Osmosis - Plasmolysis & Deplasmolysis in plant cells

1) Plasmolysis?

When plant cells are immersed in hypertonic solution, water molecules diffuse out of the plant cells (the vacuoles) by osmosis. The cells shrinks (plasmolysis) because vacuole & cytoplasm lose water, and plasma membrane pulls away from the cell wall. The plant cells become flaccid, the plant wilts and this could lead to death.
Eg: when plant is not receiving water supply for long period of time, or excessive fertilisers are given to the plant, etc.

In the video below, you will get the same result when the salt solution is replaced by excessive use of fertilisers (at high concentration).



2) Deplasmolysis?

When a plasmolysed plant cell is immersed in hypotonic solution (eg: distilled water), the plant cell becomes turgid again due to uptake of water molecules into plant cell by osmosis.

How birds fly & fish swims

These are good videos to share with you.

1) how birds fly.



2) watch this...... how the 'Golden Plover' can do a 88 hours non-stop flight from Alaska to Hawaii, which is 2,500 miles apart. Amazing!






3) how fish swims

What muscles are used during walking?

What muscles are used when we walk?

We learned this in chapter 2 (F5). Muscles involved are the calf muscles, Hamstrings/biceps femoris, Quadriceps/Quadriceps femoris. Refer yr notes.

Actually, more muscles are involved during walking. Watch this video.

Form 4 Chapter 3 - Movement of sub across the PM (Part 2)

In this part . . .

we shall look at the type of transport involves in transporting substances in & out of the cell.

1) There are 2 types of transport: Passive transport (PT) and Active transport (AT)

• PT:
  i) No energy (ATP) is used by cell during movement of substances.
  ii) substances move according to their concentration gradient.
  * concentration gradient is the difference in the concentration of a substance between 2 regions.
• AT:
  i) needs energy (ATP)
  ii) substances (ions/molecules) move against concentration gradient across the PM.

2) There are 3 different types of PT: Simple diffusion, Osmosis, Facilitated diffusion.

• Simple diffusion:
  
  
  i) a physical process
  ii) definition: is the net movement of molecules/ions from a region of higher concentration to a region of lower concentration, according to a concentration gradient, until an equilibrium is achieved. (dynamic equilibrium)
  iii) Eg: the exchange of gases between the alveoli & the blood cap. at the lungs.
  
• Osmosis:
  i) involves only water molecules.
  ii) definition: is the net movement of water molecules from a region of low solute concentration to a region of high solute concentration through a semi-permeable membrane.
  iii) you can study osmosis using a simple osmometer at the lab.
  iv) Eg: the uptake of water by the plant roots.
  
  
  
• Facilitate diffusion:
  i) definition: movement of hydrophilic molecules/ions (eg: glucose, ions) across the PM with the help of transport protein.
  ii) Carrier protein: are specific, has binding sites for molecules to bind on.
  iii) Pore protein: are transporters which are always open, usually hv charges & specific shape, to transport small, dissolved particles (ions)
  iv) Eg: Absorption of certain digested foods/nutrients in the villi of the small intestine. eg; glucose.
  
  
  *transport proteins such as uniport, symport, antiport are not in spm syllabus.

3) The Active Transport:

• i) definition: is the movement of molecules or ions across the PM against their concentration gradients, that is from a region of lower concentration to a region of higher concentration, which requires carrier proteins & cellular energy (ATP).
• ii) Carrier proteins, often called pump, has active sites. One site binds with a particular molecule/ion. The other site binds with ATP (phosphate molecule).
• iii) Eg: sodium-potassium pumps in animal cells (nerve & muscle cells)
  * 3 sodium ions are released to the outside of the cell while 2 potassium ions are brought into the cell.
• iv) other eg: the uptake of mineral ions by the plant roots.
  
  

Form 5 Chapter 2 - Locomotion & Support (Part 1)

Here are the summary . .

1) Skeleton is the supporting structure which:

• enable movement when the bones interact with the skeletal muscles
• give shape & give mechanical support for the body
• protect the internal organs. (eg: the skull protects the brain, the ribcage protects the lungs & heart)
• provide firm base for attachment of skeletal muscles.
• produces blood cells - eg Red Blood Cells are formed in the bone marrow of the long bones.
• stores minerals, eg: calcium & phosphate.

2) 3 types of skeletons:

• Hydrostatic skeleton - consists of internal fluid within a confined spaces of the body & is kept under pressure surrounded by muscles. eg: earthworm.


• Exoskeleton - non-living structure (eg: cuticle) that covers the surface of the body. It support the internal organs, protect internal structure from damages. eg: grasshopper.


• Endoskeleton - consists of a rigid framework of bones & cartilage which muscles are attached. It maintains body shape, support soft body tissues, protecting internal organ from injury.
  

3) The Human Skeletal System.

a) Is divided into 2:

• i) Axial skeleton: the skull, the vertebral column, ribs & sternum (ribcage)
• ii) Appendicular skeleton: pectoral girdle, pelvic girdle, bones of the limb

b) A typical vertebra consists of:

• 1) Centrum (solid body)
• 2) Neural canal
• 3) several neural processes

• Function of the structure of a vertebra:
  1) Neural spine - provide surface for attachment of muscles & ligaments.
  2) Transverse process - same as above
  3) Neural arch - protects the spinal cord.
  4) Centrum - provides support, absorb shocks, resists compression.
  5) Neural canal - provides the passage for spinal cord.
  
  
  6) articular processes/facets - provides surfaces which articulates with the next vertebra/bones.

4) Axial skeleton:

• consists of the skull, the vertebral column, ribs, sternum.


• i) Skull
  a) consists of cranial bones (cranium) & facial bones.
  b) functions:
  1) the cranium enclose & protect the brain.
  2) the facial bones protect & support the entrance of digestive & respiratory system.
  
  
• ii) The vertebral column:
  
  
  
  a) consists of 33 small vertebrae.
  b) divided into 5 parts :
  1) Cervical vertebrae (neck, 7 vertebrae, C1-C7, C1 is known as atlas, C2 is known as axis)
  2) Thoracic vertebrae (thorax & chest region, 12 vertebrae, T1-T12)
  3) Lumbar vertebrae (lower back region, 5 vertebrae, L1-L5)
  4) Sacrum (lower back region, 5 sacral vertebrae, fused, S1-S5)
  5) Coccyx (tailbone, 4 fused caudal vertebrae)
  c) Intervertebral disc is located in between the vertebrae.
  
  
  1) made up of cartilage.
  2) functions: act as cushion to absorb shocks when moving, to reduce friction btw
  vertebrae.
  d) Function of vertebral column:
  1) support the head/skull & body
  2) encloses & protect the spinal cord
  3) provide base for attachment of muscles to the back
  4) ...
Question: why the vertebral column is made up of 33 vertebrae, not one long bone?
e)Main characteristic of vertebrae.
1) Cervical vertebra - has a pair of vertebrarterial canals, has thin centrum (plural: centra)
2) Thoracic vertebra - has long & backward/downward pointing neural spine, fairy large centrum, heart-shaped centrum.
3) Lumbar vertebra - thick & big centrum, short & broad neural spine, large & broad/flat transverse process.
4) refer pg 4 of yr notes.



• iii) the ribcage: (ribs & sternum)
  a) 12 pairs of ribs, articulate with the thoracic vertebrae at the back & join to the sternum in the front portion.
  b) ribs are flattened, curved bones.
  c) functions:
  1) protects the heart & lungs
  2) role in breathing.
  d) sternum is a flatenned, kite-shape bone, located at the anterior thoracic wall.

click here - to view animated human skeletal system

.... to be continued ....

Form 5 Chapter 1 - Transport (Part 4)

We have come to the last part of chapter 1. We shall look at the vascular tissues, the movement of water in plant, the factors that affecting the rate of transpiration (RoT) and the potometer experiment to study RoT.

1. The vascular tissues in dicotyledonous & monocotyledonous plant.

• You shld be able to draw & label the cross-section (XS) of stem & root for both dicot. & monocot. plant.
• Able to differentiate between XS of dicot. & monocot.
• Diagram below show the XS & longitudinal section of dicot stem

2. Xylem:

• fn? to transport water & dissolved mineral salts/ions from the roots upto the stem. And to provide mechanical support in woody plant.
  
• Consists of xylem vessels, tracheids, parenchyma, fibres.
  
• Question: How does the xylem vessels adapt to function efficiently in water transportation?

3. Phloem:

• fn? transport organic food substances (eg: glucose, sucrose, amino acids) both upwards & downwards to various parts of a plant.
  
• consists of sieve tube cells, companion cells, parenchyma cells, fibres.
  

4. Movements of water from roots up to the leaves are assisted by:

• (i) Root pressure:
  - Created by osmotic pressure of xylem sap which is created by dissoved minerals & sugars.
  - It is an upward force that push water (& mineral salts) up to a certain height in plants.
  
• (ii) Capillary action:
  - combine the forces of cohesion & adhesion of water molecule.
  - hold water column together in the capillary-sized xylem vessel.
  
• (iii) Transpirational pull
  - a pulling force/suction force that move water from leaves & stems & eventually from the xylem in the roots.
  - pulling force is created due to transpiration/evaporation of water vapour from the mesophyll cells & the cohesive property of water.

5. What is transpiration?

• It is the loss of water in the form of water vapour (evaporation) from a plant to the atmosphere.
• Through the stomata of leaves (main channel), the cuticles & lenticels (woody stem).
• Roles of transpiration? create tranpiration pull, produce cooling effect, supply water for photosynthesis, support through cell turgidity.

6. What is translocation?

• is the two-way transport (upwards & downwards) of dissolved organic solute in the phloem, from the leaves to other parts of the plant.

7. Opening & closing of stomata.

8. Factors affecting the RoT.

• Light intensity
• Temperature
• Air movement
• Relative humidity

9. Potometer experiment to study RoT.

• assumption made? rate of water uptake by the root = rate of transpiration.
• Precautionary steps? make sure all connections are airtight. the leafy shoot must be cut & connected in a basin of water.

A Gift of Life

A Gift of life - Organ donation

Do you know there are about millions of people in the world who die just because they fail to find a donor?

Donating organ is a big noble step, it will help SAVE lives.
Imagine this, your eyes can continue to see while your heart continues beating after your death. Isn’t that wonderful? You continue to live through someone else!

Frequently Asked Questions:

1. Who can be a donor?
   Anyone, young or old alike can sign up to be a donor. Individuals below 18 years of age will need parental/guardian consent.


2. What is organ donation?
   It is the gift of ones body parts after death for the purpose of transplantation. Transplantation is an operation which involves the replacement of diseased and defective organs and tissues with healthy ones from donors.
   This treatment helps save lives of people. Organ and tissues donation is the ultimate humanitarian act of charity.


3. What are the organs and tissues that can be donated?
   The commonly transplanted organs are kidneys, heart, liver, lungs and pancreas while transplantable tissues are eyes, bone, skin and heart valves.
   Thus a single donor can save the lives of a number of people.


4. How can i become a donor?
   Simply complete the donor pledge form and the donor card.
   Forward the form to the National Transplant Resource Centre and keep the donor card in your wallet. Inform your parents/family members.
   
   Useful links:
   1) Touching lives through precious gift.
   TransWeb.org – A resource on Transplantation and Donation, University of Michigan Transplant Center.
   
   2) Give Life, the transplant journey - animated
   
   3) National Transplant Resources Centre - Malaysia
   4) Sign up to be an organ donor - Malaysia
   
   More readings:
   1) Chiew Fong Neo donated a pair of kidneys, cornea, liver, lungs and heart valves after her death. click here or here.
   
   2) I believe my son’s heart beats on...
   
   3) More must take up this healthy practice
   
   4) 11,000 waiting for kidney transplants
   
   5) Heartbreaking wait in IJN

Form 4 Chapter 3 - Movement of sub across the PM (Part 1)

The plasma membrane (PM)

• PM is a boundary that separates the living cells from its surrounding.
  
• Function: to regulate the movement of substances in and out of the cell.
  
• It is selectively permeable/semi-permeable. Because it allows some substances to move across the PM easily/freely while others cannot.
  
• It is made up of Phospholipids (PL) bilayer & Proteins.

The PL bilayer:
i) Each PL molecule has a polar head (phosphate) and a pair of non-polar fatty acid tails.

ii) The polar head has hydrophilic property (“like water/attract water”), therefore both the heads of the lipid bilayer point towards the aqueous environments. One head pointing to the external environment (consists of interstitial fluid/tissue fluid) while the other head pointing towards the intracellular cytoplasm.

iii) The non-polar tails hv hydrophobic property (“dislike water/repel water”). The fatty acid tails of the PL bilayer point towards each other. This part form the selective barrier of the PM.

The proteins:
i) A few different types of protein can be found on the PM. Which include transmembrane protein, integral protein, peripheral protein.

ii) Transport protein is a transmembrane protein.


iii) 2 types of transport proteins are the carrier protein & pore protein.

• Besides, the PM also has cholesterol which makes the bilayer stronger, more flexible, more fluid.
  
• Glycoproteins are branching carbohydrate chains that attached to protein molecule while glycolipids consist of branching carbohydrate chain that attached to lipid molecule.
  

Fluid-mosaic model

1. which is proposed by Singer & G. Nicolson is used to describe the PM.
   
2. The model describes both the “mosaic” arrangement of proteins embedded throughout the lipid bilayers as well as the “fluid” movements of lipids & proteins alike.
   
3. The PM form a dynamic, flexible & fluid structure.
   
   
   
   

The Size & polarity of a molecule determine whether a molecule can or can’t pass through the PM easily.

• What is Polar & Non-polar molecule?
  The arrangement or geometry of the atoms in some molecules is such that one end of the molecule has a positive electrical charge and the other side has a negative charge. If this is the case, the molecule is called a polar molecule, meaning that it has electrical poles.
  Otherwise, it is called a non-polar molecule. Whether molecules are polar or non-polar determines if they will mix to form a solution or that they don't mix well together.
  Examples:
  i) Water & sucrose are both polar molecules, therefore they mix well to form sucrose solution.
  ii) Water (a polar molecule) & oil (a non-polar molecule) will not mix!
  To learn more about Polar & Non-polar molecules, click here.
  

What are the molecules that can move easily/ freely across the PM?
i) Lipid soluble molecules – eg: fatty acids, glycerols, steroids, vit. A,D,E,K.
ii) Water – small & polar
iii) Oxygen & carbon dioxide – small uncharged molecule.

What are the molecules that cannot move freely across the PM? It requires the use of transport proteins.
i) Large , polar & water-soluble molecule. eg: glucose, amino acid.
ii) Ionic/charged, small, water –soluble molecule. eg: sodium ions, calcium ions.

to be continued . . . see you again in the next lesson. take care.

Form 4 Chapter 2 - Cell structure & cell organisation (part 3)

this is the last part of chapter 2.

1) This part covers the cell organisation in both humans & animals as well as in plants.
a) You should know how to explain each level of cell organisation. Eg: what is a tissue? why the erector muscle is a tissue while skin is an organ?
b) What is differentiation process? it is a process of cell development that enables the cell to perform a specialised function.
c) Why multicellular organisatin needs cell organisation while unicellular organisation doesn't?
d) What are the 4 different types of tissues in humans/animals? Epithelial tissue, connective tissue, muscle tissue, Nerve tissue.
e) Examples of organs & systems in humans.
f) The 3 main types of tissues in plants? Epidermal tissue, ground tissue, vascular tissue.
g) The function of xylem & phloem.
h) The structural difference btw root hair cell & palisade mesophyll cell.
i) organs & systems in plants.

2) We also look at the importance of regulating the internal environment (eg: the temperature, pH value, osmotic pressure, glucose level, etc) with examples.
a) what is homeostasis?
b) You can refer to the table at the last page of your notes to learn more about this & other examples. For instance, when your body temperature (BT) drops below normal BT, one of the response is shivering, why?
c) you will learn more about negative feedback under chapter 3, form 5.


3) We end the chapter by looking at how different organelles involve in the production of enzyme (which is a protein) in the human body. Read note 7 (b), page 8.

A useful video is attached to help you understand the whole process of enzyme/protein synthesis.

Coronary artery bypass surgery

I hope this posting could answer some of your questions on bypass surgery.


The Coronary arteries (CA) supply blood, oxygen & nutrients to the heart/cardiac muscles. It extends over the surface of the heart & branches into smaller capillaries.

CA can become blocked due to a buildup of fatty deposits called plaques on the inner wall of these arteries (a condition known as atherosclerosis). This reduce the flow of blood causing cardiac muscles receiving less blood which can lead to coronary artery disease (CAD).

Partially blocked CA (can reduce blood flow) causing chest pain (angina). A total/complete blockage of CA (can stop blood flow) causing a heart attack (myocardial infarction).



Various drugs can be used to treat CAD. Sometime, heart patients might need to undergo surgery to restore & improve blood flow. What are the available options?

Option 1:
Coronary bypass surgery/Coronary artery bypass surgery/Coronary artery bypass graft.
This is normally used to treat patients with multiple narrowed/blocked coronary arteries. By using blood vessels taken from another part of the body (either artery from the chest or a vein from the leg), a heart surgeon creates a graft to bypass the narrowed/blocked arteries. This allow blood to flow around the narrowed/blocked artery.
Most conventional bypass surgery requires open-heart surgery which means the surgeon will cut open the sternum (ribcage) in order to gain access to the heart.

Minimal invasive bypass surgery such as keyhole heart surgery maybe used when only 1 or 2 coronary arteries need a bypass and they are located around the front of the heart. A heart surgeon will make a 3- to 5-inch-long incision (cut) in the left part of the chest between the ribs to allow the surgeon to reach the heart for grafting .



Option 2: Angioplasty & stent placement

watch video number 2.



Watch this video on Coronary artery bypass surgery





Video below is about Coronary artery angioplasty