ICSE Class 9 Biology Sample Paper with Solutions Set 05

SECTION A

(Attempt all questions from this Section)

Question 1

Choose the correct answers to the questions from the given options. (Do not copy the question, write the correct answer only.) [15]

(i) Assertion (A): The papaya flower is a staminate flower.
Reason (R): It contains only stamens.
1. Both A and R are true
2. Both A and R are false
3. A is true and R is false
4. A is false and R is true

Answer: (1) Both A and R are true

Papaya plants bear unisexual flowers. A staminate papaya flower contains only male reproductive organs (stamens).

Teacher's Note:
a) Understand the difference between unisexual (staminate and pistillate) and bisexual flowers.
b) Ensure that both assertion and reason statements are independently evaluated before selecting the option.

(ii) Vallisneria is pollinated by
1. Water
2. Air
3. Insects
4. Bats

Answer: (1) Water

Vallisneria is a submerged aquatic plant where pollination takes place by the agency of water (hydrophily).

Teacher's Note:
a) Note that hydrophily is typical in aquatic plants like Vallisneria and Zostera.
b) Do not confuse aquatic habitat with water pollination for all aquatic plants; some are pollinated by insects or air.

(iii) Whole grains and rice are the sources of vitamin
1. B₂
2. B₁
3. B₄
4. B₆

Answer: (2) B₁

Vitamin B₁ (thiamine) is richly found in whole grains, unpolished rice, and cereals.

Teacher's Note:
a) Learn the specific food sources and deficiency diseases of all major vitamins.
b) Remember that polishing rice removes the outer layer containing Vitamin B₁, leading to beri-beri.

(iv) An animal of Phylum Coelenterata is
1. Hydra
2. Fasciola
3. Ascaris
4. Starfish

Answer: (1) Hydra

Hydra belongs to the Phylum Coelenterata (Cnidaria), characterized by radial symmetry and cnidoblasts.

Teacher's Note:
a) Fasciola belongs to Platyhelminthes, Ascaris to Nematoda, and Starfish to Echinodermata.
b) Memorize key examples and diagnostic features for each invertebrate phylum.

(v) Chlorenchyma is modified
1. Parenchyma
2. Collenchyma
3. Sclerenchyma
4. Aerenchyma

Answer: (1) Parenchyma

Chlorenchyma is a specialized type of parenchyma tissue containing chloroplasts that perform photosynthesis.

Teacher's Note:
a) Both aerenchyma and chlorenchyma are functional modifications of simple permanent parenchyma tissue.
b) Be precise with tissue terminology to avoid confusion between supportive and specialized plant tissues.

(vi) Ribosomes assist in
1. Protein packaging
2. Protein synthesis
3. Cell division
4. Intracellular digestion

Answer: (2) Protein synthesis

Ribosomes are known as the protein factories of the cell because they translate genetic instructions into proteins.

Teacher's Note:
a) Associate ribosomes directly with protein synthesis and the rough endoplasmic reticulum.
b) Golgi bodies handle protein packaging, while lysosomes handle intracellular digestion.

(vii) Assertion (A): Hepatitis is a bacterial infection of the liver causing its inflammation.
Reason (R): Hepatitis A virus is transmitted through contaminated syringes and blood transfusions.
1. Both A and R are true
2. Both A and R are false
3. A is true and R is false
4. A is false and R is true

Answer: (2) Both A and R are false

Hepatitis is a viral infection (caused by Hepatitis viruses), not bacterial. Hepatitis A is typically transmitted through contaminated food and water, whereas Hepatitis B and C are transmitted through contaminated syringes and blood.

Teacher's Note:
a) Read both pathogen type and transmission routes carefully in disease-related questions.
b) Differentiate clearly between the transmission modes of Hepatitis A versus Hepatitis B.

(viii) The following two chemical reactions are supposed to indicate a certain process occurring in the green plants under two different conditions:
A: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 38 ATP
B: C₆H₁₂O₆ → C₂H₅OH + 2CO₂ + 2 ATP
Identify A and B.
1. A - Aerobic respiration, B - Anaerobic respiration
2. A - Anaerobic respiration, B - Aerobic respiration
3. A - Aerobic respiration, B - Combustion
4. A - Combustion, B - Anaerobic respiration

[Figure: Box A shows equation for aerobic respiration producing 38 ATP, and Box B shows equation for alcoholic fermentation producing 2 ATP and ethanol.]

Answer: (1) A - Aerobic respiration, B - Anaerobic respiration

Reaction A requires oxygen and releases carbon dioxide, water, and high energy (38 ATP), representing aerobic respiration. Reaction B breaks down glucose into ethanol, carbon dioxide, and low energy (2 ATP) without oxygen, representing anaerobic respiration (fermentation).

Teacher's Note:
a) Memorize the net chemical equations and ATP yields for both aerobic and anaerobic pathways.
b) Look for oxygen usage and by-products like ethanol or lactic acid to distinguish anaerobic respiration.

(ix) Incomplete breakdown of organic matter by bacteria is called
1. Fermentation
2. Intracellular digestion
3. Decomposition
4. Putrefaction

Answer: (4) Putrefaction

Putrefaction refers to the anaerobic decomposition of proteins by bacteria and fungi, resulting in foul-smelling compounds.

Teacher's Note:
a) Distinguish between general decomposition, fermentation of carbohydrates, and putrefaction of proteins.
b) Learn precise biological definitions for ecological and microbiological terms.

(x) Assertion (A): Absorption of digested food mainly occurs in the stomach.
Reason (R): Stomach produces the hormone secretin and the intrinsic factor and it liquifies the ingested food
1. Both A and R are true
2. Both A and R are false
3. A is true and R is false
4. A is false and R is true

Answer: (4) A is false and R is true

Absorption of digested food primarily takes place in the small intestine, not the stomach. The stomach mainly stores, churns, and partially digests food while secreting gastric juice, intrinsic factor, and hormones.

Teacher's Note:
a) Note that the stomach absorbs only water, alcohol, and certain drugs, whereas the small intestine is the main site of absorption.
b) Verify each part of an assertion-reason pair independently before concluding.

(xi) Although Rakesh and Suresh are real brothers, Rakesh has black hair while Suresh has brown hair. Their father and mother both have grey hair. These differences in the colour of the hair are due to varying quantities of
1. Keratin
2. Melanin
3. Rhodopsin
4. Lutein

Answer: (2) Melanin

Melanin is the pigment responsible for the colour of hair, skin, and eyes in humans.

Teacher's Note:
a) Associate melanin with skin and hair pigmentation.
b) Keratin is a structural protein found in hair and nails, while rhodopsin is a visual pigment in the retina.

(xii) Which of the following involves the arrangement of sepals in a flower?
1. Polyadelphous
2. Diadelphous
3. Polysepalous
4. Monadelphous

Answer: (3) Polysepalous

Polysepalous describes a condition where the sepals are free from one another. The other terms relate to the arrangement of stamens (androecium).

Teacher's Note:
a) Distinguish prefix and suffix terms related to floral whorls (sepals/calyx vs. stamens/androecium).
b) Poly- means free, while -adelphous refers to fused stamen bundles.

(xiii) Seema had gone for trekking to the Himalayas with her friends. As she climbed higher and higher, she began to experience headache, dizziness, and shortness of breath. Which of the following could be the reason for this condition?
1. Asphyxiation
2. Hypoxia
3. Claustrophobia
4. Leukaemia

Answer: (2) Hypoxia

At high altitudes, atmospheric pressure and oxygen concentration decrease, leading to a deficiency of oxygen in body tissues, known as hypoxia (altitude sickness).

Teacher's Note:
a) Hypoxia refers specifically to low oxygen levels in tissues due to environmental or physiological factors.
b) Asphyxiation is suffocation caused by lack of breathable air, distinct from mountain sickness hypoxia.

(xiv) Assertion (A): Development of immunity to chickenpox is considered as acquired immunity.
Reason (R): Immunity that is inherited from parents is considered as acquired immunity.
1. Both A and R are true
2. Both A and R are false
3. A is true and R is false
4. A is false and R is true

Answer: (3) A is true and R is false

Immunity developed after contracting an infection like chickenpox is indeed acquired (adaptive) immunity. However, immunity inherited from parents is called innate or inherited immunity, making the reason false.

Teacher's Note:
a) Differentiate clearly between innate (inborn/inherited) immunity and acquired (adaptive/developed during lifetime) immunity.
b) Read all statements carefully to catch swapped definitions in reason statements.

(xv) The bone not associated with the chest cavity is the
1. Sternum
2. Rib
3. Cartilage
4. Femur

Answer: (4) Femur

The femur is the thigh bone located in the lower limb, whereas the sternum, ribs, and costal cartilages form the thoracic (chest) cage.

Teacher's Note:
a) Memorize the major bones of the axial and appendicular skeleton.
b) The sternum and ribs protect the thoracic organs, whereas limb bones function in locomotion.

Question 2

(i) Name the following: [5]
(a) The outermost hard, brownish layer of the seed coat.

Answer: Testa

Teacher's Note:
a) Testa is the protective outer coat of a seed derived from the integuments of the ovule.
b) Spelling must be accurate in biological terminology.

(b) The sense organ which belongs to the integumentary system of our body.

Answer: Skin

Teacher's Note:
a) The skin forms the primary outer covering and constitutes the integumentary system.
b) It also serves as the largest sensory organ for touch, temperature, and pain.

(c) The biological energy currency of the cell.

Answer: ATP (Adenosine triphosphate)

Teacher's Note:
a) ATP stores and transports chemical energy within cells for metabolism.
b) Writing the full expanded form along with the abbreviation is good practice.

(d) The diseases which are present at birth.

Answer: Congenital diseases

Teacher's Note:
a) Congenital diseases are present from birth, often due to genetic abnormalities or prenatal developmental issues.
b) Distinguish them from acquired diseases contracted later in life.

(e) The undigested fibrous material present in food.

Answer: Roughage (Dietary fibre)

Teacher's Note:
a) Roughage consists mainly of cellulose which cannot be digested by humans but aids bowel movement.
b) Essential for preventing constipation and maintaining a healthy digestive tract.

(ii) Match the following: [5]

Answer:
1. Honeybee - c. Apis indica
2. Cobra - e. Naja naja
3. Onion - a. Allium cepa
4. China rose - b. Hibiscus rosa sinensis
5. Peacock - d. Pavo cristatus

Teacher's Note:
a) Binomial nomenclature follows the format Genus followed by species name, with both italicised or underlined when handwritten.
b) Practice common and scientific names of standard organisms prescribed in the curriculum.

(iii) State whether the following statements are True or False. Correct and rewrite the false statements. [5]
(a) Cross pollination requires abiotic and biotic agents.

Answer: True.

Teacher's Note:
a) Cross-pollination relies on external agents such as wind, water, insects, birds, and bats.
b) Self-pollination can occur without external agents within the same flower.

(b) Fungi reproduce by producing spores.

Answer: True.

Teacher's Note:
a) Fungi commonly reproduce asexually or sexually through the production of spores.
b) Spores are lightweight and easily dispersed by wind or water.

(c) Enzymes are pH sensitive.

Answer: True.

Teacher's Note:
a) Each enzyme has an optimum pH at which its catalytic activity is maximum.
b) Extreme changes in pH can denature enzymes and render them inactive.

(d) Sulphonamides are effective in treating fungal diseases.

Answer: False. Sulphonamides are effective in treating bacterial diseases.

Teacher's Note:
a) Sulphonamides are synthetic antimicrobial drugs active against bacterial infections.
b) Fungal infections require antifungal agents rather than antibacterial sulfa drugs.

(e) DDT is a biodegradable waste.

Answer: False. DDT is a non-biodegradable waste.

Teacher's Note:
a) DDT persists in the environment for a long time and undergoes biological magnification along food chains.
b) Biodegradable wastes are easily decomposed by microorganisms, unlike synthetic pesticides like DDT.

(iv) State one point of difference between the following pairs on the basis of what is indicated in the brackets. [5]
(a) Annelids and molluscs [mode of respiration]

Answer:

Teacher's Note:
a) Always stick strictly to the specified parameter in brackets when stating differences.
b) Annelid skin is vascular and kept moist for cutaneous respiration.

(b) Ciliated epithelium and columnar epithelium [location]

Answer:

Teacher's Note:
a) Ciliated epithelium possesses hair-like cilia to move particles in one direction.
b) Columnar epithelium is specialised for absorption and secretion in the alimentary canal.

(c) Jaundice and mumps [mode of transmission]

Answer:

Teacher's Note:
a) Water-borne diseases like Hepatitis A (jaundice) spread via the faecal-oral route.
b) Mumps is a viral infection transmitted via airborne droplets and saliva.

(d) Premolars and incisors [function]

Answer:

Teacher's Note:
a) Incisors are chisel-shaped front teeth adapted for biting.
b) Premolars and molars have broad surfaces ideal for grinding food.

(e) Air-borne disease and water-borne disease [example]

Answer:

Teacher's Note:
a) Airborne pathogens travel through droplets released during coughing or sneezing.
b) Waterborne pathogens contaminate drinking water supplies.

(v) Given below is an example of a certain structure and its special function. Based on a similar pattern, fill in the given blanks: [5]
E.g., Chloroplast - Photosynthesis
(a) Ribosome
(b) Centrosome
(c) Haustoria
(d) Epiglottis
(e) Glenoid cavity

Answer:

Teacher's Note:
a) Match each organelle or anatomical structure precisely with its primary biological role.
b) Ensure concise and scientifically accurate phrasing for functions.

SECTION B

(Attempt any four questions from this section.)

Question 3

(i) What happens to the energy liberated during respiration? [1]

Answer:
The energy liberated during respiration is stored in the form of ATP (Adenosine Triphosphate) inside the cells, while some part of it is lost as heat to the surroundings.

Teacher's Note:
a) Emphasise that cellular respiration traps energy as ATP rather than releasing it all as heat.
b) Mentioning ATP is essential for full credit.

(ii) It is said that protoplasm cannot be analysed chemically. Why? [2]

Answer:
1. The chemical composition of protoplasm is extremely complex and varies slightly from one cell to another.
2. When chemical analysis is attempted, the protoplasm is destroyed or killed, altering its original state and composition.

Teacher's Note:
a) Protoplasm is a living, dynamic system of organic and inorganic compounds.
b) Analytical techniques destroy the structural integrity of living matter.

(iii) Can you consider a cluster of eggs as a tissue? Why? [2]

Answer:
No, a cluster of eggs cannot be considered a tissue. A tissue is defined as a group of similar cells from the same origin that together carry out a specific function. A single egg is a zygote or cell, and a cluster of eggs are individual reproductive cells that do not form a coordinated structural or functional tissue unit.

Teacher's Note:
a) Reiterate the standard biological definition of a tissue.
b) Eggs are individual cells meant for reproduction, not interdependent somatic cells.

(iv) What are the advantages of the following in the flower?
(a) Long and feathery stigma
(b) Smooth and light pollen [2]

Answer:
(a) Long and feathery stigma - Allows effective trapping of dispersed pollen grains carried by wind and increases the adhesiveness of attachment.
(b) Smooth and light pollen - Easily carried by wind over long distances, making it characteristic of wind-pollinated (anemophilous) plants.

Teacher's Note:
a) Relate floral adaptations directly to the mode of pollination (wind pollination in this case).
b) Keywords like wind dispersal and surface area capture are important.

(v) Answer the following questions:
(a) Germinated grams are considered highly nutritive. What is the reason?
(b) Sometimes the potatoes kept in a basket during the late rainy season start giving out small shoots. Is it germination? If yes, give reason. [3]

Answer:
(a) Germinated grams are considered highly nutritive because the cotyledon absorbs mobilised food reserves from the endosperm during germination, making it rich in easily digestible carbohydrates, proteins, and vitamins.
(b) No, it is not germination from a seed. It is vegetative propagation (sprouting of buds/eyes on the potato tuber) stimulated by moisture and favourable temperature during the rainy season.

Teacher's Note:
a) Distinguish between true seed germination and vegetative sprouting from modified stems (tubers).
b) Sprouting in potatoes occurs from dormant buds called eyes.

Question 4

(i) Rearrange the following categories of classification in their proper sequence starting with the highest.
Species, Family, Genus, Class, Order, Phylum [1]

Answer:
Phylum, Class, Order, Family, Genus, Species

Teacher's Note:
a) Taxonomic hierarchy must be memorised strictly from broad categories to specific ones.
b) Check the order of listing when the question specifies starting with the highest category.

(ii) Why is spore formation in bacteria not considered as a form of reproduction? [2]

Answer:
Spore formation (endospore formation) in bacteria is not considered a form of reproduction because no new individuals are produced. Bacteria reproduce solely asexually through binary fission or cell division, while spore development is merely a survival mechanism to tide over adverse environmental conditions.

Teacher's Note:
a) Reproduction results in an increase in the number of individuals.
b) Endospores are dormant, highly resistant structures for survival under unfavourable conditions.

(iii) Define the terms:
(a) Balanced diet
(b) Malnutrition [2]

Answer:
(a) Balanced diet: A diet that contains all the principal constituents of food (carbohydrates, fats, proteins, vitamins, minerals, water) in proper quantities and proportions required for a particular person based on age, sex, and physical activity.
(b) Malnutrition: The condition in which a person suffers from an unbalanced diet, which includes both deficiency of essential nutrients or excess intake leading to nutritional disorders.

Teacher's Note:
a) Ensure all essential food components are mentioned in the definition of a balanced diet.
b) Highlight that malnutrition covers both undernutrition (deficiencies) and overnutrition (excess).

(iv) How is thorough chewing of food helpful in digestion? [2]

Answer:
1. Thorough chewing breaks down large food pieces into smaller particles, increasing the surface area for enzymatic action.
2. It thoroughly mixes food with saliva, which moistens it into a bolus for easy swallowing and initiates the digestion of starch via salivary amylase.

Teacher's Note:
a) Mechanical digestion in the mouth aids subsequent chemical digestion.
b) Mention surface area enhancement and saliva mixing for complete credit.

(v) What are antagonistic muscles? Describe briefly. [3]

Answer:
Antagonistic muscles are pairs of muscles that work in opposition to each other to produce movement at a joint, where when one muscle contracts, the other relaxes.
For example, the biceps and triceps in the human arm work antagonistically: contraction of the biceps bends (flexes) the arm at the elbow while the triceps relaxes, whereas contraction of the triceps straightens (extends) the arm while the biceps relaxes.

Teacher's Note:
a) Muscles can only pull and cannot push, hence they require opposing pairs for bidirectional movement.
b) Give the classic biceps-triceps example to illustrate the concept clearly.

Question 5

(i) Name one modified sweat gland and any one modified sebaceous gland. [1]

Answer:
Modified sweat gland: Mammary gland (or Ceruminous gland)
Modified sebaceous gland: Meibomian gland (or Zeis gland)

Teacher's Note:
a) Mammary glands are modified sweat glands specialised for milk secretion.
b) Meibomian glands are modified sebaceous glands located in the eyelids.

(ii) Why is it important to know how the germs leave the body of an infected person? [2]

Answer:
It is important to know how germs leave an infected body because different pathogens exit through specific routes (such as respiratory droplets, faeces, urine, or blood) and spread via corresponding transmission modes. Understanding this helps in adopting targeted preventive measures, quarantine protocols, and disinfection to stop the spread of infection to healthy individuals.

Teacher's Note:
a) Knowing the exit portal of a pathogen aids in interrupting the chain of infection.
b) Essential knowledge for epidemiology and public health control measures.

(iii) What are the group names for the following categories of animals?
(a) Animals with a hairy skin
(b) Animals with feathers [2]

Answer:
(a) Animals with a hairy skin: Mammals (Mammalia)
(b) Animals with feathers: Birds (Aves)

Teacher's Note:
a) Hair or fur is a unique diagnostic characteristic of mammals.
b) Feathers are unique epidermal structures exclusive to birds (Aves).

(iv) Name one body part where ciliated epithelium is found in humans. What is its function? [2]

Answer:
Location: Trachea (windpipe) or Fallopian tube.
Function: The beating action of cilia moves mucus and trapped dust particles upward out of the respiratory tract (or propels the ovum in the oviduct).

Teacher's Note:
a) Cilia provide directional movement to fluids or particles across epithelial surfaces.
b) Mention both location and specific function to secure full marks.

(v) Observe the figure given below and answer the questions based on it. [3]
(a) Which major organ of the flower does the figure A represent?
(b) What do the contents of the pollen sacs in figure B represent?
(c) How will the contents of the pollen sacs come out?

[Figure: Diagram of a stamen showing anther lobes and filament, with pollen grains spilling from an open pollen sac.]

Answer:
(a) Figure A represents the androecium (stamen), which is the male reproductive organ of the flower.
(b) The contents of the pollen sacs represent pollen grains containing male gametes.
(c) The contents of the pollen sacs come out through dehiscence (splitting) of the anther wall when mature, aiding pollination.

Teacher's Note:
a) Identify floral whorls and parts accurately from diagrams.
b) Dehiscence is the terminal splitting of anthers to release pollen.

Question 6

(i) Why does gaseous exchange continue in the lungs even during expiration? [1]

Answer:
Gaseous exchange continues during expiration because a residual volume of air remains in the lungs at all times, ensuring continuous diffusion of oxygen into the blood and carbon dioxide out of the blood.

Teacher's Note:
a) Lungs are never completely emptied of air during normal breathing cycles.
b) Residual volume maintains a constant partial pressure gradient for gas exchange.

(ii) How does the skin protect the body against excessive loss of heat in severe cold? [2]

Answer:
In severe cold, the blood vessels in the dermis constrict (vasoconstriction), reducing blood flow to the skin surface and thus minimising heat loss. Additionally, the layer of subcutaneous fat acts as an insulating blanket, conserving body heat.

Teacher's Note:
a) Vasoconstriction helps retain core body temperature in cold environments.
b) Subcutaneous adipose tissue provides thermal insulation.

(iii) Do the muscles pull the structures or push them? Explain. [2]

Answer:
Muscles only pull structures; they never push. A muscle can actively contract to shorten and pull a bone via a tendon, but it cannot actively lengthen to push it back. Movement in the opposite direction is achieved by the contraction of an antagonistic muscle.

Teacher's Note:
a) Emphasise the fundamental physiological property that skeletal muscle tissue can only generate pulling force.
b) This explains why muscles always occur in opposing antagonistic pairs.

(iv) What is roughage? Give two examples. [2]

Answer:
Roughage (dietary fibre) is the indigestible plant material, mainly composed of cellulose, present in our food that adds bulk and aids bowel movements.
Examples: Whole grains and green leafy vegetables (or fruits).

Teacher's Note:
a) Roughage does not provide nutrients but is essential for normal digestive tract function.
b) Cellulose cannot be digested by human enzymes due to the lack of cellulase.

(v) Give any three roles of microorganisms in industrial production. [3]

Answer:
1. Production of organic acids and vinegar through bacterial fermentation.
2. Brewing of alcoholic beverages and leavening of bread using yeast.
3. Large-scale manufacture of antibiotics, enzymes, hormones, and vaccines using bacteria and fungi.

Teacher's Note:
a) Biotechnology relies heavily on microbial fermentation processes.
b) Give precise industrial applications such as antibiotics or vinegar production.

Question 7

(i) One should breathe by nose and never by mouth. Give reason. [1]

Answer:
Breathing through the nose filters dust particles and microorganisms using nasal hair and mucus, warms the incoming air, and moistens it before it reaches the lungs, which is not possible when breathing through the mouth.

Teacher's Note:
a) Nasal passages provide conditioning (filtering, warming, and humidifying) of inhaled air.
b) Mouth breathing bypasses these protective mechanisms.

(ii) Mention any three ways by which potable water can be contaminated. [2]

Answer:
1. Improper disposal and leakage of sewage into water supply lines.
2. Defecation and urination near water bodies such as lakes, rivers, or ponds.
3. Drainage of animal wastes and washings from dairies and poultry farms into water sources.

Teacher's Note:
a) Water pollution leads to major water-borne epidemics like cholera and typhoid.
b) Point out anthropogenic contamination sources clearly.

(iii) Name any three vaccines and the diseases for which they provide immunity. [2]

Answer:

Teacher's Note:
a) Match specific vaccines with their corresponding bacterial or viral targets.
b) DPT combination vaccine protects against three distinct bacterial infections.

(iv) State two functions of World Health Organisation. [2]

Answer:
1. To promote and support research on major diseases such as cancer, malaria, and infectious epidemics.
2. To lay down international pharmaceutical standards for drugs and ensure global health safety and quarantine measures.

Teacher's Note:
a) WHO coordinates international public health responses.
b) Mention standard health promotion and disease control functions.

(v) Describe the usefulness of incineration of waste along with the safety precautions required for it. [3]

Answer:
Usefulness of waste incineration:
1. It drastically reduces the volume and weight of municipal and biomedical waste.
2. It destroys harmful pathogens and toxic materials safely.
Safety precautions:
1. Incineration must be carried out at extremely high temperatures in specialised furnaces.
2. Plants must be equipped with modern pollution-control devices (scrubbers, filters) to prevent toxic emissions, and located away from residential zones.

Teacher's Note:
a) Incineration is vital for hazardous and biomedical waste disposal.
b) Mention both the volume reduction advantage and air pollution control precautions.

Question 8

(i) Give the scientific name of man. [1]

Answer:
Homo sapiens

Teacher's Note:
a) Binomial nomenclature rules require genus to start with a capital letter and species with a small letter.
b) Underlining or italicising scientific names is mandatory in formal biology writing.

(ii) Why is it usually difficult to demonstrate respiration in green plants? [2]

Answer:
During daylight, green plants perform both photosynthesis and respiration simultaneously. The carbon dioxide produced during respiration is consumed inside the plant for photosynthesis, masking carbon dioxide evolution and making it difficult to demonstrate respiration during the day.

Teacher's Note:
a) Photosynthesis occurs at a much faster rate than respiration in bright light.
b) To demonstrate plant respiration experimentally, dark conditions must be used to stop photosynthesis.

(iii) What is goose flesh? How is it brought about? [2]

Answer:
Goose flesh (goosebumps) is a temporary roughness of the skin caused by cold or fear.
It is brought about by the contraction of arrector pili muscles attached to hair follicles in the dermis, which pulls the hair upright and depresses the surrounding skin.

Teacher's Note:
a) Arrector pili are smooth muscles innervated by the sympathetic nervous system.
b) This reflex is a vestigial response meant to trap a layer of insulating air in animals with thick fur.

(iv) Mention two ways in which the ileum of the mammal is adapted for the absorption of digested food. [2]

Answer:
1. The inner wall of the ileum is extremely long and folded into circular folds, providing a large surface area for absorption.
2. It bears millions of tiny finger-like projections called villi and microvilli, which further maximise the surface area and contain blood capillaries and lacteals.

Teacher's Note:
a) Adaptations for absorption always centre around increasing surface area and rich blood supply.
b) Mention villi and length for complete marks.

(v) Describe the advantages and disadvantages of cross-pollination in the plant. [3]

Answer:
Advantages of cross-pollination:
1. The resulting offspring are healthier, more vigorous, and better adapted to environmental changes.
2. It can introduce desirable new genetic variations in the species.
Disadvantages of cross-pollination:
1. It depends heavily on external agents (wind, insects, water), making pollination uncertain.
2. It is an uneconomical process for the plant as it requires large quantities of pollen and showy petals, nectar, and scent to attract pollinators.

Teacher's Note:
a) Cross-pollination promotes genetic diversity.
b) However, reliance on external pollination agents and wastage of resources are major drawbacks.