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Biology Unit 2 ☁️ > 2.4 Adaptations for nutrition > Flashcards

2.4 Adaptations for nutrition Flashcards

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1
Q

Define autotrophic.

A

• An organism that produces its own food
• It manufactures complex organic compounds from simpler inorganic molecules such as water and carbon dioxide

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2
Q

Name the two types of autotrophic organisms.

A

• Photoautotrophic
• Heterotrophic

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3
Q

What is a photoautotrophic organism?

A

An organism which obtains its nutrition through photosynthesis.

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4
Q

What is a chemoautotrophic organism?

A

An organism which obtains its nutrition through inorganic molecules, such as sulfur, in the absence of light.

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5
Q

Define heterotrophic.

A

An organism that cannot produce its own food. It obtains energy by feeding on organic compounds produced by other organisms.

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6
Q

What is a saprotroph?

A

An organism that feeds by extracellular digestion, e.g. fungi.

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7
Q

Describe extracellular digestion by saprotrophs.

A

• Release enzymes which catalyse the breakdown of dead plant and animal material into simpler organic matter
• Absorb the products of digestion

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8
Q

What is meant by the term ‘holozoic’?

A

Describes a heterotrophic organism that internally digests food substances.

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9
Q

What processes does holozoic nutrition involve?

A

Ingestion, digestion, absorption, assimilation and egestion.

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10
Q

Define ingestion.

A

The process by which organisms take food into their bodies.

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11
Q

Define digestion.

A

The processes by which large, insoluble molecules are broken down into smaller, soluble molecules that can be absorbed across cell membranes.

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12
Q

Name the two types of digestion.

A

• Mechanical digestion
• Chemical digestion

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13
Q

What is mechanical digestion?

A

• Type of digestion that involves physically breaking down food material into smaller pieces
• Increases the total surface area for chemical digestion

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14
Q

What is chemical digestion?

A

A type of digestion that involves breaking down large, insoluble molecules into smaller, soluble molecules using enzymes.

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15
Q

What is assimilation?

A

The synthesis of biological compounds from absorbed simpler molecules.

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16
Q

Define absorption.

A

The movement of useful substances into the bloodstream.

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17
Q

Define egestion.

A

The removal of undigested waste material from the body.

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18
Q

Describe how unicellular organisms obtain nutrients.

A

• Ingestion via phagocytosis
• Intracellular digestion (using hydrolytic enzymes) breaks down large, insoluble molecules into smaller, soluble molecules
• Products of digestion pass into the cytoplasm by diffusion and active transport
• Undigested material removed by exocytosis

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19
Q

What is a Hydra?

A

A small, multicellular, freshwater organism of the phylum Cnidaria.

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20
Q

Describe the structure of Hydra.

A

• Basic, undifferentiated sac-like gut
• Single opening, surrounded by tentacles, that serves as a mouth and an anus
• Single gut cavity (known as the enteron)

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21
Q

Outline the process of digestion in Hydra.

A

• Hydrolytic enzymes secreted into the enteron by the endodermis
• Extracellular digestion partially digests food molecules
• Partially digested food transported, via phagocytosis, into endodermal cells where intracellular digestion takes place
• Undigested material egested from the enteron via the single opening

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22
Q

Describe the shape of the gut in more complex organisms.

A

Tube-like with two openings, a mouth for ingestion and anus for egestion.

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23
Q

What type of diet is the human gut adapted to?

A

An omnivorous diet consisting of plant and animal material.

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24
Q

State the names of the different layers of the gut wall.

A

• Epithelium
• Mucosa
• Submucosa
• Muscle layer
• Serosa

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25
Q

What is the epithelium?

A

A single layer of cells that line the gut wall.

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26
Q

Describe the structure of the mucosa layer of the gut wall.

A

• Mucous membrane lining the gut wall
• Contains glands that secrete digestive enzymes, mucus, and an acid or alkaline liquid that provides an optimum pH

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27
Q

Describe the structure of the sub-mucosa layer of the gut wall.

A

• Layer of connective tissue below the mucous membrane
• Contains blood vessels and lymph for the transport of digestion product and glands that secrete an alkaline fluid

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28
Q

Describe the muscle layer of the human gut.

A

A layer of circular and longitudinal muscles beneath the submucosa.

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29
Q

Explain the action of circular and longitudinal muscles in peristalsis.

A

The contraction of the circular muscle behind the bolus of food and the relaxation of the longitudinal muscle in front forces food down the gut.

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30
Q

What is the serosa?

A

The tough, protective layer that surrounds the gut.

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31
Q

What is the buccal cavity?

A

The oral cavity through which food enters the body.

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32
Q

Which type(s) of digestion take place in the buccal cavity?

A

Mechanical digestion and chemical digestion of starch.

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33
Q

What is the normal pH range of the buccal cavity?

A

pH 6.5 to 7.5

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34
Q

What is the function of the teeth?

A

Crush and grind food into smaller pieces, increasing its surface area.

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35
Q

What is the tongue?

A

A muscular organ in the buccal cavity that is vital in the chewing and swallowing of food.

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36
Q

Describe the function of salivary glands.

A

Secrete amylase, mineral ions and mucus into the buccal cavity.

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37
Q

What is the function of the oesophagus?

A

Carries food from the buccal cavity to the stomach by peristalsis.

38
Q

Describe the processes that take place in the stomach.

A

Mechanical digestion (mixing and grinding) and chemical digestion of protein.

39
Q

What type of glands are found in the stomach?

A

Gastric glands

40
Q

Describe the function of gastric glands.

A

Secrete endopeptidases, hydrochloric acid and an alkaline mucus into the stomach.

41
Q

What is the normal pH of the stomach?

A

pH 2

42
Q

What is the role of the liver?

A

Secretes bile into the small intestine via the gallbladder and bile duct.

43
Q

Describe the composition and function of bile.

A

• Consists of bile salts and an alkaline fluid
• Neutralises stomach acid, providing an ideal pH for lipase

44
Q

State the two main divisions of the small intestine.

A

• Duodenum
• lleum

45
Q

What is the duodenum?

A

The first section of the small intestine where proteins and lipids are hydrolysed.

46
Q

What is the ileum?

A

The second section of the small intestine that serves as the main site of absorption of the products of digestion.

47
Q

What is the normal pH range of the small intestine?

A

pH 7 to 8

48
Q

What is the pancreas and where is it located?

A

A gland situated behind the stomach.

49
Q

Describe the role of the pancreas.

A

It secretes enzymes and an alkaline fluid into the duodenum via the pancreatic duct.

50
Q

What is the large intestine also called?

A

Colon

51
Q

Describe the function of the colon.

A

Reabsorbs water and minerals from the waste material.

52
Q

What is the rectum?

A

The segment of the large intestine that stores faeces prior to egestion.

53
Q

Which enzymes are involved in carbohydrate digestion? Where are they found?

A

• Amylase in saliva and pancreatic juice
• Maltase, sucrase, lactase on the membrane of the epithelial cells of the small intestine

54
Q

What are the substrates and products of the carbohydrases?

A

• Amylase hydrolyses starch to maltose

• Maltase hydrolyses maltose to alpha-glucose

• Sucrase hydrolyses sucrose to glucose and fructose

• Lactase hydrolyses lactose to glucose and galactose

55
Q

What is the optimum pH of amylase?

A

pH 8

56
Q

Which enzymes are involved in protein digestion?
What are their roles?

A

• Endopeptidases - hydrolyse non-terminal peptide bonds within a protein to form smaller peptides

• Exopeptidases - hydrolyse the terminal peptide bonds of a protein to form dipeptides and amino acids

57
Q

Give some examples of endopeptidases.

A

• Trypsin
• Pepsin

58
Q

Describe how trypsin is produced.

A

• Secreted by the pancreas as inactive trypsinogen
• Enterokinase converts inactive trypsinogen into active trypsin in the duodenum

59
Q

Name the inactive form of pepsin.

A

Pepsinogen

60
Q

Where is pepsinogen secreted from?

A

Gastric glands

61
Q

Describe how inactive pepsinogen is converted into its active form, pepsin.

A

Hydrochloric acid converts inactive pepsinogen into active pepsin.

62
Q

Where are lipids digested?

A

Small intestine

63
Q

What must happen before lipids can be digested?

A

They must be emulsified by bile salts produced by the liver. This breaks down large fat molecules into smaller, soluble molecules called micelles, increasing the surface area.

64
Q

How are lipids digested?

A

Lipases hydrolyse lipids into monoglycerides, fatty acids and glycerol.

65
Q

Where are lipases found?

A

In pancreatic juice.

66
Q

State the processes by which absorption takes place in the ileum.

A

• Simple diffusion
• Facilitated diffusion
• Active transport
• Osmosis

67
Q

Which molecules are absorbed by simple diffusion in the ileum?

A

Monoglycerides, fatty acids and glycerol.

68
Q

Why can monoglycerides, fatty acids and glycerol be absorbed via simple diffusion?

A

They are non-polar molecules so can easily diffuse across the membrane of the epithelial cells.

69
Q

What happens to monoglycerides, fatty acids and glycerol once they are absorbed into cells?

A

They are reformed into triglycerides, absorbed into the lacteals and transported via the lymphatic system into the blood.

70
Q

How are amino acids absorbed from the lumen of the gut?

A

Via active transport into epithelial cells and then into the bloodstream by facilitated diffusion.

71
Q

Which molecules rely on co-transport from the lumen of the gut into the cytoplasm of the epithelial cells?

A

Glucose and other monosaccharides.

72
Q

Explain how sodium ions are involved in co-transport.

A

Sodium ions (Na⁺) are actively transported out of the cell into the lumen, creating a diffusion gradient. Nutrients are then taken up into the cells along with Na⁺ ions.

73
Q

How do monosaccharides pass from the epithelial cells into the bloodstream?

A

Via facilitated diffusion.

74
Q

What are herbivores?

A

Animals that only eat plants.

75
Q

Describe the adaptations of herbivores to a high cellulose diet.

A

• Long gut
• Loose articulation of the lower jaw
• Horny pad on the upper jaw
• Specialised dentition for grinding tough plant material

76
Q

Describe how the dentition of a herbivore is adapted to its diet.

A

• Small, flat incisors on lower jaw for cutting grass against upper horny pad

• Diastema between incisors and premolars - separates fresh grass from the cud and enables manipulation of food by the tongue

• Premolars and molars have a large surface area and sharply ridged biting surfaces for grinding plant material

77
Q

What are ruminants?

A

Mammals that digest plant material slowly in a specialised four-chambered stomach and regurgitate it to chew it again, enabling the efficient breakdown of fibre.

78
Q

Name the four chambers of the ruminant stomach.

A

• Rumen
• Reticulum
• Omasum
• Abomasum

79
Q

Describe the rumen.

A

The first stomach of a ruminant. It contains mutualistic bacteria that are able to hydrolyse cellulose into glucose.

80
Q

What is a carnivore?

A

An animal that preys on and eats other animals.

81
Q

Describe the adaptations of carnivores to a high protein diet.

A

• Short gut
• Powerful jaw muscles
• Specialised dentition for cutting and tearing meat

82
Q

Describe how the dentition of a carnivore is adapted to its diet.

A

• Sharp incisors to remove flesh from bone

• Large, pointed canines required to grip and kill prey

• Sharp carnassials (modified premolars and molars) to slice and shear meat

• Molars with sharp, flattened edges to crush bone

83
Q

What is a parasite?

A

An organism that lives on or in a host and takes nourishment at the expense of the other organism

84
Q

Name the two types of parasite.

A

• Ectoparasites
• Endoparasites

85
Q

What are ectoparasites? Give an example.

A

Parasites that live on the host e.g. Head louse, Pediculus humanus.

86
Q

What are endoparasites? Give an example.

A

Parasites that live in the host e.g. Pork tapeworm, Taenia solium.

87
Q

How does the head louse feed and transfer from one host to another?

A

• Feeds by sucking blood from the host’s scalp
• Transfers between hosts by direct contact

88
Q

Where does the pork tapeworm live?

A

• Primary host - adult tapeworm lives in the human gut
• Secondary host - larval form can develop in pigs

89
Q

How can humans and pigs become infected by the pork tapeworm?

A

• Humans become infected by consuming undercooked pork (containing larval forms of the tapeworm)
• Pigs may become infected by ingesting contaminated faeces

90
Q

How does the pork tapeworm feed?

A

Absorbs pre-digested nutrients in the gut through its cuticle.

91
Q

How is the pork tapeworm adapted to living in the gut?

A

• Thick cuticle
• Secretes anti-enzymes that prevent its digestion by host enzymes
• Scolex has suckers and hooks for attachment to gut wall
• Long, thin body proves large surface-area-to-volume ratio for absorption

Biology Unit 2 ☁️ (4 decks)

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