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Biology

Made Easy

VirtualNotesFORM 4



2

CHAPTER 1 Introduction to BiologyF

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4 Objective State the aim of the experiment.Problem Pose questions about the observations made.statement

Hypothesis Formulate a possible explanation or predictionbased on the observations.

Variables Identify and control the manipulated, respondingand constant variables.

Materials List the materials and apparatus which will beand used during the experiment.apparatus

Technique State the technique involved in obtainingthe results.

Procedure • Write the instructions to carry out the experiment. • The procedures should be written using reported

speech. For example, ‘Examine the slide under themicroscope’ should be written as ‘The slide is

examined under the microscope’. • Diagrams can be drawn to show the set-up of the experiment. They should be simple and two-

dimensional. The apparatus should be drawn witha clear outline and labelled accordingly.

Results Present the results in the form of simple diagrams,charts, graphs or tables. Include calculations wherenecessary.

Discussion Discuss, analyse and interpret the data obtained, then determine the relationship between the manipulated variable and responding variable.

Conclusion Draw a conclusion based on the hypothesis given earlier.

© Oxford Fajar Sdn. Bhd. (008974-T) 2014



Human cells and the adaptations to their functions

CHAPTER 2 Cell Structure and Cell Organisation

3

Red blood cellsShaped like biconcave discs and arevery flexible, allowing them to move

easily along the narrowest bloodvessels.

White blood cellsCan change their shape to migrateto the sites of injuries to fight

infections.

Nerve cellsHave long, thin fibres called axonsto conduct nerve impulses.

Sperm cells• The tail allows the sperm to swim

towards the ovum.• The head contains one set of

chromosomes from the maleorganism.




Cellular components of a plant cell

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4

Nucleus • Controls all cellular activities.• Contains DNA which determines

the characteristics of a cell.

outer membrane

inner

membrane

nucleoplasm

nucleolus

nuclear

membrane

pore in nuclearmembrane

mitochondrion

plasma membrane

chloroplast

cell wall ofadjacent cell

Golgiapparatus

nucleus

vacuole

lysosome

smooth ER

ribosome

rough ER

1

2

3

4

5

1




vesicles

nuclear envelopenucleus

roughendoplasmicreticulum

ribosomes

smoothendoplasmicreticulum

•

Ribosomes − sites of protein synthesis

• Rough endoplasmic reticulum (RER) − transports proteins made by ribosomesthroughout the cell

• Smooth endoplasmic reticulum (SER) − synthesises lipids and carriesout detoxification of drugs and metabolic

by-products

Mitochondrionsite of cellularrespiration

Golgi apparatusProcesses,packages and actsas a transportcentre ofcarbohydrates,

proteins andglycoproteins.

ChloroplastCaptures the energyof sunlight and convertslight energy intochemical energy during

photosynthesis.

outer membrane

inner membrane

stroma

granum

thylakoid

matrix

cristae

inner membrane

outer membrane

2

3

4

5




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4 Human tissues

Epithelial tissues at thesurface of the skin

Epithelial tissues at thelining of glands, ductsand kidney tubules

Epithelial cells whichline the alveoli and bloodcapillaries

Skeletal muscles

Cardiac muscles

Smooth muscles

Nerve tissues

Connective tissues

Form a protective barrier against infectionsand mechanical injuries.

Secrete substances.Example: Sweat glands in the skin secretesweat.

Thin, flat and arranged in a single layer toallow for easy diffusion of respiratory gases.

Contract and relax to produce movements ofbody parts.

Contract to pump blood from the heart.

Contract and relax to produce involuntarymovements.

Generate and transmit nerve impulses overlong distances.

Bind and support other tissues.Bone tissue – provides protection to internalorgans and supports the body.Tendon – attaches muscles to bones.Blood tissue – transports nutrients andrespiratory gases, fights infections and helps

in blood clotting.

Tissues Functions




Plant tissues

Tissues

Epidermal tissues

Ground tissues:

(a) Parenchymatissue

(b) Collenchyma

tissue

(c) Sclerenchyma

tissue

Meristematic

tissues

Vascular tissues:

(a) Xylem tissue

(b) Phloem tissue

Protect plants from mechanical injuries.

Stores products of photosynthesis suchas sugar.

Provides support in herbaceous plants.

Supports and strengthens plants.

Divide through mitosis to increase the

number of cells.

• Conducts water and minerals from the

roots to the shoots.

• Provides support and mechanical

strength to the plants.

Transports organic substances from the

leaves to other parts of the plant.

Functions




8

CHAPTER 3Movement of Substances across the

Plasma Membrane

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4

phospholipid hydrophilichead

hydrophobic

tails

hydrophilic

head

Structure of the membrane

carbohydrate

cholesterol porephospholipid

carrier protein

pore protein

Structure of the plasma

membrane according to

the fluid mosaic model:

The components of the

plasma membrane are not

rigid but form a dynamic and

fluid structure. The proteins

form a mosaic pattern.

Proteins and phospholipids

can move sideways within

the membrane.




CHAPTER 3Movement of Substances across the

Plasma Membrane

9

Effects of hypotonic, isotonic and hypertonic solutions on animal cells

Effects of hypotonic

solutions on animal

cells (red blood

cells)

The solution outside

the cell is less

concentrated than the

inside of the cell.

Water diffuses into the

cell by osmosis.

The cell starts to swell

and eventually burst.

This condition is known

as haemolysis.

Effects of isotonic

solutions on animal

cells (red blood

cells)


the cell has the same

concentration as the

cytoplasm fluid within

the cell.

Water diffuses into

and out of the cell at

equal rates.

The cell maintains its

normal shape.

Effects of hypertonic

solutions on animal

cells (red blood

cells)


the cell is more


inside of the cell.

Water diffuses out of

the cell by osmosis.

The cell shrinks and

the plasma membrane

crinkles up.

The red blood cells are

said to have crenated

(crenation).




10

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4Effects of hypotonic, isotonic and hypertonic solutions on plant cells

Effects of hypotonic

solutions on plant

cells

The solution outsidethe cell is less


inside of the cell.

Water diffuses into

the large central

vacuole by osmosis.

The large central

vacuole expands andswells up. The

plasma membrane

presses hard against

the cell wall.

The cell is said to beturgid.

Effects of isotonic

solutions on plant

cells

The solution outsidethe cell has the

same concentration

as the cytoplasm

fluid within the cell.

Water diffuses into

and out of the cell at

equal rates.

The cell maintains

its normal shape.

Effects of hypertonic

solutions on plant

cells

The solution outsidethe cell is more


inside of the cell.

Water diffuses out of

the cell by osmosis.

The vacuole and

cytoplasm shrink andthe plasma membrane

pulls away from the cell

wall.

The plant cell becomes

flaccid and undergoesplasmolysis.




CHAPTER 4 Chemical Composition of the CellCHAPTER 4 Chemical Composition of the Cell

11

Medium ofbiochemical

reactions

Transportmedium

Maintains

bodytemperature

Providesmoisture

Providessupport

Lubrication

Maintainsosmoticbalance

Importanceof

water




CHAPTER 4 Chemical Composition of the Cell

12

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4

DNA consists of

two strands ofpolynucleotidestwisted aroundeach other toform a doublehelix.

Glucose + glucose maltose + water

Glucose + fructose sucrose + water

Glucose + galactose lactose + water

condensation

hydrolysis

condensation

hydrolysis

condensation

hydrolysis

Carbohydrates

GlucoseFructose

Galactose

Monosaccharides

MaltoseSucroseLactose

Disaccharides

StarchGlycogenCellulose

Polysaccharides

Nucleic acids

deoxyribonucleic acid (DNA)




13

Secondary structure Quarternary structure

Tertiary structureply

leu

val

lys

val

lya

gly

his

ala

lys

lys

pro

glylau

val

lys

lys

gly

hisala

lysval

lys

pro

Primary structure

Structure of a nucleotide

Protein structure

nitrogenous base

phosphate group

pentose sugar


F



14

F

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4 The production of extracellular enzymes

1 The nucleus contains DNA which carries the information for the synthesis of

enzymes.

2 Proteins are synthesised at the ribosomes.

3 The synthesised proteins travel through the rough ER.

4 The protein departs from the rough ER in vesicles that bud off from the membranes

of the rough ER.

5 These transport vesicles fuse with the Golgi apparatus.

6 The proteins are then modified in the Golgi apparatus.

7 Secretory vesicles containing these proteins bud off from the Golgi apparatus

and fuse with the plasma membrane before releasing the proteins as enzymes

outside the cells.

1

2

3

456

plasma membrane

protein secreted outsidethe cell as enzymes

secretory vesicle

transport vesicle

rough endoplasmicreticulum

nucleus

Golgi apparatus

DNA

7




15

Amylase and amyglucoxidase convert starch to sugar in the

making of syrup.

Trypsin removes hair from animal hides.

Zymase converts sugar into ethanol.

Amylase removes starch stains on clothes.

Lipase ripens cheese.

Rennin solidifies milk proteins.

The uses of enzymes in daily life and industry

Cellulase breaks down cellulose and removes seed coats from

cereal grains. It also extracts agar from seaweed.

Protease tenderises meat and removes the skin of fish.




CHAPTER 4 Chemical Composition of the Cell

16

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4

CHAPTER 5 Cell Division

Early prophase• Centrioles migrate.• Chromosomes condense.• Nucleolus disappears.• Nuclear membrane disintegrates.

Late prophase• Spindle fibres form.•

Spindle fibres attach tochromosomes.

MetaphaseChromosomes line upat the equatorial plane(metaphase plate).

centrioles

chromosome

spindlefibres

chromosome

metaphase plate





17

daughter cells

cleavage furrow

centromere

Anaphase• Centromeres divide.

• Sister chromatids move towardopposite poles.

Telophase• Spindle fibres disappear.• Chromosomes uncoil.• Nuclear membrane and

nucleolus re-appear.

CytokinesisCleavage furrow dividesthe cell into two identicaldaughter cells.





18

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4

Prophase I• Nuclear membrane disintegrates.• Synapsis (pairing of homologous

chromosomes) and crossing

over occur.• Spindle fibres form.

Metaphase I• Homologous chromosomes line up on the metaphase plate.• Each homologous chromosome

is attached to the fibres from one pole.

Prophase II• Nuclear membrane disintegrates.• Spindle fibres form.

Metaphase II• Spindle fibres attach to both sides of the centromere.• Chromosomes line up on the metaphase plate.

Meiosis I

Meiosis II





19

Anaphase I• Homologous chromosomes are pulled apart.• Centromeres do not divide.• Sister chromatids stay joined.

Telophase I• Chromosomes uncoil (partially).• Nuclear membrane forms.• Cytokinesis occurs.

Anaphase IICentromeres separateand chromatids (daughterchromosomes) are drawntowards opposite poles.

Telophase II• Nuclear membrane forms.• Cytokinesis occurs.• Four haploid cells are formed

from one diploid parent cell.


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20

CHAPTER 6 NutritionF

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4The human digestive system

Teeth Cut, tear and grind food.

Salivary glands Secrete salivary amylaseto break down starch.

Oesophagus A tube connectingthe mouth to thestomach.

Tongue Helps swallow food.

EpiglottisPrevents food fromentering trachea.

Pancreas Secretes pancreatic

amylase, trypsinand lipase.

Small intestineDigested foodsubstances absorbed

into blood.

AnusFaeces egested.

StomachGastric glands secretepepsin which hydrolyses

proteins and renninwhich coagulates milk.Liver• Removes toxins from blood.• Regulates food substances.

• Converts excessamino acids

to urea.• Produces bile.

Gall bladder•

Stores bile.• Bile neutralises stomach acid.

Large intestine Excess water

reabsorbedinto blood.

RectumStores faeces.




CHAPTER 6 Nutrition

21

The villi:• are numerous in number to increase the surface area for

absorption• have thin walls for easy absorption of digested food• have a network of blood capillaries for the efficient

transport of digested food• have lacteals for the absorption of fatty acids and glycerol

Adaptation of the small intestine for absorption

epithelial cells (absorbglucose, amino acids,

fatty acids and glycerol)

fatty acid

glycerol

lacteal(absorbs

fatty acidsandglycerol)

to blood

circulatorysystem

to liver

bloodcapillaries(absorbglucose andaminoacids)

blood capillaries

lymphatic

vessel


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CHAPTER 6 Nutrition

22

F

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4Absorption and assimilation of nutrients

End products Absorbed through Assimilation

Glucose

Amino acids

Fatty acids,

glycerol,

vitamins A, D,

E, K

Blood capillaries by

facilitated diffusion

and transported tothe liver via the

hepatic portal vein.

Lacteals by diffusion

and transported in

the lymphatic system

and finally in the

bloodstream.

• Substrate for cellular

respiration.

• Excess glucose is convertedinto glycogen and stored in the

liver.

• In the cell, glucose is oxidised

during cellular respiration.

• Used in the synthesis of

plasma proteins.

• Excess amino acids are

deaminated, and urea is

excreted.

•In the cell, amino acids areneeded to synthesise

enzymes and hormones.

• Major components of the

plasma membrane

(phospholipids).

• Excess fats are stored in

adipose tissue as reserve

energy.




23

The adaptation of leaf cells for photosynthesis

Cross section of a leaf

• Xylem transports mineral ions and water to the leaf.• Phloem transports products of photosynthesis away from the

leaf.

• Have large air spaces between the cells for easy

diffusion of waterand carbon dioxide

to the palisade cells.• Contain

chloroplasts which carry out photosynthesis.

• Packed tightly together in an upright arrangement to receive maximum sunlight.• Have a high density of

chloroplasts to carry out photosynthesis.

Thin and transparent to allowlight to penetrate the leaf and

reach the chloroplasts

cuticle

upperepidermis

palisade mesophyll

spongymesophyll

stomaxylem

phloem

collenchyma

bundle sheath

lowerepidermis


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The mechanism of photosynthesis

1 2

4 3

• During the light reaction,

chlorophyll captures light

energy which excites the

electrons. The electrons

leave the chlorophyll

molecules.

• Light energy splits water

molecules (photolysis of

water) into hydrogen ions

and hydroxyl ions.

• Hydrogen ions combine

with electrons released

by the chlorophyll molecules

to form hydrogen atoms.

• ATP molecules are also

formed.

•Each hydroxyl ion loses an

electron to form a hydroxyl

group.

• The electron is received by

a chlorophyll molecule.

• The hydroxyl groups

combine to form water and

oxygen.

•In the dark reaction,hydrogen atoms are used

to fix carbon dioxide in a

series of reactions catalysed

by photosynthetic enzymes.

• CH2O is formed.

• 6 units of CH2O combine to

form one molecule of

glucose.

Word equation for photosynthesis:

6CO2 + 6H2O C6H12O6 + 6O2

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CHAPTER 7 Respiration

25

Aerobic and anaerobic respiration

Aerobic respiration

• Complete oxidation ofglucose in the presence

of oxygen to form

carbon dioxide, waterand energy.

• 38 molecules of ATP are

produced.• 2898 kJ of energy is

released.• Takes place in the

mitochondria.

• In all organisms:

Anaerobic respiration

• Incomplete oxidation ofglucose in the absence of

oxygen to form lactic acid and

energy (in muscle cells) orethanol, carbon dioxide and

energy (in yeast).

• 2 molecules of ATP areproduced.

• 210 kJ of energy is releasedduring fermentation by yeast

and 150 kJ of energy is

released during anaerobicrespiration in the muscle cells.

• Takes place in the cytoplasm.• In muscle cells:

• In yeast:

C6H12O6glucose

6O2oxygen

+

+6CO2

carbon

dioxide

6H2O

water

2898 kJenergy

C6H12O6

glucose

2C3H6O3

lactic acid

+ 150 kJ energy

C6H12O6

glucose

2C2H5OH

ethanol

+ 210 kJ

energy

2CO2

carbon

dioxide

+


F



CHAPTER 6 Nutrition

26

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4Respiratory structure of fish Respiratory structure of frogs

Respiratory structure of insects

Characteristics of therespiratory structures

• Numerous folded linings increase surface area

to volume ratio for an efficient gaseous exchange.• The linings are thin,

one-cell thick to allow a higher rate of gaseous exchange.• The surfaces for the gaseous exchange

are constantly moist for easy diffusion of

respiratory gases.

gill arch

filaments

mouth

opercularchamber

gills

lamellae

spiracle

trachea

muscle

tracheole

air sac

spiracles

lamella blood flowflow of water

water flows in the oppositedirection to the blood flow

heart

lungs

bloodvessels




27

Respiratory structure of humans

•

Oxygen diffuses from the alveolus to the blood capillaries.• Carbon dioxide diffuses from the blood capillaries to the alveolus.

pulmonary venule

(O2 rich)

pulmonary arteriole(O

2 poor)

bloodcapillariescovering

alveoli

bronchiole

alveolarspace

alveolus

deoxygenated bloodoxygenated blood

air

CO2

CO2CO

2

O2

O2

O2


CHAPTER 7 R i i

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CHAPTER 7 Respiration

28

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4

H+Hb

Hb

Hb

(carbonic acid)

carbonicanhydrase

carbonicanhydrase

CO2

CO2

H2O

H2O

H2CO3

H2CO3

CO2

H+

Carbon dioxide released by respiring cells is transported as• dissolved carbon dioxide (CO2) in the blood plasma (7%)• carbaminohaemoglobin (23%)• bicarbonate ions (70%)

Transport of carbon dioxide from body cells to lungs

Hb : Haemoglobin

Lung

Tissue

Blood plasma

Excreted

H+Hb

Hb

Hb

(carbonic acid) (bicarbonate ion)

(carbaminohaemoglobin)

carbonic

red blood cell

anhydrase

carbonicanhydrase

CO2

CO2

CO2

CO2

H2O

H2O

H2CO3

H2CO3

CO2

HbCO2

HCO3–

HCO3– HCO3

–

H+


CHAPTER 8 Dynamic Ecosystem




29

When secondary consumers eat primary

consumers, 10% of the primary consumers’

energy is transferred to the secondary

consumers.

The carnivores also lose energy through

respiration, defaecation and excretion.The secondary consumers are then eaten by

tertiary consumers and subsequently the

quarternary consumers feed on the tertiary

consumers.

This is how energy flows from one trophic

level to the next.

Energy flow within a food chain

Quarternaryconsumer

Tertiaryconsumer

Secondaryconsumer

Primaryconsumer

Producer

8

9

10

11

When primary consumers eat the producers,

10% of the energy stored in the producer is

transferred to the primary consumers.

90% of the energy is lost to the environment.

Primary consumers use this energy forgrowth and movement, and to maintain body

temperature.

When consumers excrete and defaecate,

energy is made available to the decomposers.

4

5

6

7

The producer absorbs solar energy andconverts it into chemical energy during

photosynthesis.

Some of the energy is used by the producer

for cellular growth.

When the producer dies, this energy is made

available to other organisms by decomposers.

1

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4 Colonisation and succession in a pond

submerged plants

submergedplants

emergent plants

(sedges)

floating

plants

floating plants

organic matter

sedges

herbaceous plants

primary forest

sedges cattails

cattails

Succession begins with the growth of

submerged plants like Hydrilla sp. and

Elodea sp.

• When submerged plants die and

decompose, their organic matter is

converted into humus at the pond base.

• The shallower condition becomes

more suitable for the growth of

floating plants such as Lemna sp.

and Eichornia sp.

• The addition of more organic matter tothe pond base causes the pond to

become shallower.

• The floating plants are replaced by

emergent (amphibious) plants such

as sedges and cattails.

• When emergent plants die, their

decomposed remains add to the

sediments at the base of the pond.

• The shallow condition of the pond

favours the growth of herbaceousplants.

• As time passes, the land becomes

drier and favours the growth of

land plants such as shrubs and bushes.

• A primary forest emerges and eventually

turns into a tropical rainforest which is

known as a climax community.


CHAPTER 9 Endangered Ecosystem



CHAPTER 9 Endangered Ecosystem

31

The process of eutrophication

The effects of global warming

• Melting of polar ice caps and glaciers causes sea levels to rise and subsequently floods

in low-lying areas.

• Droughts occur in more areas and this leads to a drop in crop yields.

• Changes the wind direction and distribution of rainfall. Affects agricultural activities.

• Spread of disease-carrying vectors such as the vector for dengue fever.

The effects of ozone depletion

• Prolonged exposure to ultraviolet (UV) radiation leads to higher risks of skin cancer,

cataracts and sunburns.

• UV light weakens the immune system.

• UV light reduces nutrient contents in soil and this decreases crop yields.

• UV light damages chlorophyll and reduces photosynthesis in plants.

• UV light kills phytoplankton which affects marine food chains.

• Ozone depletion leads to an increase in Earth’s temperature.

Eutrophication is the artificial nutrient enrichment of an aquatic system with organic matter

or inorganic nutrients which cause the excessive growth of aquatic plant life.

1 Excess nutrients cause the rapid growth of algae (algal bloom) in a lake.

2 Algae consume a lot of oxygen and block sunlight penetration.

3 Photosynthesis decreases further the oxygen level in the lake.

4 Algae die without being consumed because they grow faster than their consumers.

5 Photosynthetic organisms die and organic matter accumulates at the bottom of the

lake.

6 Dead organic matter is a food source for microorganisms such as aerobic bacteria.

7 Aerobic bacteria use up and deplete the oxygen content in the water.

8 Aquatic organisms compete for oxygen. This results in a high biochemical oxygen

demand (BOD).

9 Low concentration of oxygen kills fish.



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32

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S U N

A T M O S P H E R E

E A R T H

Some of the infraredradiation passes through

the atmosphere and islost in space.

Some solar radiationis reflected by the

atmosphereand Earth's surface.

G R E E N H O U S E G A S E S

Solar radia tion pass es

t hroug h t h e cl ear a tmosp h er e.

Some of the inf r ar ed r adiation is absor bed and r e-emittedby the gr eenhouse gas molecules. T he dir ect ef f ect isthe w ar ming of the Ear th's sur f ace and the tr opospher e.

Surface gains more heat and infraredradiation is emitted again.

Solar energy is absorbed by theEarth's surface and warms it...

...and is converted into heat causingthe emission of the infrared

radiation back to the atmosphere

1

2 5

6

3

4

© Oxford Fajar Sdn. Bhd. (008974-T) 2014First published 2015

ISBN 978 983 47 1339 3

All rights reserved.No part of this publication may be reproduced,

stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying,recording or otherwise, without the prior permission ofOxford Fajar Sdn. Bhd. (008974-T)

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