My 2007 and 2008 stuff

These were published in 2007- Blog A Biology SPM Form 5
...and 2008 Web A Biology SPM Form 5.


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Support in Aquatic Plants

Submerged plants Eg. Hydrilla or Elodea sp

Fact : Thin, narrow, flexible leaves .

Explanation : provides little resistance to water flow.

• Fact: Air sacs/ air spaces inside leaves and stems .
• Explanation : which keep the plants afloat close to the surface to obtain maximum sunlight
  
• Fact : their stems have no woody tissue.
• Explanation: Water buoyancy provides support for these plants .//If the plants are removed from water, they become limp and floppy.

Hydrilla sp

Elodea sp

Floating plants Eg. Eichornia crassipes (water hyacinth)

Fact: Broad leaves that are firm but flexible
Explanation: to resist tearing by wave action

Fact:Aerenchyma tissues in the stems and leaves //Aerenchyma are spongy tissues with large air spaces between the cells.

Explanation:They provide buoyancy so that plants can float on the water surface

Aerenchyma cells

Muscle Cramp

What do you require to know about Muscle Cramp?

WHAT?
It is not a disease...
A muscle cramp is an involuntarily and forcibly contracted muscle that does not relax.

( When we use the muscles that can be controlled voluntarily, such as those of our arms and legs, they alternately contract and relax as we move our limbs. Muscles that support our head, neck, and trunk contract similarly in a synchronized fashion to maintain our posture.)

A muscle (or even a few fibers of a muscle) that involuntarily (without consciously willing it) contracts is in a "spasm." If the spasm is forceful and sustained, it becomes a cramp. Muscle cramps cause a visible or palpable hardening of the involved muscle.

Muscle cramps can last anywhere from a few seconds to a quarter of an hour or occasionally longer.

It is not uncommon for a cramp to recur multiple times until it finally goes away.

The cramp may involve a part of a muscle, the entire muscle, or several muscles that usually act together, such as those that flex adjacent fingers.

WHO ?

Cramps are extremely common.

Almost everyone (one estimate is about 95%) experiences a cramp at some time in their life. Cramps are common in adults and become increasingly frequent with aging.

However, children also experience cramps.
Any of the muscles that are under our voluntary control (skeletal muscles) can cramp.

Cramps of the extremities, especially the legs and feet, and most particularly the calf (the classic "charley horse"), are very common.

Involuntary muscles of the various organs (uterus, blood vessel wall, intestinal tract, bile and urine passages, bronchial tree, etc.) are also subject to cramps.

WHY?....and.... WHEN ?

Vigorous activity: True cramps are commonly associated with the vigorous use of muscles and muscle fatigue (in sports or with unaccustomed activities).

Such cramps may come during the activity or later, sometimes many hours later.

Likewise, muscle fatigue from sitting or lying for an extended period in an awkward position or any repetitive use can cause cramps.

Older adults are at risk for cramps when performing vigorous or strenuous physical activities.

Rest cramps: Cramps at rest are very common, especially in older adults, but may be experienced at any age, including childhood. Rest cramps often occur during the night. While not life-threatening, night cramps (commonly known as nocturnal cramps) can be painful, disruptive of sleep, and they can recur frequently (that is, many times a night, and/or many nights each week).

The actual cause of night cramps is unknown. Sometimes, such cramps are initiated by making a movement that shortens the muscle. An example is pointing the toe down while lying in bed, which shortens the calf muscle, a common site of cramps.

Dehydration: Sports and other vigorous activities can cause excessive fluid loss from perspiration. This kind of dehydration increases the likelihood of true cramps. These cramps are more likely to occur in warm weather and can be an early sign of heat stroke.

Chronic volume depletion of body fluids from diuretics (medicine that promote urination) and poor fluid intake may act similarly to predispose to cramps in seniors.

HOW?

How can muscle cramps be prevented?
Activity: Authorities recommend stretching before and after exercise or sports, along with an adequate warm-up and cooldown, to prevent cramps that are caused by vigorous physical activity.

Good hydration before, during, and after the activity is important, especially if the duration exceeds one hour, and replacement of lost electrolytes (especially sodium and potassium, which are major components of perspiration) can also be helpful.

Excessive fatigue, especially in warm weather, should be avoided.

Rest cramps: Night cramps and other rest cramps can often be prevented by regular stretching exercises, particularly if done before going to bed.

Even the simple calf-stretching maneuver (described in the first paragraph of the section on treatment), if held for 10 to 15 seconds and repeated two or three times just before going to bed, can be a great help in preventing cramps.

Another important aspect of prevention of night cramps is adequate calcium and magnesium. . Calcium intake of at least 1 gram daily is reasonable, and 1.5 grams may be appropriate, particularly for women with osteoporosis.

An extra dose of calcium at bedtime may help prevent cramps.

DETAILS ABOUT MUSCLE CRAMP? PLS VISIT THE LINK:

http://www.medicinenet.com/muscle_cramps/article.htm

Locomotion in Grasshopper

Some of the explanation for grasshopper is also applicable for frogs

Grasshopper have an exoskeleton

Muscles are attached to the inside of the exoskeleton, across the joints

They exist in antagonistic pairs known as flexor and extensor muscles
(Grasshoppers have three pairs of legs)

During walking movements:

body is supported on a tripod of three legs //the other three legs pull or push the body forward

The rear legs are bigger and longer, (adapted for jumping)

The extensor muscles attached to tendons

During a jump, the flexor muscles relaxed, extensor muscles contracts suddenly

Causing the rear legs to straighten

Energy stored in tendon propels the grasshopper into the air.

During flight, the wings moved forwards and backwards // upwards and downwards through the air

Owing to the contractions of the flight muscles

Which produces a lift ( by driving the air downwards which in turn )enables the grasshopper to( lift off and) fly.

Locomotion in Earthworm

LOCOMOTION IN AN EARTHWORM-SPM 2005 ( 5 marks)
-An invertebrate which has a hydrostatic skeleton.
-Body wall has longitudinal and circular muscles
-These muscles act antagonistically to cause movement
-Contractions of circular muscles cause the segments to extend while longitudinal muscles relax //Conversely the contractions of the longitudinal muscles cause segments to shorten.
-Locomotion takes place when the chaetae secure shortened segments in the posterior to the ground while //The anterior segments extend owing to contractions of the circular muscles.
-Fluid in the body cavity helps the earthworm to move.

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Cartilage and Joints

FUNCTIONS OF CARTILAGE AND SYNOVIAL FLUID AT JOINTS
1. The places where two bones meet in the body are called joints.
2. In movable joint, the bones forming the joint are surrounded by a fibrous capsule.
3. Within the capsule is a membrane : synovial membrane which secretes synovial fluid
4. The fluid fills the space that separates the articulating surfaces of two bones,

5. Function of Synovial Fluid?
is to lubricate the joint, REDUCING friction when bones move And to nourish the cartilage found on the end surfaces of the bones which forms the joint.

6. Function of the cartilage?
AS A SHOCK ABSORBER PREVENTING THE BONES FROM DAMAGE WHEN A PERSON MOVES.

(Skeletal) Muscles,Ligaments,Tendons, Bones~IN MOVEMENT

ROLE OF THE MUSCLES, LIGAMENTS AND TENDONS IN MOVEMENT SKELETAL MUSCLES:
1. The skeletal muscles are made up of bundles of muscle fibres.
2. These muscles are attached to the bones of the skeleton to effect movement.
3. The skeletal muscles are not attached directly to the bones. They are attached to at least two bones across joints through the tendons.
4. The bones of the skeleton to which the muscles are attached operate as levers.
5. Skeletal muscles produce movements by exerting the force to pull on the tendons which are attached to bones.
6. All skeletal muscles exist in pairs
7. They act as antagonistic pairs, meaning: when one member of a pair of muscles contract, the other must relax.
8. Example: The movement of forelimb is brought about by the contraction and relaxation of a pair of antagonistic muscles, which is called the biceps and triceps.

TENDONS:
9. Tendons are tough, strong and inelastic strands of dense connective tissues made up of fibres.
10. Tendons join skeletal muscles to the bone

LIGAMENTS:
11. Ligaments held the bones together at the joints.
12. Ligaments are connective tissues which are flexible, strong and elastic.
13. This allows two bones to be held together and,
14. Permits limited movement but at the same time, ensures that bones do not become dislocated.
15. Since muscles can only contract, at least two muscles must be used to move a bone in a position and back again.
16. Movements of the body are brought about by the contraction of a pair of antagonistic muscles.
17. All muscles have two primary proteins :
i. Actin
ii. Myosin
Together they form ACTOMYOSIN complex that, in presence of ATP, will contract.

18. Energy for this contraction comes from ATP produced by the mitochondria in the muscles.
19. Muscles which contract when receiving impulses from the brain are voluntary muscles.

Task 2 Explain how the bones, skeletal muscles, tendons and joints bring out movement in the arm or leg. (10 marks)

....................Ligaments pic:

All pics are extracted from various sources from the net for educational purposes. TQ.