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1. C 2 ➜ CELL STRUCRURE AND CELL ORGANISATION Cell Wall Provides mechanical strength and supports
a) Identify the cellular components of animal cell and plant cell :- ▪ Rigid and tough cellulose layer the cell
Plasma membrane  Separates the cell from the surrounding surrounding the plasma membrane Maintains the shape of cell.
▪ Thin, flexible layer surround the environment ▪ Composed of cellulose ( a tough and Prevents the cell from busting due to
cytoplasm of a cell  Acts as selective barrier for the import and fibrous carbohydrate) excessive intake of water.
▪ Semi permeable/Selectively permeable export of materials ▪ Permeable to all fluids because it has
▪ Consists of phospholipids and proteins  Regulates the movement of substances tiny pores that allow substances to move
▪ Protective and selective outer barrier entering and leaving the cell freely through the cell wall.
 Allows the exchange of nutrients, respiratory Vacuoles  Isolates/ Separates materials that might be
gases and waste product between the cell ▪ Fluid-filled sacs enclosed by harmful to the cell.
and its environment. semi-permeable membrane = tonoplast  Maintains internal hydrostatic pressure.
Cytoplasm  Provides cell organelles with substances ▪ Fluid is called cell sap  Exports unwanted substances from the cell
▪ Rest of the material of the cell within the obtained from the external environment. ▪ Formed through the fusion of multiple  Stores chemicals such as organic acids,
plasma membrane  Acts as a medium where biochemical membrane vesicles sugars, amino acids, mineral salts, oxygen,
▪ Consists of a fluid portion called the reactions and living processes occur within <<< Tonoplast: The cytoplasmic carbon dioxide, waste materials, pigments
cytosol ( cytosol mainly composed of cell. membrane surrounding the vacuole, and metabolic by-products.
water with free-floating molecules )  Provides support, shape and protects the cell separating the vacuolar contents from the <<< By-product: a product of a chemical reaction
▪ Jelly-like medium in which the organelles. cytoplasm in a cell. or industrial process which is different from the
organelles are suspended  Stores water, enzymes, nutrient, salts and desired product.
▪ Contains cytoskeleton fibers// organic dissolved gases. Chloroplasts  The thylakoids and grana (singular = granum)
and inorganic substances ▪ Contains chlorophyll, provide the green where photosynthesis takes place.
Nucleus  Maintains the integrity of DNA. pigment  Membranes inside the stroma are organized
▪ Core or the central part of cell Controls cellular activities (metabolism, ▪ Have a double membrane into thylakoids that house chlorophyll.
▪ Largest// Membrane-bounded organelle growth, and reproduction by regulating gene ▪ Lens-shaped organelles  Chlorophyll traps the energy from sunlight
▪ Dense and spherical expression). ▪ Bounded by two membranes enclosing and converts light energy into chemical
▪ Consists of 3 main components:  Contains DNA which determines the a fluid-filled stroma that contains energy during photosynthesis.
1.) Nuclear envelope separates the characteristics of a cell and its metabolic enzymes. Carbohydrates are made in the stroma.
contents of nucleus from cytoplasm. functions. <<< Stroma: The matrix of the chloroplast which is
2.) Chromatin contains the genetic  The information carried by DNA controls the a thick fluid in between grana where various
material in the form of DNA. activities of the cell. enzymes, molecules and ions are found where the
3.) Darker region called nucleolus. >>> DNA: a double-stranded nucleic acid that dark reaction (or carbohydrate formation reactions)
contains the genetic information. of photosynthesis occurs.

2. Mitochondria  Sites of cellular respiration. Golgi Apparatus  Modifies proteins & carbohydrates.
▪ Cylindrical-shaped / Spherical or  Vitals energy source for cellular processes.  Transports proteins throughout the cell.
▪ composed of membrane-bound stacks
rod-shaped  Produces large amounts of energy through  Creation of lysosomes.
known as cisternae
▪ Have double membrane oxidation of glucose // oxidative  Sorts & packages protein into secretory
▪ New membrane is continuously added
▪ Contain respiratory enzymes ( for phosphorylation of organic molecules. vesicles.
to one end of G.A and buds off as
respiration )  Energy that generated in form of ATP
vesicles at the other end
(adenosine triphosphate).
Lysosomes  Function as digestive compartments in a cell.
 Uses glucose and oxygen to produce energy
▪ Small, spherical sacs surrounded by a  Hydrolytic enzymes digest & break down
(and releasing carbon dioxide and water in
single membrane complex organic molecules (protein, nucleic
the process) for metabolic process.
▪ contain hydrolytic enzymes (digestive acid, lipid, polysaccharides).
Ribosomes  Site of protein synthesis.
enzymes)  Unicellular organism, lysosomes fuse with
▪ Sphere-shaped structure  Instruction required for the synthesis of
food vacuoles & release their enzymes into
▪ Compact, spherical organelle proteins is stored in the chromatin.
these vacuoles to digest the contents of
▪ Composed of 2 sub-units (each
vacuoles. The breakdown products are
contains ribonucleic acid [RNA] &
absorbed into cytoplasm of cell.
protein)
 Hydrolytic enzyme also break down
▪ Occur freely in the cytoplasm & are
unwanted structures (old organelles or whole
attached to the nuclear membrane or to
cells).
the rough endoplasmic reticulum (RER)
Endoplasmic Reticulum (ER) Rough ER:
▪ Membrane-bounded organelle that  Transports proteins made by ribosomes
forms interconnected tubes & sacs that is throughout the cell.
connected to the nuclear membrane
▪ The outer surface of RER is covered Smooth ER:
with ribosomes, SER does not have  Synthesises lipids (phospholipids & steroids)
ribosomes  Carries out detoxification of drugs &
▪ metabolic by-products.
Centrioles  Composed of a complex arrangement of
▪ Small cylindrical structures microtubules.
▪ Not present in plant cells  Form spindle fibres during cell division in
animal cells.

3. b) Compare and contrast an animal and plant cell : c) Relate the density of certain organelles with the function of specific cells
 comparison between the structure of an animal cell and plant cell Organelles Types of cells Functions
found
Mitochondria Sperm cells a) Require energy to swim through the uterus
towards the Fallopian tubes, so that fertilisation
can take place.
Muscle cells b) Contract and relax to enable movement & flight.
Meristematic cells (plant) c) Require large amounts of energy during active
cell division to produce new cells.
RER & G.A Pancreatic cells a) Synthesise and secrete enzymes and
hormones.
Cells in salivary glands b) Synthesise and secrete enzymes.
Interstitial & stomach c) Secretes digestive enzymes.
epithelium
G.A Goblet cells a) Secrete mucus.
Cells in the root cap b) Secrete a slimy lubricant that helps the
movement of roots between soil particles.
SER Interstitial cells in testes Synthesise and secrete steroids & hormones.
& adrenal glands
Liver cells Carbohydrate metabolism & detoxification of drugs
and poisons.
Chloroplasts Palisade mesophyll cells Absorb sunlight during photosynthesis.

4. d) State the necessity for cell specialization in unicellular organism : are assimilated.
Amoeba v. Undigested material is left behind when Amoeba moves away.
1. Habitat:-
□ Respiration
 Lives in freshwater lakes, ponds, marine environment & also in damp soil.
 Most species of Amoeba are free-living while others are parasites.  Exchange of oxygen & carbon dioxide by simple diffusion.
□ Excretion
2. General characteristics:-
 Carbon dioxide & ammonia are excreted by diffusion.
 Irregular in shape.
 Contractile vacuole is involved in osmoregulation.
 Consists of a single cell surrounded by a plasma membrane.
 Water diffuses into the cell & fills the contractile vacuole.
 Changes shape constantly when meets obstacles & responds to stimuli.
 When vacuole is filled to its maximum size, it contracts to remove its contents from time
 Gel-like outer part of cytoplasm – ectoplasm, inner part – endoplasm.
to time.
3. Living processes:-
□ Reproduction
□ Locomotion
 Reproduces asexually by binary fission & forming spores.
 Moves & feeds by using pseudopodia.  Environment is not conducive for reproduction – not enough food and the condition is
 Moves by cytoplasmic projection (extending pseudopodia or ‘false feet’ towards the dry, Amoeba forms spores. The spores germinate when the environment becomes
direction it wants to move). conducive again.
 Follow by the flow of cytoplasm into the pseudopodia.
 This locomotion – ameboid movement.
□ Responses to stimuli
 Move towards to favourable stimuli (food).
□ Feeding
 Move away to adverse stimuli (bright light, acidic condition).
 Feed on bacteria & diatoms.
 Method of engulfing food is called phagocytosis.
□ Growth
i. Approaches the food particle.
ii. Two pseudopodia extend out & enclose the food particle.  Grows by synthesising new cytoplasm.
iii. Food particle is packaged in a food vacuole which fuses with a lysosome
containing a hydrolytic enzyme called lysozyme.
iv. Food particle is digested by the lysozyme. The nutrients diffuse into cytoplasm and

5. iv. Nutrients from digested food dissolve & diffuse into cytoplasm and used to generate
energy.
v. The undigested contents are released through the anal pore.
□ Respiration
 Gaseous exchange occurs by diffusion.
Paramecium
1. Habitat:-
□ Excretion
 Lives in freshwater ponds rich in decaying organic matter.
 Carbon dioxide & waste products are excreted by simple diffusion.
2. General characteristics:-
 Control of water balance (osmoregulation) is aided by 2 contractile vacuoles ( anterior &
 Has a fixed slipper-like shape.
posterior end).
 Surface covered by numerous rows of cilia.
 Water enters the cell constantly from the hypotonic environment by osmosis.
 Cilia are short hair-like outgrowths * involved in locomotion & feeding.
(a) Excess water in the cell enters the contractile vacuole by osmosis.
 Has 2 nuclei – Macronucleus controls cellular metabolism of cell + asexual reproduction.
(b) Contractile vacuole enlarges.
– Micronucleus required for sexual reproduction.
(c) Contractile vacuole contracts & eliminates excess water to surroundings.
3. Living processes:-  Contractile vacuole expand, filling with water, contract to eliminate their contents to
exterior of cell.
□ Locomotion
>>> Osmoregulation: The process of regulating water potential in order to keep fluid and
 Moves by means of the regular beating of cilia. electrolyte balance within a cell or organism relative to the surrounding.
 Enables to move forward while rotating & spiralling along its axis. >>> Contractile vacuole: A specialized vacuole of eukaryote cells, that fills with water from
the cytoplasm and then discharges this externally by the opening of a permanent narrow
neck. Function is probably osmoregulatory.
□ Feeding
 Feed on microscopic organisms.
□ Reproduction
 Nutrition in Paramecium:
i. Regular beating of cilia along a mouth-like opening (oral groove) sweeps water and  Reproduces asexually & sexually.
suspended food particles into the cytostome.  In favourable environment – reproduces rapidly by binary fission.
ii. In the cytostome, food vacuoles containing the food particles are formed.  Sexual reproduction is known as conjugation – when environment condition is not
iii. Food particles in the food vacuoles are digested by hydrolytic enzymes from favourable.
cytoplasm.

6. □ Responses to stimuli
Organs:
 Cilia functions as sensory structures.
- a group of different tissues that work together to carry out a function.
 Sensitive to chemicals, O2 & CO2, pH and physical stimuli ( light, contact, temperature).
 Moves in the opposite direction – contact with negative stimulus.
Systems:
□ Growth - several organs are organised into a system.
 Grows to a certain size by synthesising new cytoplasm.
Organism:
-various systems make up the organism.
e) Describe cell specialization in multicellular organisms g) Describe the necessity for cell organisation & cell specialisation.
 Multicellular organism consists of many cells or more than one cell. Cell specialisation : a process of change & adaptation that a cell undergoes to give it special
 Differentiation = A single-celled zygote develops into a multicellular embryo. The cells structure and specific functions.
grow, change size//shape & adapt to carry out specific functions. Cells Characteristics
 Cells differentiate & become more specialised in order to perform specific tasks more 1. Nerve cell - has long, thin fibres called axons.
efficiently. <<< Neurons can be the longest cells - specialise to conduct nerve impulses.
known, a single axon can be several - carry nerve impulses throughout body.
f) Describe cell organisation in multicellular organisms metres in length.
2. Muscle cell - long with multiple nuclei & contain protein fibres.
CELL ORGANISATION <<< Formed by fusion of embryonic - fibres can contract to produce movement.
myoblasts.
Cells:
3. Red blood cell - biconcave disc shape & does not have nuclei.
- become more specialised to carry out particular tasks are organised into
<<< Specialised for oxygen transport & - this increases the surface area of cell & allows
tissues.
high concentration of haemoglobin in oxygen to diffuse into cell at a faster rate.
Differentiation/ Specialisation the cytoplasm.
4. White blood cell - can change shape easily to move through the
Tissues:
<<< The blood cells that lack walls of blood vessels
- a group of cells which are similar in structure & perform same function.
haemoglobin, colourless and with - can migrate to the sites of injuries to fight

7. nucleus. infections. Surface of skin &  Form a protective barrier against infections, mechanical,
Lining of mouth // oesophagus injuries, chemicals & dehydration
 Regulate body temperature
5. Sperm cell - has long tail & a high density of mitochondria
<<< Mature male gamete or - allow to swim towards the ovum.
reproductive cell. - nucleus contains one set of chromosomes.
6. Epithelial cell - with simple glands are found in intestines. Lining of body cavities  Line the alveoli of lungs & form walls of blood capillaries
<<< Cells that cover the surface of the - function is to secrete mucus. (heart, blood vessels, lungs) - thin, flattened & arranged in a single layer
body and line its cavities. - highly folded with secretory cells arranged  Allow the exchange of gases take place efficiently
compactly to increase the surface area for mucus
secretion. Lining of small intestine  Absorb nutrient after completed digestion
>>> Gland: organ specialised for secretion by the  Undergo modification to form mucus-secreting goblet
infolding of an epithelial sheet. cells ( secrete mucus into the digestive tract )
>>> Goblet cells :cells within the epithelium of the
respiratory system which secrete mucus in order to remove
h) Describe cell organisation in the formation of tissues, organs and system in dirt and bacteria from the air entering the lungs.
multicellular organisms Lining of glands, ducts, kidney  Modified to form glands in the skin
 TISSUES tubules  e.g. : sweat glands, sebaceous glands (oil-secreting)
Tissues are groups of specialised cells with same structure & function.
Epithelial tissues >>> Sebaceous glands: A cutaneous gland that secretes
- consist of 1 or more layers of cells. sebum for lubricating hair and skin.
- tightly interconnected, with little space between them.
- form a continuous later over body surfaces & inner lining of cavities (digestive tract, lungs).
- form glands (exocrine & endocrine glands). Lining of trachea  Line the trachea consists of elongated cells with hair-like
___________________________________________________________________________ projections called cilia
◇Protective covering against entry of pathogens & water loss  Cilia – secrete mucus
◇Regulates movement of gases, nutrients & wastes  Mucus traps dust particles while cilia sweep the
◇Ciliated epithelium traps dust & microbial spores impurities away from lungs
◇Glandular epithelium secretes enzymes, hormones, sweat & sebum
Epithelial tissues Adaptations & Functions >>> Mucus: The free slime of the mucous membranes,
composed of secretion of the glands, along with various

8. inorganic salts, desquamated cells and leucocytes. Adipose Tissue  Store fat
Protective secretion of the mucous membranes; in the gut it <<< Contains adipocytes (fat cells). The tissue  Stores energy & insulates the body
lubricates the passage of food and protects the epithelial stores energy in the form of fat within the
cells; in the nose and throat and lungs it can make it difficult adipocytes. The tissue is also used for
for bacteria to penetrate the body through the epithelium. cushioning, thermal insulation of vital organs,
A slimy, sticky material. lubrication (chiefly in the pericardium), and
producing hormones (such as leptin).
Nerve tissues Functions
Consists neurons// nerve cells  Specialised in transmitting nerve impulses.
Each neuron consists of a cell body & nerve  Control & coordinate activity of the body.
fibres – dendrites & axons
3 Type of neurones:
-Afferent neurone
-Efferent neurones
-Interneurones
Type of connective tissues Functions
Loose connective tissue  Found in the spaces between organs
<<< Holds organs and epithelia in place, and  Hold the organs together
has a variety of proteinaceous fibers, including Type of connective tissues Functions
→ Most widespread
collagen and elastin. It also surrounds the blood Cartilage  Collagen fibres are densely packed to form
vessels and nerves. The cells of this tissue are • Strong and flexible tendons & ligaments
→ Binds epithelia to underlying tissues and
loosely separated in the rich extracellular matrix. <<< Dominated by extracellular matrix  Tendons attach muscles to bones
holds organs containing collagen type II and large amounts  Ligaments attach bones to bones
Fibrous connective tissue  Forms tendons & Ligament of proteoglycan, particularly chondroitin  Provide support to nose, ears and covers
<<< Contains fibroblasts, and also the fibrils and  Tendons: Connect bones to muscles. sulphate. bone ends at joints
fibres of connective tissue formed by such cells.  Ligament: Connect bones to bones  Forms discs between vertebrae ( acts as
<<< White fibrous tissue or white fibre: cushions to absorb pressure )
→ A lot of closely-packed collagenous
– for example: ligaments and tendons Bone (Rigid tissue)  Provides protection to organs & supports
fibres • Form the skeleton body
• Cells located deep in collagen matrix,  Involves in body movement

9. hardened by calcium ends to a bone and so move parts of the produce movements of various body
• Harder than cartilage skeleton. parts.
<<< Bone tissues consist of collagen fibers
and ground substance containing calcium, • Cardiac muscles  Contract to pump blood to all parts of
magnesium, and phosphate ions that -- Form the contractile wall of heart. body.
chemically combine and harden into a  Contractions are involuntary
mineral, hydroxyapatite. The combination of
hard mineral and flexible collagen makes
Tissue Function Example
bone harder than cartilage without being
brittle. Epithelial Forms thin sheets that line and cover body Ciliated cells that line the
Blood  Transports nutrients throughout the body tissue structure; The function depends on its respiratory tract
• Consist of R.B.C & W.B.C & platelet ( Cell  Carries and delivers oxygen to the cells location in an organ
fragment ), suspended in a fluid called blood  Removes carbon dioxide and waste
Connective Holds the body together Bone, cartilage, blood,
plasma products through excretion
tissue tendon, ligament
• Manufactured in the bone marrow, located at  Regulates the body pH and temperature
the ends of long bones  Protected against // immune defense Muscular Contract to produce movement Skeletal muscles, smooth
<<< The circulating fluid ( blood plasma) and against pathogenic and harmful antigens. tissue muscle, cardiac muscle
suspended formed elements, such as red  Blood clot formation
blood cells, white blood cells and platelets. Nervous Conduct nerve impulses Densely packed nerve
tissue cells
Type of muscle tissues Functions
• Smooth muscles  Responsible for the involuntary actions  ORGANS
-- Found along the walls of digestive tract, blood of body. ( When the smooth muscle of The Skin as an Organ  Covers the entire body & protects it against
vessels, bladder & reproductive tract. the intestine contract, food moved to the infections, physical trauma & water loss.
<<< A muscle that contracts without conscious digestive tract. )  The largest organ of body.
control and found in walls of internal organs  Responsible for the churning action of  Because it consists of various types of
such as stomach and intestine and bladder and stomach & the constriction of arteries. tissues combined together to perform
blood vessels (excluding the heart). Has the specific functions.
form of thin layers or sheets.  Epidermis: outermost, thinner layer
• Skeletal muscles  Responsible for the voluntary movement  Dermis: connective/nerve/epithelial/muscle
-- Attached to the bones of the skeleton. of body. tissues.
<<< A muscle that is connected at either or both  Contractions of skeletal muscles

10.  SYSTEM Reproductive system  Male: produce sperms & hormones
Organ System Function  Male: Testes, penis  Female: produce ova & hormones
Circulatory system  Transport respiratory gases, nutrients/ hormones &  Female, Ovaries, uterus, vagina  Carry out reproduction
 Heart, blood vessels waste products throughout the body Integumentary system  Cover & protect the body
Respiratory system  Exchange gases between blood & external  Skin
 Lung, trachea, nose environment
 Allow uptake of oxygen & disposal of carbon dioxide
Digestive system  Break up food into small molecules by physical & i) State the meaning of internal environment
 Mouth, oesophagus, stomach, chemical means j) Indentify factors affecting the internal environment
liver, pancreas, small intestine,  Absorb nutrients from ingested food k) Explain the necessity to maintain optimal internal environment
large intestine l) Describe the involvement of various systems in maintaining optimal internal environment
Excretory system  Remove metabolic wastes such as CO2 & urea m) Predict the state of certain cells without a particular cellular component
 Kidney, urinary bladder, lung,  Maintain homeostatic conditions in the body n) Illustrate that most cells are specialised for the job that they perform
skin
Skeletal system  Protect internal organs
 Bone, cartilage, tendon,  Provide support for locomotion and movement Ques:
ligament 1. Name the membrane valves that open and close for potassium efflux and sodium influx.
ion channels/ vacuoles/ capillaries/ cytokines
Muscular system  Produce body movement by contraction & shortening
2. What roles does the cytoskeleton play in a living cell?
 Skeletal muscle, smooth of muscles
= Maintaining cell shape,movement,contraction.
muscle, cardiac muscle
3. A cell in interphase is sometimes said to be resting. Why is this misleading?
Lymphatic system  Return excess tissue fluid to the circulatory system
= Interphase cells are synthesizing RNA and proteins, and growing in size
 Spleen, thymus gland, lymph  Provide defenses to microbial infection & cancer
nodes, lymphatic vessel
Nervous system  Receive stimuli, integrate information & direct the
Cell Specialisation in Plant
 Brain, spinal cord, nerve, body
Cell Function
sense organ
Palisade Mesophyll Cell Carries out photosynthesis
Endocrine system  Coordinate the activities of the body in conjunction
 Endocrine gland (pancreas, with the nervous system Guard Cell Control the size of the stomata pore to allow gaseous
thyroid, adreanal, pituitary) exchange.
Xylem Transport water and mineral salt
Phloem Transport dissolved food.

11. I Lysosomes Releases enzymes outside the No enzymes being
cell. released
J Chloroplast Carries out photosynthesis Photosynthesis cannot
occur
Golgi apparatus Storing and transporting lipids. Formation of lysosomes
Produces glycoprotein, will not happen
polysaccharide and secretory
enzyme.
Name of organelle / Function Consequence if absent
structure
A Rough endoplasmic Transporting proteins No transportation of
reticulum proteins
B Mitochondrion Site for energy production Energy cannot be
produced
C Cell wall Give fixed shape to the cell Have irregular shape (e.g.
Animal cell)
D Smooth endoplasmic Transport lipid and glycerol Lipid and glycerol cannot
reticulum be transport
E Nucleus Control cell activities, contains No cell division, all cell
genetic material. activities stop.
F Vacuole Storing nutrients (sugar and Cannot store nutrients
amino acid) in its sap.
G Cytoplasm Food storage, medium for No site for metabolic
metabolic reaction reaction
H Plasma membrane Controlling entry and exit of No selective barrier
substances