Sunday, 1 April 2012
Sunday, 25 March 2012
Saturday, 24 March 2012
What is DHA?
DHA is a kind of FAT that is most important for the BRAIN. It is a GOOD FAT for the development of the FRONTAL LOBE and NERVOUS SYSTEM in young children.
THE FRONTAL LOBE:
Responsible for cognitive abilities such as; PROBLEM SOLVING, ATTENTION, LEARNING AND MEMORIZING
NERVOUS SYSTEM:
Transmit nerve impulses from receptors to the brain, involve in Sensory, Integrative and Motor.
An adult can get enough DHA from food, but young children cannot synthesize it enough. They need a direct intake of DHA.
THE FRONTAL LOBE:
Responsible for cognitive abilities such as; PROBLEM SOLVING, ATTENTION, LEARNING AND MEMORIZING
NERVOUS SYSTEM:
Transmit nerve impulses from receptors to the brain, involve in Sensory, Integrative and Motor.
An adult can get enough DHA from food, but young children cannot synthesize it enough. They need a direct intake of DHA.
Thursday, 16 June 2011
Form 4 Chapter 4
Paper 1
1. C 2. D 3. B 4. C 5. A
6. C 7. A 8. D 9. B 10. C
11. A 12. D 13. A 14.B 15. D
16. A 17. D 18. D 19. D 20. D
21. A 22. C 23.A 24. B 25. C
26. A 27. C 28. C 29. B 30. C
31. A
Paper 2
Section A
1 (a) U : Enzyme V : Substrate
W : Enzyme-substrate complex
X : Product
(b) U : Maltase V : Maltose
X : Glucose (c) Lock : Enzyme
Key : Substrate
(d) Temperature / pH / Substrate concentration / Enzyme concentration
2 (a) (i) X : Monosaccharides Y : Disaccharides
Z : Polysaccharides
(b) Similarity : Both are major storage products of carbohydrates.
Difference : Glycogen is the major storage product of carbohydrates in
animals while starch is the major storage product of carbohydrates in plants.
Section B
3 (a) (i) Protease enzyme. Shirt A has a considerable amount of stains as
enzyme is less active at 15°C. Shirt C has the largest amount of blood
stains remaining. The enzyme must have been denatured at the high
temperature of the wash at 65°C. Shirt B does not have blood stain
remaining. The temperature of the wash at 35°C must be at the optimum
temperature of the enzyme to digest most of the blood stains efficiently.
(ii) The protease enzyme in the washing powder will act on the blood stains
which contain protein and removes blood stains from the shirt.
(iii) Lipase
(b) • Enzymes are highly specifi c in action.
• Enzymes are made up of protein.
• Enzymes speed up the rate of biochemical reactions but remain
unchanged at the end of reaction.
(d) • In the lock and key hypothesis, the enzyme molecule represents the
‘lock’ while the substrate molecule represents the ‘key’.
• An enzyme-substrate complex formed when the substrate molecule
binds to the active site of the enzyme molecule.
• Products formed after the enzyme catalyses the substrate, then leave
the active site.
• The enzyme molecule is free to bind other substrate molecules.
Paper 3
(ii) – Inference 1 : pH 2 is not suitable for amylase actions. Therefore
starch is not hydrolysed and dark blue remains.
– Inference 2 : pH 7 is suitable for amylase action. Therefore starch
is hydrolysed and the colour of iodine change from
dark blue to brown.
(c) Enzyme act optimally at its pH.
(f) 1. The rate of amylase reaction is very low in an acidic medium.
2. The rate of amylase reaction is very high or at the maximum rate in a
neutral medium.
3. The rate of amylase reaction is very low in an alkaline medium.
(g) The colour of the blue-dark iodine solution does not change to brown.
This is because at 60°C, the amylase denatures. Therefore the substrate
which is starch could not be change to its simple product.
(h) The rate of enzyme reaction is highest at the optimum pH.
(i) Optimum pH is pH neutral whereby amylase reaction is very high or at
the maximum rate.
1 (a) (i) Observation 1 : At pH 2, the colour of the iodine remains dark blue after
10 minute.
Observation 2 : At pH 7, the colour of iodine remains dark blue until the
second minute.
(ii) – Inference 1 : pH 2 is not suitable for amylase actions. Therefore
starch is not hydrolysed and dark blue remains. – Inference 2 : pH 7 is suitable for amylase action. Therefore starch
is hydrolysed and the colour of iodine change from
dark blue to brown.
(c) Enzyme act optimally at its pH.
(f) 1. The rate of amylase reaction is very low in an acidic medium.
2. The rate of amylase reaction is very high or at the maximum rate in a
neutral medium.
3. The rate of amylase reaction is very low in an alkaline medium.
(g) The colour of the blue-dark iodine solution does not change to brown.
This is because at 60°C, the amylase denatures. Therefore the substrate
which is starch could not be change to its simple product.
(h) The rate of enzyme reaction is highest at the optimum pH.
(i) Optimum pH is pH neutral whereby amylase reaction is very high or at
the maximum rate.
2. Aim: To study the effect of temperature on the activity of enzyme
amylase.
Problem Statement : At what temperature does enzyme amylase
function most efficiently?
Hypothesis : Enzyme amylase achieves its optimum rate of reaction
at 37°C. (40°C experimentally)
Manipulated : Temperature
Responding : Rate of reaction
Constant : Amylase, pH, starch
Materials : 2% starch solution, salivary solution, ice cubes, distilled
water and iodine solution.
Apparatus : Dropper, stopwatch, large beaker, small beaker, test tubes,
thermometer, white tile, Bunsen burner, tripod stand, test tube
rack and wire gauze.
Technique : Testing for the presence of starch and recording the time
taken for the hydrolysis of starch by salivary amylase to
complete.
Procedure :
1. 3 ml of saliva is collected in a small beaker.
2. The same amount of distilled water is added into the small beaker to produce
a salivary solution.
3. Three test tubes is labelled as A, B and C.
4. A drop of iodine solution is put into all the cavities of a white tile.
5. 1 ml of salivary solution and 10 ml of 2% starch solution is poured
into test tube A and B respectively.
6. Test tubes A, B and C is immersed in a water bath at 20°C for 5 minutes.
7. The contents of test tube A and B is poured into test tube C, and the
Stopwatch is started.
8. Dropper is used to transfer a drop of mixture from test tube C into a
cavity of the white tile.
9. Steps 8 is repeated at one-minute intervals until the blue-black colour of the
iodine solution disappears.
10. The time taken for the blue-black colour to disappear is recorded in a table
11. A new set of three test tubes is used to repeat steps 3 – 10 for temperatures of
30°C, 40°C, 50°C and 60°C.
12. The rate of reaction of amylase is calculated by using 1t , where t =
time taken for the blue-black colour disappears.
Conclusion: The results shows that rate of reaction of amylase achieve maximum rate at
optimum temperature (40°C). The hypothesis is accepted
Saturday, 11 June 2011
Form 5 Chapter 2
PAPER 1
1. B 2. C 3. A 4. A 5. C 6. A 7. D 8. C 9. C 10. A
11. C 12. A 13. D 14. A 15. A 16. C 17. A 18. A 19. D 20. C
21. C 22. B 23. A 24. B 25. C 26. D 27. A 28. B 29. D 30. B
31. C 32. D 33. A 34. C 35. A 36. C
PAPER 2
SECTION A
1 (a) P : Synovial fluid Q : Synovial membrane
R : Cartilage S : Ligament
(b) P : Lubricates the joint to reduce the friction.
Q : Produces synovial fl uid.
R : Acts as a shock absorber during movement.
S : Joins one bone to another bone.
(c) Ball-and-socket joint
(d) Shoulder joint
(e) (i) • The bone mass in Diagram 1.3 decreases.
• The bone tissue in Diagram 1.3 become hollow and brittle.
(ii) • Practice a balanced diet including an adequate calcium intake.
• Increase physical activity or exercise.
2 (a) Lotus / Water hyacinth / Hydrilla sp. (Any of aquatic plant)
(b) (i) Air sac (ii) Reduce the density of plant so that the plant to stay upright in the
water.
(c) (i) Hydrostatic skeleton.
(ii) Circular muscle and longitudinal muscle.
(iii) The circular muscles and the longitudinal muscles on the body wall contract and relax
antagonistically.When the circular muscle contracts, the longitudinal muscle relaxes.
The earthworm becomes thinner and longer. The segments extend and body moves
forward. When the circular muscle relaxes, the longitudinal muscle contracts. The
earthworm becomes shorter and thicker.
(iv) Leech / Caterpillar
SECTION B
3 (a) (i) Organism X:
• Exoskeleton
• Support derived from external cuticle which is made up of chitin
Organism Y:
• Endoskeleton
• Support derived from hard skeleton of bones inside the body
• Hydrostatic skeleton
• Support derived from body fluid contained within the body cavity.
• Supports important body organ
• Protects the internal organ from exposure
(b) • Aerenchyma tissues in the stems, roots and leaves make the plant light.
• Aerenchyma tissues found on plant cells allow air to be trapped between cells.
• The base of the leaves are swollen and filled with air causes the plant to float easily.
• Few vascular tissues found in the middle of the stem because transport of water is
minimal.
• Xylem tissue is not lignified as the plant is supported by the buoyancy of water.
• Large air sacs in the roots and leaves keep the plant floating on the water surfaces.
• The muscles are connected to the bones by tendons.
• When the biceps contracts and the triceps relaxes, the arm is bent.
• When the biceps relaxes and the triceps contracts, the arm is straightened
4 (a) Arthritis
• A diseases that involves the inflammation of the joints.
• The joints become painful, swollen and stiff, thus movements are limited in the affected
joints.
• Caused by the exhaustion of cartilage, depletion of synovial fluid and degeneration of
synovial membrane at the joints.
• Treatment for this problem are taking drugs to reduce the pain, exercise to straighten the
affected joints to prevent stiffness and others.
Muscular dystrophy
• A disease of the skeletal muscle in which the muscle gradually degenerate.
• The skeletal muscle become weaker and finally losses its ability to contract as they are
replaced by fibrous tissue.
• This disease is caused by a mutated gene.
• The condition progresses from their hands and legs to the chest and head. If the
intercostal muscle between the ribs are involved, it can cause failure in the breathing
mechanism and may lead to death.
• Ways to overcome: Undergo physiotherapy.
• A disease related to the thinning of bones due to reduced bone mass.
• Causes the bones to become thinner, more brittle and more porous.
• Usually occurs during old age, especially for women after menopause.
• Caused by the reabsorption of calcium and phosphate into the blood stream during bone formation.
• Also may caused by insufficient calcium intake in the daily diet and lack of exercise.
• Bones are fragile and easily to fracture
• Ways to overcome: having a balanced diet, exercise regularly.
• The musculoskeletal system provides support and enables us to move.
• The bones, muscles, ligaments and tendons work together like a machine to bring
about movement.
• We will suffer if there is problem in our musculoskeletal system such as osteoporosis,
arthritis and muscular dystrophy. We might experience discomfort, pain and loss of
mobility.
• Other organs and the physiological process in the body, such as respiration and
digestion will also be affected.
• Having a balanced diet
– Calcium and phosphorus are essential to build up strong bones
– Practice a balanced diet including the intake of suffi cient calcium,
phosphorus and vitamin D.
• Having a good posture
– A good posture is necessary to ensure the vertebral column is straight and the volume of
thoracic cavity is not reduced.
– Should adopt a good posture while standing, sitting, walking and while carrying out daily
physical activities.
– Poor posture will cause tiredness and backache.
– Poor posture will also put under pressure on our muscle and spine that will in turn affect the
functions of our internal organs such as the lungs, heart and stomach.
• Wear a proper attire for daily activities.
– Wear a proper attire for daily activities such as exercise and recreation
is important to prevent injuries to musculoskeletal system.
– Wear loose and comfortable clothes at all times.
– Wearing clothes that are too tight might hinder the muscular
activities and movements of bones.
– Wear shoes that are comfortable. Avoid high-heeled shoes.
– For example, warm up before doing vigorous activities, follow
the rules of activity to prevent accidents or injury.
• Practising correct and safe exercise techniques.
– This is to prevent serious injuries to the musculoskeletal system.
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