O Level Biology Notes (Zafar Sulehri)

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/ IGCSE

Biology Notes Subject Code:5090 Article No. 206 2018–19 Edition

Zafar Sulehri SICAS, LGS, BSS, The City School


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O Level Biology Notes

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Zafar Sulehri Cell: +92 321 8800091

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Contents Unit-1 1.1 1.2

Cell Structure and Organization ......................................................................................... 8 Plant and animal cells: ........................................................................................................... 8 Specialized cells, tissues and organs: ................................................................................. 11

Unit-2 2.1 2.2 2.3

Diffusion and Osmosis ...................................................................................................... 16 Diffusion: .............................................................................................................................. 16 Osmosis: .............................................................................................................................. 16 Active transport: ................................................................................................................... 18

Unit 3 3.1 3.2

Enzyme ................................................................................................................................ 20 Enzyme action: .................................................................................................................... 20 Factors affecting the rate of an enzyme action: ................................................................... 20

Unit-4 4.1 4.2 4.3

Plant Nutrition..................................................................................................................... 24 Photosynthesis:.................................................................................................................... 24 Structure of dicot leaf: .......................................................................................................... 27 Mineral nutrition: .................................................................................................................. 28

Unit-5 5.1 5.2 5.3 5.4 5.5 5.6

Animal Nutrition ................................................................................................................. 30 Nutrients: .............................................................................................................................. 30 Diet: ...................................................................................................................................... 30 World food supplies: ............................................................................................................ 40 Digestion in humans: ........................................................................................................... 40 Chemical digestion:.............................................................................................................. 44 Absorption and assimilation: ................................................................................................ 45

Unit-6 6.1

Transport in Flowering Plants .......................................................................................... 48 Water and ion uptake: .......................................................................................................... 50

Unit-7 7.1

Transport in Humans ......................................................................................................... 54 Blood circulatory system: ..................................................................................................... 54

Unit 8 8.1 8.2 8.3

Respiration.......................................................................................................................... 62 Aerobic respiration: .............................................................................................................. 62 Anaerobic respiration: .......................................................................................................... 62 Human gas exchange .......................................................................................................... 64

Unit-9 9.1 9.2

Excretion ............................................................................................................................. 70 Structure and function of kidneys ........................................................................................ 70 Kidney dialysis: .................................................................................................................... 71

Unit-10 Homeostasis ....................................................................................................................... 76 10.1 Structure and function of the skin: ....................................................................................... 76 Unit-11 11.1 11.2 11.3 11.4

Coordination and Response ............................................................................................. 80 Nervous system: .................................................................................................................. 80 Different stimuli and receptors: ............................................................................................ 80 Reflex action: ....................................................................................................................... 82 Harmone: ............................................................................................................................. 87

Unit-12 12.1 12.2 12.3

Support, Movement and Locomotion .............................................................................. 90 Bones: .................................................................................................................................. 91 Joint: .................................................................................................................................... 92 Antagonistic muscles: .......................................................................................................... 93

UNIT-13 13.1 13.2 13.3 13.4

The Use and Abuse of Drugs ............................................................................................ 96 Antibiotics: ............................................................................................................................ 96 Heroin: ................................................................................................................................. 97 Effects of alcohol:................................................................................................................. 97 Effects of tobacco smoke: .................................................................................................... 98


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Unit-14 14.1 14.2 14.3

Microorganisms and Biotechnology .............................................................................. 102 Microorganisms:................................................................................................................. 102 Food biotechnology: .......................................................................................................... 105 Industrial biotechnology: .................................................................................................... 106

Unit-15 15.1 15.2 15.3 15.4 15.5 15.7 15.8

Relationships of Organisms with One Another and with the Environment ............... 110 Energy flow: ....................................................................................................................... 110 Food chain and food webs: ................................................................................................ 112 Carbon cycle: ..................................................................................................................... 112 Nitrogen cycle: ................................................................................................................... 112 Parasitism: ......................................................................................................................... 114 Pollution: ............................................................................................................................ 115 Conservation: ..................................................................................................................... 117

Unit-16 16.1 16.2 16.3 16.4

Development of Organisms and Continuity of Life ...................................................... 120 Asexual reproduction: ........................................................................................................ 120 Sexual reproduction in plants: ........................................................................................... 123 Sexual reproduction in human: .......................................................................................... 126 Sexually transmitted diseases: .......................................................................................... 129

Unit-17 17.1 17.2 17.3 17.4 17.5

Inheritance ........................................................................................................................ 132 Variation: ............................................................................................................................ 132 Chromosomes and dna: .................................................................................................... 133 Monohybrid inheritance: .................................................................................................... 133 selection ............................................................................................................................. 136 Genetic engineering: .......................................................................................................... 137


Unit-1

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Cell Structure and Organization

Syllabus 2016 – 18

Cell Structure and Organization

1.1 Plant and animal cells  Preparation of a Microscopic Slide  Viewing under a light Microscop  Recording observation  Structure of Light microscope  Different types of cells observed under an ordinary Microscope  Animal cells:  Difference between Animals and Plant cells  Similarity between Animal and Plant cells  Components of Cell 1.2 Specialised cells, tissues and organs  R.B.C  Lymphocytes  Phagocytes  Root hairs  Xylem vessels

O Level Biology Zafar Sulehri Cell: 0321-8800091


Unit-1

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UNIT-1 1.1

Cell Structure and Organization

CELL STRUCTURE AND ORGANIZATION

PLANT AND ANIMAL CELLS:

It is a basic unit of structure and function of all living things (Except Viruses). New cells come from division of old cells.

Preparation of a Microscopic Slide: Preparation of an onion epidermal slide:      

Cut a piece of onion with the help of a razor. Remove the epidermis with the help of forceps. Place the epidermis in the canter of a slide. Pour few drops of Dye / Stain on it. Place a cover glass on the mounted material in such a way that the cover glass is held on the pointed tip of a needle and gradually lower it down. So the air bubbles are not trapped. Remove the extra stain using blotting paper.

Viewing under a light Microscope:    

Place the slide on the stage. Turn on the lamp. Adjust the power of the objective Looking through the eye piece focus the image by moving adjustment knobs.

Recording observation:  

Take a photomicrograph. Draw the outline of the image seen.

Structure of Light microscope:

Label different parts


Unit-1

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Cell Structure and Organization

Different types of cells observed under an ordinary Microscope: Onion Epidermis:

Animal cells: Cheek cell:

Nerve Cells:


Unit-1

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Cell Structure and Organization

Mesophyll cell:

Difference between Animals and Plant cells:      

Cell wall is absent in animal cell whereas plant cells have cell wall. Sap vacuole is absent in animal cell whereas sap vacuole is present in plant cell. Chloroplast is absent in an animal cell where as it is present in a plant cell. Nucleus is present in the centre in an animal cell where as it is in plant cells slightly on its side. Size of plant cell is big whereas the size of cell is small in animals. Starch is reserve food in a plant cell whereas glycogen in an animal cell.

Similarity between Animal and Plant cells:   

They both contain cell membrane. They both have cytoplasm. They both have nucleus in them.

Components of Cell: Cell wall: It is found in plant cells. It is composed of cellulose (A carbohydrate). It is rigid dead layer. It is fully permeable layer which protects a plant cell from bursting and maintains its shape.

Cell Membrane: It is a partially permeable membrane. Outer most boundary in animal cells. It is beneath the cell wall in a plant cell. Prevents mixing up of the contents of various cells together. Controls the inward and outward movement of substances.

Cytoplasm: It is a jelly like substance which covers the space between cell membrane and the nuclear membrane. It is a site for chemical reactions e.g. Respiration.

Nucleus: It is densely stain region in the center of an animal cell and slightly away from the center in a plant cell. It consists of a nuclear membrane which is partially permeable. It also contains chromosomes. Chromosomes carry the hereditary materials. Nucleus controls the division of cells.


Unit-1

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Cell Structure and Organization

Chloroplast: It is found in mesophyll and guard cells in a plant cell. It is double membrane bound cell organelle. Non Living components in the cytoplasm are called inclusions e.g. Starch. Living components in the cytoplasm are called organelles. Chloroplast contains green pigment called chlorophyll embedded in it. Chlorophyll traps the light energy and converted into chemical energy. This chemical energy is used in formation of carbohydrates from CO2& H2O by photosynthesis

Magnification: The following figure is a photomicrograph of a white blood cell.

X 900 Fig.1.1 Draw and label the white blood cell shown in figure 1.1 Measure the Width of the cell in the figure Measure the Width of the cell in the diagram Magnification Magnification

1.2

= = = =

__________________mm __________________mm X_____________________

SPECIALIZED CELLS, TISSUES AND ORGANS:

Cells that have specific shape and perform some specific function are called specialized cells.

R.B.C: Structural features:  They are tiny.  They are flat.  They are biconcave.  They lack nucleus.  They contain hemoglobin.


Unit-1

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Cell Structure and Organization

Adaptation of structure to function: The advantage of being tiny is that it has large surface so more efficient exchange of oxygen. Being flat they have more surface area and exchange of gases is easy. Being flat they can pass through narrow capillaries. Lack of nucleus provides more room for hemoglobin. Hemoglobin combines reversibly with oxygen to form oxy-hemoglobin.

Lymphocytes: Structural features  Spherical cell.  Large central nucleus.  To release anti bodies (proteins) to fight against pathogens.

Adaptation of structure to function: The antibodies are specific in their function. They are produced in wide range against variety of pathogens. Many copies of genes are needed for the formation of wide range of antibodies. The lymphocytes have large nucleus to contain many copies of genes.

Phagocytes:


Unit-1

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Cell Structure and Organization

Structural features:  Irregular shape.  Lobed nucleus.

Adaptation of structure to function: Phagocytes can squeeze out of the blood capillaries through narrow pores.

Root hairs:

Structural features:  Elongated.  Contain cell membrane.  Cell wall present.  Cytoplasm present.

Adaptation of structure to function: Being elongated increases surface area to volume ratio for absorption of water and mineral ions. Cell membrane controls the movement of substances into and out of cell. It maintains concentration gradient between inside and outside. As water moves into the cells it exerts hydrostatic pressure on the cell. Cell wall prevents cell from bursting. Respiration in cell cytoplasm releases energy from sugars which is used for active uptake of mineral ions.

Xylem vessels:

Surface View

Cross Sectional View


Unit-1

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Cell Structure and Organization

Structural features:  Cylindrical cells.  Hollow.  No cross walls.  Lack cytoplasm and lack nucleus.  Lignified cell walls.

Adaptation of structure to function: Being cylindrical they are joined end to end to extend from roots to leaves. Lack of nucleus and cytoplasm reduces resistance offered to flow of water and minerals. Lignified walls provide strength which provides mechanical support to the plant.


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