PSEB Notes

This PSEB 7th Class Science Notes Chapter 6 Physical and Chemical Changes will help you in revision during exams.

PSEB 7th Class Science Notes Chapter 6 Physical and Chemical Changes

→ Change is the tendency of life. There are many changes in our daily life.

→ There are two types of changes:

• Physical changes
• Chemical changes

→ There is always a reason for the change.

→ Some changes can be controlled and some others cannot be controlled.

→ No new matter is formed in physical change.

→ Chemical changes usually cannot be reversed.

→ The properties of new substances produced in a chemical change are completely different (new).

→ Changes can be classified based on their similarities.

→ The properties of a substance such as size, measure, color, state are called its physical properties.

→ The change that takes place in the physical properties of a substance is called a physical change.

→ The magnesium strip (ribbon) is bums with bright white light.

→ When Carbon dioxide is passed through lime water, it becomes milky.

→ Chemical change produces sound, light, heat, smell, gas, color, and so on.

→ Burning is a chemical change in which there is always an outflow of heat.

→ There is a layer of Ozone in the atmosphere.

→ For the occurrence of rust both oxygen and water are required.

→ In the galvanization process, a layer of zinc is deposited on the iron.

→ Iron can be saved from rust by applying paint.

→ Large crystals can be obtained from a saturated solution of a substance by crystallisation method.

→ Physical changes: Changes in which only the physical properties of matter change and no new matter is created are called physical changes. Example: Salt solution in water.

→ Chemical changes: Changes that involve the formation of new substances with new properties are called chemical changes. Example: Burning of coal.

→ Rust: The process in which iron gets covered with a layer of brownish substance in the presence of moist air is called rust.

→ Galvanization: The process of depositing zinc on iron to protect it from corrosion is called Galvanization.

→ Crystallisation: The process of obtaining large size crystals of a soluble substance is called crystallisation.

This PSEB 7th Class Science Notes Chapter 5 Acids, Bases and Salts will help you in revision during exams.

PSEB 7th Class Science Notes Chapter 5 Acids, Bases and Salts

→ We eat many foods with different tastes in our daily life.

→ Some foods taste bitter, sour, sweet, and salty.

→ The sour taste of the substance is due to the acid present in them.

→ The word acid is derived from the Latin word ‘acere’, which means sour.

→ Substances that have a bitter taste and are soapy to touch, are called the base.

→ Indicators are substances that give different colours to substances or solutions of acidic and basic nature.

→ They are used to test the acidic or alkaline nature of substances.

→ Turmeric, litmus, and China rose petals (Gudhal) are natural indicators.

→ Neutral solutions do not change the color of litmus red or blue because they are neither acidic nor basic.

→ Phenolphthalein is a synthetic indicator that is prepared in the laboratory.

→ Some acids are strong and some are weak.

→ The reaction between an acid and a base is called Neutralisation.

→ Antacids are used to treat indigestion.

→ Solution of baking soda (Sodium hydrogen carbonate) rubbed to treat the effects of insect bites.

→ The basicity of the soil is eliminated by the use of organic matter.

→ The acidity of the soil is treated with bases like a quick (calcium oxide) or slaked lime (Calcium hydroxide).

→ Waste products from factories should be released into the water only after treatment with basic substances.

→ Acids: Substances that have a sour taste and which react with blue litmus solution to make its color red are called acids.

→ Bases (Alkali): Substances that have a bitter taste and which react with red litmus solution to make it blue are called bases.

→ Neutralisation: The reaction between an acid and an alkali is called neutralisation.

→ Neutral solution: A solution that is neither acidic in nature nor alkaline in nature is called a neutral solution or solution which does not change the color of the indicator is called a neutral solution.

→ Indicators: Indicators are substances that show different colours by reacting with different acids, salts, and bases.

This PSEB 8th Class Agriculture Notes Chapter 11 Processing of Fruits and Vegetables will help you in revision during exams.

PSEB 8th Class Agriculture Notes Chapter 11 Processing of Fruits and Vegetables

→ India is second in the production of fruits and vegetables in the world.

→ During 2012-13 India produced 81.285 million metric tonnes of fruits and 162.19 million metric tonnes of vegetables.

→ Kernow production is highest among other fruits in Punjab.

→ Potato production is highest among other vegetables in Punjab.

→ Only 2% of the fruits and vegetables produced are processed.

→ Fruits and vegetables are processed to obtain various products.

→ Various products are lemon syrup, mango squash, malta squash, lime and barley syrup, tomato juice, lime pickle, mango pickle, amla pickle, carrot pickle, lemon, chilli and ginger pickle, tomato ketchup, amla preserve.

→ Cut pieces of cauliflower, trunip, carrot, potato, bitter guard, fenugreek, spinach, etc. can be dried and preserved.

→ The solar dryer can be used for drying purposes.

→ More income can be taken by processing fruits and vegetables.

This PSEB 8th Class Agriculture Notes Chapter 10 Post Harvest Handling of Fruits and Vegetables will help you in revision during exams.

PSEB 8th Class Agriculture Notes Chapter 10 Post Harvest Handling of Fruits and Vegetables

→ According to World Health Organisation, every person should take 300 grams of fresh vegetables and 80 grams of fresh fruits per day.

→ In India, only 30 grams of fruits and 80 grams of vegetables are available per person per day.

→ Post-harvest handling techniques of fruit and vegetables consist of the following sub-heads: harvesting, packaging, storage, and transportation of fruits and vegetables.

→ Parameters used to judge the maturity of fruits and vegetables for harvesting are colour, firmness, size and shape, total soluble solids (TSS), and TSS/acid ratio.

→ Immediately cool the produce after harvesting,

→ To reduce the loss of water from the produce food-grade wax is applied to fruits and vegetables.

→ The food safety standard authority of India has approved three types of wax.

→ Wax used can be shellac wax, carnauba wax, and beeswax.

→ Produce should be graded before marketing.

→ For packaging, wooden baskets, jute sacks, plastic crates, corrugated fiber board (CFB) boxes, etc. can be used.

→ While transporting vehicle should be padded or lined with a thick layer of straw.

→ For ripening bananas and papaya, calcium carbide is used which is harmful to health.

→ The use of ethylene for ripening is an internationally accepted technique.

This PSEB 8th Class Agriculture Notes Chapter 9 Care and Maintenance of Farm Machinery will help you in revision during exams.

PSEB 8th Class Agriculture Notes Chapter 9 Care and Maintenance of Farm Machinery

→ After the cost of land, the next heavy investment is in farm machinery.

→ Proper maintenance of the machinery increases in working life.

→ Farm machines are of three types.

→ The first category of machines is of prime movers e.g. tractors, engines, motors, etc.

→ The second type of machine is tractor or engine operated equipment, like, cultivators, happy seeder, disc harrows, seed cum fertilizer drill Etc.

→ The third type of machine is self-propelled machines, like, combine harvesters, paddy transplanted, etc.

→ The tractor is the head of the farm machinery.

→ Servicing of the tractor should be done after 10 hours, 50 hours, 125 hours, 250 hours, 500 hours, and 1000 hours.

→ The tractor should be got overhauled from a good workshop after using it for 4000 hours.

→ When the tractor is not required for the long term it should be stored properly.

→ Combine harvester should be maintained and stored like a tractor.

This PSEB 7th Class Science Notes Chapter 4 Heat will help you in revision during exams.

PSEB 7th Class Science Notes Chapter 4 Heat

→ The method of determining whether an object is hot or cold by touching it is not reliable.

→ Temperature is the degree of hotness or coldness of an object.

→ The hot or cold state of an object, i.e. the temperature is measured with an instrument called a thermometer.

→ The temperature of a human or living organism is measured with a medical thermometer (or clinical thermometer)

→ A scale is present on a medical thermometer. This scale is either in Celsius [°C] or Fahrenheit [°F] or both.

→ Medical thermometers have a narrow, homogeneous tube of glass with a bulb at the bottom.

→ There is a kink near the bulb of a medical thermometer that prevents the mercury level from falling as a result of its weight.

→ Should clean with antiseptic solution before and after use of a medical thermometer.

→ The scale range of medical thermometers is from 35°C to 42°C.

→ Before using a medical thermometer, make sure that the mercury level is below 35° C.

→ If not, hold the thermometer firmly and shake it to bring a level of mercury below 35°C.

→ The normal temperature of a healthy person is 37°C or 98.4°F.

→ There are other thermometers to measure the temperature of objects.

→ One of these is the Lab thermometer. The lab thermometer ranges from -10°C to 110° C.

→ The temperature of the object should be measured with a lab thermometer when the mercury level in the thermometer becomes stable.

→ The method by which heat is transferred from the hotter end of an object to the cold end by the particles of material of the object is called conduction. Solids are heated by the conduction method.

→ Materials that transmit heat are called conductors.

→ Items made of iron, silver, copper, aluminium are heat conductors.

→ Substances that do not conduct heat well are called insulators or non-conductors, e.g. Wood, plastic, and rubber.

→ Air is not a good conductor of heat.

→ The method of heat transfer in which heat is transmitted by the motion of hot molecules of a substance is called convection.

→ Heat is transmitted in liquids and gases by the convection method,

→ In coastal areas, the wind that blows from the sea to the coast during the day is called Sea breeze.

→ In coastal areas, the air that blows from the coast to the sea at night is called land breeze.

→ Radiation is the method of transfer of heat due to the emission of radiations by hot objects without a medium.

→ Dark coloured fabrics absorb heat more than light coloured fabrics.

→ So in winter, we wear dark colours and in summer we wear light coloured clothes.

→ Woolen garments keep us warm in winter because of the air trapped in the wool fibres which is a bad conductor of heat.

→ Heat: It is an agent which produces in us the sensation of warmth. This is a kind of energy.

→ Temperature: Degree of hotness or coldness measured on a definite scale.

→ Thermometer: An instrument used to measure the temperature of an object.

→ Celsius Scale: The Celsius scale is a scale for measuring temperature. Sometimes it is also called as the centigrade scale.

→ Resistor: A substance through which heat cannot be transmitted properly is considered to be resistor or resistant to heat.

→ Conduction: This is the method of heat transfer in which heat passes from the hot end of the object to the cold end through the molecules of the material, but the molecules of the object remain fixed in their place.

→ Convection(Liquid or Gas): This is the method of heat transfer in which heat is transferred from the source of heat to the cold part due to the motion of hot molecules and the cold molecules come down to take their place. This method is used for heating liquids and gases.

→ Radiation: This is the method of heat transfer in which heat is transmitted from a hot source or body directly to a cool body without affecting the medium.

→ Sea breeze: Due to the heat of the sun during the day, the soil of the land gets heated very quickly when water molecules of the ocean are not so hot. Therefore, the air near the ground gets warmer and rises up due to being lighter.

→ To replace it, cool air begins to flow from the ocean, causing air currents to flow. The wind that blows from the ocean to the land is called the sea breeze.

→ Land breeze: Due to high heat absorption capacity, water cools later than land, due to which cold air starts flowing towards seawater which is called land breeze.

→ Fahrenheit Scale: The Fahrenheit scale is a scale designed to measure temperature.

This PSEB 7th Class Science Notes Chapter 3 Fibre to Fabric will help you in revision during exams.

PSEB 7th Class Science Notes Chapter 3 Fibre to Fabric

→ Fibre of wool and silk is derived from animals in nature.

→ The fibre of wool is obtained from sheep, goats, or yaks.

→ The thin skin of a sheep has two types of fibres:

• Coarse beard hair
• Fine soft hair under the hair close to the skin.

→ Some breeds of sheep possess only fine under hair, their parents are specially chosen to give birth to sheep which have only soft under hair, such selection of parents for the specific characters is called ‘selective breeding’.

→ There are different types of wool, such as sheep’s wool, Angora, and cashmere wool.

→ Sheep are reared to obtain wool.

→ Sorters disease is spread by the bacterium Anthrax.

→ Raising silkworms to get silk is called Sericulture.

→ Female silkworms lay hundreds of eggs.

→ The larvae that hatch out from eggs are called caterpillars.

→ Caterpillars grow in size and become pupae (adult).

→ Then pupa swings its head from side to side in the form of a figure of eight(8).

→ During this movement, caterpillar secret fibre is made up of a protein that hardens on exposure to air and becomes silk fibre.

→ Caterpillar also covers itself completely with these silk fibers and this covering is known as Cocoon.

→ The most common silk moth is a mulberry silk moth. Other types of silk are Tassar silk, Mooga silk, and Kosa silk, etc.

→ The process by which cocoons are boiled or given steam to extract silk fibres is called Reeling of silk.

→ Reeling is done with special machines.

→ Silk thread is used to weave silk fabric.

→ Tuft: A cluster of sheep’s body hair.

→ Reeling: The process of extracting silk fibres by boiling or steaming silk cocoons.

→ Scouring: The sheared skin with hair is washed thoroughly to remove grease, dust, and sweat, which is called scouring.

→ Cocoon: A layer of silk fibres that covers the caterpillar is called a cocoon.

→ Sericulture (rearing silkworms): Rearing of silkworms to get silk, is called Sericulture.

→ Shearing or shaving: The process of removing a thin layer of sheep’s hair and skin from a sheep’s body is called shearing.

→ Throwing: Raw silk is spun to make raw silk stronger (thick). This process is called throwing. This protects the fibres from breaking down.

→ Combing: The process of removing small swollen fibres called burrs is called combing.

→ Dyeing or colouring: Sheep wool can be dyed in different colours as the natural color is only black, brown or white.

→ Selective Breeding: Two sheep with special required traits are selected as parents for breeding and reproducing a sheep of required traits. This process is said selective reproduction.

This PSEB 7th Class Science Notes Chapter 2 Nutrition in Animals will help you in revision during exams.

PSEB 7th Class Science Notes Chapter 2 Nutrition in Animals

→ Animals do not make their own food like plants. They get their food directly or indirectly from plants.

→ Animals eat complex foods and then break them down into simpler substances.

→ Different animals require nutrients, different ways of consuming food, and different ways of using food in the body.

→ Those who eat only plants are called vegetarians.

→ Animals that only feed on other animals are called carnivores.

→ Animals that eat both plants and other animals are called omnivorous animals.

→ Different types of animals have different ways of getting food.

→ There are three types of nourishment:

• Decomposer nutrition
• Parasitic nutrition
• Animal nutrition

→ During animal nutrition, complex food is transported to the body where it is broken down into simple soluble substances (compounds) with the help of enzymes, which are absorbed by the body.

→ Five stages during the process of receiving food are:

• Food intake
• Digestion
• Absorption
• Self-adaptation
• Excretion

→ The human digestive system includes the mouth cavity, food pipe, stomach, small intestine, large intestine, Rectum, and Anus.

→ There are four types of teeth in the human mouth:

• Incisors
• Canines
• Pre-molars
• Molars teeth

→ Food is digested starting from the mouth and up to the small intestine.

→ Digested food is transmitted through the blood to different parts of the body.

→ Absorption of water and some salts occurs in the large intestine.

→ Undigested and unabsorbed food remains in the rectum in the form of feces and is then excreted through the anus.

→ Carnivores: Animals that only feed on other animals are called carnivores.

→ Omnivorous: Animals that eat plants and other animals as food are called omnivorous animals.

→ Eating: The act of taking food into the body is called eating.

→ Digestion: This is the biological process during which complex substances are broken down into simpler substances. Enzymes (chemicals) that leak from the glands in the body help in this digestive process. Digestion starts from the mouth cavity and ends in a small intestine.

→ Absorption: This is the stage of food acquisition in which the digested food is absorbed through the inner walls of the small intestine.

→ Excretion: Undigested food passes out of the oesophagus. This process is called excretion.

→ Mouth cavity: The food received through the mouth then goes into the mouth cavity. It is the part that comes after the teeth area.

→ Enamel: A strong protective substance on the teeth is a layer of enamel.

→ Food Pipe: It is the longest part of the oesophagus, extending from the mouth to the anus. Here enzymes break down complex food into simple molecules.

→ Gallbladder: This is a pouch that sits just under the liver, it stores the bile produced by the liver.

→ Caecum: A diaphragm-like structure between the small intestine and the large intestine is called the caecum organ.

→ Bile Juice: The liver is the largest gland of our body from which leakage occurs which accumulates in the gallbladder. This leakage is called bile juice.

→ Ruminants: Grass-eating animals such as cows, buffaloes, are called ruminants.

→ Automation: Food absorbed by the intestines is transported through the blood to different parts of the body. This action is called automation.

This PSEB 7th Class Science Notes Chapter 1 Nutrition in Plants will help you in revision during exams.

PSEB 7th Class Science Notes Chapter 1 Nutrition in Plants

→ For all living things such as plants, animals, human beings food is necessary.

→ The main components of food are carbohydrates, fats, protein, vitamins, and minerals which are important for the building and growth of the human body.

→ The process of taking in food and using it for growth and development is called nutrition.

→ Different organisms require different types of nutrition.

→ On the basis of habits of intake of nutrients, nutrition can be divided into two types:

• Autotrophic nutrition
• Heterotrophic nutrition

→ Organisms that use simple inorganic matters and prepare their food on their own are called Autotrophs and the nutrition produced by them is called autotrophic nutrition.

→ All green plants and bacteria are Autotrophs.

→ Organisms that depend upon other organisms for food to survive are called Heterotrophs.

→ All animals, humans, and certain types of fungi are heterotrophs.

→ Euglena is a type of organism which produces both autotrophic nutrition as well as heterotrophic nutrition.

→ Leaves are called the food factory of plants.

→ Leaves produce their food by photosynthesis. During photosynthesis in green plants, the green coloured pigments (chlorophylls) are capable of trapping sunlight and taking carbon dioxide (CO₂) from the air in the presence of water to produce food in the form of carbohydrates.

→ The leaves of the plants have tiny pores on their top layer, through which the carbon dioxide (taken in) and oxygen (given out) are exchanged and these exchange pores are called stomata.

→ Stomata are surrounded by the guard cells.

→ Soil provides water and minerals to plants, which are absorbed by the roots of the plants through Xylem tissues present in roots and further sent to other parts of the plant.

→ Sun is the main source of energy for all living organisms.

→ In the photosynthesis process, the energy of the sun is converted into chemical energy.

→ The leaves of some plants are not green in colour but of some other colour as for example red leaves of coleus, red cabbage has violet leaves.

→ Such leaves also show photosynthesis because they also contain chlorophylls but are lesser in amount than green plants.

→ The basic products of photosynthesis are oxygen and glucose.

→ Heterotrophs are divided into four types:

• Decomposers
• Parasites
• Insect eaters
• Symbiotic

→ The organisms that get nourishment from the body of other living beings are called parasites.

→ Organisms that depend on dead bodies and rotten substances for their nourishment are called decomposers.

→ In a symbiotic relationship, two types of organisms depend on each other for food, from which both the organisms are benefited.

→ Dead and decaying plants and animals are decomposed by the decomposers which provide essential nutrients to the soil.

→ Nutrients: The main components of food such as carbohydrates, fats, proteins, vitamins, and minerals that help in the growth and development of the body are called nutrients.

→ Self-nutrition: Organisms that make their own food from simple substances are called self-nourishment. This type of nutrition is called autotrophic nutrition.

→ Heterotrophic nutrition: Organisms that can’t prepare their own food but depend on other organisms are called Heterotrophs and this type of nutrition is called heterotrophic nutrition.

→ Dead food: A diet in which dead creatures or rotten substances are providing food to other organisms.

→ Parasites: Organisms that depend on other plants and organisms for food are called parasites.

→ Photosynthesis: This is an activity in which the leaves of a plant contain green colour pigment-chlorophyll, carbon dioxide of the air, and water in the presence of sunlight prepare food in the form of carbohydrates. Here solar energy is converted into chemical energy.

→ Chlorophyll: This is a green pigment that is present in plants. This is important for plants to prepare their own food.

→ Carbohydrates: A type of micronutrient that is present in many foods such as sugar, starch, and fiber. Our body needs these micronutrients to stay healthy.

→ Stomata: Stomata are found on the outer surface of the aerial parts of the plant. The maximum amount of stomata is found on leaves. Gases are exchanged through Stomata (holes).

→ Host: The plants or organisms on which the parasite depends for its food are called the host.

→ Chemical Fertilizer: This is a factory-made chemical (a mixture of inorganic salts). It contains a lot of nutrients for plants. It fulfills the deficiency in the soil so that the soil remains fertile.

→ Rhizobium: A Bacterium found in the roots and buds of leguminous plants. It makes the nitrogen in the air usable, which is used by plants, and in return, plants provide shelter and food to this bacteria.

This PSEB 8th Class Agriculture Notes Chapter 8 Organic Farming will help you in revision during exams.

PSEB 8th Class Agriculture Notes Chapter 8 Organic Farming

→ Organic farming helps in maintaining natural balance and also in conserving natural resources.

→ Inorganic farming we do not use chemical fertilizers, herbicides, fungicides, and insecticides, etc.

→ Organic farming is based on the concept that feeds the soil and not the plants.

→ Advantages of organic farming are fertility of the soil is increased, lower production cost, good income from organic produce, availability of pesticide residue-free food, etc.

→ Excessive use of fertilizers and pesticides, burning of rice and wheat straw, etc. have deteriorated greatly the soil health and the environment.

→ Due to the adoption of the Rice-Wheat cropping system for many years, it has reduced the area under the traditional pulse and oilseed crops.

→ There is a huge demand for tea, basmati rice, vegetables, fruits, pulses, etc. which are grown by adopting organic farming practices, in the world organic food market.

→ The government of India has established a National Centre for Organic Fanning (NCOF) at Ghaziabad to promote organic farming. Its Regional centre in North India is situated at Panchkula, Haryana.

→ In the year 2004 India has formulated certain organic standards which are also acceptable in other countries.

→ Agricultural practices followed in organic farming are the same as that of conventional farming e.g. seeds, sowing method, varieties, etc.

→ Nutritional requirements of crops are met by using compost, vermicompost, farmyard manure, bio-fertilizers, non-edible cakes like castor cakes, etc.

→ Protection of crops from pests and insects is done by using beneficial insects, birds, etc.

→ Extract of neem is also used against pests and insects etc.

→ Organic certification guarantees that organic products are produced as per the organic set standards.

→ Information about organic standards can be obtained from site www.apeda.gov.in.