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CBSE Class 10 Science Board Exam 2018: Important Very Short Answer Type Questions

Feb 12, 2018 10:59 IST
    Important Very Short Answer Type Questions
    Important Very Short Answer Type Questions

    In this article you will get important very short answer type questions for CBSE Class 10 Science Annual Exam 2018.

    These are the questions which may be asked for 1 or 2 marks each, in section- A of class 10 Science exam.

    • Question numbers 1 and 2 in Section-A will be one mark questions. 
    • Question numbers 3 to 5 in Section- A will be two marks questions.

    The set of important questions given here will surely help you to make an easy and effective preparation for the exam and score high marks.

    Given below are some very important questions for ‘very short answer type questions’ category in class 10 Science exam 2018:

    1. Explain why a ray of light passing through the centre of curvature of concave minor gets reflected along the same path. 

    Answer.

    The light falling on the centre of curvature is reflected back along the same path because

    incident ray falls on the mirror along the normal to the reflecting surface.

    2. What is the important function of presence of ozone in earth’s atmosphere?

    Answer.

    Ozone is the Earth’s natural process for all life forms. It shields our planet from the UV radiations, as these ultraviolet rays are harmful for all the living things. Therefore, any change in the size of this layer will automatically affect the life of people, plants and animals living on earth. 

    3. Dark reaction of photosynthesis does not need light. Do plants undergo dark reaction at night? Explain.

    Answer.

    Dark reaction does not mean that it occurs in the absence of light i.e., at night. Infact, it is the reaction occuring simultaneously with light reaction. It a chemical process occurring independent of light. This reaction is completely based on enzymes.

    4. What is a solenoid? Draw the pattern of magnetic Field lines of a solenoid through which a steady current flows. What does the pattern of field lines‟? Inside the solenoid indicate? 

    Answer.

    Solenoid can be defined as a coil of many circular turn of insulated copper wire wrapped in cylindrical structure.

    Following diagram shows the pattern of magnetic Field lines of a solenoid through which a steady current flows:

    current carrying solenoid

    5. What is meant by acquired and inherited traits? Explain with one example each.

    Answer.

    Acquired Trait: A trait or characteristic of an organism which is not inherited but develops in response to the environment is called an acquired trait. Example: The cut tail of the mouse which has been brought about by some agents in its environment is an acquired trait.

    Inherited Trait: A trait or characteristic of an organism which is caused by a change in its genes is called an inherited trait. Example: The characteristics received by a child from its parents like the son inherits his father’s red hair.

    6. Write the molecular formula of first two members of homologous series having functional group – OH.  

    Answer.

    The general formula for the homologous series of functional group −OH is CnH2n+1OH.

    The two consecutive members of this series are: 

    a. CH3OH(Methanol)

    b. CH3CH2OH (Ethanol)

    where n is 1 and 2 respectively

    The molecular formula for both of them are CH4O and C2H6O.

     

    7. How is menarche different from menopause?

    Answer.

    The first occurrence of menstruation at the age of 12 in females is called menarche. Menarche is the beginning of the reproductive life of a girl. Menstruation stops when a woman reaches the age of 50 approx. At this age she loses her ability to bear child in her womb, i.e., she becomes infertile. This stage of permanent stoppage of menstruation is called the menopause. Thus, reproductive life of a woman starts at menarche and ends at menopause.

    8. What kind of combustion is observed in alkanes? Why do air holes of a gas burner have to be adjusted when vessel being heated gets blackened by the flame?

    Answer.

    Alkanes are saturated hydrocarbons and generally burn in air with a blue, non-sooty flame.

    If the bottoms of the cooking vessels in our homes are getting blackened, it shows that the air holes of the gas stove are getting blocked and the fuel is not burning completely.

    9. A concave mirror of focal length 15 cm can form a magnified, erect as well as inverted image of an object placed in front of it." Justify this statement stating the position of the object with respect to the pole of the mirror in both the cases  for obtaining the images.

    Answer.

    For magnified and erect image the object is placed between pole P and focus F. For magnified and inverted image the object is placed either at focus or anywhere between F and C.

    10. "Energy flow in a food chain is unidirectional" Justify this statement.

    Answer.

    The flow of energy in the ecosystem is said to be unidirectional because the energy lost as heat from the living organisms of a food chain cannot be reused by plants in photosynthesis.

    11. What is the effect of DNA copying, which is not perfectly accurate, on the reproduction process?

    Answer.

    The DNA copying which is not perfectly accurate in the reproduction process results in variations in

    12. What is the function of retina in human eye. 

    Answer.

    The retina acts as a screen on which the image is formed in the eye. The retina has a large number of light-sensitive cells. When the image falls on the retina then these light-sensitive cells get activated and generate electrical signals. 

    13. (a) If a normal human cell has 46 chromosomes, how many chromosomes will be there in a human:

    (i) Sperm

    (ii) Zygote

    (b) Name an animal in which individuals can change sex. What does this indicate?

    Answer.

    (a) A normal human being has 46 chromosomes in which 23 chromosomes come from males and 23 chromosomes come from female.

    (i) Sperms coming from males have 23 chromosomes.

    (ii) Zygote forming in the womb of a woman has 46 chromosomes in all.

    (b) Snail. This indicates that sex is not determined genetically in such animals.

    14. List any four characteristics of a good fuel.

    Answer.

    Characteristics of a good fuel:

    (i) It should possess low ignition temperature.

    (ii) It should not leave residue after burning, i.e., it should burn completely.

    (iii) It should be easily available and accessible

    (iv) It should be easy to store and transport.

    15. Name the two sets of nerves that constitute the peripheral nervous system.

    Answer.

    Sympathetic nervous system and Parasympathetic nervous system.

    16. What is hyperacidity? How antacid works to cure it?

    Answer.

    Hyperacidity is caused by excess of hydrochloric acid in stomach.

    Antacid is basic in nature. It neutralizes excess of acid and gives relief from pain caused by hyperacidity.               

    17. State difference between the wire used in the element of an electric heater and in a fuse wire.

    Answer.

    The wire used in the element of electric heater has a high resistivity and have a high melting point, so that even at a high temperature element do not burn while fuse wire have a low melting point and high resistivity so that it will melt if a current of large magnitude passes through the wire.     

    18. A ray of light passing through the centre of curvature of concave minor gets reflected along the same path. Why?

    Answer.

    The light falling on the centre of curvature is reflected back along the same path because incident ray falls on the mirror along the normal to the reflecting surface.          

    19. Name the stimulus involved in each of the following phenomenon:

    (i) Phototropism               (ii) Geotropism.

    Answer.

    (i) Light (ii) Gravity.

    20. For what position of a current carrying conductor placed in a magnetic field, the maximum force acts on it?

    Answer.

    To obtain the maximum force acting on the current carrying conductor placed in a magnetic field, the conductor should be placed perpendicular to the magnetic field, i.e. the direction of current should be at right angle to the direction of the magnetic field.

    CBSE Class 10 Science Board Exam: Important Short Answer Type Questions

    CBSE Class 10 Science Exam 2018: Important Long Answer Type Questions

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