CBSE Class 7 Science Revision Worksheet Set 12

SCIENCE

LN. 9: SOIL

I. Fill in the blanks:

Question 1. The rotting dead matter in the soil is called __________________.
Answer: Humus
In simple words: Humus is the organic component of soil formed by the decomposition of leaves and other plant material.

Exam Tip: Remember that humus provides essential nutrients to the soil for plant growth.

Question 2. A vertical section through different layers of the soil is called _______________.
Answer: Soil profile
In simple words: Each layer of soil has different texture, color, and chemical composition, known as horizons.

Exam Tip: Soil profile is a frequently asked definition in exams.

Question 3. The mixture of _____________ and humus is called the soil.
Answer: Rock particles
In simple words: Soil is a complex mixture of weathered rock particles and decayed organic matter (humus).

Exam Tip: Always include both weathered rock particles and organic matter when describing soil composition.

Question 4. Percolation rate of water is the highest in the ____________ soil and least in the ___________ soil.
Answer: Sandy, clayey
In simple words: Sandy soil has large spaces allowing water to pass through quickly, whereas clayey soil has tiny particles holding water tightly.

Exam Tip: Connect particle size inversely to percolation rate: larger particles mean higher percolation.

Question 5. The best top soil for growing plants is _____________.
Answer: Loamy soil
In simple words: Loam contains the right balance of sand, silt, and clay with plenty of humus for plant roots.

Exam Tip: Loamy soil provides optimal water retention and aeration for agriculture.

Question 6. The removal of land surface by water, wind or ice is known as __________.
Answer: Soil erosion
In simple words: Soil erosion strips away the fertile top layer, reducing land productivity.

Exam Tip: Mention agents like wind and water when defining soil erosion.

II. Write True or False:

Question 1. If the amount of large and fine particles is about the same, then the soil is called loamy soil.
Answer: True
In simple words: Loam is a balanced mixture of sand, silt, and clay.

Exam Tip: Equal proportion of sand and silt/clay forms loamy soil.

Question 2. The layer which is hard and difficult to dig with spade is called top soil.
Answer: False
In simple words: The hard layer is the bedrock or C-horizon, whereas top soil is soft and rich in humus.

Exam Tip: Bedrock is hard and rocky, not the topsoil.

Question 3. Sandy soil is used to make pots, toys and statues.
Answer: False
In simple words: Clayey soil is sticky and plastic when wet, making it ideal for pottery.

Exam Tip: Clay is used for pottery due to its fine particle cohesion.

Question 4. Soil is affected by climatic factors.
Answer: True
In simple words: Temperature, rainfall, and wind speed dictate weathering rates and soil formation.

Exam Tip: Climate is a major active factor in soil formation and profile development.

Question 5. The soil which is light, well aerated and rather dry is clayey soil.
Answer: False
In simple words: Sandy soil is light, well aerated, and dry, while clayey soil is heavy and holds water.

Exam Tip: Do not confuse sandy properties with clayey soil properties.

Question 6. In deserts, soil erosion occurs through wind.
Answer: True
In simple words: Strong winds blow away loose sand particles in barren desert regions.

Question 7. Cotton is grown in sandy loam soil.
Answer: True
In simple words: Cotton thrives in well-drained soils like sandy loam or black soil.

Exam Tip: Sandy loam allows proper air circulation around cotton roots.

Question 8. Soil erosion takes place in areas of heavy vegetation.
Answer: False
In simple words: Plant roots bind the soil firmly, preventing erosion. Erosion is severe where vegetation is absent.

Exam Tip: Deforestation increases soil erosion rates.

III. Name the following:

Question 1. Two agents of weathering.
Answer: Water and Wind (or Temperature changes, frost)
In simple words: Natural forces that break down rocks into smaller particles.

Exam Tip: Mention physical or climatic agents clearly.

Question 2. The uppermost layer of soil.
Answer: Topsoil (A-horizon)
In simple words: The dark, humus-rich layer where most plant roots grow.

Exam Tip: Topsoil is rich in minerals and organic matter.

Question 3. The type of soil that can hold more water.
Answer: Clayey soil
In simple words: Small particle size and tiny pore spaces trap water effectively.

Exam Tip: High water holding capacity means low percolation rate.

Question 4. The soil which is a mixture of sand, clay and silt.
Answer: Loamy soil
In simple words: The balanced agricultural soil.

Exam Tip: Silt is an important component of loam along with sand and clay.

Question 5. Three agents of soil erosion.
Answer: Water, Wind, and Ice (or Human activities like deforestation)
In simple words: Forces that detach and transport soil particles.

Exam Tip: List natural environmental agents.

IV. Define the following:

Question 1. Soil
Answer: Soil is the uppermost layer of the Earth's crust consisting of weathered rock particles mixed with organic matter (humus), water, air, and living organisms.
In simple words: It is the natural medium for plant growth.

Exam Tip: Mention its composition of minerals and organic matter.

Question 2. Weathering
Answer: Weathering is the breaking down or dissolving of rocks and minerals on Earth's surface by the action of water, ice, acids, salts, plants, animals, and temperature changes.
In simple words: The slow wearing away of rocks to form soil.

Exam Tip: Weathering is a continuous geological process.

Question 3. Soil Profile
Answer: A vertical section through different layers of the soil, revealing various strata called horizons (A-horizon, B-horizon, C-horizon, and bedrock), is called a soil profile.
In simple words: A side-view cross-section of soil layers.

Question 1. Breathing is a part of _________________.
Answer: Respiration
In simple words: Breathing is the physical process of taking in oxygen and giving out carbon dioxide, which is a part of cellular respiration.

Exam Tip: Distinguish clearly between breathing (external) and cellular respiration (internal).

Question 2. Breathing involves the movement of the ___________ and ______________.
Answer: Diaphragm, rib cage
In simple words: Chest cavity volume changes due to ribs moving up/out and diaphragm moving down during inhalation.

Exam Tip: Both skeletal muscles and ribs cooperate in breathing mechanics.

Question 3. The food has ____________ which is released during respiration.
Answer: Energy stored in chemical bonds (or glucose / energy)
In simple words: Respiration breaks down digested food to release usable chemical energy.

Exam Tip: Glucose is broken down to release energy.

Question 4. The accumulation of ___________ causes muscle cramps.
Answer: Lactic acid
In simple words: Vigorous exercise causes temporary anaerobic respiration in muscles, producing lactic acid.

Exam Tip: Warm baths or massage relieve cramps by improving blood circulation and lactic acid removal.

Question 5. Yeast can survive in absence of oxygen, they are called ___________.
Answer: Anaerobes (or anaerobic organisms)
In simple words: Organisms that respire without oxygen are anaerobes.

Question 6. The taking in of air rich in oxygen into the body is called ____________.
Answer: Inhalation
In simple words: Drawing atmospheric air into the lungs.

Question 7. _____________is the food which is broken down in respiration to release energy.
Answer: Glucose
In simple words: Simple sugar molecules obtained from digested food.

Exam Tip: Glucose is the primary substrate for cellular respiration.

II. Write true or false:

Question 1. Cellular respiration takes place in all the cells of living organisms.
Answer: True
In simple words: Every living cell requires energy produced via cellular respiration.

Exam Tip: Cellular respiration occurs within microscopic cell organelles like mitochondria.

Question 2. All living organisms respire to get energy from food.
Answer: True
In simple words: Respiration is a vital life process common to plants, animals, and microorganisms.

Question 3. Our muscle cells do anaerobic respiration only when there is temporary deficiency of oxygen.
Answer: True
In simple words: During heavy workouts, oxygen supply falls short, triggering partial breakdown of glucose.

Exam Tip: This results in lactic acid build-up and fatigue.

Question 4. Breathing involves the movement of the diaphragm and the rib cage.
Answer: True
In simple words: Both structures alter thoracic cavity volume.

Exam Tip: Understand chest expansion mechanics thoroughly.

Question 5. Whales and dolphins have gills for breathing.
Answer: False
In simple words: Whales and dolphins are mammals that breathe atmospheric air through blowholes using lungs.

Exam Tip: Marine mammals surface frequently to breathe air through lungs.

Question 6. Gills are projections of the skin.
Answer: True (specifically vascular skin outgrowths specialized for aquatic gas exchange)
In simple words: Gills absorb dissolved oxygen from water in aquatic animals like fish.

Exam Tip: Gills are richly supplied with blood vessels for gas diffusion.

Question 7. The percentage of carbon dioxide is higher in inhaled air in comparision to exhaled air.
Answer: False
In simple words: Exhaled air contains much more carbon dioxide than inhaled air because cellular waste is expelled.

Exam Tip: Inhaled air has about 0.04% CO2, while exhaled air has about 4.4% CO2.

Question 8. We often feel hungry after a physical exercise.
Answer: True
In simple words: Physical exertion burns up glucose rapidly, prompting the body to demand more food energy.

Exam Tip: Increased metabolic rate burns calories faster.

Question 9. Increased physical activity reduces the rate of breathing.
Answer: False
In simple words: Exercise increases oxygen demand, raising the breathing rate.

Exam Tip: Respiratory rate speeds up during vigorous activity.

Question 10. Elephants, snakes and birds have lungs for breathing.
Answer: True
In simple words: All these vertebrates rely on pulmonary respiration (lungs).

Exam Tip: Reptiles, birds, and mammals possess lungs.

III. Define the following:

Question 1. Breathing
Answer: Breathing is the process in which an organism takes in oxygen-rich air from the atmosphere and releases carbon dioxide-rich air out of the body with the help of respiratory organs.
In simple words: The mechanical exchange of gases between an organism and its environment.

Exam Tip: Differentiate clearly between breathing and cellular respiration.

Question 2. Cellular respiration.
Answer: Cellular respiration is the biochemical process occurring within cells where food (glucose) is broken down, with or without oxygen, to release energy along with carbon dioxide and water.
In simple words: Energy generation inside cells.

Exam Tip: Mention the release of energy and occurrence inside cells.

IV. Name the following:

Question 1. Tiny pores on the surface of leaves for exchange of gases.
Answer: Stomata
In simple words: Microscopic pores on leaves used for breathing and transpiration.

Exam Tip: Guard cells regulate the opening and closing of stomata.

Question 2. An organism with tracheal system.
Answer: Cockroach (or Insects)
In simple words: Insects breathe through a network of air tubes called tracheae.

Exam Tip: Insects do not use lungs; they use spiracles and tracheae.

Question 3. Skeletal structures surrounding the chest cavity.
Answer: Ribs (Rib cage)
In simple words: Bony cage protecting heart and lungs.

Exam Tip: Ribs move upward and outward during inhalation.

Question 4. An aerobic organism.
Answer: Human beings (or dogs, cats, birds, etc.)
In simple words: Organisms that require oxygen to respire.

Exam Tip: Most multicellular animals are aerobic.

Question 5. The breathing organ of earthworm.
Answer: Moist skin
In simple words: Earthworms breathe through their wet, slimy skin directly.

Exam Tip: Skin must remain moist for oxygen diffusion in earthworms.

Question 6. The openings through which we inhale.
Answer: Nostrils (Nasal cavity)
In simple words: Front openings of the respiratory tract.

Exam Tip: Nasal hairs filter dust particles during inhalation.

Question 7. The anaerobic organism used in production of beer and wine.
Answer: Yeast
In simple words: Single-celled fungus performing fermentation.

Question 1. Why do all animals respire? -2marks.
Answer: All animals respire to release energy from food. This energy is essential for carrying out various life processes, growth, repair, and movement within the body.
In simple words: Respiration provides necessary energy for survival.

Question 2. Describe the mechanism of breathing in humans. -5marks.
Answer: Breathing involves two main steps: inhalation and exhalation.
1. During inhalation, ribs move upward and outward, and the diaphragm moves downward. This increases the space in the chest cavity, drawing air rich in oxygen into the lungs.
2. During exhalation, ribs move downward and inward, and the diaphragm moves up to its original position. This decreases the chest cavity volume, pushing air rich in carbon dioxide out of the lungs.
In simple words: Chest expansion sucks air in, and chest contraction pushes air out.

Question 3. Describe the process of respiration in cockroach. -5marks.
Answer: 1. Cockroaches have small openings called spiracles on the sides of their bodies.
2. Oxygen-rich air enters through spiracles into a network of air tubes called tracheae.
3. The oxygen diffuses directly into the body tissues and cells.
4. Carbon dioxide from cells enters the tracheae and is expelled outward through the spiracles.
In simple words: Insects use a tracheal network connected to side holes called spiracles.

Question 1. The human respiratory system.
Answer: [Schematic description of human respiratory system with labeled parts: Nasal cavity, Windpipe (Trachea), Bronchi, Lungs, and Diaphragm].
In simple words: A diagram showing air passage from nose down to lungs and diaphragm.

Nasal cavity Trachea (Windpipe) Lungs Diaphragm

Exam Tip: Practice drawing smooth symmetrical outlines of the lungs and windpipe with clearly marked cartilage rings.

CHAPTER - II

LN.: TRANSPORTATION IN ANIMALS AND PLANTS

FILL IN THE BLANKS

Question 1. The fluid part of blood is called ______________.
Answer: Plasma
In simple words: Plasma is the yellowish liquid matrix carrying blood cells.

Exam Tip: Plasma transports water, dissolved nutrients, and waste products.

Question 2. Blood is red in colour due to the presence of a pigment called _________.
Answer: Haemoglobin
In simple words: Haemoglobin binds oxygen molecules to transport them throughout the body.

Exam Tip: Haemoglobin is an iron-containing respiratory pigment.

Question 3. The ___________ cells in our body fight against germs.
Answer: White Blood Cells (WBC)
In simple words: WBCs act as infection-fighting soldiers of the immune system.

Exam Tip: WBCs engulf pathogens or produce antibodies.

Question 4. ___________ help in clotting of blood.
Answer: Platelets
In simple words: Platelets form a clot at injury sites to stop bleeding.

Exam Tip: Blood clotting prevents excessive blood loss during wounds.

Question 5. The number of heart beats per minute is called _______________.
Answer: Pulse rate
In simple words: Pulse rate measures how fast the heart pumps blood.

Exam Tip: Normal resting pulse rate in humans is 72 to 80 beats per minute.

Question 6. The waste dissolved in water is removed as ______________.
Answer: Urine
In simple words: Urea and other liquid wastes dissolve in water to form urine.

Exam Tip: Kidneys filter urine out of the blood.

Question 7. The filtering of blood through an artificial kidney is called _____________.
Answer: Dialysis
In simple words: A life-saving medical process for patients with kidney failure.

Exam Tip: Dialysis removes toxic urea artificially when kidneys fail.

Question 8. Salts and urea is removed along with water as ______________.
Answer: Sweat (or urine)
In simple words: Excretory glands eliminate excess salts and urea through perspiration.

Exam Tip: Sweat glands help regulate body temperature and excrete minor wastes.

Question 9. _________________ carry blood from the heart to all parts of the body.
Answer: Arteries
In simple words: Thick-walled blood vessels carrying oxygen-rich blood away from the heart.

Question 10. ________________ carry blood from all parts of the body to the heart.
Answer: Veins
In simple words: Thin-walled blood vessels with valves carrying deoxygenated blood back to the heart.

Exam Tip: Pulmonary vein is the only exception carrying oxygenated blood.

Question 11. ___________________ is the instrument to amplify the sound of the heart.
Answer: Stethoscope
In simple words: Doctors listen to heartbeat sounds ("lub-dub") using a stethoscope.

Exam Tip: Stethoscope consists of a chest piece and two earpieces connected by tubes.

NAME THE FOLLOWING:

Question 1. The organ which pumps blood.
Answer: Heart
In simple words: Muscular pumping organ situated in the chest cavity.

Exam Tip: Heart never rests throughout an individual's lifetime.

Question 2. The chambers of heart.
Answer: Atria (upper two chambers) and Ventricles (lower two chambers)
In simple words: Four distinct chambers preventing mixing of oxygenated and deoxygenated blood.

Exam Tip: Mention right and left atria and ventricles.

Question 3. The scientist who discovered blood circulation.
Answer: William Harvey
In simple words: English physician who proved blood circulates in a closed loop.

Exam Tip: William Harvey's discovery revolutionized medical science.

Question 4. The parts of excretory system.
Answer: Kidneys, ureters, urinary bladder, and urethra
In simple words: Organs filtering liquid waste and expelling it.

Exam Tip: List all four organs in correct anatomical order.

Question 5. A group of cells that perform a particular function.
Answer: Tissue
In simple words: Tissues form organs and organ systems.

Exam Tip: Blood is a specialized fluid connective tissue.

Question 6. The vein which carries oxygen rich blood to the heart.
Answer: Pulmonary vein
In simple words: Connects lungs to the left atrium of the heart.

Exam Tip: Pulmonary vein is an exception since veins normally carry deoxygenated blood.

Question 7. The artery which carries carbon dioxide rich blood away from the heart.
Answer: Pulmonary artery
In simple words: Connects right ventricle of the heart to the lungs.

Exam Tip: Pulmonary artery is an exception since arteries normally carry oxygenated blood.

Question 8. The vascular tissues in plants.
Answer: Xylem and Phloem
In simple words: Plant transport pipes for water and food.

Exam Tip: Xylem transports water; phloem transports food.

CHOOSE THE CORRECT ANSWER:

Question 1. Pulmonary (vein / artery ) carry pure blood.
Answer: (vein) Pulmonary vein
In simple words: Pulmonary vein carries oxygenated (pure) blood from lungs to heart.

Exam Tip: Pure blood means oxygen-rich blood.

Question 2. (Ammonia / urea ) is the excretory waste in fishes.
Answer: (Ammonia) Ammonia
In simple words: Aquatic animals excrete toxic ammonia directly into surrounding water.

Exam Tip: Ammonia requires large amounts of water for disposal.

Question 3. Phloem helps in the transport of (food / water)in plants.
Answer: (food) Food
In simple words: Phloem distributes synthesized food from leaves to other plant parts.

Exam Tip: Remember: Xylem for water, Phloem for food.

Question 4. Birds excrete (urea / uric acid).
Answer: (uric acid) Uric acid
In simple words: Birds excrete white semi-solid uric acid paste to conserve water.

Exam Tip: Uric acid excretion requires minimal water loss.

Question 5. ( Right / Left )side of the heart carries oxygen rich blood.
Answer: (Left) Left
In simple words: Left atrium and left ventricle handle oxygenated blood destined for body tissues.

Exam Tip: Right side handles deoxygenated blood; left side handles oxygenated blood.

Question 6. Blood is a (solid/liquid ) tissue.
Answer: (liquid) Liquid
In simple words: Blood is a fluid connective tissue consisting of cells suspended in plasma.

Exam Tip: Liquid state allows blood to flow smoothly through narrow capillaries.

Question 7. ( William Harvey / William Beaumont ) discovered the circulation of blood in humans.
Answer: (William Harvey) William Harvey
In simple words: William Harvey discovered blood circulation in the 17th century.

Exam Tip: Do not confuse with William Beaumont who studied digestion.

Question 8. ( Photosynthesis /Transpiration ) is the process responsible for suction pull in plants.
Answer: (Transpiration) Transpiration
In simple words: Loss of water vapor from leaves creates a suction pull drawing water upward.

Exam Tip: Transpiration pull acts like a straw sucking water from roots to leaves.

WRITE TRUE OR FALSE:

Question 1. WBC transports oxygen.
Answer: False
In simple words: RBCs transport oxygen, whereas WBCs fight germs.

Exam Tip: Haemoglobin in RBC carries oxygen.

Question 2. Pulse rate indicate the rate of heart beat.
Answer: True
In simple words: Every heart beat generates a pulse wave in arteries.

Exam Tip: Pulse can be felt easily on the wrist or neck.

Question 3. Pure blood is circulated through the left part of heart.
Answer: True
In simple words: Oxygenated blood enters the left atrium and left ventricle.

Exam Tip: Left side deals with oxygenated blood.

Question 4. Xylem helps in the transport of food in plants.
Answer: False
In simple words: Xylem transports water and minerals, while phloem transports food.

Exam Tip: Check food versus water transport channels carefully.

Question 5. Hydra and sponges posses blood circulatory system.
Answer: False
In simple words: Simple aquatic organisms like Hydra lack a circulatory system; water circulating through their bodies delivers food and oxygen.

Exam Tip: Lower organisms do not need complex circulatory systems.

Question 6. Human urine consists of 95% water, 2.5% urea and 2.5% other waste products.
Answer: True
In simple words: Urine is mostly water containing dissolved urea and mineral salts.

Exam Tip: Remember standard urine composition percentages.

DEFINE: 1. Excretion

Question 1. Excretion
Answer: Excretion is the biological process of removal of toxic metabolic waste products produced in the cells of living organisms from the body.
In simple words: Expelling waste products out of the body.

Exam Tip: Differentiate excretion from egestion (removal of undigested food).

DISTINGUISH: 1. Arteries and veins 2. Xylem and Phloem

Question 1. Arteries and veins
Answer: Arteries carry oxygenated blood away from the heart (except pulmonary artery), have thick elastic walls, and have no valves. Veins carry deoxygenated blood toward the heart (except pulmonary vein), have thin walls, and possess valves to prevent backflow.
In simple words: Arteries carry blood away under high pressure; veins return blood under low pressure using valves.

Exam Tip: Always present distinctions in clear comparative points or tables.

Question 2. Xylem and Phloem
Answer: Xylem is the vascular tissue responsible for the transport of water and dissolved minerals upward from roots to leaves. Phloem is the vascular tissue responsible for the transport of synthesized food from leaves to all other parts of the plant.
In simple words: Xylem carries water upward; phloem distributes food in all directions.

Exam Tip: Mention direction of flow and materials transported.

DIAGRAMS:

1. Schematic human blood circulatory system (fig: 11.3)

Question 1. Schematic human blood circulatory system
Answer: [Schematic flowchart showing lungs, heart (left and right atria/ventricles), and body organs in a closed circulatory loop].
In simple words: A diagram showing how blood travels between heart, lungs, and body organs.

Exam Tip: Use arrows to show the direction of blood flow clearly.

2. Human excretory system (fig: 11.6)

Question 2. Human excretory system
Answer: [Diagram showing bean-shaped kidneys, ureters, urinary bladder, and urethra].
In simple words: Diagram showing urine-producing and storing organs in humans.

Exam Tip: Clearly label kidneys, ureters, urinary bladder, and urethra.

CH. 12: REPRODUCTION IN PLANTS

I. Fill in the blanks:

Question 1. Male reproductive part of a plant is __________________.
Answer: Stamen
In simple words: Stamen consists of anther and filament producing pollen grains.

Exam Tip: Remember: Stamen is male, pistil is female.

Question 2. Plants produce seeds as a result of _______________ reproduction.
Answer: Sexual
In simple words: Fusion of male and female gametes produces seeds

Exam Tip: Sexual reproduction involves flower pollination and fertilization.

Question 3. Asexual reproduction in spirogyra is ________________.
Answer: Fragmentation
In simple words: Spirogyra breaks into two or more fragments, each growing into a new individual.

Exam Tip: Fragmentation is common in algae like Spirogyra.

Question 4. Mustard and Rose have _____________ flowers.
Answer: Unisexual (or Bisexual depending on context; usually mustard and rose are bisexual)
In simple words: Flowers containing both male and female reproductive organs are bisexual.

Exam Tip: Mustard, rose, and petunia are bisexual flowers.

Question 5. The seeds develop from the _________________.
Answer: Ovules
In simple words: After fertilization, ovules transform into seeds.

Exam Tip: Ovules become seeds and the ovary becomes the fruit.

Question 6. Production of new individuals from vegetative parts of a plant is called _________________.
Answer: Vegetative propagation
In simple words: Growing new plants from roots, stems, or leaves.

Exam Tip: Examples include potato tubers and bryophyllum leaves.

II Write True or False:

Question 1. Yeast is a single celled organism.
Answer: True
In simple words: Yeast is a microscopic fungus made of a single cell.

Exam Tip: Yeast reproduces asexually by budding.

Question 2. The zygote develops into an embryo.
Answer: True
In simple words: Fertilized egg cell (zygote) divides and develops into an embryo inside the seed.

Exam Tip: Zygote is formed by the fusion of male and female gametes.

Question 3. The production of new individuals from their parents is known as respiration.
Answer: False
In simple words: Production of new individuals is called reproduction, not respiration.

Exam Tip: Do not confuse reproduction with respiration.

Question 4. Pistil is the female reproductive part of a plant.
Answer: True
In simple words: Pistil consists of stigma, style, and ovary.

Exam Tip: Pistil is also known as carpel.

Question 5. Corn and Papaya produce bisexual flowers.
Answer: False
In simple words: Corn and papaya produce unisexual flowers having either male or female organs.

Exam Tip: Papaya and cucumber bear unisexual flowers.

Question 6. Plants produce seeds as a result of asexual reproduction.
Answer: False
In simple words: Seeds are produced through sexual reproduction.

Exam Tip: Asexual reproduction does not involve seeds or gamete fusion.

Question 7. The fruit is a ripened ovary.
Answer: True
In simple words: After fertilization, the ovary swells up and ripens into a fruit.

Exam Tip: Other floral parts wither and fall off.

Question 8. In asexual reproduction, only one parent is involved.
Answer: True
In simple words: New plants arise from a single parent without gamete fusion.

Exam Tip: Offspring are genetically identical to the single parent.

III Name the following:

Question 1. Two types of pollination seen in flowers.
Answer: Self-pollination and Cross-pollination
In simple words: Transfer of pollen grains within the same flower or to another flower.

Exam Tip: Distinguish between self and cross-pollination clearly.

Question 2. Two seeds dispersed by animals.
Answer: Xanthium and Urena
In simple words: Spiky seeds equipped with hooks attaching to animal fur.

Exam Tip: Animal dispersal prevents overcrowding around parent plants.

Question 3. Asexual reproduction in yeast.
Answer: Budding
In simple words: Small bulb-like projections (buds) detach to form new yeast cells.

Exam Tip: Budding is a common form of asexual reproduction in single-celled fungi.

Question 4. Two spore producing plants.
Answer: Ferns and Mosses (or Fungi/Bread mold)
In simple words: Non-flowering plants reproducing via microscopic spores.

Exam Tip: Spores are covered by a hard protective coat to survive harsh conditions.

Question 5. Two winged seeds.
Answer: Maple and Drumstick (or Sycamore)
In simple words: Seeds adapted for wind dispersal using wing-like structures.

Exam Tip: Winged seeds float easily in the wind.

IV Define:

Question 1. Pollination
Answer: The transfer of pollen grains from the anther to the stigma of a flower of the same kind is called pollination.
In simple words: Transfer of pollen grains to the stigma.

Exam Tip: Mention agents of pollination like wind, water, and insects.

Question 2. Fertilisation
Answer: The fusion of male gamete with the female gamete to form a zygote is known as fertilisation.
In simple words: Joining of male and female reproductive cells.

Exam Tip: Fertilisation results in zygote formation.

Question 3. Reproduction
Answer: Reproduction is the biological process by which living organisms produce new individuals of their own kind.
In simple words: Production of young ones of the same species.

Exam Tip: Essential for the continuation of species on Earth.

V Distinguish: Unisexual and bisexual flowers.

Question 1. Unisexual and bisexual flowers
Answer: Unisexual flowers contain either only male reproductive organs (stamen) or only female reproductive organs (pistil), such as corn and papaya. Bisexual flowers contain both male and female reproductive organs in the same flower, such as mustard and rose.
In simple words: Unisexual flowers have one gender organ; bisexual flowers have both.

Exam Tip: Give examples for both types of flowers.

LN. 13: MOTION AND TIME

I Fill in the blanks:

Question 1. The distance moved by an object in a unit time is called its ___________.
Answer: Speed
In simple words: Speed measures how fast an object is moving.

Exam Tip: Formula: \(\text{Speed} = \frac{\text{Distance}}{\text{Time}}\).

Question 2. Basic unit of measuring speed is _____________.
Answer: Meter per second (m/s)
In simple words: Standard SI unit for speed.

Exam Tip: Kilometer per hour (km/h) is another common unit.

Question 3. ______________ events are used for the measurement of time.
Answer: Periodic (or repetitive)
In simple words: Events that repeat at regular intervals measure time.

Exam Tip: Pendulum oscillations are classic periodic events.

Question 4. A _______________ consists of a small metallic ball or a piece of stone suspended from a rigid stand by a thread.
Answer: Simple pendulum
In simple words: A device used to demonstrate periodic oscillatory motion.

Exam Tip: The metallic ball is termed the bob.

Question 5. The metallic ball is called the ______________ of the pendulum.
Answer: Bob
In simple words: Suspended heavy mass of a pendulum.

Exam Tip: Bob swings back and forth in periodic motion.

Question 6. The to and fro motion of a simple pendulum is an example of a ____________ or an ______________ motion.
Answer: Periodic, oscillatory
In simple words: Motion repeating itself in equal intervals of time.

Exam Tip: Oscillatory motion is a type of periodic motion.

Question 7. Meter that measures the distance moved by the vehicle is known as ____________________.
Answer: Odometer
In simple words: Instrument recording total distance traveled on a vehicle's dashboard.

Exam Tip: Do not confuse odometer (distance) with speedometer (speed).

Question 8. Motion of objects can be presented in pictorial from by their __________.
Answer: Graphs
In simple words: Distance-time graphs display motion visually.

Exam Tip: Line graphs are commonly used to represent motion.

Question 9. Rockets, launching satellites into earth’s orbit often attain speeds up to ___________________ Km/s.
Answer: 8 km/s (or 11.2 km/s escape velocity)
In simple words: Enormous velocities required to overcome Earth's gravity.

Exam Tip: Spacecraft require high speeds to reach orbital altitude.

Question 10. The basic unit of time is ________________.
Answer: Second (s)
In simple words: Standard SI unit of time.

Exam Tip: Minutes and hours are larger units derived from seconds.

II. Write true or false:

Question 1. A year was fixed as the time taken by the earth to complete one revolution of the sun.
Answer: True
In simple words: One solar year equals one complete Earth orbit around the sun.

Exam Tip: Earth's revolution defines the calendar year.

Question 2. A nanosecond is one billionth of a second.
Answer: True
In simple words: \(10^{-9}\) seconds is a nanosecond

Question 3. The motion of a pendulum is an example of non-periodic motion.
Answer: False
In simple words: Pendulum motion is periodic because it repeats in equal time intervals.

Exam Tip: Periodic motion repeats at regular time intervals.

Question 4. In ancient time people used to measure time with help of clock or wristwatch.
Answer: False
In simple words: Ancient people used sundials, water clocks, and sand clocks, not modern watches.

Exam Tip: Mechanical watches were invented much later in history.

Question 5. The time taken by the pendulum to complete one oscillation is called its time period.
Answer: True
In simple words: Time period is the duration of one complete swing (to and fro).

Exam Tip: Time period remains constant for a pendulum of fixed length.

Question 6. The graph for non-uniform motion is a curve line.
Answer: True
In simple words: A curved distance-time graph indicates changing (non-uniform) speed.

Exam Tip: Uniform motion produces a straight line graph.

III Name the following:

Question 1. Name any two ancient - time measuring devices.
Answer: Sundial and Water clock (Hourglass / Sand clock)
In simple words: Primitive devices based on shadow movement or steady flow.

Exam Tip: Sundials tracked shadow positions throughout the day.

Question 2. Name the scientist who discovered pendulum.
Answer: Galileo Galilei
In simple words: Italian astronomer who noticed swinging chandeliers in a cathedral.

Question 3. Name the meter in vehicles which records the speed directly in Km/h.
Answer: Speedometer
In simple words: Dashboard gauge indicating instantaneous speed.

Exam Tip: Speedometer measures speed; odometer measures distance.

Question 4. Name the ancient clock located at Jantar Mantar, Delhi.
Answer: Samrat Yantra (Sundial)
In simple words: Massive stone sundial built by Maharaja Jai Singh II.

Exam Tip: Jantar Mantar features fascinating architectural astronomical instruments.

IV Define the following:

Question 1. Motion
Answer: Motion is defined as the change in position of an object with respect to its surroundings over time.
In simple words: Movement of an object from one place to another.

Exam Tip: Motion is relative to an observer's frame of reference.

Question 2. Speed
Answer: Speed is the distance covered by an object in unit time.
In simple words: How fast an object travels.

Exam Tip: State the formula \(\text{Speed} = \frac{\text{Distance}}{\text{Time}}\).

Question 3. Oscillation
Answer: One complete to and fro motion of a simple pendulum is called an oscillation.
In simple words: One full swing back and forth.

Exam Tip: Moving from extreme position A to B and back to A counts as one oscillation.

V Distinguish between: 1. Uniform motion and Non-uniform motion.

Question 1. Uniform motion and Non-uniform motion
Answer: An object moving along a straight line with a constant speed is said to have uniform motion, producing a straight line distance-time graph. An object moving along a straight line with changing speed is said to have non-uniform motion, producing a curved distance-time graph.
In simple words: Uniform motion covers equal distances in equal time intervals; non-uniform motion does not.

Exam Tip: Mention graph shapes (straight line vs. curve) as key distinguishing points.

CH. 14: ELECTRIC CURRENT AND ITS EFFECTS

I Fill in the blanks:

Question 1. A thin wire in the bulb that glows when an electric current passes through it is called the ____________________.
Answer: Filament
In simple words: High-resistance tungsten wire emitting light when heated.

Exam Tip: Filaments glow white-hot due to the heating effect of electric current.

Question 2. When the bulb gets _______________, its filament is broken.
Answer: Fused
In simple words: A broken filament interrupts the circuit, stopping current flow.

Exam Tip: Fused bulbs do not glow because the circuit is incomplete.

Question 3. The coil of wire in an electric heater is known as ________________.
Answer: Element
In simple words: Nichrome wire coil producing heat in appliances like irons and heaters.

Exam Tip: Heating elements are made of high-resistance alloys like nichrome.

Question 4. The amount of heat produced in a wire depends on its, ______________, ________________ and __________________.
Answer: Material, length, and thickness
In simple words: Heat generation depends on wire properties and current magnitude.

Exam Tip: Thinner and longer wires produce more heat for the same current.

Question 5. When an electric current flows through a wire, it behaves like a _________________.
Answer: Magnet
In simple words: Demonstrates the magnetic effect of electric current.

Exam Tip: Discovered first by Hans Christian Oersted.

Question 6. The ___________of an electric bell acts as an electromagnet in its working.
Answer: Iron piece (or iron core / electromagnet coil)
In simple words: Electromagnet attracts the iron armature to ring the bell.

Exam Tip: Electric bells rely on magnetic interruption circuits.

II State whether the following statements are True or False:

Question 1. When the electric current is switched off, the coil generally loses its magnetism.
Answer: True
In simple words: Electromagnets are temporary magnets losing magnetism when power is cut.

Exam Tip: This property makes electromagnets useful in cranes and switches.

Question 2. The wires used for making electric circuits do not normally become hot.
Answer: True
In simple words: Circuit wires have very low resistance, producing negligible heat.

Question 3. The filament of an electric bulb never gets heated.
Answer: False
In simple words: Filaments get extremely hot to emit light.

Exam Tip: Intense heating causes filament glowing.

Question 4. In a battery, the electric cells are always placed one after the other.
Answer: True (positive terminal of one connected to negative of next)
In simple words: Cells are connected in series to form a battery.

Exam Tip: Series connection increases total voltage.

Question 5. Connecting many devices in a single socket does not affect the flow of current in a circuit.
Answer: False
In simple words: Overloading a single socket draws excessive current, causing overheating and potential fire hazards.

Exam Tip: Overloading leads to short circuits and tripped fuses.

Question 6. Wear and tear of insulated wires can cause short circuits.
Answer: True
In simple words: Damaged insulation allows live and neutral wires to touch directly.

Exam Tip: Short circuits produce dangerous sparking and high currents.

Question 7. CFLs consume more electricity than ordinary bulbs.
Answer: False
In simple words: CFLs and LEDs consume much less electricity than incandescent bulbs.

Exam Tip: Energy-efficient bulbs reduce electricity bills and wastage.

III Name the following:

Question 1. The name of the scientist who first noticed the magnetic effect of current.
Answer: Hans Christian Oersted
In simple words: Danish physicist who observed compass needle deflection near a live wire.

Exam Tip: Oersted's discovery linked electricity and magnetism.

Question 2. The switches being used in place of fuses.
Answer: MCB (Miniature Circuit Breakers)
In simple words: Safety switches that automatically trip off during overload.

Exam Tip: MCBs are reusable safety devices replacing traditional wire fuses.

Question 3. A diagram made using symbols of electric components.
Answer: Circuit diagram
In simple words: Standard schematic representation of an electric circuit.

Question 4. The mark of safety necessary on electrical appliances.
Answer: ISI mark (or BIS mark)
In simple words: Quality certification assuring safety standards.

Exam Tip: Always check for ISI certification on electrical goods.

IV Define:

Question 1. Battery
Answer: A battery is a combination of two or more electric cells connected in series, where the positive terminal of one cell is connected to the negative terminal of the next cell.
In simple words: Combination of multiple cells providing electrical energy.

Exam Tip: Mention series connection of cells.

Question 2. Electromagnet
Answer: A coil of insulated wire wrapped around a soft iron core that behaves like a magnet when electric current flows through it is called an electromagnet.
In simple words: A temporary magnet working on electric current.

Exam Tip: Electromagnets lose magnetism instantly when current stops.

Question 3. Fuse
Answer: A safety device used in electrical circuits containing a wire made of a special alloy that melts quickly and breaks the circuit when excessive current flows through it.
In simple words: Safety wire protecting appliances from power surges.

Exam Tip: Fuses prevent fires and appliance damage caused by overloading.

LN. 15: LIGHT

I. Fill in the blanks:

Question 1. The change in the direction of light by a mirror is called ______________.
Answer: Reflection of light
In simple words: Bouncing back of light rays from shining surfaces.

Exam Tip: Angle of incidence equals angle of reflection.

Question 2. The image formed by a ____________ lens is always virtual, erect and smaller in size.
Answer: Concave lens
In simple words: Diverging lens producing diminished virtual images.

Exam Tip: Concave lens is thinner at the center and thicker at edges.

Question 3. White light is composed of ______________ colours.
Answer: Seven (VIBGYOR)
In simple words: Sunlight splits into seven distinct spectral colors.

Exam Tip: VIBGYOR stands for Violet, Indigo, Blue, Green, Yellow, Orange, and Red.

Question 4. The image of an object formed by a _____________ cannot be obtained on a screen.
Answer: Plane mirror (or concave mirror/convex lens when virtual)
In simple words: Virtual images cannot be projected onto physical screens.

Question 5. _____________ are used by dentists to see an enlarged image of the teeth.
Answer: Concave mirrors
In simple words: Concave mirrors produce enlarged erect images when objects are kept close.

Exam Tip: Dentists use concave mirrors for magnified views of teeth.

II Name the following:

Question 1. An image that can be obtained on the screen -
Answer: Real image
In simple words: Image formed by actual intersection of light rays.

Exam Tip: Real images are generally inverted.

Question 2. The lens which feel thinner in the middle than at the edges -
Answer: Concave lens
In simple words: Diverging lens with depressed center.

Exam Tip: Opposite of convex lens.

Question 3. The lens known as magnifying glass -
Answer: Convex lens
In simple words: Converging lens producing enlarged images.

Exam Tip: Used in reading glasses and microscopes.

Question 4. The lens known as diverging lens -
Answer: Concave lens
In simple words: Spreads parallel light rays outward.

Exam Tip: Corrects nearsightedness (myopia).

Question 5. The mirror which can form both real as well as virtual images.
Answer: Concave mirror
In simple words: Spherical mirror forming real images when distant and virtual when close.

Exam Tip: Convex mirrors and plane mirrors only form virtual images.

Question 6. The large arc of seven colours VIBGYOR in the sky.
Answer: Rainbow
In simple words: Natural spectrum formed by sunlight dispersion through water droplets.

Exam Tip: Raindrops act like tiny glass prisms dispersing sunlight.

III State whether True or False:

Question 1. The image formed by a plane mirror is inverted -
Answer: False (it is erect and laterally inverted)
In simple words: Plane mirrors form upright images showing lateral inversion (left appears right).

Exam Tip: Lateral inversion is a characteristic feature of plane mirror images.

Question 2. A convex lens is thicker in the middle than at the edges -
Answer: True
In simple words: Bulging center characterizes convex lenses.

Exam Tip: Converges light rays to a focal point.

Question 3. A concave mirror always forms real image -
Answer: False
In simple words: Concave mirrors form virtual, magnified images when objects are placed very close to them.

Question 4. Any polished or shining surface can act as mirror -
Answer: True
In simple words: Polished metallic surfaces reflect light regularly acting like mirrors.

Exam Tip: Regular reflection requires smooth, shining surfaces.

IV Define: Reflection of light

Question 1. Reflection of light
Answer: The bouncing back of light rays from a polished, shining surface into the same medium is called reflection of light.
In simple words: Light bouncing off a mirror.

Exam Tip: Laws of reflection state angle of incidence equals angle of reflection.

V Distinguish: Real image & Virtual image

Question 1. Real image & Virtual image
Answer: A real image is formed when light rays actually intersect after reflection or refraction, and it can be caught on a screen (generally inverted). A virtual image is formed when light rays appear to diverge from a point, and it cannot be caught on a screen (always erect).
In simple words: Real images can be projected on screens; virtual images cannot.

Exam Tip: Screen projection is the definitive test for real images.

CH. 16: WATER: A PRECIOUS RESOURCE

I Fill in the blanks:

Question 1. The ________________ in the soil indicates the presence of underground water.
Answer: Moisture (or dampness)
In simple words: Damp soil reflects underlying groundwater presence.

Exam Tip: Capillary action draws groundwater upward, keeping upper soil damp.

Question 2. Water in the aquifers can be usually pumped out with help of __________ or ______________.
Answer: Tubewells, handpumps
In simple words: Mechanical devices drawing underground water to the surface.

Exam Tip: Aquifers store massive underground water reserves.

Question 3. _____________ was the traditional way of collecting water.
Answer: Bawri (or Rainwater harvesting / stepwell)
In simple words: Traditional stepwells storing rainwater for dry seasons.

Question 4. Shortage of ___________ has become a matter of concern.
Answer: Usable water (Freshwater)
In simple words: Growing populations face severe freshwater scarcity.

Exam Tip: Conservation and rainwater harvesting help mitigate water shortages.

II Write True or False:

Question 1. Celebration of water day is to attract the attention of everybody towards the importance of conserving water.
Answer: True
In simple words: World Water Day promotes global awareness regarding water conservation.

Exam Tip: Celebrated annually on March 22nd.

Question 2. 76% of the earth’s surface is covered with water.
Answer: False (about 71%)
In simple words: Roughly 71% of Earth is covered by oceans and water bodies.

Question 3. Glaciers are the solid form of water.
Answer: True
In simple words: Polar ice caps and glaciers store vast quantities of freshwater in solid ice form.

Exam Tip: Glaciers represent a major freshwater reserve on Earth.

Question 4. Excessive rains cause droughts whereas the absence of rains results in floods.
Answer: False (excessive rains cause floods, absence causes droughts)
In simple words: Heavy rains cause flooding, while lack of rain causes severe droughts.

Exam Tip: Do not interchange floods and droughts.

III Define: 1. Drip irrigation.

Question 1. Drip irrigation
Answer: Drip irrigation is a watering technique where narrow pipes deliver water drop by drop directly at the base of plant roots, minimizing water wastage through evaporation.
In simple words: Water-saving irrigation delivering drops directly to plant roots.

Exam Tip: Highly efficient method preventing agricultural water loss.

IV Diagram: Ground water and Water table.

Question 1. Ground water and Water table
Answer: [Diagram showing upper soil layers, water table line, and saturated groundwater zone in aquifers].
In simple words: Diagram showing underground water levels beneath soil layers.

Exam Tip: Clearly mark the water table boundary separating dry soil and saturated groundwater.

CH. 17 - FOREST: OUR LIFE LINE

I Fill in the blanks:

Question 1. Decomposers convert dead plants and animals into __________________.
Answer: Humus (Nutrients)
In simple words: Microorganisms break down dead remains into rich soil humus.

Exam Tip: Decomposers play a vital role in nutrient recycling in forests.

Question 2. Tall trees which look like roof over other plants in the forest is called ______________.
Answer: Canopy
In simple words: Upper leafy roof formed by tall forest trees.

Exam Tip: Canopy shields the forest floor from direct sunlight.

Question 3. The various components of the forests are ___________ on another.
Answer: Interdependent (Interconnected)
In simple words: Plants, animals, and soil rely mutually on each other in an ecosystem.

Exam Tip: Disturbance in one component affects the entire forest food web.

Question 4. Forests are the ___________ for the forest dwelling communities.
Answer: Lifeline (home / source of food and shelter)
In simple words: Tribal communities depend entirely on forests for survival.

Exam Tip: Forests provide livelihood, medicine, and shelter.

Question 5. ______________ help forest to grow and regenerate.
Answer: Animals and birds (seed dispersal and pollination)
In simple words: Fauna aids plant propagation and forest regeneration.

Exam Tip: Seed dispersal by animals helps forests spread naturally.

Question 6. ______________ forms the uppermost layer in the forest.
Answer: Crown of tall trees (Canopy)
In simple words: Branchy upper treetops receiving maximum sunlight.

Exam Tip: Crown shapes vary across different tree species.

II State whether True or False:

Question 1. The different horizontal layers in the forest are known as under storeys.
Answer: True
In simple words: Different vegetation heights create layers called understoreys.

Exam Tip: Herbs, shrubs, and tall trees form distinct forest strata.

Question 2. Forest help in causing floods.
Answer: False (forests prevent floods)
In simple words: Forest roots absorb rainwater and slow down runoff, preventing floods.

Exam Tip: Deforestation increases flood risks.

Question 3. Forest are called green lungs.
Answer: True
In simple words: Forests release oxygen and absorb carbon dioxide, acting like lungs for the planet.

Exam Tip: Crucial for maintaining atmospheric oxygen balance.

Question 4. The type of animals remain same from forest to forest.
Answer: False
In simple words: Animal species vary depending on climate, geography, and flora of each forest.

Exam Tip: Biodiversity differs across tropical, temperate, and boreal forests.

Question 5. Deforestation will endanger our life and environment.
Answer: True
In simple words: Cutting down forests causes global warming, soil erosion, and habitat loss.

Exam Tip: Afforestation is vital to combat climate change.

Question 6. Forest is a dynamic living entity.
Answer: True
In simple words: Forests are constantly growing, regenerating, and supporting vibrant ecosystems.

Exam Tip: A forest is full of life and constant biological activity.

III Name the following:

Question 1. The branchy part of a tree above the stem.
Answer: Crown
In simple words: Upper portion of a tree bearing branches and leaves.

Exam Tip: Crowns can be conical, dome-shaped, or spread out.

Question 2. Two forest products.
Answer: Timber and Honey (or Gum, medicinal herbs, sealing wax)
In simple words: Useful materials obtained naturally from forests.

Exam Tip: Forests provide diverse raw materials for industries.

Question 3. The lowest layer of vegetation in a forest.
Answer: Herbs and grasses (Herb layer)
In simple words: Small plants growing closest to the forest floor.

Exam Tip: Receives the least sunlight among all forest layers.

IV Define:

Question 1. Forest.
Answer: A forest is a large area covered chiefly with trees and undergrowth, supporting a complex ecosystem of diverse plants and animals.
In simple words: A dense natural community of trees and wildlife.

Exam Tip: Forests cover about 30% of Earth's land surface.

Question 2. Deforestation.
Answer: Deforestation is the large-scale clearing or removal of forest trees for agricultural, industrial, or urban use.
In simple words: Destruction of forests by human activities.

Exam Tip: Deforestation severely impacts climate and wildlife habitats.

Question 3. Canopy.
Answer: The uppermost branches and leaves of tall trees forming a roof-like cover over the forest floor is called a canopy.
In simple words: Leafy roof formed by tall trees.

Exam Tip: Canopy blocks direct sunlight from reaching lower forest strata.

Question 4. Crown
Answer: The branchy part of a tree that is above the stem is known as the crown.
In simple words: Upper leafy head of a tree.

Exam Tip: Different tree species have characteristic crown shapes.

CH. 18: WASTE WATER STORY

I. Fill in the blanks:

Question 1. Waste water is treated in a ________________.
Answer: WWTP (Waste Water Treatment Plant / Sewage Treatment Plant)
In simple words: Facility purifying dirty water before releasing into water bodies.

Exam Tip: Sewage treatment involves physical, chemical, and biological processes.

Question 2. The sludge is decomposed by ____________ bacteria.
Answer: Anaerobic
In simple words: Bacteria decomposing organic sludge without oxygen.

Exam Tip: Anaerobic digestion produces biogas as a byproduct.

Question 3. _____________ and contaminated drinking water is the cause of a large number of diseases.
Answer: Untreated sewage (or polluted water)
In simple words: Consumption of contaminated water transmits waterborne diseases.

Exam Tip: Cholera and typhoid spread via contaminated drinking water.

Question 4. The process of waste water treatment is known as _______________.
Answer: Sewage treatment (Purification)
In simple words: Cleaning dirty wastewater to make it safe.

Exam Tip: Removes physical, chemical, and biological impurities.

Question 5. Sewage is a _____________________ waste.
Answer: Liquid (or complex mixture containing suspended and dissolved solids)
In simple words: Wastewater generated from homes, industries, and hospitals.

Exam Tip: Sewage contains human excreta, food waste, and chemicals.

Question 6. The activated sludge is about _____________ % water.
Answer: 96 to 97%
In simple words: Sludge is mostly water with a small percentage of solid organic matter.

Exam Tip: Dried sludge is frequently used as manure.

Question 7. The suspended impurities dissolved in swage are called ______________.
Answer: Contaminants (or impurities / solids)
In simple words: Harmful pollutants present in sewage water.

Exam Tip: Separated during primary filtration stages.

II Name the following:

Question 1. The nutrient present in sewage.
Answer: Nitrogen, Phosphorus, and Potassium (or Organic nutrients)
In simple words: Chemical nutrients found in organic sewage waste.

Exam Tip: Excessive nutrients cause algal blooms in water bodies.

Question 2. By products of waste water treatment.
Answer: Sludge and Biogas
In simple words: Useful materials generated during sewage treatment.

Exam Tip: Biogas is used as fuel, and sludge as manure.

Question 3. A plant which can absorb waste water rapidly and release pure water vapour to the atmosphere.
Answer: Eucalyptus
In simple words: Fast-transpiring trees planted near sewage ponds.

Exam Tip: Eucalyptus trees absorb excess wastewater effectively.

Question 4. Solid waste extracted in sewage treatment.
Answer: Sludge
In simple words: Solid waste settling at the bottom during sedimentation.

Exam Tip: Cleared out and processed using anaerobic bacteria.

Question 5. Any two water borne disease.
Answer: Cholera and Typhoid (or Dysentery, Jaundice)
In simple words: Illnesses caused by drinking contaminated water.

Exam Tip: Caused by pathogenic bacteria and viruses in polluted water.

Question 6. Expand WWTP.
Answer: Waste Water Treatment Plant
In simple words: Facility for treating sewage and wastewater.

Exam Tip: Learn full expansions of standard abbreviations.

III State whether True or False:

Question 1. Urea is an inorganic impurity present in sewage.
Answer: False (Urea is an organic impurity)
In simple words: Urea is a carbon-containing organic compound present in human waste.

Exam Tip: Categorize impurities into organic and inorganic correctly.

Question 2. Sewerage is a transport system that carries sewage to the treatment plant.
Answer: True
In simple words: Network of underground pipes (sewers) transporting sewage.

Exam Tip: Distinguish between sewage (waste) and sewerage (drainage network).

Question 3. Chemical toilet is a low cost onsite sewage disposal system.
Answer: True
In simple words: Sanitary toilets operating without complex underground drainage systems.

Question 4. Sewage is solid waste which causes water and soil pollution.
Answer: True
In simple words: Untreated sewage contaminates water bodies and soil destructively.

Exam Tip: Proper treatment prevents environmental pollution.

Question 5. Untreated human excreta is a health hazard.
Answer: True
In simple words: Contains pathogens spreading deadly waterborne diseases.

Exam Tip: Proper sanitation prevents disease outbreaks.