SPM Form 4/Form 5 Biology Revision Notes

Form 4 Biology

 02 Cell Structure

Objective Questions

  1. Cell Structure and Function 1 (6 Questions) 
  2. Cell Structure and Function 2 (5 Questions) 
  3. Cell Organisation 1 (5 Questions) 
  4. Cell Organisation 2 (5 Questions) 
  5. Cell Organisation 3 (3 Questions) 

03 Movement across Plasma Membrane

Objective Questions

  1. Movement of Substances Across the Plasma Membrane 1 (5 Questions) 
  2. Movement of Substances Across the Plasma Membrane 2 (5 Questions) 
  3. Movement of Substances Across the Plasma Membrane 3 (5 Questions) 
  4. Movement of Substances Across the Plasma Membrane in Everyday Life (5 Questions) 

04 Chemical Composition of Cell Chemical

Objective Questions

  1. Composition of the Cell (3 Questions) 
  2. Carbohydrate (6 Questions) 
  3. Proteins (5 Questions) 
  4. Lipids (3 Questions) 
  5. Enzymes 1 (4 Questions) 
  6. Enzymes 2 (4 Questions) 

    05 Meiosis and Mitosis

    1. Mitosis
    2. Meiosis
    3. Appreciating the Movement of Chromosomes During Mitosis and Meiosis

    Objective Questions

    1. Mitosis 1 (6 Questions) 
    2. Mitosis 2 – (6 Questions) 
    3. Meiosis 1 – (6 Questions) 
    4. Meiosis 2 – (7 Questions) 

    06 Nutrition

    1. The Types of Nutrition
    2. The Concept of a Balanced Diet
    3. Malnutrition
    4. Food Digestion
      1. Digestion in the Mouth and Stomach
      2. Digestion in the Small Intestine
    5. The Process of Absorption and Assimilation of Digested Food
      1. Functions of the Liver and Assimilation
    6. The Formation of Faeces and Defecation
    7. Evaluating Eating Habits
    8. The Importance of a Healthy Digestive System
    9. The Importance of Macronutrients and Micronutrients in Plants
    10. Photosynthesis
    11. The Mechanism of Photosynthesis
    12. Factors Affecting Photosynthesis
    13. Practising a Caring Attitude Towards Plants
    14. The Technology Used in Food Production
    15. Technological Development in Food Processing

    Objective Questions

    1. Balanced Diet (6 Questions) 
    2. Malnutrition (3 Questions) 
    3. Food Digestion (7 Questions) 
    4. Absorption and Assimilation of Digested Food (4 Questions) 

    07 Respiration

    1. The Respiratory Process in Energy Production
    2. The Respiratory Structures and Breathing Mechanisms in Humans and Animals
    3. The Concept of Gaseous Exchange Across the Respiratory Surfaces and the Transport of Gases in Human
    4. The Regulatory Mechanism in Respiration
    5. The Importance of Maintaining a Healthy Respiratory System
    6. Respiration in Plants

    Objective Questions

    1. The Respiratory Process in Energy Production (4 Questions) 
    2. Respiratory Mechanisms in Humans and Animals (7 Questions) 
    3. Gaseous Exchange in Humans (4 Questions) 
    4. The Regulatory Mechanism in Respiration (4 Questions) 
    5. Respiration in Plants (4 Questions) 

    08 Dynamic Ecosystem

    1. The Abiotic and Biotic Components of The Environment
    2. The Processes of Colonisation and Succession in An Ecosystem
    3. Population Ecology
    4. The Concept of Biodiversity
    5. The Impact of Microorganisms on Life
    6. Appreciating Biodiversity

    Objective Questions

    1. The Abiotic and Biotic Components of the Environment (7 Questions) 
    2. The Process of Colonisation and Sucession in an Ecosystem (3 Questions) 
    3. Population Ecology (3 Questions) 
    4. Biodiversity (3 Questions) 
    5. The Impact of Microorganisms on Life (6 Questions) 

    09 Endangered Ecosystem

    1. Human Activities that Endanger the Ecosystem
    2. The Greenhouse Effect and Thinning of the Ozone Layer
    3. The Importance of Proper Management of Development Activities and the Ecosystem

    Objective Questions

    1. Human Activities that Endanger the Ecosystem (7 Questions) 
    2. The Greenhouse Effect and Thinning of the Ozone Layer (6 Questions) 
    3. Proper Management of Development Activities and the Ecosystem (3 Questions)

    Form 5 Biology

    01 Transport

    1. The Importance of Transport System in Multicellular Organisms
    2. The Concept of Circulatory System
      1. Composition of Human Blood
      2. Function of Blood in Transport
      3. Function of Haemolymph in Transport
      4. Types of Circulatory System
      5. Circulatory System in Humans
        1. The Blood Vessels
        2. The Heart
        3. Circulation of Blood in Humans
      6. Regulation of Blood Pressure
    3. Blood Clotting
      1. Mechanism of Blood Clotting
      2. Consequences of Blood Clotting Related Problem
    4. The Lymphatic System
      1. Formation of the Interstitial Fluid and Lymph
      2. Structure of the Lymphatic System
      3. Relationship between the Composition of Blood, Interstitial Fluid and Lymph
      4. Relationship between the Lymphatic System and the Circulatory System
    5. The Role of Circulatory System in Body Defence Mechanism
      1. The Body's Defense Mechanism
      2. Immunity and Immunisation
      3. Types of Immunity
      4. HIV and Body's Defense Mechanism
    6. A Healthy Cardiovascular System
    7. Transport of Substances in Plants
      1. Distribution of Vascular System in Dicotyledon Plants
      2. Vascular Tissue in Plant
      3. Vascular System as a Continuous Tube System
      4. Transport of Organic Substances in Plants
      5. Transport of  Water in Plants
      6. The External Conditions that Affect the Rate of Transpiration

    Objective Questions

    1. The Circulatory System (7 Questions) 
    2. The Mechanism of Blood Clotting (3 Questions) 
    3. The Lymphatic System (4 Questions) 
    4. The Role of Circulatory System in Body Defense Mechanism (4 Questions) 

      02 Support and Locomotion

      1. Support and Locomotion in Humans and Animals
        1. The human skeleton
      2. Appreciate a Healthy Musculoskeletal System
      3. Support System in Plants

      Objective Questions

      1. Support and Locomotion in Humans and Animals 1 (6 Questions) 
      2. Support and Locomotion in Humans and Animals 2 (6 Questions) 
      3. Support System in Plants (4 Questions) 

        03 Coordination and Response

        1. Response and Coordination
        2. The Role of Human Nervous System
        3. The Role of Hormones in Humans
        4. Homeostasis in Humans
          1. The human kidney
          2. The formation of urine
        5. Practising a Healthy Lifestyle 
        6. Plant Hormones
          1. The role of auxins in the tropic movements in plants
          2. Ethylene

        Objective Questions

        1. The Role of the Human Nervous System 1 (6 Questions) 
        2. The Role of the Human Nervous System 2 (6 Questions) 
        3. The Role of Hormones in Humans (7 Questions) 
        4. Homeostasis in Humans (7 Questions) 

        04 Reproduction and Growth

        1. Gamete Formation
        2. Role of Hormones in the Menstrual Cycle
        3. Early Development of Zygote in Humans
        4. Contribution of Science and Technology to Human Reproduction
        5. Sexual Reproduction in Flowering Plants
        6. Growth in Multicellular Organisms
        7. Growth Curve
        8. Primary and Secondary Growth in Plants

        Objective Questions

        1. Formation of Gamete (5 Questions) 
        2. Roles of Hormones in the Menstrual Cycle (5 Questions) 

        05 Inheritance

        1. The Concept of Inheritance Based on Mendel's Experiment
        2. Inheritance
        3. Genes and Chromosomes

        Objective Questions

        Inheritance (10 Questions) 

        06 Variation

        1. Variation in Organisms
        2. Cause of Variation
        3. Be Respectful Towards One Another Despite Variation

        Objective Questions

        Variation (9 Questions)

        1.8.2 Lymphatic System (Structured Question 1 & 2)

        Question 1:
        Figure below shows part of the circulatory system and the lymphatic system in the human body.

        What is fluid V? [1 mark]

        What happens to the components of fluid V when it passes through the lymph node? [1 mark]

        Fluid V originates from the blood.
        Describe how fluid V is formed from the blood. [2 marks]

        State one difference between fluid V and the blood. [1 mark]

        A part of vessel T is blocked.
        Explain its effect on the system in the Figure. [2 marks]

        Vessel T in the leg is blocked.
        What would happen to the leg? [1 mark]

        The blood circulatory system and the lymphatic system function to maintain the composition of the tissue fluid.
        Explain how the composition of the tissue fluid is maintained by stating the substances transported by the blood circulatory system and the lymphatic system. [3 marks]

        Fluid V = Lymph

        Toxic substances and pathogens are neutralized/ destroyed.

        Blood plasma diffuses from the capillaries. The tissue fluid formed diffuses into the lymphatic vessels.

        Fluid V does not have erythrocytes whereas blood has erythrocytes. Fluid V is clear yellowish whereas blood is red in colour.

        Interstitial fluid fails to return to the blood circulatory system. Tissue fluid accumulates in the spaces between the cells.

        The leg will be swollen.

        Dissolved substances such as glucose and amino acids are transported in the blood circulatory system entering the body tissues forming tissue fluid. Fatty acids and glycerol are transported by the lymphatic system into the blood circulatory system. Some of the contents of the tissue fluid enter the lymphatic system and some enter the blood circulatory system at the ends of the venules.

        1.8.1 The Mechanism of Blood Clotting (Structured Question 1 & 2)

        Question 1:
        (a)(i) Diagram below shows an electron micrograph of cellular components of human blood.

        Based on Diagram I, explain how platelets help to stop bleeding when a wound occurs. [4 marks]

        A blood test shows that a man’s erythrocytes count is below normal.
        Explain the possible consequences of this condition on his health.
        What type of food should be included in his diet to improve this condition? [8 marks]

        Diagram II shows the blood circulatory system in organism P and organism Q.

        Based on Diagram II:
        (i) Give one example of organism P and organism Q. [2 marks]

        Describe the similarities and differences between the blood circulatory system in organism P and organism Q. [6 marks]



        • Platelets clump together and produce thrombokinase.
        • Thrombokinase converts prothrombin to thrombin.
        • Thrombin converts fibrinogen (a type of soluble protein plasma) to fibrin (vitamin K is needed in the formation of prothrombin).
        • Fibrin forms a network to trap the erythrocytes
        • To form a clot


        • Less red blood cells to combine with oxygen
        • Less oxygen is transported to the body cells.
        • Less energy is produced
        • Resulting in tiredness/ pale looking appearance/ anaemia
        • Need food which is rich in iron
        • Examples: Cockles, liver, spinach


        P: Fish
        Q: Human being



        • Both have a closed circulation
        • Blood flows in blood vessels

        1.4.2 The Formation of the Interstitial Fluid and Lymph

        The Formation of the Interstitial Fluid and Lymph
        1. The blood from the arteries flows at a high pressure into the blood capillaries.
        2. The high hydrostatic pressure in the capillaries forces the blood plasma to 
            leak out through the capillary walls into the space between the body cells.
        3. The fluids that fill up the spaces between the cells is called tissue fluid or 
            interstitial fluid.
        4. The interstitial fluid is made up of water, digested food, gases, hormones, 
            waste products, and small proteins from the blood.
        5. The larger molecules like erythrocytes, platelets and plasma proteins 
            cannot pass through the capillary walls. Leucocytescan squeeze into the fine 
            pores between the capillary walls and pass through it.

        6. The exchange of substances between the blood capillaries and the body cells 
            occurs in the interstitial fluid.
            (a)  Nutrients and oxygen diffuse from the blood through the interstitial fluid 
                 into the body cells.
            (b)  Carbon dioxide and other waste products diffuse from the body cells 
                  through the interstitial fluid into the blood.
        7. There are two ways the interstitial fluid is returned to the circulatory system:
            (a)  About 90% of the interstitial fluid diffuses back into the blood 
                 capillaries because the pressure in the capillary end of the venule is 
                 lower than the arteriole end.
            (b)  The remaining 10%of the fluid diffuses into the lymph capillaries of the 
                  lymphatic system. The fluid in the lymphatic vessels is known is 
                  lymphEventually, the lymph will return to the circulatory system when 
                  it flows into the subclavian veins in the shoulder.

        1.4 The Lymphatic System

        1. The lymphatic system is part of the circulatory system, comprising a network of conduits called lymphatic vessels that carry a clear fluid called lymph directionally towards the heart.
        2. The lymphatic system consist of
          1. lymophatic vessels
          2. lymphatic capillaries
          3. lymph nodes
          4. spleen
          5. thymus

        1.3.2 Consequences of Blood Clotting Related Problem


        1. Haemophilia is a group of hereditary genetic disorders that impair the body's ability to control blood clotting or coagulation.
        2. As a result, minor injuries and internal bleeding can results in death owing to excessive loss of blood.


        1. Thrombosis is the formation of a blood clot (thrombus) inside a blood vessel, obstructing the flow of blood through the circulatory system.
        2. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss.
        3. However, when a blood vessel is not injured, blood clots may form in the body under certain conditions such as a defective blood vessel causes the blood clotting factors to be released into the blood.
        4. When a blood clot can cause obstruction to the blood flow.
        5. If clotting occurs in the coronary artery, it is called coronary thrombosis. Coronary thrombosis can cause a heart attack.
        6. If it occurs in the artery in the brain, it will cause a stroke.
        7. Thrombosis may also cause atherosclerosis, which is the deposition of fat and cholesterol on the walls of arteries.

        1.3.1 Mechanism of Blood Clotting

        The figure below shows the mechanism of blood clotting.

        1. When a blood vessel is damaged, platelets will gather around the wound and coagulate.
        2. At the same time, an enzyme called thrombokinase will be released.
        3. Thrombokinase will convert the inactive prothrombin to the active thrombin.
        4. The thrombin will then catalyses the soluble fibrinogen to the insoluble fibrin.
        5. Fibrin will form a fibrous network to trap the blood cells and form the blood clot.

        1.3 Blood Clotting


        1. Hemostasis is a process which causes bleeding to stop and keep blood within a damaged blood vessel. It is the first stage of wound healing.
        2. Blood clotting is an important part of hemostasis, wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel.

        Significant of Blood Clotting

        1.2.6 Regulation of Blood Pressure

        1. Pressure is how much force exerted on one unit area of a surface.
        2. Blood pressure is the pressure exerted by the blood on the walls of the blood vessels.
        3. Sometime, it is also called the arterial blood pressure as it is the pressure in the arteries.

          Normal Blood Pressure

          1. When measuring blood pressure, we measure the
            1. systolic pressure (highest pressure measured in the aorta and the arteries during ventricular contraction)
            2. diastolic pressure (lowest pressure measured after the contraction of the heart while the chambers of the heart refill with blood.)
          2. For an adult, the normal systolic pressure is 120 mm Hg whereas the diastolic pressure is 80 mm Hg.
          3. However, blood pressure may varies throughout the day.

            Factors Affecting Blood Pressure

            1. Blood pressure can be affected by the following factors:
              1. Rate of heart beat
                Higher heart rate, higher blood pressure.
              2. Volume of blood in the body
                Bigger volume, higher blood pressure.
              3. Rate and volume of blood flow
                Higher rate and volume of blood flow, higher rate of heart pumping, higher blood pressure.
              4. Resistance of blood vessels
                Higher resistance (smaller blood vessels, rough blood vessel wall), higher blood pressure. 

            Regulation of Blood Pressure

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            1.2.5c Circulation of Blood in Humans

            1. The circulation of blood in human is due to the pumping of the heart.
            2. The cardiac muscles contract to produce heartbeat which pumps the blood to the whole body.

            The Cardiac Cycle

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            1. The heartbeat is initiated by the sinoatrial node (also called the SAN or pacemaker) .
            2. The SAN consists of specialised cardiac muscle fibres that generates nerve impulses.
            3. From the SAN, the electrical impulses spread to the atrioventricular node (AVN) located at the base of the right atrium (See image above).
            4. Special muscle fibres called His Bundle and the Purkinje fibres then sends the impulses to the ventricles and then stimulates both ventricles to contract simultaneously and pumps the blood out of the heart.

            Contraction of the Skeletal Muscles Around Veins

            1. The blood pressure in the vein is low and hence make it hard for the blood to flow back to the heart.
            2. Therefore, there are skeletal muscles presence around the veins to help blood circulation.
            3. When the skeletal muscles contract, blood is forced to move along the veins.
            4. The valves in the veins prevent the back flow of the blood and hence direct the blood back to the heart.

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