Chapter 3 : Movement of Substances Across the Plasma Membrane

A. Passive Transport

i) Simple Diffusion

• not selective: lipid-soluble molecules, gases and water.
• not control by cell.
• movement of the molecules from a region of higher concentration to a region of lower concentration.
• Factors affecting the rate of diffusion are temperature, size of molecules/ions, diffusion gradient, surface area and diffusion medium.
• example: diffusion of oxygen and carbon dioxide at the alveolus.

ii) Osmosis:

• only water molecules.
• not control by cell.
• movement of water from a region of higher concentration to one of lower concentration and often occurs across a semipermeable membrane.
• strong sucrose solution = less water molecule = low water potential.
• weak sucrose solution = more water molecule = high water potential.
• example: absorption of water by root hairs.

iii) Facilitated Diffusion:

• very specific: glucose, nucleic aicds, amino acids, protein and mineral ions.
• control by cell.
• transport of molecules (only certain molecules) across the outer membrane of living cell by a process of carrier protein (hydrophilic group) / channel protein (Ions: Na⁺, Ca²⁺, K⁺) within the cell membrane.
• normally take place from a region with higher concentration of molecules to a region of lower concentration.
• example: absorption of digested food in the villus.

B. Process of Active Transport

• very specific: minerals ions and amino acids.
• control by cell.
• This process needs carrier proteins and energy (due to against concentration gradient) from a region of lower concentration to a region of higher concentration).
• Cell must expend energy that derived from ATP (adenosine triphosphate)
• example: human nerve cells (sodium ions are constantly transport out of the cell) / ions intake by root hairs of a plant.

Chapter 2 : Cell Structure and Cell Organisation

Unicellular – A single cell performs all the basic life process. Example: Amoeba sp., Paramecium sp.,

Multi cellular – An organism consists of more than one cell. Each group of cell specialized to carry our life processes. Example: Homo sapien (human), animals and plants. It has five levels of organisation

Cells: basic units of structure and function.
Example: Red blood cells and xylem vessel cells.

Tissues: made up of cells with similar in structure and function.
Example: Epithelial tissues and vascular tissues.

Organs: made up of tissues that perform a specific function.
Example: Heart and flower.

System: two of more organs that perform a specific function.
Example: Digestive system and root system.

Organisms: whole living thing that carry out all the basic life processes.
Example: Human and durian tree.

Cell Organisation (Unicellular) in Amoeba sp. (lives in freshwater ponds) and Paramecium sp. (lives in soil and moist area)

1. Cell structure

Amoeba sp.: plasma membrane, food vacuole, contractile vacuole, pseudopodia, nucleus, ectoplasm, endoplasm.

Paramecium sp.: food vacuole, posterior contractile vacuole, cytostome, gullet, oral groove, cilia, macronucleus, micronucleus, anterior contractile vacuole.

2. Locomotion

Amoeba sp.: Pseudopodium (false foot) helps it to move forward slowly and it is known as amoeboid movement.

Paramecium sp.: Hair-like cilia to beat against water. It beats its cilia backwards diagonally (swim forward) and it rotates on its axis. It beats its cilia forward (swim backwards).

3. Feeding

Amoeba sp.: Omnivore. Eat bacteria, plant cells, algae and other microscopic organisms.

Entrapment – extend pseudopodium.

Engulfment – engulf tiny food (phagocytosis) with its pseudopodia.

Digestion – food enclosed in food vacuole

Absorption – enzyme digests the bacteria

Egesting – expel indigestible material.

~Paramecium sp.: Eat bacteria, organic material and other microscopic organisms.

Sweeping – movement of cilia. Food moves along the oral groove into the gullet and cytostome.

Digestion – food vacuole circulates round the cell.

Elimination – undigested food is eliminated at the anal pore.

4. Reproduction

Amoeba sp.: two types of reproduction.

Binary Fission – nucleus divides (favourable condition) and then follows by division of cytoplasm. Two daughter cells are formed (mitotic division).

Spore Formation – spores form (bad condition) and germinate into new amoeba under favourable condition.

Paramecium sp.: two types of reproduction.

Binary Fission – micronucleus undergoes mitosis (favourable condition). Macronucleus begins to elongation and form two. Cell content divide and two daughter cells are formed.

Conjugation (Sexual reproduction) – two same species parent paramecia exchange genetic material of their micronuclei. Each parent divides and forms four daughter cells.

5. Osmoregulation

Amoeba sp.: water moves into the cell by osmosis and prevention of bursting, it has a contractile vacuole.

Paramecium sp.: water moves into the cell by osmosis and prevention of bursting, it has two contractile vacuoles.

6. Respiration

Amoeba sp. and Paramecium sp. (both): exchange gases throughout the whole cell membrane

7. Excretion

Amoeba sp. and Paramecium sp. (both): waste products are ammonia and carbon dioxide by diffusion. Solid waste in paramecium is expelled through its anal pore.

Cell Organisation (Multicellular) in Human

Cells: Epithelial cells, muscle cells, white blood cells, red blood cells, sperm, nerve cells.

Tissues: Epithelial tissue, smooth muscle tissue, connective tissue, skeletal tissue, nerve tissue.

Organs: Stomach, heart, kidney, lung, liver.

Systems: Circulatory system, respiratory system, digestive system, excretory system, muscular system, lymphatic system, integumentary system, skeletal system, nervous system, endocrine system, reproductive system.

Organisms: Human.

Cell Organisation in Plant

Cells: Parenchyma cells, collenchyma cells, sclerenchyma cells, epidermal cells.

Tissues: Epidermal tissue, meristem tissue, vascular tissue.
Organs: Leaf organ, flower organ, stem organ, root organ.

Systems: Shoot system, root system.

Organisms: Plant.

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Chapter 1 : Introduction to Biology

Chapter 1: Introduction to Biology 

• The word “Biology” comes from Greek words, ‘Bios’ meaning ‘Life’and ‘Logos’ meaning ‘Knowledge’.

• Biology is the study of every aspect of life at a every level of its organization

• Biology is the scientific study of life 

Importance of Biology

•  Biology has enabled us to understand heredity and the inheritance of genetic abnormalities that cause diseases.

•  Many people use biology in their leisure activities, for example, gardening, fishing and cooking.

• Biology teaching us to empathize with living things and this generates awareness of ourselves as biological organisms.

•  The fields of study in biology can also be classified according to their scope as follows:

1. Structure and Function                            

        Anatomy, Biochemistry, Cytology, Histology, morphology, physiology

2. Major groupings of organisms                            

        Bacteriology, Botany, Entomology, ichthyology, microbiology, Mycology,Ornithology, Taxonomy, Virology 

3. Development of organisms  

                       Embryology, Evolutionary Biology, Genetic, Developmental Biology       
              4. Organisms and their environment    

                      Ecology, Ethnology, Bio-geography                                                                                         
              5.  Applied Biology

     Agriculture, Biotechnology, fisheries, Forestry, Medicine, veterinary medicine, density

                                                                                                  

The Scientific Method

• The scientific method involves a series of ordered steps:
a)     Make an observation

b)    State the problem

c)     Form of hypothesis

d)    Identify the variables

e)     Design and perform an experiment

f)      Record and analyze data

g)     State the conclusion

For more information, you can watch this video by IITV

( Chapter 1 The Study of Biology)

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Form 4

Form 4 Syllabus

Chapter 1: Introduction To Biology

1.1 Study of Biology
1.2 Scientific Investigation

Chapter 2: Cell Structure and Cell Organisation

2.1 Cell Structure and Function
2.2 Cell Organisation
2.3 Uniqueness of a cell

Chapter 3: Movement of Substances across the Plasma Membrane

3.1 Movement of Substances across the Plasma Membrane 
3.2 Movement of Substances across the Plasma Membrane in Everyday Life
3.3 Appreciating the Movement of Substances across the Plasma Membrane

Chapter 4: Chemical Composition of the Cell

4.1 Chemical Composition of the cell
4.2 Carbohydrates
4.3 Proteins
4.4 Lipids
4.5 Enzymes
4.6 The Importance of Chemical Composition in Cells

Chapter 5: Cell Division

5.1 Mitosis
5.2 Meiosis
5.3 Appreciating the Movement of Chromosomes During Mitosis and Meiosis

Chapter 6: Nutrition

6.1 Types of Nutrition
6.2 Balanced Diet
6.3 Malnutrition
6.4 Food Digestion
6.5 Absorption and Assimilation of Digested Food
6.6 Formation of Faeces and Defecation
6.7 Evaluating Eating Habits
6.8 The Importance of a Healthy Digestive System  
6.9 The Importance of Macronutrients and Micronutrients in Plants
6.10 Photosynthesis
6.11 The Mechanism of Photosynthesis
6.12 Factors Affecting Photosynthesis
6.13 A Caring Attitudes towards Plants
6.14 Technology Used in Food Production
6.15 Technological Development in Food Processing

Chapter 7: Respiration

7.1 The Respiratory Process in Energy Production
7.2 The Respiratory Structures and Breathing Mechanisms in Humans and Animals
7.3 Gaseous Exchange across the Respiratory Surfaces and Transport of Gases in Humans
7.4 The Regulatory Mechanism in Respiration
7.5 The Importance of Maintaining a Healthy Respiratory System
7.6 Respiration in Plants

Chapter 8: Dynamic Ecosystem

8.1 The Abiotic and Biotic Components in the Environment
8.2 The Processes of Colonisation and Succession in an Ecosystem
8.3 Population Ecology
8.4 Biodiversity
8.5 The Impact of Microorganisms on Life
8.6 Appreciating Biodiversity

Chapter 9: Endangered Ecosystem

9.1 Human Activities that Endangered an Ecosystem
9.2 Greenhouse Effect and Thinning of the Ozone Layer
9.3 The Importance of Proper Management of Development Activities and the Ecosystem