5 Food and humans
5.1
Modes of
nutrition營養方式 (Book 1A , p. 5-3)
Ø Various modes of nutrition (營養模式) in different organisms:
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Carbon source (碳來源)
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Autotrophic (自養營養)
Utilize CO2
(inorganic carbon source)
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Heterotrophic (異養營養)
Utilize organic
carbon source
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Energy souce
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Phototrophic
(光合營養)
Use light
energy
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Photoautotrophic (光合自養)
l All green
plants
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Photoheterotrophic (光合異養)
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Chemotophic
(化合營養)
Use chemical
energy
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Chemoautotrophic (化能自養) /
Chemosynthetic (化能合成)
l Some bacteria
such as Nitrosomonas (亞硝化單胞菌屬)
l Some nitrogen cycle bacteria (氮循環細菌)
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Chemoheterotrophic (化能異養)
l All animals
and fungi (真菌)
l Most bacteria
l Some parasites (寄生生物)
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Ø
Plants
can make their own food by photosynthesis.
This mode of nutrition is called
(1) autotrophic
nutrition (自養營養) and plants are (2) autotrophs (自養生物).
Ø
Humans
and many other organisms have to take in organic matter (有機物) from their surroundings.
This
mode of nutrition is called (3) heterotrophic
nutrition (異養營養).
Organisms
that carry out this mode of nutrition are called (4) heterotrophs (異養生物).
5.2 The food requirements of humans (Book 1A , p. 5-4)
A Why
do we need food? (Book 1A ,
p. 5-4)
Ø Food provides us with:
l (1) energy for supporting daily activities and keeping us warm.
l raw materials for (2)growth and repair of body tissues.
l substances that
are important for maintaining (3) health.
B Food substances (Book
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Primary food substances (基本食物物質)
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Protective food substances (保護性食物物質)
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(4) carbohydrate (碳水化合物)
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(7) Minerals (礦物質)
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(5) lipids (脂質)
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(8) Vitamins (維生素)
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(6) proteins (蛋白質)
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(9) Dietary
fibres (食用纖維)
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water
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1 Carbohydrates
(碳水化合物)
lare organic substances which are made up
of:
n(10) Carbon (C) atom
n(11)Hydrogen (H)
atom
n(12) Oxygen (O)
atom.
lH : O = 2 : 1
lClassification of carbohydrates:
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Type of carbohydrates
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Feature & example
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Food source
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(13)
Monosaccharides
(單糖)
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² The simplest form
² Taste sweet and are (14) soluble /
²
all are (15) reducing sugars (還原糖)
² Example:
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R (16) glucose (葡萄糖)
R
fructose (果糖)
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Fruits and
honey
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R
Galactose (半乳糖)
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Milk and dairy products
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(17)
Disaccharides
(雙糖)
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² Formed by (18) condensation (縮合) of two monosaccharide molecules
²
Can be broken
down into monosaccharides by (19) hydrolysis (水解)
²
Taste sweet and are (20) soluble in water
²
except (21) sucrose, all are reducing sugars
² Example:
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R (22)maltose
(麥芽糖):
=
glucose + glucose
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Germinating
barley (大麥)
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R
Sucrose (蔗糖):
=
glucose
+ (23) fructose
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Sugar cane (甘蔗) and sugar beet
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R (24)lactose (乳糖)
= glucose + (25) galactose
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Milk and dairy
products
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(26)
Polysaccharides
(多糖)
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²
Long chains of (27) monosaccharides joined by
condensation
²
Do not taste
sweet and are (28) insoluble in water
² Example:
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R
(29)Starch (澱粉): the storage form of carbohydrates in plants.
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Potatoes and cereal (穀類) products
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R
(30)Glycogen (糖原): the storage
form in animals
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Animal liver and muscle
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R (31)Cellulose (纖維素)
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Plant products
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lFate of excess (過量)
carbohydrates in our body:
n converted to (39)glycogen and stored in liver and
muscle
n further
converted to (40)lipids which is stored under skin
and around internal organs
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