Chapter 2: Cell Biology and Organisation PDF

2 CHAPTER Cell Biology and Organisation Do you KNOW... What are the compo...

2 CHAPTER Cell Biology and Organisation Do you KNOW... What are the compo nents of plant cells and anim al cells? What is the life process of the unicellular organism ? Which cell What is the relat ionship between specialise d cell has the longest structures and their What are the lev functions? els of life span? organisation in mult organisms? icellular 20 BioT4(NC)-B2-FA_EN New 6th.indd 20 1/9/2020 12:15:19 PM  2.1 Cell Structure and Function 2.1.1 Prepare microscope slides of animal and plant cells. 2.1.2 Identify the structures of animal and plant cells based on observations through a light microscope. 2.1.3 Analyse the components of animal and plant cells as seen on micrographs. 2.1.4 State the main functions of components of animal and plant cells as seen on micrographs. 2.1.5 Compare and contrast components of animal and plant cells. 2.2 Living Processes in Unicellular Organisms 2.2.1 Conceptualise living processes in unicellular organisms such as Amoeba sp. and Paramecium sp. 2.2.2 Deduce living processes in unicellular organisms as seen through a light microscope. 2.3 Living Processes in Multicellular Organisms 2.3.1 Correlate the uniqueness of specialised cell structures with their functions in multicellular organisms. 2.3.2 Identify specialised cells in multicellular organisms. 2.3.3 Analyse the density of certain organelles with the functions of specialised cells in multicellular organisms. 2.3.4 Describe the effects of deficiency, absence or failure in the function of an organelle of certain cells in multicellular organisms. 2.4 Levels of Organisation in Multicellular Organisms 2.4.1 Make a sequence of levels of organisation in multicellular organisms. 2.4.2 Identify cells, tissues or organs in an organ system. 2.4.3 Communicate about organ systems in multicellular organisms with their main functions. 21 BioT4(NC)-B2-FA_EN New 6th.indd 21 1/9/2020 12:15:20 PM  2.1 Cell Structure and Function You may still recall the shape of cells you learned in Form 1. Much like the bee hive which is made up of hexagonal-shaped units, all living things are also made up of cells that are combined together. Cells are the basic units of all living things. Let us examine the structure of animal cells and plant cells through a light microscope. 1.2seiti2.1 Activity vitcA Preparing and examining slides of plant cells Observation Materials One big onion, iodine solution, distilled water and filter paper Apparatus Glass slides, cover slips, light microscope, scalpel, a pair of forceps, dropper and mounting needle Procedure 1 Cut a piece of scale leaf from a big onion (a). 2 Remove the translucent epidermis from the inside of the scale leaf using a scalpel. 3 Add a drop of distilled water at the centre of the slide and lay the onion epidermis on the water (b). 4 Using a mounting needle, cover the onion epidermis with a cover slip by placing it at a 45° angle to the slide and slowly press it down. The temporary slide of this specimen is named as wet mount. Make sure there are no air bubbles trapped in the wet mount slide (c) and the onion epidermis is not folded. 5 Add a drop of iodine solution on one side of the cover slip. Place the filter paper at the opposite end of the cover slip to draw the iodine solution to absorb and stain the entire onion epidermis. This technique is known as the irrigation technique (d). jarum tenggek larutan iodin bawang besar a pair of forseps forceps bawang besar one bigepidermis onion forseps epidermis epidermis kaca penutup tenggek jarum larutan iodin epidermis epidermis epidermis kaca penutup glass setitis drop ofairdistilled slide waterair setitis (a) (b) Take Note! (a) (b) Air bubbles that are (c) (d) (a) jarum tenggek larutan iodin(b) (c)trapped under the (d) forseps mounting needle cover slip can be jarum tenggek iodine larutansolution iodin forseps cover kacaslip penutup removed by gently dermis kaca penutup epidermis tapping the cover slip with the tip of a setitis air filter paper sharp pencil. setitis air (c) (d) (b) (b) (c) (c) (d)(d) Preparation of plant cell slide 22 2.1.1 2.1.2 BioT4(NC)-B2-FA_EN New 6th.indd 22 1/9/2020 12:15:23 PM  6 Use a piece of filter paper to absorb excess iodine and distilled water. 7 Observe the slide through a light microscope with a low-power objective lens and then with a high-power objective lens. CHAPTER 2 8 Draw the epidermal cells structure that can be observed and label it completely. Record the magnification power. Discussion 1 What are the components of the cell that can be observed through the light microscope? 2 Does a plant cell have a fixed shape? 3 Name another type of plant that can be used in this activity to replace the onion. Conclusion Suggest a suitable conclusion for this observation. Using the same slide preparation method, prepare a slide of cheek cells (slide of animal cells) using a methylene blue solution. 1.s2eitiv2.2 Activity itcA Preparing and examining slides of animal cells Observation Materials Animal cell (cheek cell), methylene blue solution, distilled water, filter paper and toothpick Apparatus Glass slides, cover slips, light microscope, dropper and mounting needle Procedure 1 Gently scrape the inside of the cheek with a blunt tooth pick. 2 Transfer the scrapping into a drop of water on a clean glass slide and cover with the cover slip. 3 Stain the cheek cells with methylene blue solution using the irrigation technique. methylene blue solution filter paper 4 Examine the cheek cells through a light microscope. Draw the cheek cells that can be observed. Record the Preparation of animal cell slide magnification power. Discussion 1 What are the components of the cell that can be observed through the light microscope? 2 Does the human cheek cell have a permanent shape? 3 Can you see dark blue spots on the prepared cheek cell? 4 What are the similarities between animal cells and plant cells? Which component is present in the onion cell but is not present in the cheek cell? Conclusion Suggest a suitable conclusion for this observation. 2.1.1 2.1.2 23 BioT4(NC)-B2-FA_EN New 6th.indd 23 1/9/2020 12:15:23 PM  Components of animal and plant cells and their functions MITOCHONDRION (PLURAL: MITOCHONDRIA) It is rod-shaped or spherical It consists of two layers of membranes, which are the smooth outer membrane and folded inner membrane Contains enzymes that play a role in cellular respiration Function: A site that generates energy through the glucose oxidation process during cellular respiration Energy released in the form of ATP molecules (adenosine triphosphate) to be used by the cells CENTRIOLE cytoplasm lysosome nucleus Small cylindrical components that exist in pairs in mitochondrion nucleolus animal cells Made up of complex arrangement of microtubules centriole Does not exist in plant cells Golgi Function: apparatus Forms spindle fibre during cell division in animal cells GOLGI APPARATUS Consists of a stack of parallel flattened sacs that are coated by a single cell membrane New membrane is added at one end of the Golgi apparatus and vesicles bud off from the other end. Function: ribosome Processes, modifies, packs and transports chemicals such as protein, rough carbohydrate and glycoprotein plasma membrane smooth endoplasmic (combination of carbohydrate and endoplasmic reticulum protein) reticulum FIGURE 2.1 Animal cells PLASMA MEMBRANE Outer membrane that surrounds the entire content of cell outer environment Made of proteins and phospholipids plasma Thin and elastic film membrane Partially permeable Function: cytoplasm Separates content of cell from the external environment Controls movement of substances into and out of the cell Allows exchange of nutrients, respiratory gases and waste materials between cells and their surroundings 24 2.1.3 2.1.4 BioT4(NC)-B2-FA_EN New 6th.indd 24 1/9/2020 12:15:25 PM  LYSOSOME Small spherical sac enclosed in a single membrane lysosome Contains hydrolytic enzymes CHAPTER 2 Function: Hydrolyses complex organic molecules such as protein, nucleic acid and lipid Breaks down bacteria and components of damaged cells NUCLEUS (PLURAL: NUCLEI) RIBOSOME Largest component in the cell Small, compact and spherical granules Spherical, compressed and enclosed in a Consists of protein and ribonucleic acid nuclear membrane with many pores (RNA) The nucleus contains chromosomes, nucleolus Ribosomes are present on the surface of and nucleoplasm. the rough endoplasmic reticulum or exist Function: freely in the cytoplasm. Controls all cell activities Function: Has chromosomes that contain Site for protein synthesis deoxyribonucleic acid (DNA). DNA determines ribosome the cell characteristics and metabolic function. nuclear nucleoplasm membrane nucleolus chromatin ENDOPLASMIC RETICULUM Consists of a system of interconnected folded flattened sacs Endoplasmic reticulum membrane is continuous with the nuclear membrane. There are two types of endoplasmic reticulum: – Rough endoplasmic reticulum has ribosomes attached to the surface – Smooth endoplasmic reticulum does not have ribosomes Function: smooth endoplasmic reticulum The transport system within the cell Provides a wide surface for enzyme attachment and biochemical reactions The rough endoplasmic reticulum transports proteins synthesised by ribosomes. The smooth endoplasmic reticulum synthesises and transports glycerol and lipids, and carries out the detoxification of drugs and metabolic by-products. rough endoplasmic reticulum 2.1.3 2.1.4 25 BioT4(NC)-B2-FA_EN New 6th.indd 25 1/9/2020 12:15:26 PM  VACUOLE CHLOROPLAST Liquid-filled sac, which is the cell sap. Oval shaped A vacuole is surrounded by the tonoplast Consists of two layers of membrane membrane. Contains chlorophyll pigments in the Young plant cells have many small vacuoles while grana that give plants a green colour mature plant cells have a large vacuole. Function: chloroplast The vacuole in animal cells is small. Chlorophyll absorbs Cell sap contains water, organic acids, sugars, sunlight and converts amino acids, enzymes, mineral salts, oxygen, it to chemical carbon dioxide and metabolic by-products. energy during Function: tonoplast photosynthesis. vacuole Water is absorbed into the vacuole plant cell and the cell becomes turgid. In unicellular animals, the vacuole contracts during osmoregulation, osmosis and excretion. nuclear membrane vacuole nucleolus nucleus chloroplast endoplasmic CYTOPLASM reticulum Consists of a jelly-like cytoplasm medium that contains components of the suspended cells Golgi appratus mitochondrion Contains organic compounds (such cell wall as protein, lipid and carbohydrate) and plasma membrane inorganic compounds FIGURE 2.2 Plant cell (such as potassium ions) Function: Acts as a medium for biochemical reactions in cells CELL WALL cytoplasm A strong and rigid outer layer Made from cellulose fibre cytoplasm Fully permeable plasma Function: membrane Maintains the shape of plant cells Provides mechanical support to cell wall plant cells 26 2.1.3 2.1.4 BioT4(NC)-B2-FA_EN New 6th.indd 26 1/9/2020 12:15:27 PM  Compare and contrast the components of animal cells and plant cells CHAPTER 2 You have learned about the components in animal and plant cells. What are the similarities and differences between the components in animal and plant cells? cell wall nucleus cytoplasm plasma nucleus cytoplasm membrane plasma membrane vacuole PHOTOGRAPH 2.1 Structure of plant and animal cells through a light microscope SIMILARITIES Both cells are made of nucleus, cytoplasm, plasma membrane, Golgi apparatus, mitochondrion, endoplasmic reticulum and ribosomes. PLANT CELLS DIFFERENCES ANIMAL CELLS Has a fixed shape Does not have a fixed shape Has a cell wall Does not have a cell wall Has chloroplasts Does not have chloroplasts Has a large vacuole No vacuole/if present, it is small Stores carbohydrate in the form of starch Stores carbohydrate in the form of Does not have a centriole glycogen Has centrioles Formative Practice 2.1 1 State one structural difference between 3 Chloroplast is found in some plant cells the rough endoplasmic reticulum and the only. Give one example of a plant cell that smooth endoplasmic reticulum. does not have chloroplast and give your 2 Why is the use of an electron microscope reasons. important in studying cells? 4 Compare and contrast animal cells and plant cells. 2.1.5 27 BioT4(NC)-B2-FA_EN New 6th.indd 27 1/9/2020 12:15:29 PM  2.2 Living Processes in Unicellular Organisms Unicellular organisms are made up of only one cell. However, this cell is a complete unit of life like multicellular organisms. Unicellular organisms carry out all life processes: respiration, movement, nutrition, responding to stimulus, reproduction, growth and excretion. Protozoans are the simplest form of unicellular organisms. Examples of protozoa ICT 2.1 are Amoeba sp. and Paramecium sp. Let us look at the life processes of Amoeba sp. and Paramecium sp. Activity: Studying the life processes of unicellular organisms pseudopodium vakuol makanan MOVEMENT RESPONDING TO STIMULI Amoeba sp. constantly changes its shape when Amoeba sp. and Paramecium sp. respond to it encounters obstacles. Amoeba sp. moves by stimuli such as chemicals, touch or bright light extending out its pseudopodium (false feet). by moving away from the stimuli. This is followed by the flow of cytoplasm into the extended pseudopodium. Paramecium sp. moves using rhythmic cilia endoplasma beats. ektoplasma RESPIRATION Exchange of oxygen and carbon dioxide NUTRITION nukleus gases occur through the plasma membrane by simple diffusion on the surface of the cell. 1 Amoeba sp. moves towards food by extending its pseudopodium to trap food membran particles by phagocytosis (Figure 2.3). For Paramecium sp. the presence of cilium beat 1 food plasma lysosome helps transfer food particles into the oral groove. vakuol mengecut 2 The food vacuole is combined with lysosome. The food particles are hydrolysed by the 2 enzyme lysozyme in the lysosomes. 3 The nutrients are absorbed into the pseudopodium cytoplasm. 4 Undigested food is discharged when the food vacuole Amoeba sp. moves. Undigested food in the 3 4 Paramecium sp. is discharged through the anus. digested GROWTH food undigested food nutrients absorbed Ameoba sp. and Paramecium sp. grow by synthesising new cytoplasm. FIGURE 2.3 Nutrition in Amoeba sp. 28 2.2.1 2.2.2 BioT4(NC)-B2-FA_EN New 6th.indd 28 1/9/2020 12:15:30 PM  EXCRETION REPRODUCTION Waste such as carbon dioxide and ammonia are When the conditions removed by diffusion. are suitable and there CHAPTER 2 As Amoeba sp. and Paramecium sp. live in is plenty of food, freshwater environments, water will diffuse by Amoeba sp. and osmosis and fill the contractile vacuole. Paramecium sp. will When the vacuole expands to the maximum size, reproduce via contraction occurs and water is excreted from asexual reproduction time to time. that is binary fission through mitosis. Binary fission This process is called osmoregulation. However, when the environmental conditions are not suitable, such as dry conditions, low temperature and plasma membrane food shortage, the Amoeba sp. Conjugation forms spores that will only germinate when the environment improves. For Paramecium sp., sexual reproduction, that is conjugation occurs when environmental conditions are not suitable. nucleus contractile cilium vacuole food vacuole pseudopodium oral groove anus contractile PHOTOGRAPH 2.2 Amoeba sp. vacuole PHOTOGRAPH 2.3 Paramecium sp. nucleus Formative Practice 2.2 1 What is the function of the reproduce when the contractile vacuole in a environment is unfavourable? Activity Zone Paramecium sp.? 4 Predict what will happen to Conduct an 2 How does the Amoeba sp. the contractile vacuole if the experiment using move? Paramecium sp. is placed in a a light microscope concentrated salt solution. to examine the 3 How does the Amoeba sp. living processes of unicellular organisms. 2.2.1 2.2.2 29 BioT4(NC)-B2-FA_EN New 6th.indd 29 1/9/2020 12:15:32 PM  2.3 Living Processes in Multicellular Organisms There are various types of cells in multicellular organisms which are different in size, shape and arrangement. The cell structure correlates to its function, and each type of cell is specialised to carry out a specific function. Photographs 2.4 and 2.5 show several types of specialised cells found in humans and plants as well as how these cells are adapted to carry out their respective functions. MUSCLE CELL NERVE CELL Arranged as Long and thin in multinuclear striated shape fibres Functions in sending Contract and relax to nerve impulses generate movement WHITE BLOOD EPITHELIAL CELL CELL shape Can change Thin and flat cells Can change shape Coats the surface Functions in of organs such as destroying pathogens the digestive tract SPERM CELL RED BLOOD CELL Has a long tail to enable it to Does not contain a swim towards the ovum in nucleus the Fallopian tube Shaped as a The head carries a set of biconcave disc chromosomes from the male Functions to optimise transportation of oxygen PHOTOGRAPH 2.4 Several types of human cells that undergo specialisation to carry out different functions 30 2.3.1 BioT4(NC)-B2-FA_EN New 6th.indd 30 1/9/2020 12:15:37 PM  SIEVE TUBE ELEMENT XYLEM VESSEL Long cylindrical tubes arranged Long, continuous hollow tube from end to end Functions in transporting CHAPTER 2 Transports organic materials from water and mineral salts ICT 2.2 leaves to storage organs from the roots to the Activity: Observe plant such as fruits other parts of the tissue and animal tissue plant slides through a light microscope PALISADE MESOPHYLL CELL Consists of long cylindrical cells, arranged vertically and close to Cross section each other of leaf Contains high chlorophyll density This arrangement allows maximum absorption of sunlight for photosynthesis SPONGY MESOPHYLL CELL Cells are loosely arranged with lots of air space in between Large air space allows exchange of gas from the inside of the leaves to the palisade mesophyll cells GUARD CELL Modified lower epidermal cells with the thicker cell wall on the inner side Controls the opening and closing of the stoma. Stoma is the opening that allows PHOTOGRAPH 2.5 Certain types of plant cells the exchange of oxygen and undergo specialisation to carry out different functions carbon dioxide ROOT HAIR CELL Has a long projection which adds surface area for the absorption of water and mineral salts 2.3.1 31 BioT4(NC)-B2-FA_EN New 6th.indd 31 1/9/2020 12:15:41 PM  Cell organisation in humans You have learned that multicellular organisms (such as humans) consist of different types of cells with specific functions. How are these cells arranged to form a complex organism? Tissues are a group of cells that have the same structure and function and are arranged together to carry out a specific function. In organisms, tissues can be classified into four different types which are epithelial tissue, muscle tissue, nerve tissue and connective tissue. Epithelial tissue Epithelial tissue covers the outer surface (skin) and hollow surfaces in the body (digestive tract and respiratory tract) (Figure 2.4). The epithelial tissue structure is adapted based on its function. For example, the epithelial tissue on the skin protects against infections, injuries, chemicals and dehydration. Epithelial tissues that coat the trachea have projections like hair, known as cilia (singular: cilium). Epithelial tissue covers the surface of the mouth and oesophagus Epithelial tissue covers the surface of lungs, body cavities and blood vessels Epithelial tissue covers the surface of the trachea and bronchus Epithelial tissue lines tubules, glands and kidney ducts Epithelial tissue covers the small intestine FIGURE 2.4 Types of epithelial and muscle tissues 32 2.3.1 2.3.2 BioT4(NC)-B2-FA_EN New 6th.indd 32 1/9/2020 12:15:42 PM  Muscle tissue There are three types of muscle tissue: smooth muscle (found in the digestive tract, blood vessel, urinary tract and reproductive tract), skeletal muscle (found in legs and hands) and cardiac muscle (found in the heart wall) (Figure 2.4). CHAPTER 2 Contraction and relaxation of smooth muscle enable involuntary activities such as peristalsis along the digestive tract. Skeletal muscle is involved in controlled movement. Skeletal muscles contract and relax to generate movement in bones and limbs. Cardiac muscle builds walls of the heart that contract to pump blood to the whole body. Cardiac muscle contraction is involuntary. Nerve tissue Nerve tissue is made of neuron or nerve cells (Photograph 2.6). Each neuron consists of a cell body and nerve fibre called dendrite and axon. Nerve tissues can detect stimuli and then send information in the form of an electrical signal (nerve impulses) to the muscles or glands. Nerve tissue regulates and controls body activity. PHOTOGRAPH 2.6 Nerve tissue 2.3.1 2.3.2 33 BioT4(NC)-B2-FA_EN New 6th.indd 33 1/9/2020 12:15:44 PM  Connective tissue The connective tissue consists of various types of tissues and fibres (Figure 2.5). This tissue is distributed all over the body and has many functions. One of its functions is to link the organs. ICT 2.3 Activity: Discuss the importance of cell specialisation in white BLOOD TISSUE multicellular animals and plants blood cell Blood plays a functional LOOSE CONNECTIVE role in regulation, TISSUE transportation and protection. It links the epithelial tissue to the tissue below it, and fixes the red blood organs in their positions. cell BONE Bone forms the body frame and protects the FIBROUS CONNECTIVE internal organs. TISSUE These tissues form tendons and ligaments. The tendon connects bones and muscles ADIPOSE TISSUE while the ligaments connect bones to bones. Connective tissues keep fat under the skin dermis and the surface of all main organs. CARTILAGE nucleus Cartilage encloses bone tips to prevent the bone from collagen fibres wearing out. FIGURE 2.5 Connective tissue 34 2.3.1 2.3.2 BioT4(NC)-B2-FA_EN New 6th.indd 34 1/9/2020 12:15:45 PM  Tissue organisation in plants Tissue organisation in plants is summarised in Figure 2.6. CHAPTER 2 PLANT TISSUE Meristem tissue Permanent tissue Apical Lateral Dermal Ground Vascular meristem meristem tissue tissue tissue tissue tissue Parenchyma tissue Xylem tissue Collenchyma tissue Phloem tissue Sclerenchyma tissue FIGURE 2.6 Tissue organisation in plants PHOTOGRAPH 2.7 PARENCHYMA TISSUE Meristem tissue at the tip of the root Functions to store starch, protein and water. This tissue can also carry out photosynthesis. COLLENCHYMA TISSUE Functions in giving support to young, non-woody stems (herbaceous plants). SCLERENCHYMA TISSUE Functions in providing support and mechanical strength to all mature parts of the plant. PHOTOGRAPH 2.8 Different types of ground tissues 35 2.3.1 2.3.2 BioT4(NC)-B2-FA_EN New 6th.indd 35 1/9/2020 12:15:46 PM  xylem vessel VASCULAR TISSUE Vascular tissues are made up of xylem tissue and phloem tissue. XYLEM TISSUE PHLOEM TISSUE The xylem functions in The phloem functions in transporting water and transporting organic matters mineral salts from the roots such as sucrose from the leaves to other parts of the plant. to all parts of the plant. Ligneous xylem tissue wall provides support and mechanical strength to the plants. sieve tube Density of certain cell components and specialised cell functions Since the functions performed by cells are different, some cells have a higher density of certain cell components. The density of a cell component in a particular cell is related to the specific function of the cell. Table 2.1 provides examples of cells that have a higher density of certain cell components. TABLE 2.1 Relationship between cell component density with specialised cell functions Cell component found in Types of cell Function abundance Sperm cell Requires a lot of energy to swim towards the uterus and Fallopian tube to fertilise the secondary oocytes Muscle cell such as flight Requires a lot of energy to muscle cells in insects and Mitochondrion contract and relax to enable birds movement and flight Plant meristem cell Requires a lot of energy to carry out active cell division process to produce new cells Palisade mesophyll cell Absorbs more sunlight to Chloroplast carry out the process of Spongy mesophyll cell photosynthesis Pancreatic cell Increases synthesis and secretion of digestive enzymes Goblet cell in intestinal Produces mucus epithelium and respiratory Rough endoplasmic reticulum tract Golgi apparatus Liver cell Metabolises carbohydrates Detoxification of drugs and poisons 36 2.3.3 BioT4(NC)-B2-FA_EN New 6th.indd 36 1/9/2020 12:15:46 PM  All cell components perform their respective functions to ensure that the cells function at the optimum level. The collaboration of all the components of the cells is similar to a factory with different parts and each with its specific function. What happens to the cell if there is a deficiency, absence or failure in any of the cell components such as lysosomes, mitochondrion, chloroplasts CHAPTER 2 or ribosomes? Failure of the mitochondrion function or a mitochondrion disjunction can cause stunted growth, weak muscles, hearing and vision problems. Tay-Sachs is a hereditary disease caused by the failure of enzymes to produce in the lysosomes. Tay-Sachs patients will experience stunted growth and mental retardation. Formative Practice 2.3 1 State the components of cells found in high 3 Explain why the palisade mesophyll cell density in cells that secrete protein products. contains a lot of chloroplast. 2 Briefly describe the structure and 4 Fat cells have three adaptive characteristics function of the nerve tissue. to allow the storage of fat. Describe the three characteristics. 2.4 Levels of Organisation in Multicellular Organisms A group of different tissues epith elia l tiss ue combine to form organs. Organs perform special functions as a result of the combination of tissues that form the organ. For example, the heart organ is composed cardia of epithelial tissue, cardiac c m u s c l e ti s s u e muscle tissue, connective heart tissue and nerve tissue. The epithelial tissue fills up space in the heart. Cardiac muscle tissue functions in pumping blood to the rest of the body. Connective tissues such as the blood, connect the systems in the organ. Nerve ne tissue regulates the rhythm rve e tiss ti s su ue ve of the heartbeat. nn ecti co PHOTOGRAPH 2.9 Tissues that form the heart organ 2.3.4 2.4.1 37 BioT4(NC)-B2-FA_EN New 6th.indd 37 1/9/2020 12:15:48 PM  Each multicellular organism is made up of many ENDOCRINE SYSTEM organs. Different organs work together to carry out a specific function to form an organ system. The endocrine gland that secretes There are 11 main organ systems in the human hormones body (Figure 2.7), which are the respiratory Main function system, digestive system, blood circulatory system, lymphatic system, nervous system, Coordinates body activities with the integumentary system, endocrine system, nervous system skeletal system, muscular system, urinary system and reproductive system. RESPIRATORY SYSTEM Trachea, nose, lungs and diaphragm Main function Exchange of oxygen and carbon dioxide gases between the body and external environment MUSCULAR SYSTEM Skeletal muscles, smooth muscles and cardiac muscles Main function Contracts and relaxes to produce movements in different parts of the body MALE REPRODUCTIVE SYSTEM Testes, prostate gland and penis Main function LYMPHATIC SYSTEM Produces sperm and male sex Spleen, lymph nodes and hormone lymph vessels Main function Maintains balance of bodily FEMALE REPRODUCTIVE SYSTEM fluids and prevents infectious diseases Ovary, uterus, Fallopian tube, vagina and cervix Main function Produces ovum and female sex hormones FIGURE 2.7 Main organ systems in the human body 38 2.4.1 2.4.2 2.4.3 BioT4(NC)-B2-FA_EN New 6th.indd 38 1/9/2020 12:15:51 PM  NERVOUS SYSTEM Cell All the organ systems are coordinated and Brain, spinal cord and peripheral nerves collaborated as one Tissue complete organism. Main function CHAPTER 2 Detects and sends information in the body, as The sequence of the well as coordinates body activities Organ organisation of cells in a multicellular organism is shown in System Figure 2.8. BLOOD CIRCULATORY SYSTEM Heart, artery, vein and blood capillary Multicellular Main function organism Transports nutrients, respiratory gases and waste products DIGESTIVE SYSTEM Mouth, oesophagus, stomach, liver, pancreas, small intestine and large intestine Cell Main function Digests food into a simpler form for easy absorption URINARY SYSTEM Tissue Kidney, ureter, urethra and bladder Main function Eliminates waste products such as urea and uric acid from the body SKELETAL SYSTEM Organ Bone, cartilage, ligament and tendon Main function Supports the body, protects the internal organs and provides a base for muscle adhesion System INTEGUMENTARY SYSTEM Skin Main function Protects the body from physical injury, FIGURE 2.8 The sequence infection and dehydration of the organisation of cells in human beings Multicellular organism 2.4.1 2.4.2 2.4.3 39 BioT4(NC)-B2-FA_EN New 6th.indd 39 1/9/2020 12:15:59 PM  The plant system is divided into the shoot leaf system and the root system (Figure 2.9). fruit The shoot system consists of stems, leaves, shoot shoots, flowers and fruits. flower system Stems and twigs are support systems that support the leaves at a vertical position to allow maximum absorption of sunlight during photosynthesis. stem Flowers are involved in the pollination process. root The root system consists of all roots in a root plant that function in absorbing water and system mineral salts as well as providing support for plants. FIGURE 2.9 Two main systems in plants Formative Practice 2.4 1 State arrangement of sequence in the 3 Stems, twigs and flowers are organs in organisation of cells in a multicellular a plant. Describe how stems, twigs and organism. flowers function in the shoot system. 2 The skin is the largest organ in the body. 4 Predict what will happen if the organisation Why is skin classified as an organ? level of cells does not exist in an organism. Summary CELL BIOLOGY AND ORGANISATION Cell Structure and Living Processes in Living Processes in Levels of Function Unicellular Organisms Multicellular Organisms Organisation Cell components Relationship Amoeba sp. and Cell Tissue Nucleus Mitochondrion between specific Paramecium sp. Organ Ribosome Centriole cell structure Movement System Golgi apparatus Chloroplast and cell function Response to Organism Cell membrane Cell wall stimuli Relationship Vacuole Cytoplasm Nutrition between cell Lysosome Respiration component Rough endoplasmic reticulum Growth density and cell Smooth endoplasmic reticulum Excretion function Reproduction Effect of the absence of cell components to the cell 40 2.4.2 2.4.3 BioT4(NC)-B2-FA_EN New 6th.indd 40 1/9/2020 12:16:00 PM  Self Reflection Have you mastered the following important concepts? CHAPTER 2 Structure and function of animal cells and plant cells Similarities and differences bet ween animal cells and plant cells Living process of unicellular organism Living process of multicellular organism Relationship bet ween cell component densit y in a cell and its specific function Effect of the absence or failure of the cell component function in multicellular organisms Sequence of levels of organisation in multicellular organisms Organ systems with its main functions in multicellular organisms Summative Practice 2 1 Why is chloroplast only found in plant cells and not in animal cells? 2 Explain the asexual reproduction of Amoeba sp. 3 An aphid is a small insect which sucks sap in plants. An aphid puts its mouth in the stem of a plant and sucks its nutrients. Name the liquid obtained from the plant and explain why aphids are mostly found in the daytime. 4 Figure 1 shows a plant cell. P P FIGURE 1 State the characteristics of P and its function. 41 BioT4(NC)-B2-FA_EN New 6th.indd 41 1/9/2020 12:16:01 PM  5 X is a digestive organ consisting of cells with a high concentration of rough endoplasmic reticulum for protein digestion. What is X? Explain your answer. 6 Plant cells undergo process X to form xylem vessels. Name process X. Explain how xylem vessels are specialised in transporting water and mineral salts. 7 Arif is a farmer. He uses a weed killer to control the weed population growth on his farm. Weed killers can stop the transportion of certain minerals in plants through the hair root tissue. Explain why. 8 Explain how an Amoeba sp. can survive in fresh water that is hypotonic to the cytoplasm of the organism. 9 Figure 2 shows one cell that can be seen through an electron microscope. (a) (i) Name structure K. (ii) State the function of structures K and N. (b) Explain how L mantains the turgidity of the cell. N 10 State the differences between the following: (a) meristematic tissue with plant epidermal tissue, L (b) cell and tissue, (c) epithelial tissue and muscle tissue. K 11 Figure 3 shows the structure of a leaf. FIGURE 2 R P S Q FIGURE 3 (a) Name the cells labelled P and R. (b) State the functions of cells P and R. (c) Explain the role of cell Q in increasing the rate of photosynthesis. (d) S contains two types of tissue. (i) Name the two tissues. 42 BioT4(NC)-B2-FA_EN New 6th.indd 42 1/9/2020 12:16:02 PM  (ii) Explain the adaptive features of tissues in S that help in the transportation of materials in plants. Essay Questions CHAPTER 2 12 Using an example of a unicellular organism, explain the five living processes of this organism. 13 Figure 4 shows a unicellular organism that lives in a fresh water pond. X FIGURE 4 (a) Explain the function of X in osmoregulation. (b) Predict what will happen if a cell does not have a Golgi apparatus. Explain your answer. (c) For each of the following cell, explain the relationship between structure and function. (i) (ii) cell P cell Q FIGURE 5 Enrichment 14 Many cancers start with the epithelial tissue. This includes lung cancer, colon cancer and skin cancer. What are the two characteristics of this tissue that can cause cancer? 15 The damage to the cartilage disc between the vertebrae of the spine is difficult to repair by their own cells. What is the latest technology that can be used to develop new cartilage tissues? Complete answers are available by scanning the QR code provided 43 BioT4(NC)-B2-FA_EN New 6th.indd 43 1/9/2020 12:16:06 PM