CBSE Class 7 Science Nutrition Worksheet

Chapter 1 : Nutrition in Plants

Fill in the blanks :

Question 1. The components of food which are necessary for our body are called _______________
Answer: nutrients
In simple words: Nutrients are essential substances found in food that our body needs to function properly.

Exam Tip: Remember the major nutrients include carbohydrates, proteins, fats, vitamins, and minerals.

Question 2. Green plants synthesise their own food themselves by the process of __________________.
Answer: photosynthesis
In simple words: Photosynthesis is the method plants use to make food using sunlight, water, and carbon dioxide.

Exam Tip: Key ingredients for photosynthesis are chlorophyll, sunlight, carbon dioxide, and water.

Question 3. ______________________ is the mode of taking food by an organism and its utilization by the body.
Answer: Nutrition
In simple words: Nutrition is how living things get food and use it for growth and energy.

Exam Tip: Do not confuse nutrition with nutrients; nutrition is the overall process.

Question 4. Complex chemical substances such as ______________ are the products of photosynthesis.
Answer: carbohydrates (starch)
In simple words: Plants produce simple sugars during photosynthesis, which are then stored as complex carbohydrates like starch.

Exam Tip: Starch is the primary stored food in plants.

Question 5. ___________________ gas is produced during photosynthesis.
Answer: Oxygen
In simple words: Oxygen is released into the air as a byproduct when plants make their food.

Question 6. Organisms that are dependent on others for their nutrition are called ______________________
Answer: heterotrophs
In simple words: Heterotrophs rely on plants or other animals for their food supply.

Exam Tip: Animals and non-green plants fall under this category.

Question 7. _________________ are the tiny pores present on the surface of the leaves and are surrounded by guard cells.
Answer: Stomata
In simple words: Stomata are microscopic openings on leaves that help in gas exchange.

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

Question 8. ____________________is the ultimate source of energy for all living organisms.
Answer: The sun
In simple words: All living things directly or indirectly depend on solar energy captured by plants.

Exam Tip: Highlight that solar energy is trapped by chlorophyll in plants.

Question 9. Organisms which derive their nutrition from dead decaying matter are called _______________.
Answer: saprotrophs (saprophytes)
In simple words: Saprotrophs feed on dead and decaying organic material by secreting digestive juices on it.

Exam Tip: Fungi and bacteria are common examples of saprotrophs.

Question 10. Some organisms live together and share shelter and nutrients, this is called _____________________.
Answer: symbiosis (symbiotic relationship)
In simple words: Symbiosis is a close partnership where two different organisms help each other survive.

Exam Tip: Classic examples include lichens (alga and fungus) and Rhizobium bacteria in root nodules.

Question 11. Carbohydrates are made up of _________,__________ and __________.
Answer: carbon, hydrogen, oxygen
In simple words: Carbohydrates are organic compounds consisting of carbon, hydrogen, and oxygen atoms.

Exam Tip: Memorize the chemical constituents of basic food components.

Name the following :

Question 1. A bacterium that can take atmospheric nitrogen and convert it into a soluble form.
Answer: Rhizobium
In simple words: Rhizobium bacteria live in the roots of leguminous plants and fix atmospheric nitrogen.

Exam Tip: Rhizobium cannot make its own food; it lives in a symbiotic association with legume roots.

Question 2. An insectivorous plant.
Answer: Pitcher plant (or Venus flytrap)
In simple words: Insectivorous plants trap insects to fulfill their nitrogen requirements in nutrient-deficient soil.

Exam Tip: Pitcher plants are modified leaves shaped like a pitcher with a lid.

Question 3. The mode of nutrition in mushrooms.
Answer: Saprotrophic nutrition
In simple words: Mushrooms absorb nutrients from dead and decaying matter.

Exam Tip: They release digestive juices onto dead matter to convert it into a solution before absorbing it.

Question 4. The indicator used to test the presence of starch in leaves.
Answer: Iodine solution
In simple words: Iodine turns blue-black when it comes in contact with starch.

Exam Tip: Leaves are usually boiled in alcohol to remove chlorophyll before adding iodine.

II) Write True or False :

Question 1. Some fungi are used in medicines.[ ]
Answer: True
In simple words: Certain fungi like Penicillium are used to produce life-saving antibiotics.

Exam Tip: Penicillin is derived from the fungus *Penicillium notatum*.

Question 2. Most of the pulses are obtained from leguminous plants. [ ]
Answer: True
In simple words: Pulses (dals) come from plants belonging to the legume family.

Exam Tip: Leguminous plants help enrich the soil with nitrogen.

Question 3. Cuscuta (Amarbel) is a host.[ ]
Answer: False
In simple words: Cuscuta is a parasite, not a host; it climbs on a host plant to steal food.

Exam Tip: The plant on which Cuscuta climbs is called the host.

Question 4. Lichens, an alga and a fungus show symbiotic relationship. [ ]
Answer: True
In simple words: Algae provide food through photosynthesis while fungi provide shelter, water, and minerals.

Exam Tip: Lichens are classic textbook examples of mutualism.

Question 5. In desert plants, green stems carry out photosynthesis.[ ]
Answer: True
In simple words: Desert plants like cacti have leaves modified into spines to reduce water loss, so their green stems perform photosynthesis.

Exam Tip: Modifications in xerophytic plants prevent excessive transpiration.

III) Define the following

Question 1. Autotrophs
Answer: Organisms that make their own food simply from inorganic substances like carbon dioxide and water using light energy are called autotrophs. Example: Green plants.
In simple words: Self-nourishing organisms that produce their own food.

Exam Tip: "Auto" means self, "troph" means nourishment.

Question 2. Saprotrophs
Answer: Organisms that obtain their nutrients in solution form from dead and decaying organic matter are called saprotrophs. Example: Fungi and certain bacteria.
In simple words: Organisms that feed on dead matter.

Exam Tip: They secrete digestive juices onto decaying matter to externally digest it.

Question 3. Heterotrophs
Answer: Organisms that cannot manufacture their own food and depend directly or indirectly on plants or other organisms for nutrition are called heterotrophs. Example: Animals, humans, and non-green plants.
In simple words: Organisms that depend on others for food.

Exam Tip: "Hetero" means other, "troph" means nourishment.

Question 4. Nutrition
Answer: Nutrition is the mode of taking food by an organism and its utilization by the body for energy, growth, and repair of damaged parts.
In simple words: The process of consuming and utilizing food.

Question 1. Cell
Answer: Draw a plant or animal cell showing the cell membrane, cytoplasm, nucleus, and organelles.
In simple words: A basic structural and functional unit of life.

Exam Tip: Clearly label the nucleus in the center and the surrounding cytoplasm.

Question 2. Photosynthesis in plants.
Answer: Draw a plant showing roots absorbing water, leaves absorbing sunlight and carbon dioxide, and releasing oxygen.
In simple words: A diagram showing raw materials entering a plant and products being released.

Exam Tip: Use arrows to indicate the inward flow of carbon dioxide and water and outward flow of oxygen.

Chapter 2 : Nutrition in Animals

Fill in the blanks :

Question 1. The mode of taking food into the body is called ___________________
Answer: ingestion
In simple words: Ingestion is the act of putting food into the mouth.

Exam Tip: Ingestion is the first step of animal nutrition.

Question 2. In the process of ________________ food is broken down in to simpler substances.
Answer: digestion
In simple words: Digestion converts complex food molecules into simple, absorbable forms.

Question 3. The _______________ canal start with mouth and ends in anus.
Answer: alimentary canal (or digestive tract)
In simple words: The continuous muscular tube through which food passes during digestion.

Exam Tip: It includes the buccal cavity, oesophagus, stomach, small intestine, large intestine, rectum, and anus.

Question 4. ___________________glands are present in mouth.
Answer: Salivary glands
In simple words: Salivary glands secrete saliva into the mouth cavity.

Exam Tip: Humans have three pairs of major salivary glands.

Question 5. Saliva helps in the digestion of ___________________ in food.
Answer: starch (carbohydrates)
In simple words: Saliva contains an enzyme that breaks down starch into sugars.

Exam Tip: The salivary amylase enzyme is responsible for this chemical breakdown.

Question 6. _____________ are the sensory cells present in mouth. (Note: specifically on tongue)
Answer: Taste buds
In simple words: Taste buds help us identify different tastes like sweet, sour, salty, and bitter.

Exam Tip: They are located on various parts of the tongue surface.

Question 7. The digestive juices of the stomach digest the _____________ in the food.
Answer: proteins
In simple words: Gastric juices in the stomach specifically target and break down proteins.

Exam Tip: Pepsin is the key protein-digesting enzyme in the stomach.

Question 8. The ________________released by the bacteria in the mouth causes tooth decay.
Answer: acid
In simple words: Bacteria break down leftover food and release acids that damage tooth enamel.

Exam Tip: Regular brushing prevents acid buildup and tooth decay.

Question 9. Liver secretes ____________ and helps in the digestion of ____________in the food.
Answer: bile juice, fats
In simple words: Bile breaks large fat globules into smaller droplets to aid digestion.

Exam Tip: Bile is stored temporarily in the gall bladder.

Question 10. During the process of digestion, the carbohydrates break down to _________, the proteins into ______________ and the fats into ______________.
Answer: sugars (glucose), amino acids, fatty acids and glycerol
In simple words: Complex nutrients are simplified into their basic monomer units.

Exam Tip: Memorize these end products of digestion for examinations.

Question 11. Faecal matter is removed from the body by the process of __________
Answer: egestion
In simple words: Egestion is the removal of undigested waste from the body through the anus.

Exam Tip: Do not confuse egestion with excretion (which is the removal of metabolic wastes).

Question 12. _____________ of amoeba helps to capture food.
Answer: Pseudopodia (false feet)
In simple words: Amoeba pushes out finger-like projections called pseudopodia to engulf food particles.

Exam Tip: Pseudopodia also help amoeba in locomotion.

Question 13. The patient suffering diarrhea should be treated with ___________.
Answer: oral rehydration solution (ORS / water and salt solution)
In simple words: ORS prevents dehydration caused by excessive water loss during diarrhea.

Exam Tip: ORS consists of boiled and cooled water with a pinch of salt and sugar.

Question 14. We get hiccups or cough, if by chance food particles enters the ____
Answer: windpipe (trachea)
In simple words: Food enters the windpipe when the flap-like valve fails to close properly during swallowing.

Exam Tip: The flap covering the windpipe is called the epiglottis.

Question 15. Partially digested food in the rumen of herbivores is called ________
Answer: cud
In simple words: Ruminants swallow food quickly and store it in the rumen, where it becomes cud.

Exam Tip: The cud later returns to the mouth for thorough chewing (rumination).

Question 16. The process of utilizing absorbed food particles (nutrients) into the living cells is called ________________.
Answer: assimilation
In simple words: Assimilation is the incorporation of absorbed nutrients into body cells for energy and growth.

Exam Tip: Steps of nutrition include ingestion, digestion, absorption, assimilation, and egestion.

II) Name the following :

Question 1. 4 types of teeth.
Answer: Incisors, canines, premolars, and molars
In simple words: Human teeth are categorized into four types based on their shape and function.

Exam Tip: Dental formula in adult humans reflects these four types.

Question 2. Digestive glands in human body.
Answer: Salivary glands, liver, and pancreas
In simple words: Major glands that secrete digestive juices into the alimentary canal.

Exam Tip: The stomach and small intestine walls also secrete digestive juices.

Question 3. Acid produced in stomach.
Answer: Hydrochloric acid (HCl)
In simple words: A strong acid produced in the stomach to kill bacteria and create an acidic medium for pepsin.

Question 4. Scientist who discovered the working of stomach.
Answer: William Beaumont
In simple words: He discovered how the stomach works by observing a patient with a permanent opening in his stomach.

Exam Tip: This accidental discovery was made on a patient named Alexis St. Martin.

Question 5. The sac like structure present between the small intestine & large intestine in ruminants.
Answer: Cecum
In simple words: A large bag-like structure where cellulose is digested with the help of specific bacteria.

Exam Tip: The cecum is absent or vestigial in humans.

True or False :

Question 1. Canines are meant for tearing flesh.[ ]
Answer: True
In simple words: Sharp canine teeth are adapted for piercing and tearing food items like meat.

Exam Tip: Carnivorous animals have very prominent canines.

Question 2. Oesophagus is also known as food pipe.[ ]
Answer: True
In simple words: The muscular tube connecting the mouth cavity to the stomach is the food pipe or oesophagus.

Exam Tip: Food moves down the oesophagus through wave-like muscular contractions called peristalsis.

Question 3. Mouth cavity contains teeth and salivary glands only.[ ]
Answer: False
In simple words: The mouth cavity also contains the tongue along with teeth and salivary glands.

Exam Tip: The tongue is a muscular sensory organ attached to the floor of the buccal cavity.

Question 4. Deer is a ruminant.[ ]
Answer: True
In simple words: Plant-eating animals like cows, buffaloes, and deer are ruminants that chew the cud.

Question 5. Large intestine is longer than small intestine. [ ]
Answer: False
In simple words: The small intestine is much longer (about 7.5 meters) than the large intestine (about 1.5 meters).

Exam Tip: It is called "large" because of its wider diameter, not its length.

Define :

Question 1. Digestion
Answer: The breakdown of complex components of food into simpler, absorbable substances is called digestion.
In simple words: Converting complex food into simple soluble forms.

Exam Tip: Digestion makes nutrients available for absorption into the blood.

Question 2. Rumination
Answer: The process in which grass-eating animals quickly swallow grass and store it in the rumen, and later bring it back to the mouth in small lumps to chew it again, is called rumination.
In simple words: The act of chewing the cud by grass-eating animals.

Exam Tip: Animals that perform rumination are called ruminants.

Distinguish between : Milk teeth and permanent teeth

Question 1. Distinguish between Milk teeth and permanent teeth.
Answer:

In simple words: Milk teeth are baby teeth that fall out, while permanent teeth stay for life.

Exam Tip: Permanent teeth should be cared for properly as they do not grow back if lost.

Draw and label:

Question 1. The human digestive system
Answer: Draw the alimentary canal showing buccal cavity, oesophagus, stomach, small intestine, large intestine, liver, and pancreas.
In simple words: A diagram showing all organs involved in human digestion.

Exam Tip: Clearly show connections between the liver, gall bladder, and small intestine.

Question 2. The feeding and digestion in Amoeba
Answer: Draw steps showing an amoeba extending pseudopodia, capturing a food particle, forming a food vacuole, and ejecting waste.
In simple words: Sequence of diagrams showing how amoeba eats and digests food.

Exam Tip: Label the food particle, pseudopodia, and food vacuole clearly.

Chapter 3 : Fibre to Fabric

Question 1. Wool is obtained from the ______________ of the sheep or yak.
Answer: fleece (hair)
In simple words: The hairy skin of sheep and yak provides wool fibres.

Exam Tip: Fleece consists of coarse beard hair and soft under-hair.

Question 2. __________ is the name of the breed of sheep from which we get Kashmiri shawls.
Answer: Pashmina (or Cashmere goat/sheep)
In simple words: Soft Pashmina wool is woven into fine Kashmiri shawls.

Exam Tip: Pashmina goats are found in the snowy regions of Jammu and Kashmir.

Question 3. By the process of _____________ we get off springs with special characters.
Answer: selective breeding
In simple words: Choosing parent animals with desirable traits to breed offspring with those specific traits.

Exam Tip: This technique helps produce sheep yielding soft hair.

Question 4. Washing of sheared skin is known as ______________
Answer: scouring
In simple words: Scouring removes dust, dirt, and grease from sheared hair.

Exam Tip: Nowadays, scouring is done using machines.

Question 5. In __________ the hairs of different textures are separated.
Answer: sorting
In simple words: Factory workers sort wool fibers based on texture and quality.

Exam Tip: Fluffy fibers called burrs are also picked out during processing.

Question 6. Silk fibre is made up of a __________
Answer: protein
In simple words: Silk is a natural protein fiber secreted by silkworms.

Exam Tip: It is strong and lustrous.

Question 7. The silk fibre is obtained from the covering of pupa known as ______________
Answer: cocoon
In simple words: The silkworm spins a protective cocoon around itself made of silk protein.

Exam Tip: Silk threads are unwound from these cocoons.

Question 8. The larva of silk worm are called______________
Answer: caterpillars (or silkworms)
In simple words: Caterpillars hatch from silkmoth eggs and feed voraciously on mulberry leaves.

Exam Tip: They feed day and night to grow in size.

Question 9. Inside cocoon, the pupa develops into ______________
Answer: silk moth
In simple words: The pupa undergoes metamorphosis inside the cocoon to form an adult silk moth.

Exam Tip: Silk is harvested before the moth emerges to keep the continuous thread intact.

Name the following :

Question 1. Two wool giving animals.
Answer: Sheep, goat (or yak, alpaca, llama)
In simple words: Animals that possess thick coats of hair used for wool production.

Exam Tip: Cashmere and Angora are popular wool-yielding animal breeds.

Question 2. Two Indian breeds of sheep.
Answer: Lohi and Rampur Bushair (or Nali, Bakharwal, Marwari, Patanwadi)
In simple words: Indian sheep breeds known for good quality wool.

Exam Tip: Lohi produces superior quality wool.

Question 3. Two types of silk.
Answer: Mulberry silk and Tassar silk (or Eri, Muga silk)
In simple words: Varieties of silk produced by different species of silkmoths.

Exam Tip: Mulberry silk is the most common variety.

Question 4. Name the most common silk.
Answer: Mulberry silk
In simple words: Silk obtained from silkworms that feed on mulberry leaves.

Exam Tip: It is soft, lustrous, and widely used in textiles.

Question 5. Bacterium which causes sorter’s disease.
Answer: Bacillus anthracis (Anthrax)
In simple words: A fatal blood disease that workers handling wool can contract from bacteria.

Exam Tip: This occupational hazard is known as sorter's disease.

Question 6. The country from where silk industry started.
Answer: China
In simple words: Silk production originated in China thousands of years ago.

Exam Tip: China kept silk production a closely guarded secret for centuries.

Question 7. Process of taking out silk - threads from cocoon.
Answer: Reeling (or filature)
In simple words: Unwinding silk threads from the cocoon to use for weaving.

Exam Tip: Reeling is done using special machines.

Write true or false:

Question 1. Soft silk yarn is strong as comparable thread of steel.
Answer: True
In simple words: A fine silk thread is surprisingly as strong as a steel wire of the same thickness.

Exam Tip: This tensile strength makes silk durable despite its delicate appearance.

Question 2. Shearing hurts the sheep.
Answer: False
In simple words: Shearing does not hurt sheep because the uppermost layer of skin is dead.

Question 3. Small fluffy fibres are called burrs.
Answer: True (Note: Burrs are actually tiny burrs stuck in hair, but fleece contains small fluffy fibers called burrs/fleece fibers)
In simple words: Fluffy fibers mixed with wool are sorted out during processing.

Exam Tip: Burrs are picked out from the hair before spinning.

Define :

Question 1. Shearing
Answer: The process of removing the fleece of a sheep along with a thin layer of dead skin is called shearing.
In simple words: Shaving off the wool coat of a sheep.

Exam Tip: Shearing is usually done in hot weather so sheep can survive without their wool coat.

Question 2. Sericulture
Answer: The rearing of silkworms for obtaining silk is called sericulture.
In simple words: Commercial farming of silkworms to produce silk.

Exam Tip: Farmers feed silkworms mulberry leaves in dedicated farms.

Question 3. Selective breeding
Answer: The process of selecting parents for obtaining special characters in their offspring, such as soft under-hair in sheep, is termed selective breeding.
In simple words: Breeding animals to get desired traits.

Exam Tip: It helps improve the quality of livestock over generations.

Question 4. Rearing
Answer: Raising, feeding, and providing medical care to animals for commercial purposes is called rearing.
In simple words: Taking care of livestock like sheep or silkworms.

Exam Tip: Rearing involves providing proper shelter, food, and healthcare.

Chapter 4 : Heat

Fill in the blanks :

Question 1. ______________ is a device used for measuring temperature.
Answer: Thermometer
In simple words: A thermometer measures how hot or cold an object is.

Exam Tip: Common units of temperature are Celsius, Fahrenheit, and Kelvin.

Question 2. The materials which allow heat to pass through them easily are __________ of heat.
Answer: conductors
In simple words: Conductors let heat travel through them easily.

Exam Tip: Metals like copper and iron are good conductors.

Question 3. Clinical thermometer is used to measure our _____________
Answer: body temperature
In simple words: Clinical thermometers measure human body temperature when ill.

Exam Tip: Its normal range is from \(35^{\circ}\text{C}\) to \(42^{\circ}\text{C}\).

Question 4. Wool is poor __________________ of heat and it has air trapped in between the fibres.
Answer: conductor (insulator)
In simple words: Wool traps air, which is a bad conductor of heat, keeping us warm in winter.

Exam Tip: Trapped air prevents heat loss from the body.

Question 5. In ______________ generally the heat is transferred by conduction.
Answer: solids
In simple words: Conduction is the primary method of heat transfer in solids.

Exam Tip: Heat travels from the hotter end to the colder end in solids.

Question 6. _______________ metal is used in the bulb of the thermometer.
Answer: Mercury
In simple words: Mercury is a liquid metal that expands uniformly when heated, making it ideal for thermometers.

Exam Tip: Mercury is toxic, so broken thermometers must be handled carefully.

Question 7. The normal temperature of the human body is __________
Answer: \(37^{\circ}\text{C}\) (or \(98.6^{\circ}\text{F}\))
In simple words: The standard temperature of a healthy human body.

Exam Tip: Always include the unit degree Celsius (\({\circ}\text{C}\)) with the value.

True or False :

Question 1. The materials which do not allow heat to pass them easily are called insulators.
Answer: True
In simple words: Insulators are poor conductors of heat.

Exam Tip: Examples include wood, plastic, and air.

Question 2. In liquids and gases the heat is transferred by conduction.
Answer: False
In simple words: Heat transfer in liquids and gases primarily takes place through convection.

Exam Tip: Convection involves the actual movement of heated fluid particles.

Question 3. A kink near the bulb of a clinical thermometer prevents mercury level from falling of its own.
Answer: True
In simple words: The kink stops the mercury from flowing back down into the bulb when removed from the mouth.

Question 4. We get heat from the sun by radiation.
Answer: True
In simple words: Heat travels through empty space from the sun to the Earth via radiation.

Exam Tip: Radiation does not require any medium.

Question 5. Digital thermometers contain mercury.
Answer: False
In simple words: Digital thermometers do not contain toxic mercury; they use electronic sensors.

Exam Tip: They are safer to use, especially for children.

Define :

Question 1. Temperature
Answer: Temperature is a reliable measure of the hotness or coldness of an object.
In simple words: How hot or cold something is.

Exam Tip: Measured using a thermometer in units like Celsius (\({\circ}\text{C}\)).

Question 2. Radiation
Answer: The transfer of heat energy through space without the necessity of any material medium is called radiation.
In simple words: Heat transfer through waves without any medium.

Exam Tip: All hot bodies radiate heat.

Question 3. Conduction
Answer: The process by which heat is transferred from the hotter end to the colder end of an object is known as conduction.
In simple words: Heat transfer through direct contact in solids.

Exam Tip: Occurs mainly in solid materials.

Question 4. Convection
Answer: The transfer of heat by the actual movement of molecules within fluids (liquids and gases) is called convection.
In simple words: Heat transfer through the movement of fluids.

Exam Tip: Warm fluid rises and cooler fluid sinks, creating convection currents.

Name the following:

Question 1. The movement of cool air from land towards sea.
Answer: Land breeze
In simple words: Cool air blowing from the land toward the sea during the night.

Exam Tip: Occurs at night when land cools faster than the sea.

Question 2. Two conductors of heat
Answer: Copper, aluminium (or iron)
In simple words: Metals that allow heat to pass through easily.

Exam Tip: Used for making cooking utensils.

Question 3. Two insulators of heat
Answer: Wood, plastic (or air, wool)
In simple words: Materials that restrict heat transfer.

Exam Tip: Used for making handles of cooking utensils.

Distinguish between

Question 1. Conductors and insulators.
Answer:

In simple words: Conductors pass heat; insulators block heat.

Exam Tip: Conductors are used for heating; insulators are used for protection against burns.

Question 2. Clinical and laboratory thermometer
Answer:

In simple words: Clinical thermometers measure body temperature; laboratory thermometers measure temperatures in experiments.

Exam Tip: Never use a laboratory thermometer to check human body temperature.

Diagram

Question 1. Clinical Thermometer / Laboratory Thermometer
Answer: Draw both thermometers showing the bulb, mercury thread, scale markings, and the kink in the clinical thermometer.
In simple words: Diagrams of instruments used to measure temperature.

Exam Tip: Clearly show the constricting kink in the clinical thermometer.

Chapter 5 : Acids, Bases and salts

Fill in the blanks :

Question 1. Spinach contains_____________ acid while tamarind contains ________________ acid.
Answer: oxalic acid, tartaric acid
In simple words: Different natural foods contain different organic acids.

Exam Tip: Memorize common acids found in household foods.

Question 2. The gas which escapes out from many aerated soft drink is _____________
Answer: carbon dioxide (\(\text{CO}_2\))
In simple words: Fizzy drinks contain dissolved carbon dioxide under pressure.

Exam Tip: Carbon dioxide turns lime water milky.

Question 3. Carbon burns in air to form _______________
Answer: carbon dioxide (\(\text{CO}_2\))
In simple words: Burning carbon in oxygen produces carbon dioxide gas.

Exam Tip: Combustion reactions release oxides of elements.

Question 4. The chemical name of lime water is ______________
Answer: calcium hydroxide
In simple words: Lime water is an aqueous solution of calcium hydroxide.

Exam Tip: It is a basic solution.

Question 5. _______________ is the reaction between an acid and base.
Answer: Neutralisation
In simple words: An acid reacts with a base to form salt and water, cancelling each other's effects.

Exam Tip: Heat is always evolved during a neutralisation reaction.

Question 6. An aqueous solution of sodium oxide changes ________________ litmus to blue.
Answer: red
In simple words: Metallic oxides form basic solutions that turn red litmus blue.

Exam Tip: Metal oxides are generally basic in nature.

Question 7. Phenolphthalein indicator turns acidic solutions to ______________ and basic solutions to _____________.
Answer: colourless, pink
In simple words: Phenolphthalein is colourless in acids and turns pink in bases.

Exam Tip: Useful synthetic indicator in laboratory titrations.

Question 8. The chemical name of moist baking soda is _____________
Answer: sodium hydrogen carbonate (sodium bicarbonate)
In simple words: Baking soda is a basic substance used in kitchens and fire extinguishers.

Exam Tip: It neutralizes stomach acidity as an antacid.

Question 9. Calamine solution contains __________________( a base ).
Answer: zinc carbonate
In simple words: Calamine lotion is applied on ant bites to neutralize the formic acid injected by the ant.

Question 10. Litmus is obtained from the _____________________
Answer: lichens
In simple words: Litmus is a natural dye extracted from lichens.

Exam Tip: It is available as red and blue litmus paper or solution.

Question 11. Curd contains __________ while vinegar contains ___________
Answer: lactic acid, acetic acid
In simple words: Curd and vinegar taste sour due to the presence of these acids.

Exam Tip: Lactic acid is formed when milk turns into curd.

Complete the following word equations :

Question 1. Zinc + hydrochloric acid ___________+ _____________
Answer: Zinc chloride + Hydrogen gas
In simple words: A metal reacting with an acid produces a salt and hydrogen gas.

Exam Tip: Hydrogen gas burns with a pop sound when brought near a burning matchstick.

Question 2. Sodium hydroxide + Hydrochloric acid ___________+ ________
Answer: Sodium chloride + Water
In simple words: Neutralisation between a strong base and strong acid produces common salt and water.

Exam Tip: \(\text{NaOH} + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O}\).

Question 3. Calcium hydroxide + sulphuric acid ___________+ ________
Answer: Calcium sulphate + Water
In simple words: Base and acid react to form calcium sulphate salt and water.

Exam Tip: Always balance word equations by matching reactants to products.

True or False :

Question 1. All acids turn blue litmus red. True / False
Answer: True
In simple words: A universal property of acids is that they turn blue litmus red.

Exam Tip: Remember: Acid turns Blue litmus Red (ABR).

Question 2. Neutral solution can change the colour of litmus. True / False
Answer: False
In simple words: Neutral solutions do not change the colour of either red or blue litmus paper.

Exam Tip: Distilled water is a neutral solution.

Question 3. Orange juice turns blue litmus red. True / False
Answer: True
In simple words: Orange juice contains citric acid, which is acidic and turns blue litmus red.

Exam Tip: Citrus fruits contain natural acids.

Question 4. Substances which are neither acidic nor basic are called neutral. True/ False
Answer: True
In simple words: Neither acidic nor basic substances are classified as neutral.

Exam Tip: They show no effect on litmus indicators.

Question 5. An acid and a base neutralize each other and from a salt. True / False.
Answer: True
In simple words: Neutralisation reactions always yield a salt and water.

Exam Tip: Salts can be acidic, basic, or neutral depending on the reacting acid and base.

Question 6. China rose indicator turns acidic solution to green. True / False
Answer: False (Note: China rose turns acidic solutions to dark pink/magenta and basic solutions to green)
In simple words: China rose indicator turns magenta in acid and green in base.

Exam Tip: Memorize natural indicator color changes.

Name the following :

Question 1. Two natural indicators.
Answer: Litmus, turmeric (or China rose)
In simple words: Indicators obtained from natural sources.

Exam Tip: Turmeric turns reddish-brown in basic solutions.

Question 2. One artificial indicator
Answer: Phenolphthalein (or methyl orange)
In simple words: Indicators synthesized in laboratories.

Exam Tip: Phenolphthalein is commonly used in school laboratories.

Question 3. Two pollutants in the air which causes acid rain.
Answer: Sulphur dioxide (\(\text{SO}_2\)) and nitrogen dioxide (\(\text{NO}_2\))
In simple words: Gases released from burning fossil fuels that dissolve in rainwater to form acids.

Question 4. Two substances which can neutralize an ant’s bite.
Answer: Moist baking soda (sodium hydrogen carbonate) and calamine solution
In simple words: Basic substances used to neutralize the acidic sting of an ant.

Exam Tip: Ant stings inject formic acid into the skin.

Question 5. Two acids found in citrus fruits.
Answer: Citric acid and ascorbic acid (Vitamin C)
In simple words: Organic acids present naturally in lemons, oranges, and amla.

Exam Tip: Citrus fruits are rich sources of Vitamin C.

Define

Question 1. Indicators
Answer: Special substances used to test whether a substance is acidic or basic are called indicators.
In simple words: Substances that change colour in acidic and basic solutions.

Exam Tip: They exhibit different colors in acidic and basic environments.

Question 2. Neutral solution
Answer: Solutions that do not change the colour of any indicator (red or blue litmus) are known as neutral solutions.
In simple words: Solutions that are neither acidic nor basic.

Exam Tip: They have a pH of 7.

CH. 17 - FOREST : OUR LIFE LINE

I Fill in the blanks:

Question 1. Decomposers convert dead plants and animals into __________________.
Answer: humus
In simple words: Decomposers break down dead organic matter into nutrient-rich humus.

Exam Tip: Humus enriches the forest soil with nutrients.

Question 2. Tall trees which look like roof over other plants in the forest is called ______________.
Answer: canopy
In simple words: The branchy upper part of tall trees acting like a roof over the forest floor.

Exam Tip: Canopies filter sunlight reaching lower vegetation layers.

Question 3. The various components of the forests are ___________ on another.
Answer: dependent
In simple words: Plants, animals, and soil in a forest depend mutually on each other.

Exam Tip: Forests function as dynamic, interconnected living systems.

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

Exam Tip: Forests provide food, medicine, and shelter to forest dwellers.

Question 5. ______________ help forest to grow and regenerate.
Answer: Animals and birds (or seeds dispersed by them)
In simple words: Animals help pollinate plants and disperse seeds for forest regeneration.

Exam Tip: Herbivores and carnivores maintain the food chain balance.

Question 6. ______________ forms the uppermost layer in the forest.
Answer: Crown (or canopy formed by tall trees)
In simple words: The top foliage layer of tall trees in a forest.

Exam Tip: It receives maximum sunlight.

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: Giant trees, shrubs, and herbs form different horizontal layers called under storeys.

Exam Tip: Different layers provide habitats for various animal species.

Question 2. Forest help in causing floods.
Answer: False
In simple words: Forests actually prevent floods by absorbing rainwater and regulating water flow.

Exam Tip: Tree roots hold soil particles together, preventing soil erosion.

Question 3. Forest are called green lungs.
Answer: True
In simple words: Forests purify air by releasing oxygen and absorbing carbon dioxide, acting like lungs for the Earth.

Exam Tip: They help maintain the balance of oxygen and carbon dioxide in the atmosphere.

Question 4. The type of animals remain same from forest to forest.
Answer: False
In simple words: Different types of forests have different climatic conditions, hence varying plant and animal species.

Exam Tip: Biodiversity varies across different geographical regions.

Question 5. Deforestation will endanger our life and environment.
Answer: True
In simple words: Cutting down forests leads to global warming, soil erosion, and loss of wildlife habitats.

Exam Tip: Afforestation must be promoted to counteract deforestation.

Question 6. Forest is a dynamic living entity.
Answer: True
In simple words: Forests are vibrant ecosystems full of life, growth, and constant interactions.

Exam Tip: They support diverse flora and fauna.

III Name the following:

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

Exam Tip: Crowns come in different shapes depending on the tree species.

Question 2. Two forest products.
Answer: Timber, honey (or gum, resin, medicinal herbs)
In simple words: Useful materials obtained from forest resources.

Exam Tip: Forests provide numerous valuable commercial products.

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

Exam Tip: Receives the least amount of sunlight.

IV Define:

Question 1. Forest.
Answer: A large area covered chiefly with trees and undergrowth is called a forest.
In simple words: A dense natural community of plants and animals.

Exam Tip: Forests are complex ecosystems supporting rich biodiversity.

Question 2. Deforestation.
Answer: The large-scale clearing of forest trees for human activities such as agriculture, mining, and urbanization is called deforestation.
In simple words: Cutting down forests on a massive scale.

Exam Tip: Deforestation has severe environmental consequences.

Question 3. Canopy.
Answer: The uppermost branches of tall trees forming a roof over the other plants in a forest is known as a canopy.
In simple words: The leafy roof formed by tall trees.

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

Question 4. Crown
Answer: The branchy part of a tree above the stem is called the crown of the tree.
In simple words: The upper portion of a tree consisting of branches and leaves.

Exam Tip: Different trees have distinct crown shapes like conical or umbrella-like.