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Biology > Component 3 - Nutriton > Flashcards

Component 3 - Nutriton Flashcards

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1
Q

How do unicellular organisms consume food e.g amoeba

A
  1. Amoeba pseudopodia move around prey and enclose it in a food vacuole
  2. Enzymes are released from lysosomes that fuse with the food vacuole and the prey is digested
  3. Products of digestion are absorbed into the cytoplasm and the undissolved waste is egested by exocytosis
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2
Q

Describe the gut of a hydra - single food source

A

Undifferentiated, sac-like gut with a single opening

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3
Q

Describe the gut of an earthworm - varied foods

A

A tube gut with different openings for ingestion and egestion and specialised regions for the digestion of different food

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4
Q

Describe the gut of a Human - Omnivorous diet

A

Specialised regions of gut. The wall of the gut contains the
following layers

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5
Q

List the different layers of the gut from the outside to the inside

A
  1. Serosa
  2. Longtitudinal Muscle
  3. Circular Muscle
  4. Sub Mucosa
  5. Mucosa
  6. Epithelium
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6
Q

What is the Serosa layer

A

Tough outer coat of connective tissue

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7
Q

What do the circular and longtitudinal mucles do

A

Longitudinal muscle contracts to shorten the gut
circular muscle contracts to reduce diameter.
These waves of contraction called peristalsis force food along the gut.

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8
Q

What does the submuosa layer do

A

Contains blood and lymph vessels to remove digested food products

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9
Q

What does the mucosa layer do

A

Inner layer that secretes mucus for lubrication. In some areas it secretes digestive juices; in others it absorbs products.

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10
Q

What does the epithelium layer do

A

Layer of cells in contact with food

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11
Q

What is autotrophic nutrition and what are the two types

A

makes complex organic molecules from simple inorganic ones
* Photoautotrophic
* Chemoautotrophic

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12
Q

What is Photoautotrophic nutrition

A

Use light as a source of energy for synthesis of
food

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13
Q

What is Chemoautotrophic nutrition

A

Oxidise inorganic molecules to provide energy for the synthesis of food

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14
Q

What is Heterotrophic nutrition and what are the two types

A

consume complex organic food molecules
* Saprophytic
* Holozoic

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15
Q

What is Saprophytic Nutrition

A

External digestion of food using secretion of enzymes followed by absorption of the products of digestion into the organism, e.g. fungi.

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16
Q

What is Holozoic nutrition

A

internal digestion of food. Involves ingestion, absorption, assimilation and egestion

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17
Q

What are the two types of proteases

A

Endopeptidase
Exopeptidase

18
Q

What do endopeptidases do

A

endopeptidases hydrolyse peptide bods between specific amino acids in the middle of the polypeptide chain to form shorter polypeptide chains

19
Q

What do exopeptidases do

A

Exopeptidases hydrolyse peptide bonds on the end of peptides, from the free amino end or the free carboxyl end

20
Q

What happens at the buccal cavity

A

Mechanical digestion
* The tongue moves food to the cutting
and grinding surfaces of the teeth
* The tongue rolls the food into a bolus which is swallowed

Chemical digestion
* Starch and glycogen into maltose by the enzyme amylase. Saliva moistens food and also maintains the pH for the enzyme

21
Q

What does the Oesophagus do

A

Peristaltic waves of muscle contraction push the bolus of food down to the stomach
Mucus lubricates the way

22
Q

What does the Stomach do

A
  • Gastric glands in the mucosa produce gastric juice
  • The Oxyntic cells produce hydrochloric acid (HCl) that kills bacteria and lowers the pH to 2
  • The chief or peptic cells produce pepsinogen, the inactive precursor of the endopeptidase enzyme, pepsin
  • This is activated by the HCl
  • Goblet cells produce mucus to protect the stomach lining
23
Q

What does the Stomach do

A
  • Gastric glands in the mucosa produce gastric juice
  • The Oxyntic cells produce hydrochloric acid (HCl) that kills bacteria and lowers the pH to 2
  • The chief or peptic cells produce pepsinogen, the inactive precursor of the endopeptidase enzyme, pepsin
  • This is activated by the HCl
  • Goblet cells produce mucus to protect the stomach lining
  • Churns Food
24
Q

What does the Liver do

A
  • Produces bile.
  • Bile emulsifies lipids to increase the surface area available for lipase enzymes to digest them.
  • It neutralises stomach acid to create a slightly alkaline pH in the duodenum for the pancreatic enzymes
25
Q

What does the Gall Bladder do

A

stores the bile before delivering it to the duodenum via the bile duct.

26
Q

What does the pancreas do

A

Produces enzymes that are transported to the duodenum via the pancreatic duct
* Carbohydrase - pancreatic amylase
* Protease – trypsinogen activated into the endopeptidase Trypsin by enterokinase in the duodenum
* Pancreatic lipase enzymes digest triglycerides into monoglycerides and eventually glycerol and fatty acids

27
Q

What does the duodenum do

A

further digestion occurs on the epithelial cells of the villi.
* Sucrose digested by sucrase into glucose and fructose.
* Maltose digested by maltase into alpha glucose.
* Lactose digested by lactase into glucose and galactose.
* Further digestion of polypeptides by endopeptidases and exopeptidases.

28
Q

What is the structure of a villus

A

On the outside, there are columnar epithelial cells. On the inside, there are capilliaries and lacteals .

29
Q

What type of diet are carnivores adapted to

A

High Protein Lipid Energy diet

30
Q

What are the features of the dentition of Carnivores

A
  • Incisors on upper and lower jaw grip and tear flesh
  • Canines – long and pointed to pierce flesh and seize and kill prey
  • Carnassial teeth - act like shears, sliding past each other to rip muscle from bone
  • Premolars and molars - have sharp cusps that cut and crush. The jaw has strong muscles and moves in a vertical plane to hold prey
31
Q

How is a carnivore’s gut adapted to it’s diet

A
  • Relatively short gut
  • Usually a large stomach for digestion of mostly protein diet
  • Small caecum
32
Q

What diet is a herbivore adapted to

A

A high Cellulose diet

33
Q

What are the 2 types of Herbivores

A
  • Ruminants
  • Non Ruminants
34
Q

How is a herbivore’s dentition adapted to it’s diet

A
  • Incisors – on lower jaw and cut vegetation against a horny pad on the upper jaw. Canines absent or indistinguishable
  • Diastema – space where tongue can push food to the grinding cheek teeth
  • Premolars and molars – cheek teeth. Fit together. Jaw moves in a horizontal plane so teeth grind food. Teeth have open, unrestricted roots and so grow throughout life
35
Q

How is a non-ruminant gut adapted to it’s diet

A
  • Very long gut for the difficult process of cellulose digestion
  • Large caecum containing bacteria that produce cellulase for cellulose digestion
36
Q

What is the main example of a Ruminant Gut

A

A cow

37
Q

How is a cow’s gut (ruminant) adapted to it’s diet

A
  1. Mouth - Grass is mixed with saliva and then chewed (forming cud) before being swallowed
  2. Rumen - Cud enters the rumen. Bacteria produce cellulase, breaking down cellulose into glucose. This ferments into organic acids which are absorbed. Produces greenhouse gasses
  3. Reticulum - Fermented cud enters the reticulum. The cud is regurgitated from here and the rumen back into the mouth to be rechewed
  4. Omasum - Rechewed cud is swallowed and enters the Omasum Water absorption occurs here
  5. Abomasum - Protein Digestion
  6. Small Intestine - Digested products absorbed into the blood
38
Q

What is a Parasite

A

Live on or in a host organism, obtaining their nutrition from the host and harming the host

39
Q

What is an ectoparasite

A

Lives on the surface of another organism

40
Q

What is an Endoparasite

A

lives inside another organism

41
Q

What is an example of an ectoparasite and how is it adapted

A

The head louse feeds by sucking blood from the scalp of the host.
* It has claws to hold onto the hairs.
* Lays eggs which are glued to the base of hairs.
* Transfer between hosts is by direct contact as it cannot jump, only crawl

42
Q

Give an example of an endoparasite and how it’s adapted

A

The adult pork tapeworm (Taenia solium) lives in the gut of humans.
1. Primary host – a larval form develops in
pigs.
2. Secondary host – infection of humans
occurs when a person eats pork containing
live larval forms (tapeworm cysts in muscle
tissue).
The gut is a hostile environment due to the
presence of various secretions and peristalsis.
The tapeworm has adapted to living in the
gut as follows:
* Thick cuticle produces anti-enzymes.
* Scolex to attach to the gut wall.
* Taenia solium has a reduced gut and feeds by absorbing pre-digested nutrients through its cuticle.
* To increase the chances of infecting a secondary host, it produces large numbers of eggs that pass out in shit

Biology (10 decks)

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