CBSE Pathshala

Q.1. What is heredity? Ans:- Heredity refers to the transmission of characters or traits from the parents to their offspring. Q.2. Name the plant on which Mendel performed his experiments? Ans:- Garden Pea ( Pisum sativum .) Q.3. Define variation? Ans:-Variation refers to the differences in the characters or traits about the individuals of a species. Q.4. Define a gene? Ans:- Gene is a small segment of DNA on a chromosome occupying specific position in which is a hereditary determinant or unit of a biological function. Q.5.Write the expanded form of DNA? Ans:- DNA - Deoxyribonucleic Acid. Q.6. What are the components of chromosome? Ans:- Each chromosome is double or replicated and consists of two thread like structures called chromatids attached to each other at centromere. .Each chromatid has a number of dense areas arranged linearly which are known as chromomeres. They represent the areas of active genes. .Internally each chromosome has two spirally coiled ...

8 th Science: Chapter:  Reproduction and Reaching of adolescence 1. How are human twins produced? Ans: There are two way twins are formed. (a) Twins occur when a single egg is fertilized to form one zygote which then divides into two separate embryos.(b) Twins occur when two separate eggs  are fertilized by two separate sperm. 2. Whose sex chromosomes is responsible for sex of unborn baby, either father’s or mother’s sex hormones. Ans: The sex chromosomes of the father determine the sex of an unborn baby. 3. Why ace and pimple appear in adolescent age of human being? Ans: This is because during puberty the secretion of sweat glands and sebaceous glands (oil glands) increases in the skin. 4. What is Adam’s apple? At puberty, the voice box or the larynx begins to grow. The growing voice box in boys can be seen as bump in the throat called Adam’s apple. 5. Why does reproductive age of women starts from menarche and end at menopause? Women start producing...

1. What are pathogens?[1] Ans. Disease-causing organisms are called pathogens 2. List any two human activities that lead to an increase in the carbon dioxide content of air.[1] Ans: a. Combustion of wood. b. Deforestation. c. Respiration 3. (a) Name any two green house gases. (b) What causes global warming?[2] Ans:  (a) Carbon dioxide (CO2), methane (CH4), ozone (O3) and water vapour (H2O) green house gases. (b) The greenhouse gases do not allow heat rays to escape from the earth resulting in an increase of temperature of the earth. Hence, green house gases cause global warming. 4. Give two examples each of biodegradable and non-biodegradable pollutants.[2] Ans: Biodegradable pollutants-cow dung and paper Non-biodegradable pollutants-polythene, plastic and DDT 5. Write two points of difference between gymnosperms and angiosperms.[2] Ans:   Gymnosperms    (i) The seeds are naked. (ii) The microspores and megaspores are produced by male and female c...

CBSE NCERT IX-Physics for term-II Chapter: Sound key points 1. Sound is a wave that is created by vibrating objects and propagated through a medium from one location to another.  2. A disturbance that travels through a medium, transporting energy from one location to another location is called wave. The medium is simply the material through which the disturbance is moving; it can be thought of as a series of interacting particles.  3. In our body Vocal cord is vibrating body that produce sound wave.  4. The sound wave is transported from one location to another by means of particle-to-particle interaction like air particles in air.  5. Air particles interact continuously throughout the entire medium that causes disturbance to its nearest neighbours till sound reach to listener.  6. A sound wave is a disturbance that is travel through a medium via the mechanism of particle-to-particle interaction. Hence sound wave is characterized as a mechanical wave....

JSUNIL TUTORIAL, BIHAR IX CH – SOUND QUESTIONS - 1 (Q)1. Fill in the blanks: (a) The loudness of sound is proportional to the _________ of the amplitude of the vibration. (b)The speed of sound __________as it moves from solid to gaseous state. (c) In any medium the speed of sound __________ with increase in temperature. (d) The distance between two consecutive compression or two consecutive rarefaction is called the ____. (e) The change in the density or pressure from a maximum value to minimum and then back to the maximum is called an ___________. (f) The number of periodic oscillations per unit time is called the ________ of the sound wave. (g) Sound is produced due to ________of different objects. (h). Sound travels as a _________ wave through a material medium. (i) Sound travels as successive _________ and ___________ in the medium. 2. Q. A person has a hearing range from 20 Hz to 20 kHz. What are the typical wavelengths of sound waves in air corresponding to these two frequenci...

Chapter wise test-Periodic Classification of elements 2 Marks Questions [2 x 5 = 10 ] 1. An element has electronic configuration 2, 8, 3. What is the atomic number of this element? To which (i) group and (ii) period this element belong? 2. State the positions of (i) isotopes of the same element and (ii) hydrogen in the Modern Periodic Table. 3. How does the tendency to gain electrons change as we go down the 16th group of periodic table? Why? 4. Give reasons for the following :  (a) Lithium atom is smaller than sodium atom. (b) Chlorine (atomic number 17) is more electronegative than sulphur (atomic number 16) 5. (a) State the Modern Periodic Law.  (b) Name the element which has twice as many electrons in its second shell as in its first shell. Write its electronic configuration also. 3 Marks Questions [ 3 x 5 = 15 ] 1. An element X belongs to group 17 and third period of the periodic table.  (a) Write electronic configuration of the element. What is it...