SHOBHA ROLLNO. 14

FUNDAMENTAL UNIT OF LIFE

EXERCISE

      

Q1. MAKE A COMPARISON AND WRITE DOWN WAYS IN WHICH PLANT CELLS ARE DIFFERENT FROM ANIMALS CELLS?

ANS.       ANIMAL CELL                                                         PLANT CELL

• CELL WALL IS ABSENT                                          CELL WALL IS PRESENT
• PLASTIDS ARE ABSENT                                          PLASTIDSIS PRESENT  
• CENTROSOME WITH ONE OR                                CENTROSOME AND CENTRIOLES   

 TWO CENTRIOLES IS PRESENT                                       ARE ABSENT

• NUCLEUS LIES PERIPHERALLY                           NUCLEUS USUALLY LIES IN THE 

IN THE CYTOPLASM                                                          CENTRE

Q2. HOW IS PROARYOTIC CELL DIFFERENT FROM A EUKARYOTIC CELL?   

ANS.         PROKARYOTIC CELL                                  EUKARYOTIC CELL

             1. MEMBRANE BOUND ORGANEUES           1. MEMBRANE BOUND ORGANELLES 

                    ABSENT                                                               PRESENT

              2.SIZE OF THE CELL IS SMALL                      2. SIZE OF THE CELL IS LARGE  

               3. PRIMITIVE NUCLERS NOT                          3.THE NUCLEUS BOUNDED BY 

              BOUNDED BY NUCLEAR MEMBRANE               NUCLEAR MEMBRANE

               AS NUCLEAD

               4. FOR EXAMPLE-BACTERIA, MYCRO-        4. FOR EXAMPLE- PLANTS, 

                    PLASMAS                                                              ANIMALS

Q3. WHAT WOULD HAPPEN IF THE PLASMA MEMBRANE RUPTURES OR BREAKS DOWN?

ANS. IF THE PLASMS MEMBRANE RUPTUREA OR BREAKS DOWN THEN WILL BE SPILLING OF CYTOPLASM AND CELL ORGANELLES BURSTING OF LYSOSOME AND DIGESTION CELLULAR CONTENTS.

 

Q4.  WHAT WOULD HAPPEN TO THE LIFE OF A CELL IF THERE WAS NO GOLGI APPARATUS ?

ANS. IF THERE WAS NO GOLGI APPARATUS THEN THE MATERIAL SYNTHESISED IN [ER] WILL NOT BE PACKAGED, STORED AND TRANSPORTED TO VARIOUS TARGETS. 

LYSOSOME  FORMATION WILL ALSO NOT TAKE PLACE .HENCEINTRACELLULAR DIGESTIONAND CLEASING OF THE CELL CANNOT BE  BROUGHT ABOUT. THIRDLY FORMATION OF NEW PLASMA MEMBRANE WILL NOT OCCUR.

Q5. WHICH ORGANELLE IS KNOWN AS THE POWERHOUSE OF THE CELL? WHY? 

ANS. MITOCHONDRIA IS KNOWN AS THE POWERHOUSE OF THE CELL. THE ENERGY REQUIRED  FOR VARIOUS CHEMICAL ACTIVIES NEEDED FOR LIFE IS RELEASED BY MIT OCHONDRIA IN THE FORM OF ATP  MOLECULES.

Q6.WHERE DO THE LIPIDS AND POROTEINS COSTITUTING THE CELLMEMBRANE GET SYNTHESISED?

ANS. PROTEINS ARE SYNTHESISED OVER RIBOSOMES OF RER WHILE LIPIDS ARE SYNTHESIZED OVER SER.

Q7. HOW DOES AN AMOEBA OBTAIN ITS FOOD?

ANS.AMOBEA ENGULFS ITS FOOD WITH YHE HELP OF PSEDOPDODIA, WHICH ARE  PROJECTIONS OF THE CELL MEMBRANE .IT ENCIRCLES THE FOOD PARTICLE AND INGESTS IT BY THE PROCESS OF PHAGOCYTOSIS .ONCE THE FOOD BECOMES A PART OF THE CELL IT IS REFERRED AS PHAGOSOME OR FOOD VACUOLE . INTRACELLULAR DIGESTION TAKE PLACE.THE DIGESTED FOOD IS ABSORED BY THE SURROUNDING   CYTOPLASM AND THE UNDIGESTION MATTER IS THROWN OUT OF THE CELLBY THE PROCESS OF EXOCYTOSIS.

Q8.WHAT IS OSMOSIS? 

ANS. OSMOSIS IS THE PROCESS OF MOVEMENT OF WATER MOLECULES FROM A REGION OF LOW SOLUTE CONCENTRATION TI THE REGION OF HIGH SOLUTE CONCENTRATION VIA SEMIPERMEABLE MEMBRANE.

 

mumtaz jarra (roll no 10)

MATTER IN OUR SURROUNDINGS

ACTIVITY- 
 Q. Why do we observe that the level of water does not change even after dissolving salt in it??

ANS-  When we dissolve salt in water , the particles of salt get into spaces between particles of water so this shows that the level of water does not change.

HOMEWORK

PROPERTIES OF PARTICLE

1. The particles of the matter are very small in size.

2. The particles of matter are continuously in motion , means they have kinetic energy.

3. The particles of matter have space between them.

Why solids are hard??

ANS- Solids are usually  hard because they are tightly packed together and solids can maintain their shape own.

GIVE REASONS

Q.1. Why is table hard?

ANS- The table is hard because its rigidity is very high and 

compressibility is not shown.

Q.2. Diver is able to cut water?

Ans- Water is fluid , i.e changes its shape when applied force.The diver is able to cut the water by applying force and changing its shape.

Q.3. The smell of hot sizzling food reaches our nose?

ANS- The smell of hot sizzling food reaches our nose as due to high speed of particles and large space between gases show the property of diffusing very fast into other gases.

Homework

Latent heat of fusion

The heat required to change 1 kg of solid into liquid completely is known as latent heat of fusion. It is absorbed by a body during a constant temperature process that is specified in some way.

Latent heat of vapourisation

 The heat required to change 1 kg of liquid into vapours at atmospheric pressure is known as the latent heat of vapourisation.

Evaporation

 The process of conversion of liquid into vapours is known as evaporation.

Factors affecting the rate of evaporation

1. Temperature- The rate of evaporation is directly proportional to the rise in temperature . more the temperature more will be the evaporation.

2. Humidity- The rate of evaporation is inversely proportional to the humidity. It means that the more the humidity is the less is the rate of evaporation.

3. Wind speed- The rate of evaporation is directly proportional to the wind speed. It means that more is the wind speed more will be the rate of evaporation.

4. Surface area- The rate of evaporation increases when the surface area increases as when the surface area will be increase the evaporation will also be increased.

EXERCISE

Q1. Convert the following into celsius scale-

(a) 293 K = 293-273 = 20*C 

(b) 470 K = 470-273 = 197*C

Q2. Convert the following into kelvin-

(a) 25*C = 25 + 273 = 298 K

(b) 373*C = 373+273 = 646 K 

Q3. Give reason for the following-

(a) Naphthalene balls disappear with time without leaving any solid.

Ans- It happen because naphthalene balls sublime and directly changes into vapour state without leaving any solid.

(b) We can get the smell of perfume sitting several meters away.

Ans- It happens because perfume contain volatile solvent and 

diffuse faster and can reach people sitting several meters away.

Q4. Arrange the following substances in increasing order of forces of attraction between the particles - water, sugar, oxygen.

Ans- Oxygen-water-sugar

Q5. What is physical state of water at-

(a) 25*C= liquid

(b) 0*C= solid or liquid

(c) 100*C= liquid and gas

Q6. Give reason-

(a) Water at room temperature is a liquid.

Ans- Water at room temperature is a liquid because its freezing point is 0*C and boiling point is 100*C.

(b) An iron almirah is a solid at room temperature.

Ans- It is because the melting point of iron is higher than room temperature.

Q7. Why is ice a 273 K more effective in cooling than water a same temperature?

Ans-Ice at 273 K will absorb heat energy or latent heat from medium to  overcome the fusion to become water. Cooling effect of ice is more than water at same temperature because water does not absorb extra heat from medium.

Q8. What produces more severe burns , boiling water or steam?

Ans- Steam at 100*C will produce more severe burns as extra heat is hidden in it called latent heat whereas the boiling water does not have this hidden heat.

FUNDAMENTAL UNIT OF LIFE 

CELL

Cell is the structural and functional unit of life.

Homework

Q. Why does the water come out from the cucumber when we add salt in it?

Ans- The salt cause water to be drawn out of the cucumber. Water is drawn to it because it goes from a higher concentration to the lower concentration. When there is random motion that will always happen and is called diffusion. In the cells of cucumber allows the water through but not the salt.

shardendu dwived.roll no.:35

Exercise(matter in our surrounding)

Question1:- Convert the following temperatures to Celsius scale.

      

                       (a) 300 K                                                (b) 573 k

Answer:- Kelvin is SI unit of temperature, where 0°C = 273.16K

                                        (a) 300 K = 300 − 273 Celsius

                                       °C = 27 °C

                                        (b) 573 K = 573 − 273 Celsius

                                      °C = 300 °C

Question2:-  Convert the following temperatures to Kelvin scale.

                                  (a) 25°C                                            (b) 373°C

Answer:- Kelvin is SI unit of temperature, where 0°C = 273.16K

                         (a) 25 °C = 25 + 273 K

                                          = 298 K 

                      (b) 373 °C = 373 + 273 K 

                                            = 646 K

Question3:-Give reason for the following observations. 

                  

(a) Naphthalene balls disappear with time without leaving any solid

Answer:-Naphthalene balls disappear with time because                                  sublimation takes place there and naphthalene balls get                     converted into vapours without coming in its liquid form.

  

(b) We can get the smell of perfume sitting several metres away. 

Answer:- Gaseous particles possess high speed and large spaces between them. Particles of perfume diffuse into these gaseous particles at a very fast rate and reach our nostrils. This enables us to smell the perfume from a distance

Question 4 :-Arrange the following substances in increasing order of forces of attraction between particles−− water, sugar, oxygen.

answer:-                Oxygen < Water < Sugar 
Question 5: What is the physical state of water at - 
(a) 25°C 
(b) 0°C 
(c) 100°C

answer:-  (a) 25°C - Water at 25°C is present in the liquid state.
(b) 0°C - solid or liquid state.
(c) 100°C - vapour or liquid state.

Question 6: Give two reasons to justify− 
(a) water at room temperature is a liquid.
 (b) an iron almirah is a solid at room temperature. answer

answer:-) At room temperature (25 °C), water is a liquid because it has the following characteristic of liquid: 
.
(i) At room temperature, water has no shape but has a fixed volume that is, it occupies the shape of the container in which it is kept.

(ii) At room temperature, water flows

(b) An iron almirah is a solid at room temperature (25 °C) because: (i) it has a definite shape and volume like a solid at room temperature.

 (ii) it is rigid as solid at room temperature.

Question 7: Why is ice at 273 K more effective in cooling than water at the same temperature? 

Answer : Ice at 273 K has less energy than water (although both are at the same temperature). Water possesses the additional latent heat of fusion. Hence, at 273 K, ice is more effective in cooling than water

Question 8: What produces more severe burns, boiling water or steam?

 Answer : Steam has more energy than boiling water. It possesses the additional latent heat of vaporization. Therefore, burns produced by steam are more severe than those produced by boiling water