1.2.1 Composition of Human Blood

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Human blood consist of
  1. cellular components
  2. plasma


Cellular Components

There are three types of blood cells:
  1. erythrocytes (red blood cell)
  2. leucocytes (white blood cell)
  3. platelets

Erythrocyte (Red blood cells)

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  1. Biconcave disc-shaped. Can move quickly in blood capillaries and increases the TSA/V ratio to facilitate the exchange of gases.
  2. Carry large amount of haemoglobin.
  3. Haemoglobin is responsible for the transport of oxygen in the form of oxyhaemoglobin and carbon dioxide in the form of carbaminohaemoglobin.
  4. No nucleus when matured. This enables it to contain more haemoglobin to carry more oxygen.
  5. Produced in the bone marrow.
  6. Life span about 120 days. After that they are destroyed in the spleen and liver.

Leucocyte

  1. Has no fixed shape.
  2. Less than the erythrocytes, but bigger in size.
  3. Has a nucleus
  4. The function is to protect the body from diseases.
  5. There are two types of leucocytes:
    1. granulocyte
    2. agranulocyte

Granulocytes
  1. With granules in the cytoplasm.
  2. With lobed nucleus.
  3. Formed in red bone marrow.
  4. There are three types of granulocytes
    1. neutrophil (carry out phagocytosis to engulf invading bacteria)
    2. eosinophil (involve in regulating the allergic responses)
    3. basophil (produce heparin to prevent the blood clotting）

Agranulocytes
  1. Have no granules in the cytoplasm.
  2. There are two types of agranulocytes:
    1. lymphocytes (responsible for producing antibodies to protect the body against diseases.)
    2. monocytes (carry out phagocytosis to engulf invading bacteria)

Platelet (Thrombocytes)

  1. Platelets, or thrombocytes , are cell fragments (i.e. cells that do not have a nucleus) of larger cells in the bone marrow called megacaryocytes.
  2. The average lifespan of a platelet is normally just 5 to 9 days.
  3. Platelets circulate in the blood of mammals and are involved in hemostasis, leading to the formation of blood clots.

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Plasma

  1. Plasma is the liquid part of the blood.
  2. Plasma is a pale yellowish liquid consisting of water, plasma protein and other dissolved substances.
  3. Plasma without plasma protein is called blood serum.

Plasma Protein

  1. The plasma protein consist of 
    1. albumins, 
    2. immunoglobulins and 
    3. fibrinogen.
  2. The albumin controls osmitic pressure of blood and acts as buffer against pH changes.
  3. Immunoglobulins are antibodies involve in body's defense mechanism.
  4. Fibrinogen is a substance important in blood clotting.

Water and Dissolved Substances

  1. Other than plasma protein, the dissolved substances in plasma include
    1. products of digestion
    2. excretory products
    3. hormones
    4. minerals
    5. vitamins.
    6. dissolved gases such as carbon dioxide, oxygen and nitrogen.



1.2 The Concept of Circulatory System

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  1. The circulatory system is an organ system that permits blood and lymph circulation to transport nutrients, oxygen, carbon dioxide, hormones, blood cells, etc. to and from cells in the body.
  2. The circulatory system in human and animals consists of blood, blood vessels and heart.
  3. Blood is the medium of transport in the circulatory system in human and animal.
  4. In SPM, you need to know
    1. the composition of human blood
    2. the function of blood and haemolymph in transport
    3. the types of circulatory system
    4. the circulatory system in humans
    5. the regulation of blood pressure



1.1 The Importance of Transport System in Multicellular Organisms

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  1. The transport system in humans and animals is the circulatory system.
  2. The transport system in plants is the vascular tissues.
  3. The vascular tissues consist of 
    1. xylem tissues and 
    2. phloem tissues.

Live Process of Cells

  1. Every cell in an organism need to obtain nutrients and oxygen from the environment and at the same time, is able to remove the waste products from the cell.
  2. Unicellular organisms obtain their nutrients and oxygen across the plasma membrane directly from the environment by diffusion.
  3. Unicellular organisms are small in size. As a result, they have a large total surface area to volume (TSA/V) ratio. This enables the exchange of substances to occur rapidly by diffusion.

Why the Transport System is Important for Multicellular Organism?

  1. Multicellular organisms are bigger and hence have a small total surface area to volume (TSA/V) ratio. As a result, the rate of diffusion of substances is low. The larger the organism, the more difficult it is for the substances to diffuse in and out of the body cells.
  2. Also, as the size of an organism increases, the amount of nutrients and oxygen gas needed also increases. So does the metabolic waste products. As such, diffusion alone is not sufficient to fulfill the needs of the body cells and to remove the waste products from the body.
  3. Other than that, for a multicellular organism, the cells are located further in the body. They are not directly in contact with the environment.
  4. Therefore, multicellular organisms need special transport systems to transport the nutrients to all the body cells and at the same time to remove the metabolic waste from the body cells. 

7.10.1 The Formation of Images by Plane Mirrors and Lenses (Structured Questions)

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Question 1:
Diagram 1.1 and Diagram 1.2 show an experiment to measure the focal length of two convex lenses.


(a) Measure and write down the focal length in Diagram 1.1. [1 mark]

(b) Observe Diagram 1.1 and 1.2.
What is the difference between the focal lengths of the two convex lenses? [1 mark]


(c) State one inference for this experiment. [1 mark]

(d) State the variables in this experiment.
(i) Constant variable [1 mark]
(ii) Manipulated variable [1 mark]


Answer:
(a) 7.0 cm

(b) The convex lens shown in Diagram 1.1 has a shorter focal length than the convex lens shown in Diagram 1.2.

(c) The thicker a convex lens is, the shorter its focal length will be.

(d)(i) Parallel light rays from a distant object passing through the convex lens.

(d)(ii) Convex lenses with different thicknesses.


9.4.1 Human Activities that Endangered an Ecosystem (Structured Question 1 & 2)

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Question 1:
(a) Diagram I shows the effects of farming activities near a pond.


Explain how the farming activities cause the death of the aquatic plants and the fishes in the pond.
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(b) Diagram II shows a new industrial area situated near a residential area.


Discuss the good and the bad effects caused by the industrial activities on human and environment in years to come.


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Answer:
(a)
- Farmers use fertilisers that usually contain nitrates and phosphates.
- Fertilisers which contain nitrates/ phosphates may leach into the pond when it rains.
- Algae in the lake grow faster.
- They may grow so much that they completely cover the water.
- Black out the light for plants growing beneath them.
- Photosynthesis rate is reduced.
- Dissolved oxygen also reduced.
- Plants on the top of the water and beneath the water eventually die.
- Their remains are a good source of food for bacteria.
- Bacteria decomposed the dead plant rapidly.
- The large population of bacteria respires, using up oxygen, so there is very little oxygen left for other living organisms.
- BOD increased.
- Water population increases.
- Those aquatic plants and fish which need oxygen die.

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(b)
Advantages:
- More job opportunities
- More economic activities and development projects
- Attract tourists
- Improve infrastructure

Disadvantages:
- Can cause respiratory problems/ asthma/ bronchitis/ irritates the eye
- Crime rate increases

Environment:
- Industries emit poisonous gases such as sulphur dioxide/ oxides of nitrogen/ smoke/ fine solid particles
- Contribute to air pollution
- Oxides of nitrogen and Sulphur dioxide dissolve in rain water to form acid rain.
- Makes the soil acidic and unsuitable for the cultivation of crops
- Smoke and haze reduce light intensity reaching stomata and cause the rate of photosynthesis to decrease
- Which subsequently reduces crop yield
- Carbon dioxide leads to the greenhouse effect, resulting in an increase in the atmospheric temperature
- Cause the extinction of organisms


6.4.3 The Need for Proper Handling of Radioactive Substances (Structured Questions)

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Question 1:
(a) Diagram 1.1 and 1.2 shows activities which involved the radioactive substances.


(i) State the radioactive radiation used in medical field in Diagram 1.1. [1 mark]


(ii) State the uses of Carbon-14 in Diagram 1.2. [1 mark]

(iii) State one effect of nuclear explosion to human being. [1 mark]

(iv) What substance is used to make a container to keep radioactive substance safe? [1 mark]

(b) Diagram 1.3 shows the nuclear power station.

(i) Name the radioactive substances used in Diagram 1.3. [1 mark]

(ii) State the energy generated from the power station in Diagram 1.3. [1 mark]


Answer:
(a)(i) Gamma radiation

(a)(ii) To estimate the age of ancient objects

(a)(iii) Can cause serious health problems or even death

(a)(iv) Thick concrete/ Thick lead

(b)(i) Uranium-235

(b)(ii) Electrical energy


6.4.2 Production of Nuclear Energy and Its Uses (Structured Questions)

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Question 1:
Diagram 1 shows a nuclear fission process of radioactive substance.


(a) Name energy S and ray T in the boxes provided in Diagram 1. [2 marks]

(b) State one use of:
(i) Energy S [1 mark]
(ii) Ray T in medical field.[1 mark]

(c) State one method to detect the presence of ray T. [1 mark]

(d) What is the effect on human beings if exposed to ray T. [1 mark]


Answer:
(a)
Energy S: Nuclear energy
Ray T: Radioactive radiation

(b)(i)
- To generate electrical energy
- To generate large amounts of heat and light in nuclear explosions
(any one)


(b)(ii)
- Used as radioactive tracers
- Used for sterilising medical supplies
- Used in radiotherapy treatment to kill certain cells such as cancer cells
(any one)

(c) Use a detector such as the Geiger-Muller counter.

(d) Causes radiation sickness, internal bleeding, infertility, cancer and mutations. 

6.4.1 Radioactive Substances (Structured Questions)

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Question 1:
Diagram 1 shows three radioactive radiations, P, Q and R.


(a) Name radioactive radiations P and R. [2 marks]

(b) State the charges of radioactive radiation P and Q.[2 marks]

(c) Name the substance that can stop the penetration of radioactive radiation R. [1 mark]

(d) Name the radioactive radiation which is used to kill cancer cells. [1 mark]


Answer:
(a)
P: Alpha radiation
R: Gamma radiation

(b)
P: Positively charged
Q: Negatively charged

(c) Thick block of lead or concrete.

(d) Gamma radiation


Question 2:
Diagram 2 shows the use of a radioactive substance in food preservation.


(a) State the function of gamma radiation in this process. [1 mark]

(b) State two uses of gamma radiation other than food preservation.[2 marks]

(c) Name one material which can stop gamma radiation. [1 mark]

(d) State two dangerous effects of gamma radiation to human beings. [2 marks]


Answer:
(a) To kill microorganisms in the potatoes without changing their taste and appearance.

(b)
- To kill cancerous cells
- To control the thickness of paper, plastic or metal
- To kill or sterilize pests
(any two)

(c) Lead which is a few centimetres thick

(d)
- Kills body cells
- Causes cancer
- Causes mutation
(any two)

6.3 Proper Handling of Radioactive Substances

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6.3 Proper Handling of Radioactive Substances

6.3.1 Effects of Radioactive Radiation on Living Things
1. Radioactive substances are highly hazardous.
2. The energy in radiation can destroy molecules in living tissues and kill cells.
3. The effects of radioactive radiation on living things depend on the total amount of radiation received.
4. Diagram below shows effects of exposure to radioactive radiation over different period of time:



6.2.3 Process of Generating Electricity from Nuclear Energy

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6.2.3 Uses of Nuclear Fusion
1. Nuclear energy is used to
(a) Generate electrical energy
(b) Operate satellites
(c) Propel cruises, aircraft carriers and submarines
 

Nuclear power station


6.2.4 Process of Generating Electricity from Nuclear Energy
1. In a nuclear power station, nuclear energy is produced in a nuclear reactor to generate electricity.
2. Figure below shows the main components in a nuclear power station.

 Nuclear power station

  a.  Graphite moderator
Fast moving neutrons are slowed down by collisions with nuclei in the moderator so that they can cause further fission. In some nuclear power plant, the moderator is water.
b.  Uranium rod (Fuel)
Produces nuclear energy from chain reactions of nuclear fission.
c.  Control rod
Control the rate of chain reaction.
d.  Coolant
To take away the heat from the nuclear reactor.
e.  Thick concrete wall
To prevent the escape of harmful radiations.
f.   Steam generator
Water in the generator is heated and changed into steam. The steam then drives the turbines.
g.  Turbine
To turn the dynamo in the electrical generator to produce electricity.



3. Figure below shows the summary of the process taking place and transformation of energy in a nuclear power station.

Energy transformation during generation of electricity