Class 8 Maths

Class 8 Biology Chapter 1st'Transport in plants' Exercise A Fill in the blanks 1. Diffusion 2. Semipermeable

3. Hypertonic

4. Low, higher

5. Carrier proteins

6. Tracheids, vessels

7. Phloem

8. Phloem fibre

9. Transpiration

10. Lenticels, cuticle

11. Calcium

12. Iron, nitrogen

B. Choose the correct option

1.(d)

2.(b)

3.(a)

4.(b)

5.(c)

6.(b)

7.(d)

8.(d)

9.(c)

10.(d)

C.Match the following

1.d

2.e

3.f

4.h

5.c

6.a

7.b

8.g

D.Answer the following questions

1.Diffusion is a process in which particles of a substance moves from an area of higher concentration to an area of lower concentration until they are evenly distributed.

For example:

(a)Plants absorb minerals by diffusion.

(b)Diffusion helps in gaseous exchange between plants and atmosphere.

(c)The release of water vapours through the stomata in plants takes place through diffusion

2.Osmosis is the movement of solvent molecules through a semipermeable membrane from an area of higher concentration to an area of lower concentration.

(a)Osmosis is the movement of solvent molecules while diffusion is the movement of particles like solid,liquids and gaseous.

(b) In osmosis semipermeable membrane is required while in diffusion there is direct movement of particles.

3.Active transport is the movement of molecules against the concentration gradient from an area of lower concentration to an area of higher concentration. This process requires expenditure of energy.

4. Xylem is made up of four type of cells:

(a) Tracheids

(b) Vessels

(c) Xylem parenchyma

(d)Xylem fibres

Phloem also has four types of cells:

(a)Seive tubes

(b)Companion cells

(c)Phloem parenchyma

(d)Phloem fibres

5.Transpiration is the process by which plants release water in the form of water vapour.

6. Transpiration creates transpiration pull which helps in the upward movement of water and minerals in plants.

(a) Transpiration helps concentrate the cytoplasm of plant cells, which helps in osmosis.

(b) It helps distribute water and minerals throughout the plant body.

(c)It helps cool the plant body as a lot of heat is taken up in converting water into water vapour.

7. The three macronutrients required by plants are:

(a) Potassium

(b) Calcium

(c)Nitrogen

Micronutrients are:

(a)Copper

(b)Iron

(c)Sodium

8.(a) Nitrogen-Yellow leaves and slow growth

(b) Phosphorus-Root and shoot are too short and late flowering

(c)Calcium-Death of tissues and weak stem.

(d)Iron-Inadequate chlorophyll in leaves.

E. Explain in brief

1.Take a large potato peel it and cut off a slice from one end to make it flat.Make a deep cavity within the potato. FIll the cavity with concentrated sugar solution.Stick a pin into the potato to mark the level of the sugar solution.Place the potato in a beaker containing water.After 2 hours observe the level of the sugar solution within the cavity.We will see that the level of the sugar solution in the cavity has risen.Water from the beaker enters a cavity by osmosis and causes a sugar solution to rise.(Diagram is on page no.3 1.4a)

2.If we place a cell in hypotonic solution the cell will get swollen due to endosmosis.If we place a cell in hypertonic solution the cell will get flaccid due to exosmosis and if we place the cell in an isotonic solution there will be no change in the shape of the cell.

3.Xylem cells are of four types-tracheids,vessels,xylem parenchyma and xylem fibres.

(a)TRACHEIDS:These are elongated, tubular cells with tapering ends and thick lignified walls. Tracheids are dead cells.

(b)VESSELS:These are also dead, elongated, tubelight structures with lignified walls. Vessels are made of cells called vessel elements.

(c)XYLEM PARENCHYMA:These aa living parenchymatous cells that help conduct water and also store food.

(d)XYLEM FIBRES: These are dead sclerenchymatous cells that provide mechanical strength to the tissue.

Diagram is on page 5 fig.1.8

4. Phloem has four types of elements:

(a)SEIVE TUBES:These are slender, elongated, tubelight cells placed end to end. Seive tubes are living cells, but they lack nuclei. Sieve tubes have seive plates

through which food is transported between cells and finally to all parts of the plants.

(b) COMPANION CELLS: Thesecells are found beside seive tubes and are connected to them through pores. The cells assist seive tubes in the conduction of food.

(c) PHLOEM PARENCHYMA: These are living cells. The cells store food and also help conduct it.

(d) PHLOEM FIBRES: These are dead sclerenchymatous cells that provide mechanical strength to the phloem tissue. The cells are also called bast fibres.

Diagram is on page no.5. fig.no.1.9

6.Take a healthy, well watered potted plant and cover the pot with a rubber sheet or a larger polythene bag.Place the potted plant in sunlight and cover it with the bell jar to make it airtight.After a few hours we will see that moisture has accumulated on the inner wall of the bell jar due to water vapours released during transpiration. This shows the process of transpiration in plants.

5.The concentration of glucose increases within the guard cells during the day and the drawing water from the surrounding cells by osmosis. As a result they bulge outwards, opening the stomach and allowing water vapour to escape from the underline intercellular spaces. In this way transpiration occurs in plants.Transpiration stops when the stomata close during the night.

The factors that affect transpiration in plants are:

(a) Intensity of light

(b) Temperature

(c) Humidity

(d) Atmospheric pressure

(e) Velocity of wind

7.The active transport of minerals into the root cells increases the concentration of their cytoplasm, does promoting absorption of water by osmosis. The entry of more and more

water into the xylem vessels creates an upward pressure called root pressure, which pushes the sap upward in the stem.

8.Take a potted plant and water it well. Using a knife, cut off the stem a few inches above the soil.Fix a long narrow glass tube to the cut end of the stem with the help of rubber tubing. Pour a little coloured water into in the glass tube and mark its level.Pour a little oil over the coloured water to prevent evaporation. Use clamp with stand to hold the glass tube straight. After sometime we will find that the level of coloured water into the glass tube has risen. The root pressure pushes the coloured water in the tube and causes it to rise.

COMPUTER

Class 8 CH – 1(OS & GUI) - Roles and Functions

1. Tick the correct answer.

a. User Interface

b. Hard Disk

c. Interface

d. Booting

e. Device driver

f. Multiprocessing

g. Solaris

2. True and False.

a. T

b. F(does not /does)

c. T

d. T

e. F(Novell’s Netware/BOSS)

f. T

g. T

h. F(Difficult /easy)

3. Fill in the blanks.

a. Bridge

b. Warm boot

c. Mac OS X

d. Multiuser

e. Stand alone

f. Server

g. Command

h. Touch

4. Define the following

a. Multitasking OS – A multitasking operating system allows a single user to work on two or more applications that reside in memory at the same time.

b. Multiprocessing OS – A multiprocessing operating system can support two or more processors that run programs at the same time.

c. Real time OS – A real time operating system (RTOS) is an operating system that guarantees to work within a specified time limit.

d. Distributed OS – A distributed operating system is a network –based operating system which is carried out on more than one machine.

5. Answer in 1-2 sentences.

a. What is a Software ?

Ans. Software consists of a series of related instructions, organized for a common purpose, that tells the computer what tasks to perform and how to perform.

b. What is the role of Operating System ?

Ans. Operating system acts as an interface between a user and the hardware. It also hides the complexity of the hardware from the user.

c. How many categories of Operating system are used ? Name them

Ans. There are three basic categories of Operating System .

1. Stand- alone Operating System.

2. Server Operating System.

3. Embedded Operating System.

d. Differentiate between Stand-alone OS and Server OS .

Ans.

Stand-alone OS

Server OS

1. An operating system that works on a desktop computer or notebook computer is called a stand-alone operating system.

2. Examples- MAC OS X, LINUX.

1. A Server operating system is an operating system that is designed specifically to support a network.

2. Examples- LINUX,UNIX, SOLARIS.

e. What is a User Interface?

Ans. A User Interface controls how you enter data and instructions as well as the display of information on the screen.

e. How many types of User Interface are used ? Name the

f. Ans. Two types of user interface are there .

1. Command Line Interface (CLI) 2. Graphical User Interface(GUI)

g. Differentiate between CUI and GUI.

Ans.

CUI

GUI

1. In a CUI , a user types commands or presses special keys on the keyboard to enter data.

2. Example- DOS (Disk Operating System)

1. In a GUI, we interact with menus, icons and etc. to issue commands.

2. Example- Mac OS, Ubuntu.

6. Answer Briefly

a. What are the functions of operating system ? Explain any three.

Ans. The functions of operating system are :

1. Processor Management- Processor management means managing the program or programs running on the processor at a given time.

2. Memory Management- The purpose of memory management is to optimize use of Random Access Memory (RAM).

3. User Interface- A user interface controls how we enter data and instruction as well as the display of information on the screen.

b. Name some popular server operating systems. Define them.

Ans. Some popular server operating system are:

1. WINDOWS SERVER- Developed by Microsoft, Windows Server enables organizations to manage applications and websites.

2. SOLARIS- It is a version of UNIX , developed by Sun Microsystems designed for e-commerce applications.

3. NOVELL’S NETWARE- It is a server operating system , designed for client/server networks.

4. BHARAT OPERATING SYSTEM SOLUTIONS(BOSS)- It is an easy- to- use version of Linux, developed by C-DAC, India.

c. What is an Embedded Operating System ? Give some examples.

Ans. The Operating system on mobile devices and many consumer electronics is called a Mobile operating system or Embedded operating system. These operating systems reside in the ROM chips. It includes calendar , contact management, text messaging, email, Touch screen , digital camera, media player and wireless connectivity such as Wi-Fi and Bluetooth.

d. What are the basic principles while designing User Interface?

Ans. The basic principles while designing User Interface are :

1. User familiarity – The interface should be based on user-oriented terms and concepts rather than computer concepts.

2. Consistency- The system should display an appropriate level of consistency.

3. Recoverability-The system should provide some flexibility to user errors and allow the user to recover from errors.

4. User guidance- Some user guidance such as help system, on-line manuals, etc should be supplied.

5. User diversity- The interface should provide appropriate interaction facilities for different types of system user.

e. What are the advantages of CLI?

Ans. 1. The user is in direct communication with the computer.

2. The user is not restricted to a number of predetermined options.

3. It is possible to alter computer configuration settings.

4. Working on CLI is fast.

f. Write down the characteristics Of GUI.

Ans. 1. Windows: Multiple windows allow different information to be displayed simultaneously on the user’s screen.

2. Icons: Icons display different types of information. Some icons represent files while others represent processes.

3. Menus: Command are selected from a menu rather than typed in a command language.

4. Pointing: A pointing device such as a mouse is used for selecting choices from menu

5. Graphics: Graphical elements can be mixed with text on the same display.

HOME

Class 8 English language

Insert the correct tense of verbs in each of the following sentences :

(1) I told him why I …. that . (do) (2) The teacher asked boys whether they ….. the sums. (solve) (3) I shall go home during the vacation so that I …... my brother. (see) (4)My son’s

health was so bad last year that he failed …. the examination .(take) (5)When I …. him last , I spoke to him .(see)(6)Although they ….. defeated , they did not lose heart. (be) (7)He tried how fast he … walk .(can) (8) Our teacher taught us that virtue …. its own reward .(be) (9) Our holy books tell us that man … mortal .(be) (10) He eats that he … live. (may) (11) He spoke so fast that I ….. not follow him .(can) (12) Just as I …. the room , the bell rang .(enter) (13) Who told you that goats … on grass ?(live) (14) I shall fire if you …. . (speak) (15) He heard that the cottage …. for sale. (be) (16) His health has improved since he …. from the hills. (return) (17) Do whatever you …. proper. (think) (18) It is clear that he …. a clever boy. (be) (19) The news that the enemey …. approaching alarmed the people. (be) (20) This is the place where Martin …. . (live) (21) He kept quiet that he …. please me.(may) (22) He would succeed if he …. . (try) (23) A great building stood where there …. a cottage now . (be) (24) However poor a man …. be, he has always something to be thankful for.(may) (25) He declared that he …. not believe it even if he saw it with his own eyes.(will)

Answers

1. did 2. had solved 3. can see 4. to take 5. saw 6. were 7. could 8.is 9. is 10. may 11. could 12. entered13.live14.speak15.was16.returned17.think18.is19.was20.lived21.might22.tries23.was24.may25.would

NOTICE WRITING :

Format:

Heading : Must be appropriate to the event 1 mark

Date : ½ mark

Time : ½ mark

Venue : Hall/auditorium+ Location Eg. Sandra Hall, St Lawrence School ½ + ½ Mark

Name of event : War with words (Inter school debate) 1 mark

For whom ? Detail of audience ,invitiees eg. Pupils from class 8 to 10 1 mark

Example :You are the Secretary of the children’s club of your society. You are planning to celebrate Diwali mela in your locality. Write a notice to be put up on the notice board of

your society giving details about the event.

Solution:

THE COLOURS OF CULTURE

Grand Diwali Mela

The Children’s Club of the society is organizing Diwali Mela .Details are as follows:

Venue: Community Hall

Date: 15th Ocotober 2020

Time: 9am to 2 pm

Stall Charges: RS 2000/-

There will be a short cultural programme to showcase the talents of children. All the members of the society are cordially invited to participate in the Mela

A sumptuous lunch awaits you.

Class 8 English Lit.

N0VEL-CLASS-8 TH

CHAPTER-1 RECALLED TO LIFE

EX.A

ANS 1) The message Recalled to life means brought back to life. This message refers to Dr. Manette who was in France and was recently released from prison. His daughter Lucie Manette thought he had been dead for the past eighteen years but he was still alive and had forgotten his past life. Slowly and slowly Jarvis Lorry and Lucie recalled him to life.

ANS 2) the story took place in the year 1775 . At that time England and France were undergoing a period of social turmoil. The people used to wear loose cloths and avoid wearing tight clothes. They felt themselves very comfortable in the loose dresses.

ANS 3) one or two centuries ago our country was under the rule of Britishers. The condition of Indians was very pathetic because the Britishers were very cruel and unjust. Yes, I would like to have life then and sacrifice my life to free my country.

EX.B

ANS 1) In the year 1775 social events brought destruction in two cities that is London and Paris. In both the cities the prosperity of the ruling class increased and the same way the poverty of underprivileged. The king and Queen in both the cities turned a blind eye to the hardships of the people.

ANS 2) When it was revealed to Miss Manette that her father was alive and was in France she lost her balance. Mr Lorry consoled her by saying that it was not easy for him to handle these emotional matters as he was he was a man of business.

ANS 3) Lucie Manette was brought up as an orphan. Her father had been dead for the last eighteen years but when Mr Lorry told her that he was still alive and had been in the prison for last eighteen years. This news was really shocking for her, she said its cant be true and going to meet the ghost of her father.

8 th (Physics) MATTER

15. We feel comfortable under a fan in summer. Why? Ans. We feel comfortable under the fan in summer because when we perspire, the running fan makes the perspiration evaporate, thereby causing cooling. It happens because circulating air sweeps up the perspiration and also takes heat out of it.

16. Write the name of the process in the given box.

1. a liquid changes into a solid. Freezing

2. liquid changes into vapour.Vapourisation

3. a solid directly changes into a gaseous state on heating.

Sublimation

17. List the properties of the particles of matter. Ans. The properties of matter are as follows:

1. Matter is made up of very-very small particles namely atoms and molecules.

2. There are many empty spaces between particles of matter.

3. There are attractive forces among atoms or molecules called intermolecular forces.

4. All the particles have kinetic energy which varies depending on the temperature of the sample of the matter.

5. The temperature of a substance indicates average kinetic energy of the particles.

6. A change in state may occur when the energy of the particles is changed.

18. Why do gases exert pressure?

Ans. Gases exert pressure because in gases the molecules are free to move in all directions at high speed . Due to their movement they collide with each other, hence exert pressure.

19. A gas fills the containing vessel fully.why? Ans. Particles of the gases are loosely packed. The inter-particle attractive forces are negligible in the case of gases.Particle of a gas can move in all directions and fill the required space quickly.

20. Why does the temperature remain constant during melting of ice?

Ans. The temperature remains constant during the melting of ice because of latent heat of fusion as the heat energy is required only to change the state by keeping the temperature constant.

21. Temperature remains constant during boiling of a liquid. Why?

Ans. Temperature remains constant during boiling of a liquid because of latent heat of vaporization, the absorbed heat energy does not change the kinetic energy of the particle, thereby not changing the temperature.

22. List the factors affecting evaporation.

Ans. The factors affecting evaporation are:

1. Temperature

2. Nature of liquid

3. Surface area

4. Circulation of air

5. Humidity

23. Why is water sprinkled on a roof during a hot summer day?

Ans. Water is sprinkled on a roof during a hot summer day because it gives a cooling effect due to evaporation.

24. Why does evaporation cause cooling?

Ans. When a substance evaporates it takes away heat from the surrounding, thereby making the surrounding cool.

25. Why do naphthalene balls disappear when kept in air for some days?

Ans. Naphthalene balls disappear when kept in air for some days due to sublimation.

Class 8 CHEMISTRY ( LESSON 1)

SHORT QUESTIONS-

1Q- What are the three states of matter?

Ans- Solids ,liquids and gases.

2Q- Arrange solids,liquids and gases in order of increasing intermolecular space.

Ans- Solids < liquids < gases.

3Q- Arrange the solids,liquids and gases in order of increasing intermolecular forces.

Ans- Gases < liquids < solids.

4Q- What will happen to the kinetic energy of a particle if it is heated?

Ans- The kinetic energy of the particles increases if it is heated.

5Q- What gives rise to the pressure of a gas?

Ans- The collision of the particles with the walls of the vessels give rise to the pressure of the gas.

6Q- In which state of matter do the particles move the longest distances?

Ans- Gaseous state of matter.

LONG QUESTIONS-

1Q- Explain the melting of ice on the basis of the kinetic theory.

Ans- The particles constituting an ice only vibrate about their mean positions. As an ice is heated, the K.E of the particles increases. With the rising temperature, the particles vibrate more and more vigorously till they move away from their fixed positions at a particular temperature called the melting point of the ice. Thus, an ice becomes a liquid (water).

2Q- Explain the evaporation of a liquid on the basis of the kinetic theory.

Ans- The particles in a liquid are in continuous motion, during which they collide among themselves. If they collide strongly, some of the particles may overcome the attractive forces and may escape from the surface. A liquid evaporates in this manner.

3Q- Explain the liquification of a gas on the basis of the kinetic theory.

Ans- In the gaseous state, the particles move very fast, independently of each other. As the temperature is lowered, kinetic energy of the particles is also lowered. When the low energy gaseous particles collide with each other, they may form bigger lumps or clusters and the gas may condense into a liquid.

4Q- Explain the freezing of a liquid on the basis of the kinetic theory.

Ans- As a liquid is cooled, the kinetic energy of the particles decreases. The particles move shorter and shorter distances as the temperature is lowered. At the freezing point, the translatory motion of the particles ceases and the particles get rigidly fixed. This is how a liquid changes into a solid.

5Q- State the law of conservation of mass.

Ans- According to the law of conservation of mass, “ Matter can neither be created nor be destroyed but can be changed from one form to another form and the total mass of the substances before and after the change remains same”.

6Q- Describe an experiment to prove the law of conservation of mass.

Ans- Put a small tube or bottle containing a solution of barium chloride into a conical flask. Put some sodium sulphate solution in the flask with the help of a dropper carefully, ensuring that the two substances do not come in contact with each other. Close the mouth of the flask with a cork and weigh the flask. Tilt the flask and swirl for sometime and weigh it again. You will find that there is no change in the weight of the flask.

( with DIAGRAM FROM THE BOOK)