2.2.1a Unicellular Organism – Amoeba sp

General Characteristic

  1. Amoeba sp. have no fixed shape.
  2. Their shape changes as they move.
  3. They have protrusions called pseudopodium used for movement and capturing victims.

(Image by Pearson Scott Foresman shared under Creative Commons Attribution-Share Alike 3.0 Unported license.)


Amoeba sp. live in water.


  1. Amoebas have protrusions called pseudopodium used for movement and capturing victims.
  2. Pseudopodium is an extension of cytoplasm
  3. Video below shows how an amoeba move in water.

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  1. In a favourable environment, Amoebas sp. reproduce through binary fusion.
  2. Binary fusion is a process where the cytoplasm of an amoeba divides and form two daughter.
  3. Under adverse conditions Amoeba sp. reproduce through spore formation.
  4. The spores are protected by cyst walls which resist to heat, cold and dryness.


  1. Amoeba feeds by a process called phagocytosis.
  2. During phagocytosis, amoebas sp engulf a food particle and takes it into its cytoplasm where it forms a food vacuole.
  3. Enzymes are added to digest the food, and the nutrients diffuse through the cytoplasm.

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2.2.1 Unicellular Organism

  1. Unicellular organisms are simple organisms consisting of only one cell.
  2. Each cell is a complete unit of life that is able to carry out all the living processes.
  3. The main groups of unicellular organisms are 
    1. bacteria, 
    2. archaea, 
    3. protozoa, 
    4. unicellular algae and 
    5. unicellular fungi.
  4. Two important unicellular organisms that you need to know in SPM biology are the Amoeba sp. and Paramecium sp. 

2.2 Cell Organisation

Unicellular and Multicellular Organism

  1. In general, organisms are divided into two types: 
    1. unicellular organisms
    2. multi-cellular organisms.
  2. Unicellular organisms are the organism with just 1 cell.
  3. Each cell is able to carry out all the functions of life independently.
  4. Examples of unicellular organism
    1. Paramecium
    2. Amoeba
    3. Yeast
    4. Chlamydomonas
  5. Multicellular organisms are the organism made up of more than 1 cell
  6. They are larger organisms that contain many different types of cell to carry out different functions of life.
    1. The living processes of organisms include
      1. Feeding
      2. Locomotion
      3. Reproduction
      4. Respiration
      5. Growth
      6. Excretion
      7. Response to stimuli
      8. Heredity
    (Paramecium. This file was upload by Barfooz at the English Wikipedia.)

    2.8 Effects of Drug Abuse on Health

    Effects of Drug Abuse on Health
    2.8.1 What are Drugs?
    1. Drugs are chemical substance which can affect a person’s mind, emotion and body functions.
    2. Useful drugs are used to treat patient in medicine.
    3. Drug abuse occurs if it is used not for medical purposes.
    4. Drug abuse can lead to addiction and health deterioration.


    Types of drug and their characteristics

    2.8.2 Effects of Drug Abuse on Body Coordination and Health

    Drugs and their adverse effects

    2.1.3 Relation between the Density of Organelles and the Function of Cells

    Density of Organelle

    1. Density of organelle is refering to the abundance of certain organelles found in a cell.
    2. The density of an organelle in a cell is related to the specific function of the cell.
    3. Below are examples of high density of certain organelle and their reason.

    Cell with high density of chloroplast.

    Palisade mesophyll cell
    To trap sunlight to synthesise carbohydrate during photosynthesis.

    Cell with high density of mitochondria

    Sperm cells
    Reason: Need energy to move through the uterus towards the Fallopian tubes.

    Muscle cells
    Reason: Contraction of muscle during movement need a lot energy

    Meristem Cells
    Reason: Meristem cells in the plant shoots and roots are involved in cell division to produce new cells for growth. It needs a lot of energy for the activities.

    Cell with high density of endoplasmic recticulum

    Cells in salivary gland
    Reason: Active in synthesing and secreting digestive enzyme

    Pancreatic Cells
    Reason: Active in synthesing and secreting hormone and enzyme

    2.1.2 Comparison between the Animal Cell and Plant Cell

    Similarities of Animal Cell and Plant Cell

    1. Both animal cells and plant cells have
      1. plasma membrane
      2. nucleus with nucleic bounded by nuclear membrane
      3. cytoplasm
      4. ribosome
      5. mitochondria
      6. golgi apparatus
      7. endoplasmic recticulum

    Differences between Animal Cells and Plant Cells

    Animal Cells Plant Cells
    Cell Wall Absent Present
    Cytoplasm Present throughout the cell. Present, but usually confined to a thin layer at the edge of the cell.
    Chloroplast Absent Present
    Vacuole Present in some animall cells. Normally small and distributed throughout the cell. Present. Large and filled with cell sap.
    Nucleus Normally in the middle of the cell Normally at the edge of the cell
    Lysosome Present Normally absent
    Centriole Present Absent
    Storage Granule Mainly as glicogen Mainly as starch
    Shape Do not have fixed shape Have fixed shape
    Size Usually smaller than plant cell Usually bigger than animall cell
    Cilia and Flagella Present (Usually) Absent
    Secretion Produces a variety of secretions. Produces few secretions.

    2.6 Hormonal Coordination in the Body

    Hormonal Coordination in the Body

    1. Hormones are the chemical substances produced by the ductless glands called endocrine glands.
    2. Hormones are produced in a small quantity and are carried by the blood circulation system to all parts of the body.

    2.6.1 Human Endocrine System
    1. The endocrine system is made up of endocrine glands, which are ductless glands that secrete hormone directly into the bloodstream.

    Human endocrine system and the location of endocrine glands

    Endocrine glands
    Function of hormone
    Pituitary gland
    •  names of hormones not required
    •  Master gland that controls and regulates the secretion of hormones by other endocrine glands.
    •   Controls the growth of body.
    •   Controls the reabsorption of water.
    •   Controls other endocrine glands like ovary and testes.
    Thyroid gland
    •  Thyroxine
    (contains iodine)
    •  Main source of iodine is seafood.
    •   Controls metabolic rate.
    •   Controls the physical and mental growth
    •   Glucagon
    Controls sugar level in the blood by:
    •  Insulin converts excess glucose into glycogen.
    •   Glucagon changes glycogen into glucose.
    Adrenal glands
    •   Adrenaline
    (secreted during situations of emergencies, under stress, fear or anxiety)
    Increase heartbeat.
    Increase metabolic rate.
    Increase breathing rate.
    Converts glycogen into glucose.
    the male sex hormones)
    •   Testosterone
    •  Controls the development of male secondary characteristics such as deepening of voice armpit hair and moustache.
    •  Production of sperms.
    the female sex hormones)
    •   Oestrogen
    •  Controls the development of female secondary characteristics such as development of breast and enlargement of pelvis.
    •  Controls the menstrual cycle and ovulation.
    •   Stimulates development of milk glands during pregnancy.

    Effects of Hormonal Imbalance on Health
    Effect of excessive hormone
    Effect of deficiency of hormone
    Growth hormone
    •   gigantism
    •  dwarfism
    •  Increase metabolic rate
    •  Increase heartbeat
    •  Increase sweating
    •  Protruding eyes
    •  Metabolic rate decreases
    •  Retarded growth in Children
    Causes goitre
    •  Shortage of glucose in the blood.
    •  May lead to coma and fatal.
    •  Diabetes Mellitus
    High blood pressure.
    •  High salt concentration in blood.
    •  Blood sugar level increases.
    •  Muscles weaken.
    •  Ability to overcome stress reducing.
    •  Excessive salt and water in the body (Addison disease).
    •  Extremely masculine
    •  Incomplete development of secondary sexual characteristics.
    •  Immature sperms produced.
    Extremely feminine.
    Baby born before the complete gestation period.
    •  Incomplete development of secondary sexual characteristics.
    •  Irregular menstrual cycle
    •  Infertility
    •  Miscarriage

    2.1.1 Components of a Cell

    1. Each cell consists of a plasma membrane and protoplasm
    2. The protoplasm consist of cytoplasm and nucleus.
    3. Cytoplasm contains many types of organelles.
    4. The following is the illustration of the animal cell and plant cell.
    (Animal Cell)

    (Plant Cell)


    Plasma Membrane

    1. The plasma membrane separates the content of the cell from its external environment.
    2. It regulates the movement of substances entering and leaving the cell.
    3. It also allows the exchange of nutrients, respiratory gases and wastes products between the cell and its environment


    1. The cytoplasm contain variety of organelle.
    2. The function of the cytoplasm is to maintain the shape of the cell.
    3. It acts as a medium for the biochemical reactions occur within the cell
    4. It also store chemical substances such as glicogen granules (in animal cells), starch granules (inplant cells) and enzymes.

    Cell Wall

    1. The cell wall only contain in plant cell. It support the cell and the plant and maintain the shape of the cell.
    2. It also prevents the cell from bursting when too much water enters the cell through osmosis.
    3. It allows substances to move through it.


    1. The nucleus contains the genetic material of a cell.
    2. It controls the activities of the cell.
    3. It also produces ribosomes and ribonucleic acids(RNA).


    Endoplasmic Recticulum (ER)

    - Rough Endoplasmic Recticulum:

    1. Transporting the newly synthesised protein.
    2. Involve in the systhesis of protein.
    3. Provides surface for chemical reaction

    - Smooth Endoplasmic Recticulum:

    1. Transporting lipids and glycerols.
    2. Synthesising lipids and other non-protein substances.


    1. Produces ATP (Adenosine triphosphate.)
    2. Site of energy production through cellular respiration.


    1. Site for synthesising protein.
    2. Golgi Apparatus
    3. Site for the production of enzyme andlysosome.
    4. Produces polysacharides, glycoproteins andsecretory enzyme.
    5. Storing and modifying carbohydrate and glycoprotein.
    6. Transport and store lipid.


    1. Stores food (Carbohydrate, amino acid) and water.
    2. Support herbaceous plants when it is turgid.
    3. Stores organic waste (in leaf cells).


    1. Contain chlorophyll and hence a site for photosynthesis to take place.


    1. The centrosome is served as the main microtubule organizing center (MTOC) of the animal cell as well as a regulator of cell-cycle progression.
    2. It form spindle fibres during cell division in animal cell.


    1. Lysosomes contain hydrolytic enzymes that digest or break down complex organic molecules such as proteins, polysaccharides and lipids.
    2. The enzymes eliminate worn out organelles and damaged organelles.

    Golgi Apparatus

    1. The golgi apparatus processes proteins and lipids from the endoplasmic reticulum
    2. The products are sorted by the Golgi Apparatus and packaged into vesicles
    3. The vesicles then release their contents outside the cell.
    4. It also responsible to the formation of lysosomes.

    2.5.5 Voluntary Actions and Involuntary Actions

    Voluntary Actions and Involuntary Actions

    Voluntary actions are actions we are aware of and which are done according to our
    2. Voluntary actions are controlled by the cerebrum.
    3. Involuntary actions take place continuously and automatically in the body, without us
    being consciously aware of them.

    4. Involuntary actions are controlled by the medulla oblongata.

    Comparison between voluntary actions and involuntary actions