• Nutrition refers to how an organism consumes food and how the body processes it.

• Nutrients are the components of food that give the body nutrition.

• All creatures consume food and use it to obtain energy for body growth and upkeep.

• Photosynthesis is the mechanism through which green plants produce their own food. They are autotrophic organisms.

• Photosynthesis: In the presence of sunshine, green plants prepare their own food using chlorophyll (found in green plants), carbon dioxide, and water absorbed from the environment. Photosynthesis is the name for this process. For food synthesis, plants use simple chemical ingredients such as carbon dioxide, water, and minerals.

• For photosynthesis to occur, chlorophyll and sunshine are required. Photosynthesis produces complex chemical compounds such as sugars.

• With the help of chlorophyll, solar energy is stored in the form of food in the leaves. During photosynthesis, oxygen is created.

• Living species use the oxygen generated during photosynthesis to survive.

• Fungi get their food from rotting, dead things. They are saprotrophs or saprotrophic organisms. Cuscuta plants are parasitic. They eat the host plant's food.

• Heterotrophs are plants and animals that rely on others for their nutrition.

• Parasitic Creatures are parasitic organisms that live on the bodies of other organisms.

• All parasitic plants eat other plants in one of two ways:

1. Partial Parasites: They get some of their sustenance from the host, for example, a painted cup.

2. Total Parasites, such as mistletoe, are fully reliant on the host for nourishment.

• Saprophytic organisms are those that feed on dead and decaying plant and animal debris.

Mushrooms, molds, and some fungi and bacteria are examples.

• Insectivorous Plants: Green plants that get their nutrition from both the soil and the atmosphere, as well as small insects. Pitcher plant, bladderwort, and Venus flytrap, for example.

• Symbiosis is a type of nutrition in which two or more individuals work together to meet their nutritional needs.

• The relationship between algae and fungus can be seen in the form of lichens on tree trunks. The fungus provides water to algae, and algae provide food to fungus.\

• acid can cut through clothes and destroy the wool away. On exposure to skin, it can cause severe burns. They act as good conductors of electricity thus allowing the electric current to pass through them. There are several types of Acids given below:

  (i) Mineral Acids are acids that are prepared from minerals present in the earth’s crust.

  (ii) Organic Acids are those acids that are produced by plants and animals (except hydrochloric acid).

  (iii) Weak Acids are those that do not dissociate completely in solution. For example, tartaric acid, lactic acid etc.

  (iv) Strong Acids have the ability to dissociate completely in solution. For example, sulphuric acid, hydrochloric acid etc.

  3. Neutralization: A reaction between an acid and a base that results in the formation of salt and water. Acid + Base gives Salt + Water.Neutralization reactions occur in our day to day life. Some of its examples are:

  a. Indigestion: In this too much acid is formed in the stomach that causes indigestion. It is neutralized by taking an antacid like milk of magnesia that causes relief to the situation.

  b. Ant Sting: When an ant bites, it injects formic acid inside the skin. This ant sting is then neutralized by rubbing moist baking soda (chemical name- sodium hydrogen carbonate) or by rubbing calamine (which contains zinc carbonate) over the affected area.

  c. Soil Treatment: When the soil becomes too acidic, it is neutralized by adding quicklime (calcium oxide) or slaked lime (calcium hydroxide) to it.

  4. Bases: Substances that are bitter in taste and soapy in appearance. Bases are classified into two:

  a. Weak Bases: Those bases which produce fewer hydroxide ions in solution. For example, magnesium hydroxide, ammonium hydroxide etc.

  b. Strong Bases: Those bases which produce many hydroxide ions when dissolved in water. For example, Sodium hydroxide(NaOH), Potassium hydroxide (KOH) etc.

  Substances that are neither acidic nor basic are said to be neutral substances.

  When an acid and a base react with each other they neutralise and forms a salt. Salt could be acidic, basic or neutral in nature.

  5. Indicators are special chemicals that change their color to indicate the presence of a chemical substance. Solutions of substances show different colours in acidic, basic, and neutral solutions. Hence, It is widely used to confirm the presence of an acid, a base, or a neutral solution.

  Classification of Indicators is Given Below:

  1. Natural Indicators:

  a. Litmus: It is obtained from lichens. It is generally available in the form of thin strips of paper or in the form of a solution.· When acid is added to blue litmus, its colour changes to red. When bases are added to red litmus paper, it changes its color to blue.

  b. Turmeric: It is a natural indicator which remains yellow in neutral and acidic solutions but on coming in contact with alkaline solutions it turns red.

  c. China Rose: Another naturally occuring indicator which turns acidic solutions to dark pink (magenta) and basic solution to green.

  d. Red Cabbage: Turns acidic solutions to red and the basic solutions to blue.

  2. Some Other Indicators:

  a. Methyl Orange: In acidic solutions it gives pinkish-red colour whereas yellow colour with the bases.

  b. Phenolphthalein: It acts as an acid-base indicator. It remains colourless in acidic solutions but turns pink in alkali solutions.

• Physical and chemical changes are the two sorts of changes that might occur.

1. Physical alterations refer to changes in a substance's physical qualities. These alterations do not result in the formation of any new compounds. These modifications might be reversible. Crushing a can, lighting an electric bulb, ripping paper, and mixing sand and water are just a few examples.

2. Chemical alterations occur when the substance's composition and chemical characteristics are altered. New chemicals are created as a result of chemical reactions. This is a permanent and irrevocable transformation. For instance, a candle is lit, the curd is formed from milk, and fruits ripen.

• Chemical Reactions in the Real World:

1. Iron Rusting: Iron rusting is the transformation of iron into iron oxide. When iron comes into touch with water and oxygen, something happens. The process is a sort of corrosion that happens frequently in nature.

Prevention of Rusting:

i. By Painting

ii. By Oiling and greasing

iii. By Chromium plating

iv. By Galvanizing

v. By Alloying

2. Cooking of Food: Cooking breaks down complex carbs, lipids, and protein molecules into smaller molecules.

It's thought to be a breakdown process. Food that has been prepared is easier to digest than food that has not been cooked.

3. Decay of Organic Substances: Enzymes are produced by microorganisms such as fungi and bacteria, which break down complex chemical materials into simpler components. It's also referred to as a breakdown process.

• Crystallization can be used to obtain pure compounds from their solutions.

Respiration is required for living organisms to survive.

• It takes energy from the food and releases it.

• Glucose is broken down into carbon dioxide and water with the oxygen we breathe.

• In the process, energy is released.

• Glucose is broken down in an organism's cells (cellular respiration).

• Food is broken down by anaerobic respiration during strenuous activity when the supply of oxygen to our muscle cells is insufficient (without oxygen)

Types of Respiration

1. External Respiration:

• External respiration, often known as breathing, is the process of taking oxygen from the air and exhaling carbon dioxide back into the atmosphere.

• Gases are exchanged in and out of the blood at the same time.

2. Internal Respiration:

• Food is broken down in body cells by numerous chemical processes during internal respiration.

• Internal respiration is divided into two categories:

1. Aerobic Respiration:

• Aerobic respiration occurs when oxygen is present.

• The end products of aerobic respiration are carbon dioxide and water.

• Aerobic respiration occurs in the majority of organisms.

2. Anaerobic Respiration:

• Anaerobic respiration occurs when there is no oxygen present.

• The majority of microorganisms are capable of anaerobic respiration.

• At the end of anaerobic respiration, alcohol and carbon dioxide are produced.

• Lactic acid is generated at the end of anaerobic respiration in some circumstances.

Respiration in Plants:

• Plants breathe through pores called stomata, which allow gaseous exchange via diffusion.

• Lenticels are apertures in stems that allow gaseous exchange via diffusion.

• Stomatal pores in roots allow for the gaseous exchange of oxygen dissolved in soil water.

Respiration in Animals:

• Animals' respiration differs depending on their personality, such as:

• Earthworms use their skin for respiration.

• Insects do respiration through the entire body surface.

• Gills are used by fish to breathe.

• Frogs do respiration through their thin, moist, and smooth skin in the water and through their lungs on land.

Respiration in Humans:

• Inhaled air enters the nasal cavity through the nostrils and then into the lungs via the windpipe.

• Breathing is a portion of the respiration process, in which an organism takes in oxygen-rich air and exhales carbon dioxide-rich air.

• Distinct creatures have different respiratory organs for gas exchange.

• Our lungs expand during intake and subsequently contract when the air leaves our bodies during exhalation.

• The pace of breathing is accelerated by increased physical exertion.

• The respiratory organs and breathing process of animals such as cows, buffaloes, dogs, and cats are comparable to those in humans.

Motion

• The movement of an object or the tendency of an object to move from its place with respect to time is called motion

• For example Movement of the pendulum of a clock is a motion, falling of leaves from trees is a motion etc.

There are two types of motions

1. Uniform Motion: If an object moves in a straight line at a constant speed i.e., speed is not changing over time, then the motion is uniform motion.

2. Non-Uniform Motion: If an object moves in a straight line and the speed of an object changes over time, then the motion is a non-uniform motion.

Speed

• The distance covered by an object per unit time is called speed. Thus,

$S=\dfrac{D}{T}$  where $S$ represent the speed of an object, $D$ represent the distance covered by an object and $T$ represent the time taken by the object.

• SI unit of speed is $m/s$.

Measurement of Time

• In earlier periods, the shadow of objects cast by the sun was used to measure time.

• Simple Pendulum: It is a type of clock used to measure time and is the best example of periodic motion.

• Periodic or oscillatory motion is the to and fro movement of an object.

• Oscillation: The process of moving back and forth.

• The time taken by the pendulum to complete one complete oscillation is called the time period.

• The basic or SI unit of time is seconds denoted by $s$

Measuring Speed:

• Speedometer: It is a device used to measure the speed of a vehicle is $Km/hr$

• Odometer: It is a device used to measure the distance covered by a vehicle.

Distance-Time Graph

• It is used to study the motion of an object.

• The distance is represented on the Y-axis and time is represented on the X-axis.

• The motion is uniform when the distance-time graph is a straight line.

• If the distance-time graph is moving upwards then the speed of the object is increasing.

• If the distance-time graph is moving downwards then the speed of an object is decreasing

• The object is said to be at rest if the distance-time graph is parallel to the X-axis.

• The object's speed is determined by the slope of the distance-time graph.

• If there is a curve in the distance-time graph then the speed of the object is changing.

Class 7 Science Chapter Motion and Time notes PDF

These notes of Class 7 Science Motion and Time have been well-written covering all the important points of the chapter. Students need to download these notes and then refer to them when they wish to. Students get to study at their comfort and pace. The PDF version of the notes on Motion and Time Class 7 can either be referred to on a device, or one can take a hardcopy of the same and go through it. The notes have all the points covered, so instead of taking the trouble of making their notes, all that the student has to do now is to download the notes from this site and go through it.

Time and Motion Class 7 Notes Revision

Our revision CBSE Class 7 Science Chapter 13 Motion and Time notes cover the details of the chapter that lets students refer to the notes before an exam.

Motion

Distance is the absolute path that is covered by an object in a given time interval. Displacement is the shortest distance that is covered by the object in a given time interval. Distance is calculated as the product of speed and time. The distance is represented in meters, kilometres.

An object stays in motion if its position changes concerning time, like when a car moves on the road. An object is at rest if it does not change its position concerning time. Like when a person stands on the ground.

As a standard, distance is measured in meters, the unit of time in seconds, and the unit of speed is meter/second.

The Types of Motion

Motion is of three types. These are rectilinear motion or translatory motion, circular motion, and period or oscillatory motion.

The rectilinear or translatory motion is where the body moves in a straight line without it changing its direction. Like when a car moves on a straight road.

A circular motion is where the body moves in a circular shape about a fixed point and on a fixed radius, like the motion of the planets around the sun.

A period or oscillatory motion is when the body's motion repeats after a fixed time interval. Like, the to and fro movement of the pendulum.

A periodic or an oscillatory motion is where the motion of the body gets repeated after a fixed interval of time. This is like the pendulum moving. The car's motion in a circular path of the motion of the planet around the sun.

The Oscillation of a Simple Pendulum

When the bob of the pendulum moves from A to B and then back to A again, it is considered one complete oscillation. The time period is the total time taken by the pendulum to complete one oscillation.

Time and Speed

Speed or the average speed is the total distance that the object covers in a particular time interval. Speed is the distance travelled divided by the time taken. Speed is calculated as the distance travelled to the time taken. The unit of speed is measured in meters per second or kilometres per hour.

A motion could be uniform or non-uniform. A uniform motion is when the object moves along in a straight line, and with constant speed, the object is in a uniform motion. Like when a car moves in a straight line with constant speed. A non-uniform motion is when an object moves on a straight line, and it changes its speed with time. Like when a train is in motion.

Time is usually measured in sends, hours, or minutes. The period is the total amount of time taken by an object to complete one full oscillation.

• The flow of electrons across a conductor is known as electric current.

• The use of symbols to represent electric components is convenient. A circuit diagram can be used to represent an electric circuit using these.

• When an electric current is passed via a wire, it heats up. It's the current's heating impact. This effect can be used in a variety of ways.

• When enormous electric currents are pushed through wires constructed of specific materials, they melt quickly and shatter. Electric fuses, which prevent fires and damage to electrical appliances, are made from these materials.

• One cell's positive terminal is connected to the following cell's negative terminal. A battery is a collection of two or more cells in this configuration.

• A wire acts like a magnet when an electric current travels through it.

• A full path for the flow of electric current is referred to as an electric circuit.

• Components of an Electric Circuit: The following are components of an electric circuit:

1. Cell: A cell is a device that provides energy to allow current to flow.

2. Bulb: When an electric current passes through it, it illuminates.

3. Switch: Turns on or off the circuit.

4. Connecting Wires: These wires assist in the conduct of electric current and the completion of the circuit.

• Light is a naturally occurring substance that enhances vision and makes objects visible. Light follows a straight path.

• A mirror can be made out of any polished or gleaming surface.

• A true image is one that can be obtained on a computer screen. It's made up of light rays that pass through the screen.

• A virtual image is an image that cannot be obtained on a screen. It's made up of light rays that appear to travel right through the screen.

• A planar mirror produces an erect picture. It's a virtual object that's the same size as the real thing. The picture behind the mirror is the same size as the object in front of it.

The left side of an object appears on the right side of an image generated by a mirror, and the right side of the object appears on the left side of the picture.

• A true and inverted image can be created via a concave mirror. The picture generated when the object is put very close to the mirror is virtual, erect, and enlarged.

• A convex mirror is one that curves outwards and has a convex reflecting surface. The image that is created is virtual, upright, and shrunk. A convex mirror creates an image that is upright, virtual, and smaller in size than the object.

• A concave lens is one that has a thinner centre than it has at the edges. It's a convergent lens. The resulting image is imaginary, erect, and shrunken.

• A convex lens can create both a true and a distorted image. The image generated when the object is put very close to the lens is virtual, erect, and enlarged. The convex lens is known as a magnifying glass when it is used to magnify objects.

• White light is made up of seven different colours.

• Properties of Light:

1. Rectilinear Propagation of Light: The quality of light that allows it to move in a straight line in any direction. The direction in which light travels to form a ray.

2. Light Reflection: This is the phenomenon of light rebounding back after striking an object's surface. Smooth, gleaming surfaces reflect nearly all of the light.

3. Dispersion: The breaking of white light into its seven colours is referred to as dispersion. Violet, Indigo, Blue, Green, Yellow, Orange, and Red (VIBGYOR) hues make up white light.