acids and glcyerol enter epithelial cells via diffusion where they recombine into triglycerides entering lacteal of villi, smooth endoplasmic reticulum in epitherlial cells are highly developed to asssit this process
  • water absorbed by osmosis into epithelial cells and capillary of the villus
  • water soluble vitamins are absorbed directly into the blood
  • fat soluble vitamin are absorbed into the lacteals by diffusion
36
Q

Describe the role of the large intesting in digestion

A
  • appendix, caecum, colon, rectim and anus
  • has small villi present
  • responsible for the absorption of water and the formation of faeces stored in the rectum until its egested
  • mutualistic bacteria present in the colon reposible for production of vitamin k and folic acid
  • glucose and amino acids are transported by hepatic portal vein to the liver where they are processed
  • lacteals drain into teh lymphatic system drains into blood via the thoracic duct in the right subclavian vein
37
Q

what are carnassials

A
  • modified upper premolar and lower molar teeth found in carnivores that have a scissor like action for slicing bone and flesh
38
Q

Describe the dentition of carnivores

A
  • evolved sharp incisors to tear flesh
  • pointed canines to pierce flash and kill prey
  • specialised molars called carnassials that shear flah and bone
  • powerful jaw muscles which move the lower jaw vertically up and down and are able to open their jaws wide to accomodate large prey animals
  • intestines relativley short as main constituent in their diet is protein which is relativley easily digested
39
Q

Describe the dentition of herbrivore

A
  • herbivores posess incisore and canine teeth slice through vegetations cropping it
  • some herbivores lack incisors in upper jaw instead possessing a horny pad which lower teeth cut against
  • a gap called diastema allows food to be mixed during the chewing process
  • they possess interlocking molar teeth that are rough due to the preseccene of sharp enamel ridges
  • teeth are worn down by abrasive plant material always growing continuously
  • the jaws are able to move in a sideways motions to aid grinding of the food
40
Q

Why is the vegetative diet difficult to digest

A
  • difficulty n eating is that main component of cell walls in plant tissue is cellulose
  • the arrangement of b glucose molecules into microfibrils make cellulose very dificult to digest
41
Q

What are ruminants

A
  • cows and sheep
  • posess a highly modified oesophagus containing three chambers one of whcih is the rumen and true stomach
42
Q

Describe the digestion in ruminants

A
  • grass is first chewed to form a bolus known as cud which is swallowed and enters the rumen where it mixes with mutualisteic cellulose digesting bacterial producing glucose from cellulose
  • glucose is anaerobically repired by bacteria producing organic acids, carbon dioxide and methane as waste products
  • remaining grass passes to the reticulum where it is reformed into a cud which is regurgitates, re chewed to increase the surface area for the action of the bacterial cellulases before being swallowed again
  • the cud now passes to the moasum where organic acids are absorbed into the blood
  • finally material passes to the abosmasum (true stomach) where acid kills the bacteria and pepsin begins the digestion of the bacteria
  • water is absorbed int he large intestine in a similar way as in humans
43
Q

What are the two types of parasites

A
  • endoparasites - live in
  • ectoparasites - live on
44
Q

Decribe how the pork tapeworm acts as a parasite

A
  • has two hosts
  • primary host - where sexual reproduction takes place in - human
  • secondary host - the pig
  • both are needed to fully complete the parasites life cycle
  • if eggs are eaten difrectly by a human rather than infected meat cysts can form in the brain causing a far more serious condition
45
Q

Describe the cycle of the pork tapeworm as a parasite

A
  • mature proglottids containing uterus with embryos
  • the terminal proglottides fall off and are discharge with the faecres
  • eggs and embryos alive in the ground but develop further only if eatern by the pig
  • infected meat eaten
46
Q

Describe the adaptations pork tapeworms have to live inside the human digestive system

A
  • suckers and hooks - attatchement to gut wall
  • thin and large surface area to volume ratio - maximie absorption of digested food
  • produces enzymes inhibitors - prevents digestion by hosts enzymes
  • thick cuticle - protects it from hosts immune system
  • has male and female reproductive structures - allows for sexual reproduction without second tapeworm
  • produce vast number of eggs - increases chance of finding another host
  • eggs have resistant shells - survive until eaten by secondary host
47
Q

Why do tapewoms not have a digestive system

A

absorbs producs to hosts digestion directly through its cuticle

48
Q

Describe why a head louse is a parasite and its life cycle

A
  • ectoparasite
  • feeds by sucking blood from the scalp of the host
  • only pass to a new host via direct contact
  • takes 2 week for an egg to hatch into a nymph which feed on blood
  • nymph delvelop into adults which can then lay eggs
49
Q

What are the adaptations for a head louse

A
  • leg are adapted to be claw like to grip onto the hairs
  • lay eggs that are glued to the base of hairs

Biology component 3 (7 decks)

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