CBSE ADDA

1.Fill in the blanks: a. Decomposers convert dead plants and animals into ______. Compost b.Tall trees which look like roof over other plants in the forest is called_________. Canopy c.The various components of the forests are ___________ on another. Dependent d. Forests are the -------------- for the forest dwelling communities. Home e.------------------------- help forest to grow and regenerate. Animals f.----------------------- forms the uppermost layer in the forest. Canopy 2. State whether True  or  False: a.The different horizontal layers in the forest are known as under storey’s. True b.Forest help in causing floods. False c.Forest are called green lungs. True d.The type of animals remains same from forest to forest. False e.Deforestation will endanger our life and environment. True f.Forest is a dynamic living entity. True 3.Name the following: a.The branchy part of a tree above the stem. Crown b.Two for

7 th (VII) Chapter: 07: Respiration of plants and Animals Hots Questions Solved 1. Why do plants have respiratory system? Ans: Plants directly absorb CO 2 through stomata present in leaves and used to prepared food and release O 2 2. Why do we yawn when we are sleepy? Ans: when we are sleepy our brain needs more oxygen to function properly. We yawn to gather a large amount of oxygen for our brain, to help it function faster and control drowsiness. 3. Can respiration take place in absence of oxygen? Ans: Yes, Respiration takes place in absence of oxygen when we are doing some strenuous activity. It is called anaerobic respiration. 4. What do you mean by Vital Capacity? What is vital capacity of a normal man? Ans: The maximum volume of air inhaled or exhaled by lungs is called vital capacity. It is measured by Spirometer.The vital capacity of a normal man is 4 to 6 lit. Chapter: 09: Reproduction in Plants and Animals 1. Can a single plants cell develop i

Solved Questions:CBSE :Chemistry: Chapter-Periodic Classifications 1. Define valency and describe its variation in a period and a group. Ans: Valency of an element is its combining capacity. Valency of an element = number of valence electrons (if equal to or less than 4) Valency of an element = 8 — number of valence electrons (if more than 4) 2. What happens to the metallic character of the elements as we move in a period from left to right in the periodic table? Give reason. Ans: M etallic character of the element decreases along a period due to decrease in atomic size along a period or outermost electrons are closer to nucleus. So they cannot be easily lost. 3. How were the positions of different isotopes decided in modern periodic table? Ans: All the isotopes of an element have same atomic numbers. In modern periodic table, the elements have been allotted places based on their atomic numbers. Therefore, all the isotopes of an element have been assigned the

CBSE Class 7 th  Chapter: Physical and Chemical Change HOTs Questions 1. Why gas is released after opening Soda Water bottle? Ans: Soda water bottle contain CO 2  gas that released after opening the soda water bottle. 2. Why it is advised that spoon should not be placed in pickle Jar? Ans: Spoon is made up of metal that react with acid present in pickle and form another salt and spoil the pickle .Hence it is advised that spoon should not be placed in pickle Jar 3. Why does apple Slice got brown color if kept in air for long time? Ans: Apple Slice got brown color if kept in air for long time because it  react with oxygen and form layer of oxide  which spoil the apple .This is called rancidity. 4. How is Scratch resistant material is made? Ans: Scratch resistant material is made by mixing two or more metal called Alloy like steel. CBSE Class 7 th  Chapter: Electric Current a

Q. If you want to lift the water to damp against the force of gravity what is the energy used by motor.given that Mass=20Kg ; Height=20m;Gravity=9.8m/s; Time=20min Ans: Work done by the motor against the gravity, W = mgh = 20×9.8×20 = 3920 J Power delivered by the motor = W/t =3920/(20×60) = 3.27 J/s Q. when a ball is lifted to a height of height h when it is drooped just before touching the ground, what would the kinetic energy acting on the ball. Ans: mgh According to the conservation of energy Potential energy is converted into kinetic energy just above the ground. Just before touching the ground the kinetic energy of the body is equal to mgh Q. what are the conditions where the work can be zero? Ans: Work done is said to be zero if the force is acting at right angles to the displacement of the body or when there is no displacement of the body. Example: Work done by the force of gravity on box lying on a roof of a bus moving with a constant velocity on a straight

1. Excretion is the removal of metabolic waste products called --------------- (Excreta) 2. The mammalian RBCs are without -------  (nucleus) 3. The heart is covered by a protective double walled sac called -----------filled with ------- ( pericardium , pericardial fluid.) 4. The heart is made up of special type of muscles, called ------------  (cardiac muscles) 5. The separation wall between right and left side of heart is called ------------ (septum) 6. ------------ regulate the flow of blood unidirectional from right auricle to right ventricle and not backwards.  (Valves) 7. Expanded condition of right and left ventricles when full of blood is called ----------------. (Diastole) 8 The state of contraction of of right and left ventricles is called -------- (systole) 9. ---------------- are thinnest blood vessel (Capillaries) 10. Except the -------------- veins all other veins carry deoxygenated blood. ( pulmonary) 11. ----------- are