Spm Biology Chapter 6
Transcript of Spm Biology Chapter 6
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Digestive System
1. Definition of digestion:
_________________________________________________________________
____________________________________________________________________
________________________.
2. Human digestive system
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1. Mouth
• Glands: _______________________________________
• Secretion: ____________________________________
• pH: ___________________________________________
• Enzyme: _____________________________________
• Function:
• Other contents:
_______________________________________________________________
______________________
2. Stomach
• Glands: _______________________________________
• Secretion: ____________________________________
• pH: ___________________________________________
• Enzyme:
_______________________________________________________________
__________
• Function:
• Other contents:
_______________________________________________________________
______________________
3. Duodenum
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• Organ: _______________________________________
• Secretion: ____________________________________
• pH: ___________________________________________
• Function:
• Organ: _______________________________________
• Secretion: ___________________________________
• pH: ___________________________________________
• Enzyme: _____________________________________
• Function:
4. Small intestine• Glands: _______________________________________
• Secretion: ____________________________________
• pH: ___________________________________________
• Enzyme:
_______________________________________________________________
__________
• Function:
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5. Large intestine
• Function:
_______________________________________________________________
______
6. Anus
• Function:
_______________________________________________________________
______
Changes during breathing and digestion in digestive system
Peristalsis
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Peristalsis is the rhythmic
contraction and
relaxation of alimentary
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Small intestine
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Ruminant’s digestive system ex.
_________________________________________________________
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Being a ruminant, it only eats plants. Plants contain lots of
cellulose. Cellulase enzyme is needed to digest the
cellulose. In the ruminant’s digestive system, there are
bacteria and protozoa which secrete this enzyme.
Food enters the mouth and then into the oesophagus. In
the rumen, grass eaten will be fermented by bacteria and
protozoa under anaerobic condition. Part of the cellulose is
Food passes into reticulum for further hydrolysis. The foodis called the cud. The cud is regurgitated into mouth cavity
to be grounded again. After the cud is chewed, it is re-
swallowed into omasum chamber. Water and cellulose are
In abomasum, gastric juice is produced. HCl and protease
secreted digests the protein, nutrients and microorganisms.
Here the food is called chyme. Chyme is completelydigested and reabsorbed into small intestine. In large
intestine, absorption of water occurs to produce faeces.
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Rodent’s Digestive System ex.
____________________________________________________________
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Rodents have big and well developed caecum to make
digestive process efficient. It is large as it contains bacteria
and protozoa that secrete cellulase for digestion of cellulose.
However it comes after the small intestine.
Absorption of nutrients only occurs in the small intestine. So,
the absorption of nutrient for the 1st time is incomplete.
Thus rodents will re-eat their faeces to absorb more
Faeces for the 1st time is soft, contain lots of nutrients and
undigested food. They are produced at night. Faeces for the
second time are hard and dry. They are released during the
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Differences in digestive system
Criteria Human Ruminant RodentNutritionStomach chamberCaecumBacteria &
protozoaChewing cudCellulose
digestionRegurgitation of
food
Reingestion of
faeces
Absorption of Digested Food
Parts Function
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Capillaries
Lacteal
Venule
ArterioleLymphatic vessel
Epithelium
Adaptations of Small Intestine for Nutrient Absorption
1. ____________________________________________________________________
________
2. ____________________________________________________________________
________
3. ____________________________________________________________________
________
4. ____________________________________________________________________
________
5. ____________________________________________________________________
________
6. ____________________________________________________________________
________
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Assimilation of digested food
1. Definition: process where digested products are brought directly to
the liver for being processed to be used for metabolic processes in
body cells.
2. Function of liver
Function ExplanationSecretes bile • Bile salts emulsify fat into fat into
fat droplets
• Stored in gall bladder
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Absorption of digested food
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Secrete fibrinogen,
prothrombin
• Important for blood clotting
Regulate blood glucose
level
• Convert glucose into glycogen
detoxification • Remove toxic substances from
the bloodStore nutrients • Excess glucose stored as
glycogen
• Stores fat soluble vitamins,
A,D,E,K and ironDeamination of amino
acid
• Excess amino acid is broken
down into urea and excreted in
the urine
6.6 Formation of faeces and defecation
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In colon
1. The content consists of
• Water
• ___________________________
•
___________________________ • ___________________________
• ___________________________
2. It reabsorbs 90% of water from the undigested materials into the
bloodstream.
3. Lubricate secreted by colon help the movement of faeces along the
colon.
In Rectum
1. After 12-24 hours in the colon, the faeces are passed to the rectum
for __________________________________________.
2. As more water is reabsorbed, the faeces get harder.
3. When the pressure in the rectum increases, a desire to expel thefaeces occurs.
4. As the rectum is full, muscles of the rectal wall contracts to expel
the faeces.
Microorganisms in the colon
1. E.coli• symbiotic
• Digest organic substances
• Secrete vitamin B and K
• Secrete antibiotics that inhibit the growth of harmful
microorganisms
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Diseases associated to digestive system
Diseases Explanation SymptomsLactose
intolerance
• Absence of lactase in the digestive
system
• Lactose cannot be digested
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Gallstones • Cholesterol hardens to form
gallstone.
• When gallstone blocks the bile duct,
bile cannot be channelled out.
• ___________________________ stops.Constipation • When more water is reabsorbed, the
faeces harden and difficult to be
passed down.
• Intake of a lot of water and
_____________________ relieves
constipation.Haemorrhoids • High pressure in the rectum causes
the blood veins to stretch, bulge and
ruptureColon cancer • Malignant tumours grow on the colon
• Due to intake of carcinogens or food
rich in cholesterolGastritis • If food is not taken at regular times,
acidic gastric juice is secreted on the
wall of stomach lining.
• Stomach lining is injured and
inflamed.Bulemia • Occur in person who has normal
body mass and takes in foods out of
control
• The victim feels guilty upon stop
eating and
_____________________________________
___ to expel the food taken.
• Repeated vomiting leads to damage
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of digestive tract.Anorexia
nervosa
• A psychological disorder where one
is fear of getting fat and thinks one is
always fat
• A victim intentionally fast to achieve
extreme loss of weightThe importance of macronutrients and micronutrients in plants
1. Macronutrients:
____________________________________________________________________
____
2. Example:
____________________________________________________________________ ____________
3. Micronutrients:
____________________________________________________________________
____
4. Example:
____________________________________________________________________ ____________
Nutrient
deficiency
Effects
Nitrogen • The leaves turn yellow
• Growth of seedling is stunted.Phosphorus • The leaves turn dark green with red spots.
• Growth of seedling is stunted.Sulphur • The leaves turn yellow and drop off easily
• Growth of roots is stunted.Potassium • The edges of the leaves turn yellow.
• The stem becomes soft.
• The plant dies at an early stage.
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Calcium • Areas between the leaf veins become
yellow.
• The leaves have an uneven shape.
• Growth of leaves is stunted.Magnesium • The leaves turn yellow and eventually die.
Boron • Terminal bud dies.
• Leaves become thick, curled and brittleCopper • Brown spots on terminal leaves.Iron • Yellowing in young leaves.Manganese • Brown or grey spots between the veins.Molybdenum • Chlorosis of leavesZinc • Mottled leaves with irregular areas of
chlorosis
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The Structure of Leaf
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Adaptations of Leaf for Optimal Photosynthesis
External leaf adaptations
• The wide, flat and thin lamina provides a
___________________________________ for the maximum absorption of
sunlight and carbon dioxide.
• The leaf is positioned at ___________________ to sunlight and
arranged in ____________________ pattern to absorb maximum
sunlight.
• Upper epidermis is ____________________ to allow sunlight to pass
through it easily.
Internal leaf adaptations
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• Palisade mesophyll cells contain a lot of ________________________
and closely packed for maximum absorption of sunlight.
• Xylem and phloem are ____________________________ tubes that can
transport water and products of photosynthesis efficiently.
• Spongy mesophyll cells are arranged ________________________ for
diffusion of carbon dioxide and oxygen between leaf and the
environment.
• Many ______________________ at lower epidermis to allow exchange
of gases.
Adaptations of plants from different habitats for
photosynthesis
Plants growing on land with
adequate water supply
Plants totally immersed in
waterExample: Example
• Waxy epidermis
_____________________________
_______
• Large number of chloroplast
in palisade mesophyll
_____________________________
_______
• More stomata at lower
epidermis
_____________________________
_______
• A large network of veins
_____________________________
_______
• Very little or no cuticle on
epidermis _____________________________
_______
• Chloroplast throughout the
plants
_____________________________
_______
• No stomata
_____________________________
_______
• Many small leaves
_____________________________
_______
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• A lot of air spaces in the
tissue
_____________________________
_______
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Plants floating on the water
surface
Plants growing in dry places
Example: Example:
• Waxy cuticle on upper
epidermis _____________________________
________
• Tissues are arranged loosely
and full of air spaces
_____________________________
________ • Transparent epidermal layer
_____________________________
________
• Many stomata on upper
epidermis
_____________________________ _______
• Waxy and thick cuticle on the
epidermis _____________________________
_________
• Shiny surface
_____________________________
_________
• Leaves in the needle or thornform
_____________________________
_________
• Succulent and green stems
_____________________________
_________
• Stomata normally sunk into
the epidermis
_____________________________
_________
Structure of chloroplast
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Absorb
The Mechanism of Photosynthesis
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PHOTOSYNTHESIS
LIGHT REACTION DARK REACTION
Requires
Breaks
Split into
Release
Combine
Forms
6 units
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Similarities and Differences between Light and Dark Reaction
Light Reaction Differences Dark Reaction
Types of
reaction
Location
Process
involved
Energy
Light
Time of occurring
Product
output
Balance
equation
Factors Affecting the Rate of Photosynthesis
Concentration of Carbon
Dioxide
Light Intensity
Conclusion: Conclusion:
Application: Application:
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carbon dioxide is added to the
green house to increase rate of
photosynthesisSmaller plants grow on the tall
trees to absorb sunlight.
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Concentration of Carbon
Dioxide
Conclusion:
Application:
Summer is the best time for
agricultural activities
Methods Used to Improve the Quality and Quantity of FoodProduction
Methods ExplanationHydroponics
• ______________________________________________
____________
• ______________________________________________
____________Aeroponics
• ______________________________________________
____________
• ______________________________________________
____________
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Biological Control
• ______________________________________________
____________
• ______________________________________________
____________
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Direct Seeding
• ______________________________________________
____________
• ______________________________________________
____________Selective
breeding • ______________________________________________
____________
• ______________________________________________
____________
Genetic
Engineering • ______________________________________________
____________
• ______________________________________________
____________Tissue culture
•
__________________________________________________________
• ______________________________________________
____________
Technological Development in Food Processing
Method Food Process & PrincipleCooking • Food is subjected upon high
heat
• High temperature can
______________
_________________________________
______
Pickling • Food is immersed into
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concentrated solution.
• _________________________________
_______
• _________________________________
_______ Ultra Heat
Treatment
(UHT)
• Milk is heated at 132 C for 1s,̊
cooled and packaged
immediately in airtight
container.
• _________________________________
_______
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Pasteurisation • Milk is heated at 72 C for 15s or̊
63 C for 30 minutes and cooled at̊
5 C̊
• __________________________________
______ Drying • Food is dried under the sun or in
the oven
• __________________________________
______
• __________________________________
______ Fermentation • Enzymes of bacteria or yeast are
used to break down the food.
• __________________________________
______
• __________________________________
______ Canning • Food is heated at 121 C to̊
sterilize the food and packed
through vacuum seal.
• __________________________________
______ Refrigeration • Food is cooled or frozen at low
temperature.
• __________________________________
______
Important Facts!