CBSE Class 7 Science: Important Topics for SA1 Exams

The SA1 or the CBSE Summative Assessment I is just around the corner. Students are busy with their last minute revisions and trying to get the most out of their study hours these days.

But you do not need to panic as out the team of experts at Meritnation has come up with some great insights into each chapter for your Science exam. These key revision points and quick tips will help you prepare intelligently for the exams. Even if you have left out certain chapters for last minute preparations or revisions, these tips will help you get through them better.

Chapter 1: Nutrition in Plants

This chapter covers the process of food preparation by plants by utilising raw material present in the environment.

Key Points to Revise in This Chapter

> Photosynthesis: Definition, equation and importance
> Conditions required for photosynthesis
> Other modes of nutrition in plants

Method for Quick Understanding

The whole zest of the chapter is present in the equation of photosynthesis. If you remember the equation, you will be able to understand the whole process of photosynthesis and the components required in it.

MERITNATION TIP:  Photosynthesis can be easily understood by breaking the term in two parts (photo + synthesis). Photo means light and synthesis means to synthesise, so the process of photosynthesises is synthesis of organic food in presence of light. Raw materials required for that process are CO2, water and chlorophyll of plants. Do remember the example of each mode of nutrition in plants. Mostly it happens that examiner gives you name of a plant and asks you what type of nutritional habits does it display. For example Cuscuta?. Cuscuta is a parasitic plant.

Chapter 2: Nutrition in Animals

This chapter is about nutritional habits of animals. You will get to know about different organs that are involved in the process of obtaining nutrition from food that you eat. It also covers about nutrition in amoeba.

Key Points to Revise in This Chapter

> Human digestive system
> Teeth and tongue
> Digestion in ruminants
> Nutrition in amoeba

Method for Quick Understanding

The process of digestion and human digestive system can be understood by remembering the diagram of human alimentary canal. Also, this chapter will help you understand what happens to your food from the moment you put it inside your mouth and then when it passes through the various organs which process it step by step.

MERITNATION TIP:  The diagram of the human digestive system is very important. Often students are asked in exams to draw the diagram. Also, nutrition in amoeba is a very frequently asked topic. You must also remember different type of teeth, their roles and the role of the tongue.

Chapter 3: Fibre to Fibre

This chapter involves a study of wool and silk which are natural fibres. It also covers the steps involved in the processing of wool and silk fibre.

Key Points to Revise in This Chapter

> Silk
> Fleece
> Wool
> Reeling
> Sericulture
> Selective breeding
> Pashmina shawls
> Shearing, scouring and sorting
> Caterpillars, cocoon and pupa
> Rearing and breeding of sheep and silkworms

Method for Quick Understanding

> A student must know about different sources to get wool fibres.
> Try to use flow charts to understand all the steps involved in processing of wool and silk.
> Draw and label the life cycle of silk moth.

MERITNATION TIP:  Learn all the important terms (shearing, scouring, sericulture, reeling of silk etc). Make flow charts to learn the steps involved in processing. Do not get confused between the silkworm, caterpillar and larva. Similarly for sericulture, floriculture, moriculture, apiculture and silviculture. > Silviculture: Cultivation of forest trees > Floriculture: Cultivation of flowering plants > Moriculture: Cultivation of mulberry plants > Apiculture: Rearing of honey bees > Sericulture: Rearing of silkworm

RECOMMENDED RESOURCES: Revision Notes | Sample Papers | Textbook Solutions | Ask & Answer

Chapter 4: Heat

In our day-to-day life, we come across a number of objects. Some of them are hot and some of them are cold. This chapter tries to find out how hot or cold an object is.

Key Points to Revise in This Chapter

> Temperature
> Clinical and laboratory thermometers
> Conduction, convection and radiation
> Conductors and insulators
> Sea breeze and land breeze

Method for Quick Understanding

> Learn the definitions of basic terms used in this chapter.
> Practice to solve questions like “one litre of water at 20 °C is mixed with one litre of water at 60 °C. Find the temperature of the mixture.”
> Be clear about the concept that heat flows from a body at a higher temperature to a body at a lower temperature. There are three ways in which heat can flow from one object to another. These are conduction, convection and radiation.

MERITNATION TIP: For this chapter, students must have clear idea about the ways of heat flow conduction, convection and radiation. Remember the difference between them. Land breeze and sea breeze occur at night and day respectively, so students should not be confused about this.

Chapter 5: Acids, Bases and Salts

In our daily life, we use a large number of substances which are acid, base or salt. They vary in taste and touch. They also lead to changing colours of specific substances which are called indicators. Acid and base combine and form salt which may be acidic, basic or neutral in nature. This is called neutralisation which hasimportance in our daily life. This chapter covers all these things in detail.

Key Points to Revise in This Chapter

> Acids
> Bases
> Salts
> Indicators
> Litmus paper
> Neutralisation

Method for Quick Understanding

> Learn differences between acids, bases and salts.

> Learn about colour changes of indicators (litmus, turmeric, china rose and phenolphthalein) in presence of acid and bases.

> Learn the sources and names of acids and bases such as:
– Slaked lime: Calcium hydroxide (base)
– Vinegar: Acetic acid
– Orange: Citric acid
– Window cleaner: Ammonium hydroxide (base)
– Ant sting: Formic acid
– Curd: Lactic acid
– Amla: Ascorbic acid
– Baking soda: Sodium hydrogen carbonate (base)
– Milk of megnesia: Magnesium hydroxide
– Unripe mango: Tartaric acid
– Soap: Sodium/ potassium hydroxide
– Spinach: Oxalic acid
– Tamarind: Tartaric acid
– Grapes: Tartaric acid
– Lemon: Citric acid
– Quick lime: Calcium oxide

> Topic neutralisation and its application in everyday life is very important from exam point of view, learn the names of acids and bases involved in neutralisation.

MERITNATION TIP: This chapter is can be very scoring in exams if you do some smart practice. Try to remember examples of acids, bases or salts. Students can learn about colour change of indicators in presence of acid (A) or base (B) as shown in given flow chart.

Chapter 6: Physical and Chemical Changes

Every day you come across many changes in your surroundings. These changes may be physical or chemical. This chapter helps you to classify changes occurring around you as physical or chemical or both in one process.

Key Points to Revise in This Chapter

> Physical change
> Chemical change
> Rusting
> Crystallisation
> Galvanisation

Method for Quick Understanding

> Just try and understand the fundamental principle that in a chemical change new substances are formed while in physical change such things do not happen.

> Change in the colour and physical state may occur in both types of changes.

> Each chemical reaction can be represented by a chemical equation. So practice writing equations in the following few cases from the exam point of view:
– burning of Mg in air followed by dissolution of product in water
– iron nail kept in copper sulphate solution
– baking soda in vinegar
– passing of carbon dioxide through lime water
– in rusting processes

MERITNATION TIP: This chapter needs intensive practice of writing chemical equations for given reactions. Try to find the order of reactivity of metals and non-metals. This will surely help you in answering many questions. Write, write and write all the equations as many times as you can till they make a house in your brain cells! Try to list all the changes occurring during a chemical change. The questions asked on this chapter may be somewhat tricky, so be careful while understanding the questions.

RECOMMENDED RESOURCES: Sample Papers | Chapter Tests | Live Test Series | Textbook Solutions

Chapter 7: Weather, Climate, and Adaptations of Animals to Climate

In this chapter, students can learn about phenomenon like why do we have different climates on different parts of the earth and how and why seasons change after a particular time. Why sometimes it is bright and sunny in the morning and then suddenly it starts to rain. You will get answers to all such questions in this chapter.

Key Points to Revise in This Chapter

> Climate and weather and factors affecting them
> Adaptations of animals to different climatic regions

Method for Quick Understanding

To understand this chapter, you must know the relationship between the earth and the sun. It is important to understand how the earth moves on its own axis as well as in its orbit around the sun. These movements of earth are the primary cause of change of seasons and the movement of wind plays an important role in defining the weather of a place.

You can learn and remember  the adaptation of different organisms to their climate by looking at examples of organisms living in different climatic regions. By observing these organisms, you can easily remember how different animals  adapt to their climates.

MERITNATION TIP: Difference between climate and weather is very important. You must also remember the different adaptations of animals present in different climatic regions. These topics are a favourite with examiners setting up question papers.

Chapter 8: Wind, Storms and Cyclones

This chapters covers many natural phenomena related to wind and the pressure difference on earth surface. You may see such phenomena like storms and cyclones on TV and in newspapers occurring frequently on the earth in various regions.

Key Points to Revise in This Chapter

> Wind and wind current
> Wind flow pattern
> Monsoon
> Thunderstorms and cyclones
> Hurricane, tornadoes and typhoon
> Cyclone alert or Cyclone watch
> Cyclone warning
> Anemometer

Method for Quick Understanding

• It is important to know that air moves from the region where the air pressure is high to the region where the pressure is low.

• Remember some basic concepts like warm air is lighter than cold air, hence the smoke goes up. Similarly, wind currents are developed due to uneven heating between the equator and pole and land and water.

• Find out differences between thunderstorms and cyclones

• The following flow chart will help you to understand the phenomena that leads to the formation of clouds and falling of rain and creation of storms and cyclones:

Difference of temperature between two regions

Sets convection in air

  Warm air rises, creating a low-pressure area

Cool air converges to the low-pressure area

Warm air rises, cools and the water vapour condenses to form clouds

The bigger water drops in the cloud fall to the ground as rain, hail or snow

Falling water droplets and rising air move vigorously to produce thunderstorm

Under certain weather condition storms may develop into cyclones

MERITNATION TIP: To get a high score from this chapter, students must know the cause of each natural phenomenon. Hence, solve more and more reasoning questions and remember the concepts behind them. It is important to understand each term of this chapter so that questions asked in exams can be understood easily and answer can be delivered accordingly.

RECOMMENDED RESOURCES: Revision Notes | Sample Papers | Textbook Solutions | Ask & Answer

Chapter 13: Motion and Time

Once you change your position from one place to another place, you are said to be in motion. Sometimes you cover the same distance in a short time while some times it takes a long time. We say slow and fast in these cases. Distance and time are inter-related in the form of speed.

Key Points to Revise in This Chapter

> Slow and fast motion
> Rectilinear, circular and periodic motions
> Uniform and non-uniform motion
> Average and instantaneous speed
> Oscillation
> Time periodic
> Distance-time graph
> Odometer and speedometer

Method for Quick Understanding

> Speed = Total distance covered / Total time taken

> Time period = Number of oscillations / Time taken

> Distance-time graph for constant motion is a straight line

> SI unit of time and speed are second (symbol is s) and metre/second or m/s

MERITNATION TIP: Try to solve many questions based on speed. Be careful about units used in questions. Before solving the question, convert all the units in SI units. Similarly, graph based questions are frequently asked in exams, so if you want to get a good score in this chapter, practice and attempt atleast 30 questions based on distance-time graph.

Please take a moment to spread these tips with your friends. After all, Knowledge is the only thing that grows when shared! 🙂