Synapse

The nervous system, a synapse is a junction that permits a neuron to pass an electrical or chemical signal to another cell.

Synapses are essential to neuronal function: neurons are cells that are specialized to pass signals to individual target cells, and synapses are the means by which they do so.

At a synapse, the plasma membrane of the signal-passing neuron (the presynaptic neuron) comes into close apposition with the membrane of the target (postsynaptic) cell. Both the presynaptic and postsynaptic sites contain extensive arrays of molecular machinery that link the two membranes together and carry out the signaling process.

In many synapses, the presynaptic part is located on an axon, but some presynaptic sites are located on a dendrite or soma.

Kidney in homeostasis

Students may use this animated video to learn more about the kidney function. Please click at the image above to directly view the video.

Sample Qs-Microorganism

1.(a) State the difference between bacteria and virus in the following aspect : [3m]
i. Structure
ii.Method of reproduction
iii.Nutrition.
(b) (i) Parasites can cause diseases. State 3 main ways how parasitic diseases can be
transmitted in a community . [3m]
(ii) Ringworm is a disease caused by fungus. Explain how transmission of this pathogen
can be stopped. [3m]
(c) Microorganisms can be useful to human. Explain the importance of microorganisms :
(i) In food industry. [3m]
(ii) In Nitrogen cycle [3m]
(iii) Production of insulin [3m]

Suggested Answer:

1(a)Structure :
- Bacteria enclosed by cell wall made of glycoprotein, but virus only have protein coat // Bacteria have nucleus but virus only contain RNA / DNA

Method of reproduction :
- Bacteria reproduce asexually by binary fission , but virus only replicate the DNA/RNA in the host

Nutrition :
- Bacteria can be synthesis organic substances via chemosynthesis (autotroph) or feed organic substances from other organisms (heterotroph) but viruses are strickly parasit (absorp nutrient from the host)

(b)(i)- vector such as rat, housefly or others
- by food / water
- by droplet transmission
(ii)- do not share clothes with others
- wash / clean all part of your body and make sure it dry
- use anti-fungus cream
- take vitamin C
(c) (i)- Yeast used in cake industry / wine industry
- bacteria used in chocolate / dairy product industry
- fungus used as a food
(ii)- Nitrogen fixing bacteria convert the nitrogen gas to nitrates in the soil (example Rhizobium sp and Nostoc)
- Bacteria and fungi decompose dead organisms to form ammonia
- Nitrosomonas and nitrobacter convert ammonia to nitrites and nitrites to nitrates.
(iii)- Fragmen of DNA which control the formation of insulin from pancreas was inserted in the DNA of bacteria
- That bacteria will be cultured in a specific medium.
-That bacteria has ability to produce insulin in big amount and faster.

Sample Qs-Pond ecosystem

1.Figure 1 shows pond ecosystem.

(a) (i) Based on Figure 1, name TWO factors for each of the following:-

-Biotic factor

-Abiotic factor [4m]

(ii) Name the abiotic factor that controls the distribution of submerged plants in the pond. [1m]

(iii) State the relationship between the factor you have named in (a)(ii) and the distribution of submerged plants. [1m]

(b) (i) Based on Figure 1, construct :
- A food web showing the interaction of all the organisms in the figure. [2m]

- A pyramid of numbers consisting of four trophic levels [2m]

(ii) Explain how energy is transferred from the sun to the organisms in food chain. [3m]

(iii) Explain why the amount of energy received by an organism via the food chain gradually decreases from one trophic level to the other trophic levels. [3m]

(c) (i) Name the organism that is known as the pioneer species in the pond. [1m]

(ii) Most of the pioneer species have adaptations that enable them to live in the bare
habitat. Give TWO adaptations of the pioneer species you have named in (c)(i). [2m]

(iii) Explain how the ecosystem in Figure 1 can turn into a climax ecosystem. [5m]

(d) Vegetables were planted near the pond in Figure 1. A farmer used chemical fertilizers to
enhance the growth of the vegetables. He also used pesticide to control the pests.
Predict the effects arising from those activities to the pond ecosystem after several years. [5m]

Suggested Answer:

1(a)(i) Biotic factor : Producer, consumer
Abiotic factor : light intensity, pH of water , depth of the pond.

(ii)light intensity

(iii)The lower the light intensity in the pond, the higher the population of submerged plant

(b)(i)Marks given for : all organisms correct- 1 , arrow correct - 1

(ii)- light energy trap by chlorophyll (in producers) and changed to chemical
energy in food (via photosynthesis)
- producer eaten by primary consumer, so energy from producer transfer to
the primary consumer
- primary consumer eaten by other consumer, so energy will transfer to that
organism via feeding

(iii)- energy lost directly from organisms to the surrounding through radiation
- lost through excretion such as urination, constipation and sweating
- lost through respiration

(c)(i)Hydrilla sp. / Elodea / Cabomba

(ii)- Reproduce asexually
- need only low light intensity to carry out photosynthesis

(iii)- submerged plants died and sink at the bottom of the pond, it change the
nutrient content and depth of the pond.
- submerged plants replaced by the floating plants, which at the end covered
surface of the water
- light cannot enter the inner part of the pond, so all submerged plants will
die and the pond become more shallow
- now the amphibian plants will replace the floating plant, and the pond
become less water
- at the end , terrestrial plants will take over the pond and form the climax
community

(d)Pesticide :-
- the toxic substances accumulate in the organisms via the food chain
- the concentration of toxic become higher as the trophic level increase
- this will cause extinction

Fertilizers :-
- more nitrates and phosphates in the pond
- enhance the growing of floating plants which caused algal bloom
- this will reduce amount of oxygen in the pond; situation known as eutrophication

Spermatogenesis Vs Oogenesis

I guess all of you have learnt a lot about these two processes..Just to remind you the possible scope of questions are mainly:

1. The schematic diagram of spermatogenesis and Oogenesis which shows the changes of chromosome numbers and where are the meiosis I, meiosis II , mitosis, differentiation take place...Please take note for each steps of the development!!!.

2. The Diagram of the cross section of the Ovary and the seminiferous tubule which show the development of the structures starting with Primordial germ cells. (2n)...and the final products : Secondary oocyte for the oogenesis and spermatozoa for spermatogenesis..

Click ON the image to VIEW The Video

**Spermatogenesis schematic diagram came out for SPM Paper 2 structure 2009!!!

Stages Of Meiosis

Just CLICK on the image to watch the animation .

Sample Qs: The thinning of ozone layer

1. The thinning of the ozone layer is an environmental issue which is always being discussed. Describe the effect of the thinning of the ozone layer on the environment and living organisms on the earth. Suggest different ways to solve this problem.
[10marks]

Suggested Answer: (ANy 10 marks)

The effect:
P1 - More UV rays / ultraviolet radiation reaches the earth’s surface.
P2 - Increase of temperature.
P3 - UV ray will deteriorate one’s body immunity system.
P4 - An increase in the number of people suffering from skin cancer and cataract.
P5 - High UV rays destroy microorganisms and phytoplankton (the producer of marine food chain).
P6 - Rate of photosynthesis decrease.
P7 - High level of UV rays can damage the eggs of certain amphibians.

Steps to solve the problem:
P8 - Reduce / stop using CFCs.
P9 - Replace CFCs with HCFCs.
P10- Use wrapping papers instead of polystyrene boxes.
P11- Patch up the holes in the ozone layer by firing frozen ozone balls into the atmosphere.

Sample Qs-Greenhouse effect

a) Diagram 9 shows sources of greenhouse gases from human activities and natural processes Explain the sources of greenhouse gases. [10marks]

Suggested Answer:

-Sources of greenhouse gases;
F1- Emission from exhaust of motor vehicles (1m)
E1- release a lot of carbon dioxide gas and into atmosphere (1m)

F2- Combustion of fossil fuel in factories (1m)
E2- releases a large amount of carbon dioxide gas into atmosphere (1m)
E3- and also releases oxides of nitrogen (1m)

F3- Uses of aerosol spray/air conditioner (1m)
E4- with contains CFC (1m)
E5- CFC cause ozone depletion with bring about greenhouse effect (1m)

F4- Fermentation in ruminant animals / anaerobic fermentation in paddy field (1m)
E6- release methane gas into atmosphere (1m)

F5- use of inorganic fertilizer (1m)
E7- cause release of nitrogen oxide gas (1m)

Sample Qs- Microorganism

1. Most microorganisms are harmless and useful to humans. Yeast and bacteria are microorganisms. Discuss the benefits of using this two microorganisms to produce useful products for humans. [ 10 marks]

Suggested Answer:

Medical Purpose : ( Any 4)
Antibiotic
· Antibiotic are chemicals which either inhibit the growth of or kill other microorganisms, especially disease-causing bacteria
· Example : streptomycin is produced by Streptomycin sp.
· Penicillin is produced by the fungus Penicillium chrysogenum sp.
· The fungus is grown in large fermenters, and the antibiotic produced is then isolated and purified

Immunisation ( 1 mark)
· The vaccine that contains weakened or dead microorganism which stimulates the body to produce antibodies.

Food Processing Industry
Wine ( 2 marks)
· Wine is made by adding yeast to fruit sugar (glucose) from grapes.
· The yeast converts glucose in grapes into alcohol during anaerobic respiration / fermentation

Bread ( 2 marks)
· Bread is made from yeast, flour,sugar and water. The most commonly used species of yeast is Saccharomyces cerevisiae.
· Fermentation by yeast produces ethanol and carbon dioxide. The carbon dioxide causes the dough to rise

Soya Sauce ( 1mark)
· Soya sauce is made from fermented soya beans caused by the action of fungi.
**Or any suitable answer

Sample Qs-Digestive system

1. Describe the digestive actions that take place in the
(i) mouth
(ii) stomach
(iii) small intestine

Explain the roles of the glands secretion and enzymes involved in these digestive process.
(10 marks)

Suggested Answer:

Mouth
· Food is chewed and broken up into smaller pieces by the teeth.
· The small pieces of food have a larger surface area for the saliva (enzyme) to act upon.
· Salivary gland secretes saliva (that is alkaline and )contains salivary amylase (ptyalin).
· ( After the food has been thoroughly chewed and mixed with saliva) the tongue starts the process of swallowing by pushing the bolus (small mass of chewed food).
· Saliva also softens and increases the water content of the food.
· In mouth, only starch is digested.
- Starch is hydrolysed by amylase into maltose.
(Starch + Water .....Amylase ....... Maltose ) [ any 3 points]

Stomach
-Secretes gastric juices contains hydrochloric acid and enzyme (rennin and pepsin)
-Hydrochloric acid kills microorganisms and stops the activity of salivary amylase, (which functions optimally at the near-neutral pH of saliva )
- and promotes the activity of pepsin.
-Pepsin is a (hydrolytic ) enzymes that acts on protein to produce peptides
( Protein + Water .... pepsin .... Peptone + polypeptide )
- Rennin changes caseinogens to casein.
- Casein is then digested by pepsin

Ileum (small intestine) :
· There are some digestive glands on small intestine.
-All these enzymes need an alkaline medium function
· There are 5 types of enzymes produced :
1. Erypsin (peptidase) – hydrolysis of peptide to amino acids
2. Sucrase - hydrolysis of sucrose to fructose and glucose
3. Maltase - hydrolysis of maltose to glucose
4. Lactase - hydrolysis of lactose to glucose and galactose
5. Entrokinase – Activates trypsinogen to trypsin in the
duodenum.
Any of the above enzymes reaction - 4 marks

Sample Qs -Double fertilisation

Diagram 8 shows a cross section through the ovary and pollen tube of a flowering plant just before fertilisation.(a) With the aid of Diagram 8, explain the development of an embryonic sac [5 marks]

(b)(i)Explain the mechanism of double fertilisation. [10 marks]

(ii)Explain the importance of double fertilization for the survival of flowering plants

[5 marks]

Suggested Answer:

(a)

-The complete development of each ovule takes place beginning with an embryosac mother cell
-The embryonic mother cell (diploid cells) divide by meiosis to form haploid cells
-3 of them degenerate
-The nucleus of the 1 haploid cell remaining divides by mitosis
-This produces 2 haploid nuclei, which again divide by mitosis
-This produces 4 haploid nuclei, which again divide by mitosis
-Finally this produces 8 haploid nuclei, and the structure is known as a mature embryo sac

Any 3 points [ 3 marks]

Drawing 2 marks: Correct drawing and Labels.

* May use diagram from any reference book

(b)(i)
-Pollen reaches a stigma and sticks to the surface
-A pollen tube begins to grow from the pollen grain
-The proteins for this tube are produced with the help of the tube nucleus which remains near the tip of the tube
-The generative nucleus divides into 2 male nuclei which follow down the tube
-The pollen tube grows into an ovule
-One male nucleus fuses with the egg cell forming a diploid zygote;
-this (divides many time to ) form the embryo of the seed
-The other male nucleus fuses with two polar nuclei forming a triploid cell;
-this (divides many times to )form the endosperm of the mature seed.

-This is double fertilization because of the fusion to form the diploid zygote and the primary endosperm cell. [10 maximum]

(ii)

F1 This results in genetic and morphological diversity:
P1 During fertilization there is a random fusion of gametes
with the egg cells
P2 As a result every plant is different from the mother plant as
well as each other

F2 This diversity helps plant to adapt to climatic changes and
wider range of habitats:
P1 Therefore plants are able to colonize large areas of land

F3 The development of seeds with its tough coat protect them
from unfavourable condition
P1 Germination will only take place under favourable
condition
P2 The development of colourful and sweet tasting fruits
helps in the dispersal of seeds.
Or any suitable anwer [ Max 5 marks]

Bio Talk @SMK Maxwell

Another Talk...one after another...That's my usual routine in the middle of the year...year by year.... when most of the schools start organising Talk for SPM subjects. Teachers are concerned about their students achievement in SPM examination. So the counselors are searching for experience teachers or Excellent teachers to give tips and guidance as how to go about answering the examination questions with a target that majority of the students will score A in the subjects..(as in my case...BIOLOGY ! )

...and this morning.. I have completed my other task: delivering Talk @SMK Maxwell, my neighbouring school, a few yards away from seseri....

The audience was still BOYS..all boys.........with the same determination : To score A Biology..

To all SMK Maxwell boys : All the best for your Bio SPM examination..Score A as promised !

Bio Talk @ RMC

Have completed my Bio Talk @MTD a.k.a RMC..Focusing on Paper 3, the two hour talk seemed to be a bit too short for them. My audience wera all boys compared to my usual audience @seseri~ all girls !

..Be it boys or girls, my mission is very clear: to give the best tips as how to go about answering SPM Biology paper 2 and Paper 3...and of course within the two hours I have chosen the most important ones to be explained....and I need more timeeee.....

..Anyway..RMC boys are good, highly motivated and bright too...They asked questions and responded well to the Talk..I hope they will strive hard to score A+ Bio in their SPM....

..All the best to you ...Boys~ Doa from me to all of you~ Do Well and Do your best!

Malfunction of Cell Cycle

A respond to Farid of SEMASHUR:

WHAT ARE THE EFFECTS OF CELL CYCLE MALFUNCTION TO THE BODY ?

Cell reproduction is the leading cause of growth and developement in our bodies. This reproduction is caused by the cell cycle, which is defined as the life of a cell from its origin in the division of its parent cell until its own division into two.

The cell cycle goes through 5 main steps in order to reproduce: interphase, prophase, metaphase, anaphase, and telophase.
When prophase occurs, changes take place in the nucleus and cytoplasm. The cell is now prepared for anaphase, the following step, which is where the chromatid detach from one another and travel to opposite poles of the cell.

If a problem occurs in the cell cycle, and a malfunction in cell growth results, malignant tumors, also known as cancer may form.

The cell cycle is important for regulation of production of new, healthy cells in the body. If and when these cells stop dividing, ( they may do so at random points in the cycle or between phases ) , the cells usually have an irregular number of chromosomes, and if a tumor spreads through circulatory passage ways, it can cause harm or even death to the entire organism.

I hope it helps..

MidYearPaper2~Question 5 ~seseri

Diagram 5.1 shows microorganism P that attack a bacterium.

(a) i.What is microorganism P? [1 mark ]

(ii)What type of interaction between P and the bacterium? [ 1 m]
(iii) Explain the interaction that you mentioned in (a) (ii). [2m ]

(b)State one characteristics of organism P. [1m]

Siti lives in a flat area with clogged drainage and poor sanitary system. Unluckily last week she was down with fever. She had severe body pain and rashes over the body. She also experienced severe headaches and vomiting.The doctor discovered that she had been infected by microorganism Q that carried by the vector R as shown in Diagram 5.2.


(c) i. Name the microorganism Q. [1 m]
ii. Why the antibiotic cannot treat this disease? [2 m]
iii. After one week rest, Siti is recovered. State the type of immunity she obtained. [1m]
iv. Explain the immunity you mentioned in (b) (ii). [2 m]
(d)State one similarity between microorganism P and Q.

Suggested Answer:

a) i) bacteriophage
ii) parasitism
iii) It is a relationship in which virus benefits while the bacteria is harmed.
b) -virus is a non-living cell , cannot survive or reproduce on its own outside the cells of its host // all viruses are infectious; they must infect living cells to reproduce.

c) i) Dengue virus
ii) because virus did not have the metabolism that can interrupted by antibiotic.
iii) naturally acquired active immunity
iv) this immunity is obtained after a person is exposed to a pathogen, and he the pathogen stimulate an immune response that produces antibodies.

d) -They are virus / they are pathogenic / infectious / cause disease.

MidYearPaper2~Question 4 ~seseri

Table 1.1 shows a daily food intake by a teenager.
(a)(i)Suggest two health problems which the teenager could have if she continuously taking the above menu for a long time. [ 2 marks ]
(ii)Explain your answer in (a) (i).

(b)Diagram 4.1 shows a part of digestive system and Diagram 4.2 shows a process which occurs before the food enter organ B.
(i) Name the process which occurs. [1 m]

(ii)After the food enters B, state the content of the gastric juice that is secrected to help in the digestion. [2m]

(c) (i) A patient suffering from cancer of the organ B has a small part of it removed in an operation. What suitable advice would his dietician give him regarding his daily diet? [1m]
(ii)Explain your answer. [1m]

(d)(i)Besides the liver, what other organ is connected to the duodenum? [1m ]
(ii) What is produced by the organ you mentioned in (d)(i) to be seccreted into the duodenum? State its function. [2m ]

Suggested answer:

a) i) chronic heart disease/constipation. /obesity

ii) -Her diet contains large amounts of oil/cream/fat and it
causes arteriosclerosis / atherosclerosis / heart problem /
cardiovascular disease.

-Lack of fruit/vegetables / fibers leads to constipation.

b) i) peristalsis

ii) pepsin , rennin , HCL, mucus

c) i) The patient should eat more soft or liquid food which
contains less proteins / the patient should avoid a milk based
diet.

ii) Because the stomach less secreting pepsin and rennin which is responsible for the digestion of protein.

d) i) pancreas

ii) pancreatic juice
Function: contains pancreatic amylase, trypsin and lipase , protease, which involve in the digestion of starch, protein and lipid.

MidYearPaper2~Question 3 ~seseri

Diagram 3.1 shows the gaseous exchange system in an insect and respiratory structure of a unicellular organism such as Amoeba.

(a) i. Name the structures labelled P and R.[2 marks]
ii. What is the function of structure Q? [1 mark]
(b) i. State the substance that forms the ring at structure R. [1 mark]
ii. State the role of the ring. [1 mark]

(c) i. At the end of structure S, there is a type of substance that helps in gaseous exchange.
What is the substance? [ 1 mark ]
ii. Describe how this substance helps in the process of gaseous exchange in cells. [2 m ]
(d) Explain respiration in an unicellar organism such as the Amoeba and what makes
the process highly efficient? [ 4 m ]

Suggested Answer:

(a) (i) P : Spiracle
R : Trachea
(ii) Q controls the opening and closing of the spiracles

(b)(i) Chitin
(ii) To prevent the air tubes from collapsing

(c)(i) Tracheole fluid / fluid
(ii) P1 - Respiratory gases can dissolve in the fluid
P2 - before it diffuses into the body cells

(d) P1 - Concentration of oxygen is higher in the outside
environment compared to inside of cell
P2 - Oxygen diffuses into the cell by diffusion across the
plasma membrane
P3 - Concentration of carbon dioxide is higher in the
amoeba compared to the outside environment
P4 - Carbon dioxide diffuses out through the plasma
membrane by diffusion
P5 - Amoeba has a relatively large surface area as compared
to the volume of its body for diffusion of gases
P6 - Its plasma membrane is thin and

P7-constantly moist for rapid diffusion of gases.......................ANY 4 points..

MidYearPaper2~Question 2 ~seseri

(a) i. State the type of skeleton in an earthworm. [1m]
ii.What are the structures found on the ventral side of each segment of the earthworm that help in locomotion? [1 m]
iii.Name the two sets of muscles involved in the movement of an earthworm. [2 m]

(b) Diagram 2.1 shows locomotion in an earthworm

i. What happen to its body when the outer layer of muscles contract? [1 m]
ii. What happen to its body when the inner layer of muscles contract? [1m]
iii.Explain what happen at E. [3 m]

(c)i. State the type of skeleton in an insect. [ 1m]
ii. Explain the role of the long and powerful hind legs of a grasshopper during jumping. [ 2m ]

Suggested Answer:

(a) (i) Hydrostatic skeleton
(ii)Chaetae / bristles
(iii) P1 - Circular muscle
P2 - Longitudinal muscle

(b) i. Becomes longer / extended / segments become longer/ thinner and lengthened
ii. Segments bulge / shorten /thicker
iii. P1 - Circular muscles contract / outer layer contract
P2 - Longitudinal muscles relax / inner layer relax
P3 - Chaetae retracted / secure segment in the anterior to the ground.
P4- the body become thinner and lengthened
P5- its body will be extended forward

(c)i. Exoskeleton
ii. P1 - Flexor muscle in each femur contracts bringing the
tibia closer to the femur, into a Z position;
P2 - then, extensor muscles contract and propels the
grasshopper into the air

MidYearPaper2~Question 1 ~seseri

1. Diagram 1.1 and 1.2 show two different types of transport processes across the plasma membrane.
(a)Name the structure that involve in the process shown in Diagram 1.1 and 1.2 [1 m]
(b)Name each transport processes shown in Diagram 1.1 and 1.2. [2 m]
(c)Name and state the characteristics of the substances that can be transported across the plasma membrane as shown in Diagram 1.2 [2m]
(d)Explain the mechanism transport of substances across the plasma membrane as shown in Diagram 1.1 [3m]
(e)Compare and contrast the transport processes shown in Diagram 1.1 and 1.2. [4m]

Suggested Answer:

a) Carrier protein

b) Diagram: 1.1 Active transport

Diagram: 1.2 Passive transport/Facilitated Diffusion

c) Ions transported: Na+/HCO3+/K+/Ca 2+ / Glucose/Amino Acids
Name (any one of the ions or substances only) :
Characteristics : Bigger //large polar molecules OR

water, oxygen, carbon dioxide - small molecules

d) - The Na+ ion inside the cell attached themselves on the binding
sites of carrier protein

- ATP releasing phosphate and energy which is used to change
shape of the carrier protein

- The carrier protein releasing Na+ outside the cell

e)

Any 1 mark for similarity and any 3 marks for differences.

TIPS: Compare means Similarities and Differences please!!!