CBSE Class 7 Science Revision Worksheet Set 15

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 in food that our body needs to function properly.

Exam Tip: Remember that carbohydrates, proteins, fats, vitamins, and minerals are the main nutrients.

Question 2. Green plants synthesis their own food themselves by the process of
Answer: Photosynthesis
In simple words: Plants make their own food using sunlight, water, and carbon dioxide.

Exam Tip: Photo means light and synthesis means combining; plants combine substances using light.

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 energy and growth.

Exam Tip: Distinguish between nutrients (the components) and nutrition (the process).

Question 4. Complex chemical substances such as ------------------------- are the products of photosynthesis.
Answer: Carbohydrates (Starch)
In simple words: The primary food produced by plants during photosynthesis is a simple carbohydrate which gets converted into starch.

Exam Tip: Starch is tested using iodine solution which turns blue-black.

Question 5. Gas is produced during photosynthesis.
Answer: Oxygen
In simple words: Plants release oxygen gas into the air during photosynthesis.

Exam Tip: Oxygen is essential for the survival of all aerobic organisms.

Question 6. Organisms that are dependent on others for their nutrition are called
Answer: Heterotrophs
In simple words: Organisms that cannot make their own food and rely on plants or other animals are heterotrophs.

Exam Tip: 'Hetero' means other and 'troph' means nourishment.

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 used for gas exchange.

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

Question 8. Is the ultimate source of energy for all living organisms?
Answer: Sun
In simple words: Solar energy is captured by plants and transferred through all food chains.

Exam Tip: Without the sun, photosynthesis would not occur, collapsing the entire biosphere.

Question 9. Organisms which derive their nutrition from dead decaying matter are called
Answer: Saprotrophs (Saprophytes)
In simple words: Fungi and certain bacteria feed on dead and decaying organic matter.

Exam Tip: Saprotrophic nutrition involves secreting digestive juices onto dead matter and absorbing nutrients.

Question 10. Some organisms live together and share shelter and nutrients, this is called
Answer: Symbiotic relationship (Symbiosis)
In simple words: A mutually beneficial partnership between two different organisms.

Exam Tip: Classic example is lichens, where an alga and a fungus live together.

Name the following:

Question 1. The 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 has a symbiotic relationship with leguminous plants like gram, peas, and beans.

Question 2. The insectivorous plant.
Answer: Pitcher plant (Venus flytrap)
In simple words: Plants that trap and digest insects to fulfill their nitrogen requirements.

Exam Tip: Insectivorous plants grow in soil deficient in nitrogen.

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

Exam Tip: Fungi secrete digestive juices onto decaying organic matter to dissolve 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 reacts with starch.

Exam Tip: Always boil the leaf in alcohol to remove chlorophyll before adding iodine.

Question II(1). Some fungi are used in medicines.
Answer: True
In simple words: Certain fungi like Penicillium are used to produce antibiotics.

Exam Tip: Alexander Fleming discovered penicillin from a fungus.

Question II(2). Most of the pulses are obtained from leguminous plants.
Answer: True
In simple words: Pulses come from legume crops which harbor nitrogen-fixing bacteria.

Exam Tip: Leguminous plants enrich the soil with nitrogen.

Question II(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 nutrients.

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

Question II(4). Lichens, an alga and a fungus show symbiotic relationship.
Answer: True
In simple words: The fungus provides shelter, water, and minerals, while the alga prepares food through photosynthesis.

Exam Tip: Lichens are classic examples of mutualism between algae and fungi.

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

Exam Tip: Opuntia (cactus) is a prime example of stem photosynthesis.

Chapter 2: Nutrition in Animals

Fill in the blanks:

Question 1. The mode of taking food in to the body is called
Answer: Ingestion
In simple words: Ingestion is the act of eating or taking food into the body.

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: Complex food components are broken down into simple soluble forms during digestion.

Question 3. The canal star with mouth and ends in anus.
Answer: Alimentary canal (Digestive tract)
In simple words: The continuous muscular tube through which food passes from the mouth to the anus.

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

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

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 called amylase that breaks down starch into sugars.

Exam Tip: This is why chewed rice tastes sweet after a while.

Question 6. Are the sensory cells present in mouth.
Answer: Taste buds
In simple words: Taste buds on the tongue help us detect different tastes.

Exam Tip: Different regions of the tongue detect sweet, salty, sour, and bitter tastes.

Question 7. The digestive juices of the stomach digest the in the food.
Answer: Proteins
In simple words: Gastric juice in the stomach contains pepsin which digests proteins.

Exam Tip: The stomach also produces hydrochloric acid to create an acidic medium.

Question 8. The released by the bacteria in the mouth causes tooth decay.
Answer: Acid
In simple words: Bacteria break down leftover sugar in the mouth, producing acid that erodes tooth enamel.

Exam Tip: Regular brushing prevents plaque and acid buildup.

Question 9. Liver secretes and helps in the digestion of in the food.
Answer: Bile juice, fats
In simple words: The liver produces bile juice stored in the gall bladder, which breaks down large fat globules into smaller ones.

Exam Tip: Bile does not contain digestive enzymes; it emulsifies fats.

Question 10. During the process of digestion in the proteins break down in to and fats break down into.
Answer: Amino acids, fatty acids and glycerol
In simple words: Proteins turn into amino acids, and fats turn into fatty acids and glycerol.

Exam Tip: Carbohydrates break down into simple sugars like glucose.

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

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

Question 12. Of amoeba help to capture food.
Answer: Pseudopodia (False feet)
In simple words: Amoeba extends finger-like projections called pseudopodia to engulf food particles.

Exam Tip: Pseudopodia are also used for movement.

Question 13. The patient suffering diarrhea should be treated with.
Answer: Oral Rehydration Solution (ORS)
In simple words: ORS water restores water and salt balance in the body during dehydration.

Exam Tip: ORS is a mixture of boiled water, a pinch of salt, and sugar.

Name The Following:

Question 1. 4 types of teeth.
Answer: Incisors, Canines, Premolars, Molars
In simple words: Humans have four different types of teeth for biting, tearing, piercing, and grinding.

Exam Tip: Dental formula for adult humans is 2:1:2:3 per quadrant.

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

Question 3. Acid produced in stomach.
Answer: Hydrochloric acid (HCl)
In simple words: Kills bacteria entering with food and creates an acidic environment for pepsin.

Exam Tip: Mucus protects the stomach lining from its own acid.

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 gunshot wound in his stomach.

Exam Tip: The patient was Alexis St. Martin.

True or False:

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

Exam Tip: Well developed in carnivores.

Question 2. Mouth cavity is also known as food pipe.
Answer: False
In simple words: The food pipe is called the esophagus, not the mouth cavity.

Exam Tip: The mouth cavity is the buccal cavity.

Question 3. Mouth cavity contains teeth and salivary glands only.
Answer: False
In simple words: It also contains the tongue and taste buds.

Exam Tip: Salivary glands open into the buccal cavity.

Question 4. Deer is a ruminant.
Answer: True
In simple words: Grass-eating animals that regurgitate food and chew it again are ruminants.

Exam Tip: Cows, buffaloes, and deer are ruminants.

Question 5. Large intestine is longer than small intestine.
Answer: False
In simple words: The small intestine is about 7.5 meters long, whereas the large intestine is only about 1.5 meters long.

Question 1. Digestion.
Answer: The process of breakdown of complex components of food into simpler substances is called digestion.
In simple words: Converting large food molecules into small soluble molecules.

Exam Tip: Involves both physical (chewing) and chemical (enzymes) breakdown.

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

Exam Tip: Animals performing rumination are called ruminants.

Distinguish Between:

Question 1. Milk teeth and permanent teeth.
Answer: Milk teeth grow during infancy and fall out at age 6-8, replaced by permanent teeth which last through adulthood.
In simple words: Milk teeth are temporary (20 in number), while permanent teeth are lifelong (32 in number).

Exam Tip: Loss of milk teeth is a normal developmental milestone.

Chapter 3: Fibre To Fabric

Fill in the blanks:

Question 1. Wool is obtained from the of the sheep or yak.
Answer: Fleece (Hair)
In simple words: Wool fibers are sheared from the hairy skin of sheep or yak.

Exam Tip: Animals with a thick coat of hair yield wool.

Question 2. Wool obtained from the kashmiri goat is woven into shawls.
Answer: Pashmina
In simple words: Soft Pashmina shawls are made from the under-fur of Kashmiri goats.

Exam Tip: Found in regions like Jammu and Kashmir.

Question 3. By the process of we get off springs with special characters.
Answer: Selective breeding
In simple words: Breeding parents with desirable traits to get offspring with those specific features.

Exam Tip: Used to obtain sheep yielding good quality wool.

Question 4. Washing of sheared skin is known as.
Answer: Scouring
In simple words: Washing sheared skin with soap and water to remove grease, dust, and dirt.

Exam Tip: Scouring is done in tanks or modern machines.

Question 5. In the hairs of different textures are separated.
Answer: Sorting
In simple words: Sorting separates hairy skin according to its texture.

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

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

Exam Tip: Silk protein is composed of fibroin.

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: Cocoons are boiled to separate the silk threads.

Question 8. The larva of silk worm are called.
Answer: Caterpillars (Silkworms)
In simple words: The larvae hatch from eggs and feed on mulberry leaves.

Exam Tip: Sericulture is the rearing of silkworms for silk production.

Name the following:

Question 1. Two wool giving animals.
Answer: Sheep, Goat (or Yak/Camel)
In simple words: Animals that have thick coats of hair used for making wool.

Exam Tip: Angora goats yield mohair wool.

Question 2. Two types of silk.
Answer: Mulberry silk, Tassar silk (or Eri, Muga silk)
In simple words: Different varieties of silk based on the silkworm species and diet.

Exam Tip: Mulberry silk is the most common variety.

Question 3. Name most common silk.
Answer: Mulberry silk
In simple words: Silk obtained from silkworms fed on mulberry leaves.

Exam Tip: It is soft, lustrous, and elastic.

Question 4. Bacteria which causes sorters disease.
Answer: Bacillus anthracis (Anthrax)
In simple words: A fatal blood disease caused by bacteria found in infected wool sorters.

Exam Tip: An occupational hazard in the wool industry.

Question 5. The country from where silk industry started.
Answer: China
In simple words: Silk production originated in ancient China and was kept a secret for centuries.

Exam Tip: Carried to other countries via the Silk Road.

Question 6. Process of taking out silk threads from cocoon.
Answer: Reeling (Filature)
In simple words: Unwinding silk threads from cocoons for use as silk.

Exam Tip: Done using special machines.

Define:

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

Exam Tip: It does not hurt the sheep as the uppermost layer of skin is dead.

Question 2. Sericulture.
Answer: Rearing of silkworms for obtaining silk is called sericulture.
In simple words: Commercial production of silk by raising silkworms.

Exam Tip: Farmers raise silkworms on mulberry trees.

Chapter 4: Heat

Fill In The Blanks:

Question 1. Is a device used for measuring temperature.
Answer: Thermometer
In simple words: An instrument used to measure how hot or cold something is.

Exam Tip: Commonly uses mercury or alcohol as thermometric liquids.

Question 2. The materials which allow heat to pass through them easily are of heat.
Answer: Conductors
In simple words: Materials that permit heat to flow through them easily are good conductors.

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

Question 3. Clinical thermometer is used to measure our.
Answer: Body temperature
In simple words: Measures human body temperature ranging from \(35^\circ\text{C}\) to \(42^\circ\text{C}\).

Exam Tip: Normal human body temperature is \(37^\circ\text{C}\) (\(98.6^\circ\text{F}\)).

Question 4. Wool is poor of heat and it has air trapped in between the fibres.
Answer: Conductor (Insulator)
In simple words: Trapped air is a poor conductor of heat, making wool a warm winter clothing material.

Exam Tip: Two thin blankets keep us warmer than one thick blanket due to trapped air layers.

Question 5. In generally the heat is transferred by conduction.
Answer: Solids
In simple words: Heat transfer through direct physical contact occurs mainly in solids.

Exam Tip: Liquids and gases transfer heat primarily by convection.

Question 6. Metal is used in the bulb of the thermometer.
Answer: Mercury
In simple words: Mercury is a liquid metal that expands uniformly with temperature.

Exam Tip: Mercury is toxic; digital thermometers are safer alternatives.

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 average temperature of a healthy human body.

Exam Tip: Always note the unit (\(^\circ\text{C}\) or \(^\circ\text{F}\)).

True or False:

Question 1. The materials which do not allow heat pass them easily are called insulation (insulators).
Answer: True
In simple words: Poor conductors of heat are called insulators.

Exam Tip: Wood, plastic, and air are good insulators.

Question 2. In liquids and gases the heat is transferred by conduction.
Answer: False
In simple words: Heat in liquids and gases is transferred mainly by convection.

Exam Tip: Fluids expand when heated, become lighter, and rise.

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 before reading.

Exam Tip: Laboratory thermometers do not have a kink.

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

Exam Tip: Radiation does not require any medium.

Question 5. Digital thermometers contain mercury.
Answer: False
In simple words: Digital thermometers contain electronic sensors and no toxic mercury.

Exam Tip: Recommended for children to avoid mercury poisoning if broken.

Define:

Question 1. Temperature.
Answer: Temperature is a reliable measure of the hotness of an object.
In simple words: Degree of hotness or coldness of a body.

Exam Tip: Measured in Celsius, Fahrenheit, or Kelvin.

Question 2. 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 primarily in solid materials.

Question 3. Convection.
Answer: The process of transfer of heat by the movement of heated fluid (liquid or gas) particles is called convection.
In simple words: Heat transfer through fluid circulation.

Question 4. Radiation.
Answer: The transfer of heat energy without the requirement of any material medium is called radiation.
In simple words: Heat travelling in waves through space.

Exam Tip: All hot bodies radiate heat.

Name the following:

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

Exam Tip: Sea breeze occurs during the day when air moves from sea to land.

Question 2. Two conductors of heat.
Answer: Aluminium, Copper (or Iron)
In simple words: Metals that allow heat to pass through them quickly.

Exam Tip: Used for making cooking utensils.

Question 3. Two insulators of heat.
Answer: Wood, Plastic (or Air, Glass)
In simple words: Materials that do not allow heat to pass through easily.

Exam Tip: Used for handles of cooking utensils.

Distinguish between:

Question 1. Conductors and insulators.
Answer: Conductors allow heat to pass through them easily, whereas insulators do not allow heat to pass through them easily.
In simple words: Conductors transmit heat; insulators block heat.

Exam Tip: Metals are conductors; wood and plastic are insulators.

Question 2. Clinical and laboratory thermometer.
Answer: Clinical thermometer measures human body temperature (\(35^\circ\text{C}\) to \(42^\circ\text{C}\)) and has a kink, while a laboratory thermometer measures wider ranges (\(-10^\circ\text{C}\) to \(110^\circ\text{C}\)) and lacks a kink.
In simple words: Clinical is for people; laboratory is for science experiments.

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

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: Citrus fruits contain citric acid; vinegar contains acetic acid.

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

Exam Tip: 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: Carbon dioxide is an acidic oxide.

Question 4. The chemical name of lime water is.
Answer: Calcium hydroxide
In simple words: Aqueous solution of calcium oxide is calcium hydroxide.

Exam Tip: Formula is \(\text{Ca(OH)}_2\).

Question 5. Is the reaction between an acid and base.
Answer: Neutralisation
In simple words: Mixing an acid and a base results in neutralisation, producing salt and water.

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

Question 6. An aqueous solution of sodium oxide changes litmus to blue.
Answer: Red
In simple words: Metal oxides are basic in nature and turn red litmus blue.

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

Exam Tip: Synthetic indicator commonly used in 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 cooking.

Exam Tip: Formula is \(\text{NaHCO}_3\).

Question 9. Calamine solution contains (a base).
Answer: Zinc carbonate
In simple words: Applied on ant bites to neutralize formic acid.

Exam Tip: Calamine lotion soothes skin irritation.

Question 10. Litmus is obtained from the.
Answer: Lichens
In simple words: Natural dye extracted from symbiotic lichens.

Exam Tip: Most common natural indicator available as solution or paper strips.

Question 11. Curd contains while vinegar contains.
Answer: Lactic acid, Acetic acid
In simple words: Sour foods contain specific organic acids.

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

Complete the following word equations:

Question 1. \(\text{Zinc} + \text{Hydrochloric acid} \rightarrow \text{Zinc chloride} + \text{Hydrogen gas}\)
Answer: \(\text{Zinc chloride} + \text{Hydrogen}\)
In simple words: Reaction of acid with active metal produces salt and hydrogen gas.

Exam Tip: Hydrogen gas burns with a pop sound.

Question 2. \(\text{Sodium hydroxide} + \text{Hydrochloric acid} \rightarrow \text{Sodium chloride} + \text{Water}\)
Answer: \(\text{Sodium chloride} + \text{Water}\)
In simple words: Strong base and strong acid form a neutral salt and water.

Exam Tip: This is a classic neutralisation reaction.

Question 3. \(\text{Calcium hydroxide} + \text{Sulphuric acid} \rightarrow \text{Calcium sulphate} + \text{Water}\)
Answer: \(\text{Calcium sulphate} + \text{Water}\)
In simple words: Base and acid react to form calcium sulphate salt and water.

Exam Tip: Always balance word equations by naming products correctly.

True or False:

Question 1. All acids turn blue litmus red.
Answer: True
In simple words: Acids are characterized by turning blue litmus paper red.

Exam Tip: Bases turn red litmus blue.

Question 2. Neutral solution can change the colour of litmus.
Answer: False
In simple words: Neutral solutions do not change the colour of any litmus paper.

Exam Tip: Neither acidic nor basic.

Question 3. Orange juice turns blue litmus red.
Answer: True
In simple words: Orange juice is acidic due to citric acid, so it turns blue litmus red.

Exam Tip: All sour substances contain acids.

Question 4. Substances which are neither acidic nor basic are called neutral.
Answer: True
In simple words: Pure water and salt solutions are neutral.

Exam Tip: They have a pH of 7.

Question 5. An acid and a base neutralize each other and form a salt.
Answer: True
In simple words: Neutralisation produces salt and water.

Exam Tip: Salt can be acidic, basic, or neutral depending on reactants.

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

Exam Tip: Remember: Acid = Dark Pink, Base = Green.

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 red in basic solutions.

Question 2. One artificial indicator.
Answer: Phenolphthalein (or Methyl orange)
In simple words: Man-made chemical indicators used in laboratories.

Exam Tip: Phenolphthalein is colorless in acid and pink in base.

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

Exam Tip: Acid rain damages historical monuments like the Taj Mahal.

Question 4. Two substances which can neutralize an ant bite.
Answer: Moist baking soda, Calamine solution
In simple words: Bases that neutralize formic acid injected by ants.

Exam Tip: Ant sting contains formic acid.

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

Exam Tip: Essential nutrients for human health.

Define:

Question 1. Indicators.
Answer: Special substances used to test whether a substance is acidic or basic are called indicators.
In simple words: Dyes that change color in acidic or basic media.

Exam Tip: Indicators exhibit different colors in different environments.

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

Exam Tip: Pure water is a neutral solution.

Chapter 17: Forest - Our Lifeline

Fill In The Blanks:

Question 1. Decomposers convert dead plants and animals into.
Answer: Humus
In simple words: Microorganisms break down dead organic matter into dark, nutrient-rich soil called humus.

Exam Tip: Humus enriches the soil with essential nutrients for plants.

Question 2. Tall trees which look like roof over other plants in the forest is called.
Answer: Canopy
In simple words: The upper branches and leaves of tall trees form a roof-like covering called a canopy.

Exam Tip: Canopies shade the forest floor.

Question 3. The various components of the forests are on another.
Exam Tip: This interdependence maintains the balance of the ecosystem.

Question 4. Forests are the for the forest dwelling communities.
Answer: Lifeline (Home / Provider)
In simple words: Forests provide food, shelter, water, and medicines for tribal communities.

Exam Tip: Forest dwellers depend entirely on forest resources sustainably.

Question 5. Help forest to grow and regenerate.
Answer: Seed dispersal (and Animal droppings / Decomposers)
In simple words: Animals and birds help spread seeds, allowing new plants to grow.

Exam Tip: Forests are dynamic living entities capable of self-regeneration.

Question 6. Forms the uppermost layer in the forest.
Answer: Emergent layer (Tall trees / Canopy)
In simple words: The highest layer formed by the crowns of tallest trees.

Exam Tip: Receives maximum sunlight.

State whether true or false:

Question 1. The different horizontal layers in the forest are known as under stories.
Answer: False
In simple words: The different horizontal layers are called understoreys, and the overall stratification is canopy, understorey, shrub layer, and forest floor.

Exam Tip: Different layers provide habitats for different animals.

Question 2. Forest help in causing floods.
Answer: False
In simple words: Forests prevent floods by absorbing rainwater and slowing down runoff.

Exam Tip: Deforestation causes soil erosion and floods.

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

Exam Tip: Essential for maintaining atmospheric gas balance.

Question 4. The type of animals remain same from forest to forest.
Answer: False
In simple words: Different types of forests (tropical, temperate, deciduous) host different species of plants and animals.

Exam Tip: Biodiversity varies by climate and geography.

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

Exam Tip: Afforestation helps restore green cover.

Question 6. Forest is a dynamic living entity.
Answer: True
In simple words: A forest is constantly growing, changing, regenerating, and supporting life.

Exam Tip: It is a vibrant ecosystem full of interactions.

Name the following:

Question 1. The branchy part of a tree above the stem.
Answer: Crown
In simple words: The upper branched structure of a tree.

Exam Tip: Crowns vary in shape across different tree species.

Question 2. Two forest products.
Answer: Timber, Honey (or Gum, Medicinal plants, Resin)
In simple words: Useful materials obtained directly from forests.

Exam Tip: Forests provide numerous livelihood resources.

Question 3. The lowest layer of vegetation in a forest.
Answer: Herbs (Forest floor / Grass layer)
In simple words: Small plants, mosses, and grasses growing on the forest floor.

Exam Tip: Receives the least amount of sunlight.