Spm Biology Chapter 6

7/31/2019 Spm Biology Chapter 6

http://slidepdf.com/reader/full/spm-biology-chapter-6 1/32

Digestive System

1. Definition of digestion:

_________________________________________________________________

____________________________________________________________________

________________________.

2. Human digestive system

1



1. Mouth

• Glands: _______________________________________

• Secretion: ____________________________________

• pH: ___________________________________________

• Enzyme: _____________________________________

• Function:

• Other contents:

_______________________________________________________________

______________________

2. Stomach

• Glands: _______________________________________

• Secretion: ____________________________________

• pH: ___________________________________________

• Enzyme:

_______________________________________________________________

__________

• Function:

• Other contents:

_______________________________________________________________

______________________

3. Duodenum

2



• Organ: _______________________________________

• Secretion: ____________________________________

• pH: ___________________________________________

• Function:

• Organ: _______________________________________

• Secretion: ___________________________________

• pH: ___________________________________________

• Enzyme: _____________________________________

• Function:

4. Small intestine• Glands: _______________________________________

• Secretion: ____________________________________

• pH: ___________________________________________

• Enzyme:

_______________________________________________________________

__________

• Function:

3



5. Large intestine

• Function:

_______________________________________________________________

______

6. Anus

• Function:

_______________________________________________________________

______

Changes during breathing and digestion in digestive system

Peristalsis

4

Peristalsis is the rhythmic

contraction and

relaxation of alimentary



Small intestine

5



Ruminant’s digestive system ex.

_________________________________________________________

6

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.



Rodent’s Digestive System ex.

____________________________________________________________

7

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



Differences in digestive system

Criteria Human Ruminant RodentNutritionStomach chamberCaecumBacteria &

protozoaChewing cudCellulose

digestionRegurgitation of

food

Reingestion of

faeces

Absorption of Digested Food

Parts Function

8



Capillaries

Lacteal

Venule

ArterioleLymphatic vessel

Epithelium

Adaptations of Small Intestine for Nutrient Absorption

1. ____________________________________________________________________

________

2. ____________________________________________________________________

________

3. ____________________________________________________________________

________

4. ____________________________________________________________________

________

5. ____________________________________________________________________

________

6. ____________________________________________________________________

________

9



10



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

11

Absorption of digested food



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

12



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

13



Diseases associated to digestive system

Diseases Explanation SymptomsLactose

intolerance

• Absence of lactase in the digestive

system

• Lactose cannot be digested

14



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

15



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.

16



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

17



The Structure of Leaf

18



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

19



20



• 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

_____________________________

_______

21



• A lot of air spaces in the

tissue

_____________________________

_______

22



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

23



24



Absorb

The Mechanism of Photosynthesis

25

PHOTOSYNTHESIS

LIGHT REACTION DARK REACTION

Requires

Breaks

Split into

Release

Combine

Forms

6 units



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:

26



carbon dioxide is added to the

green house to increase rate of

photosynthesisSmaller plants grow on the tall

trees to absorb sunlight.

27



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

• ______________________________________________

____________

• ______________________________________________

____________

28



Biological Control

• ______________________________________________

____________

• ______________________________________________

____________

29



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

30



concentrated solution.

• _________________________________

_______

• _________________________________

_______ Ultra Heat

Treatment

(UHT)

• Milk is heated at 132 C for 1s,̊

cooled and packaged

immediately in airtight

container.

• _________________________________

_______

31



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!

Date post:	05-Apr-2018
Category:	Documents
Upload:	birintha
View:	241 times
Download:	0 times

Spm Biology Chapter 6

Documents