Ground Tissue in plants- Sclerenchyma

I have posted about Parenchyma and Aerenchyma in response to one of the students question .. But I dont think it is complete without the notes on an overall types of Ground tissue in plants....So lets have a look at the overall facts about Ground tissue in plants:

The types of ground tissue found in plants develop from ground tissue meristem and consists of three simple tissues:

1. Parenchyma (cells with thin primary walls that retain their protoplasm)
2. Collenchyma (cells with thick primary walls that retain their protoplasm)
3. Sclerenchyma (cells with lignified secondary walls that have lost their protoplasm at maturity, i.e. are 'dead')

...So I' m going to discuss here about Sclerenchyma :

Sclerenchyma is a supporting tissue in plants.

Two groups of sclerenchyma cells exist:

Fibres and Sclereids.

Their walls consist of cellulose, hemicellulose and lignin.

Sclerenchyma cells are the principal supporting cells in plant tissues that have ceased elongation. Sclerenchyma fibres are of great economical importance, since they constitute the source material for many fabrics (flax, hemp, jute, ramie).
Unlike the collenchyma, mature sclerenchyma is composed of dead cells with extremely thick cell walls (secondary walls) that make up to 90% of the whole cell volume.

The term "sclerenchyma" is derived from the Greek σκληρός ("sklē-rós"), meaning "hard".

It is the hard, thick walls that make sclerenchyma cells important strengthening and supporting elements in plant parts that have ceased elongation.

The difference between fibres and sclereids is not always clear.

(As for your SPM scope, you need not know about it so details )

Fibres usually originate from meristematic tissues.

Cambium and procambium are their main centers of production.

They are usually associated with the xylem and phloem of the vascular bundles.

The fibres of the xylem are always lignified, while those of the phloem are cellulosic.

Sclereids are small bundles of sclerenchyma tissue in plants that form durable layers, such as the cores of apples and the gritty texture of pears.

Sclereids are variable in shape.

But compared with most fibres, sclereids are relatively short

TQ Wiki...

Parenchyma Versus Aerenchyma

Parenchyma :

Parenchyma is made up of thin walled living cell. The cell wall is usually unthickened and formed of cellulose. The intercellular spaces may or may not be present.
Parenchyma is present in all the organs of plants. It fills up the spaces between different tissues and thus acts as a ground tissue or matrix.

Some of the modified parenchymatous tissues are follows:

I. chlorenchyma
II. aerenchyma


The parenchymatous tissue performs a variety of functions:

• It forms the epidermis on the outermost surface of the plant organs.
• It acts as a protective layer.
• Sometimes an impermeable layer of cutin called cuticle lines the outer surface of the epidermis. This cuticle checks he rate of transpiration.
• Guard cells of the stomata are means for exchange of respiratory gases in leaves and other organs. These guard cells are epidermal in origin.
• The epidermis and root hairs in roots are not covered by cutin. The root hairs are cylindrical outgrowths from the walls of epidermal cells of roots and increase the water absorbing capacity of roots.

Chlorenchyma :

Chlorenchyma is seen in green leaves and some other green aerial organs.
Its cells contain chloroplasts.
Chlorenchyma is differentiated into :
(a) Palisade (b) Spongy chlorenchyma

(a) Palisade:
In this tissue the cells are columnar.
The columnar cells are arranged at right angles to the upper surface of the leaf.
The intercellular spaces are relatively few.
The cells are somewhat compactly arranged.
The location of palisade in leaf and other flattened aerial, green organs is such as to receive strong, straight sun-rays.

(b) Spongy Chlorenchyma:
Spongy chlorenchyma is located in leaf and other aerial green organs in such a way as to receive mild sun rays.
Cells in spongy chlorenchyma are round or oval, parenchymatous and have large intercellular spaces.

In most leaves, the spongy chlorenchyma lies near the lower epidermis.

The cells of both palisade and spongy chlorenchyma tissues contain chloroplasts and hence perform the function of photosynthesis synthesizing glucose.



Aerenchyma :

Hydrophytes are plants growing in water or water logged habitats. E.g.Trapa, Lotus, Pistia etc. Hydrophytes have aerenchyma as one of the tissues.
Aerenchyma consists of small cells so arranged as to form large air spaces.
Due to air contained the respective plant organs become soft, light and spongy.

As a result the organs can keep themselves floating and obtain sufficient light for photosynthesis in the hydrophytes.

Some of the air spaces show special type of partition walls, which provide them mechanical strength

Extracted : TQ

Paper3~Qs 2

Its about enzyme!

There are many factors that affect the ability of an enzyme to catalyse biochemical reaction. Among the factors are pH, temperature, concentration of the substrate and concentration of enzyme. When the concentration of an enzyme increases, more enzyme molecules are available.

Based on the above information, plan a laboratory experiment to study the effect of salivary amylase concentration on the rate of biochemical reaction.

Terdapat banyak faktor yang mempengaruhi kebolehan enzim dalam memangkinkan sesuatu tindakbalas biokimia. Antara faktor-faktor tersebut ialah pH, suhu, kepekatan substrat dan kepekatan enzim. Apabila kepekatan enzim bertambah, maka terdapat lebih banyak molekul enzim.
Berdasarkan maklumat di atas, rancang satu eksperimen dalam makmal untuk mengkaji kesan kepekatan enzim amilase air liur terhadap kadar tindakbalas biokimia.

The planning of your experiment should include the following aspects:
Perancangan kerja eksperimen anda perlu meliputi aspek-aspek berikut:

Problem statement
Pernyataan masalah

Objective of investigation
Objektif kajian

Hypothesis
Hipotesis

Variables
Pembolehubah

List of apparatus and materials
Senarai alat radas dan bahan

Technique used
Teknik yang digunakan

Experimental procedure or method
Kaedah atau prosedur eksperimen

Presentation of data
Cara data dikomunikasikan

Conclusion
Kesimpulan [17 marks]

SUGGESTED ANSWER:

AIM: To study/ investigate the effect of salivary amylase / enzyme concentration on the rate of (biochemical) reaction

PROBLEM STATEMENT:

What is the effect of salivary amylase / enzyme concentration on the rate of (biochemical) reaction ?

HYPOTHESIS

The higher the salivary amylase / enzyme concentration, the higher the rate of (biochemical) reaction until it reaches a maximum rate

VARIABLES

Manipulated: Salivary amylase / enzyme concentration

Responding:Rate of (biochemical) reaction // time taken for breakdown of starch

Fixed: pH, substrate concentration, temperature

APPARATUS AND MATERIALS

Beakers, test tubes, syringe, dropper, glass rod, white tile, thermometer, stopwatch, water bath (wire gauze, bunsen burner, tripod stand), test tube rack, starch solution, iodine solution, salivary amylase/ saliva, distilled water

TECHNIQUE:

Measure and record the time taken for breakdown / hyrolysis of starch// iodine solution to change colour from blue black to brownish yellow using a stopwatch

PROCEDURE:

Able to list down the complete and correct procedure used based on the following criteria
K1 – Technique of assembling the apparatus to carry
out the experiment.
K2 – Technique of fixing the constant variables
K3 – Technique of changing the manipulated
variables
K4 – Technique of measuring the responding
variables
K5 - Technique of taking precautions to increase accuracy

Suggested Answer:

1. Label six test tubes as A, B, C, D, E and F. (K3)
2. Fill each test tube with solutions as shown in the table below. (K1, K3)

Test tube Volume of saliva (ml) Volume of distilled water (ml)

A 0.5 2.5

B 1.0 2.0

C 1.5 1.5

D 2.0 1.0

E 2.5 0.5

F 3.0 0.0

3. Drop a few drops of iodine separately on a white tile. (K1)
4. Pour 4 ml of starch solution into test tube A. (K2)
5. Start the stopwatch immediately. Use a dropper to withdraw a small amount of the mixture and add it to a drop of iodine on the white tile immediately. (K1, K5)
6.Observe the colour change in iodine. (K4)
7.Carry out the iodine test at an interval of 30 seconds until the blue-black colour no longer appears and the iodine solution remains brownish yellow. (K1, K2)

8. Record the time taken for the complete hydrolysis of starch. (K4)
9. If blue black colour is still produced after eight minutes, terminate the experiment with the reaction mixture. (K5)
10. Repeat steps 4 to 8 for test tubes B,C, D, E and F. (K1, K3)

11. Record all your observations. (K4)

12.Plot a graph of rate of reaction [1/time] against enzyme concentration. (K1)

RESULT:

CONCLUSION:

The higher the salivary amylase / enzyme concentration, the higher the rate of (biochemical) reaction until it reaches a maximum rate. Hypothesis is accepted

Paper3~Qs 2

Question 2

When a boy drinks too much water, the osmotic pressure of blood will fall below normal level. Under such condition, the hypothalamus will not be stimulated and less antideuratic hormone (ADH) will be produced. Less water will be reabsorbed and most of the water is allowed to pass out through urine.
Design a laboratory experiment to determine the urine volume released by a student who drinks different volume of mineral water.

The planning of your experimental must include the following aspects:

· Problem statement
· Aim of investigation
· Hypothesis
· Variables
· List of apparatus and materials
· Technique used
· Experimental procedures or methods
· Presentation of data
· Conclusion
[17 marks]

SAMPLE ANSWER:

Aim : To study the effect of drinking different volumes of water on urine output
Problem statement: What is the effect of water intake on urine output?
Hypothesis : If more water is taken, more urine will be released

Variables :
Manipulated variable: Volume of water
Responding variable: Volume of urine released
Constant variable: Same student/ same environment

Apparatus and Materials: Beakers, cup/mug, measuring cylinder, stop watch ,Drinking water
Specimen : Boy/ girl/ a student

Technique : Measuring and recording the volume of urine released by using a measuring cylinder

Procedure:

1. A student i(Sample A) is chosen and instructed to empty his bladders before the start of the experiment
2. Measure 200ml of water and put it into the mug
3 A student(Sample A) is given 200ml of mineral/drinking water to drink
4 A stop watch is started immediately after consuming the water.
5 During the experiment, he is kept in (any fixed suitable room) within* 1-2 hours(any suitable time range)
6 He is instructed not to eat or perform any vigorous physical activities (within the given time)
7 After half an hour, he is asked to empty his bladder.
8 The collected urine is kept in a large beaker
9 At the interval of half an hour, until two hours , a student will empty his bladder.
10 After two hours, the total collected urine is measured using measuring cylinder
11 Repeat step 2 – 9 for different amount of drinking water ( 400 ml, 600ml, 800ml, 1000ml)
* Accept four readings and more
12 Step 7 is conducted for four consecutive days in a fixed time and place
13 Dispose the measured urine properly
14 Measure and record data collected into a table/
Plot a graph of urine output against the water intake is plotted.
Results:

Conclusion:
If more water is taken, more urine will be released. Hypothesis is accepted.

Comparing Light and Dark Reaction

This Table might help you to compare Light reaction and Dark Reaction in a proper words~ Simple, direct and correct..

Bio Talk @SEMASHUR

It was on one beautiful sunday when Liza fetched me to Semashur...to deliver Bio talk to her form 5 students. It was not the first time for me..it was the third time (if I could recall) .. that I ve been there~ doing the same task~Sharing the answering techniques of Biology and giving tips for their upcoming SPM examination~

..It started at about 8.30 am and ended at about 12.30 noon..The talk revolved around Paper 2 and Paper 3 ~as how to go about it: the command words used in the questions, and the marks allocated would indicate the length of essays to be written..

...I would give an A for the boys and girls~for being attentive and responsive truout the Talk..(except for less then 5 whom I could locate..once awhile dozz off )..

Anyway, the give away 'Vochelle chocolate' to those who manage to answer my questions did open up their eyes.....Luckily the nite before it came across my mind to prepare for that...

..For Teachers:Liza and Mardiana: they seriously want their students to score A in Biology SPM and I really hope the students will meet up to their teachers expectation...

I hope my Talk has increased their interest and their skills in the technique of answering for both Biology Papers in SPM 2010...Go Go Chaiyok...SEMASHURIANS....Alwiz pray for all of you..

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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