PYQ Vault

Day 187: CBSE Class 10 Science

5 questions (8 parts). Try each one first, then open its answer.

  1. Question 1 (case study, 4 parts)

    Heredity. Asked once: 2022 (same type asked 3 times)

    The mechanism by which the sex of an individual is determined is called sex-determination. In human beings, sex of a newborn is genetically determined, whereas in some others it is not. There are 46 (23 pairs) chromosomes in human beings. Out of these, 44 (22 pairs) control the body characters and 2 (one pair) are known as sex chromosomes. The sex chromosomes are of two types — X chromosome and Y chromosome. At the time of fertilisation, depending upon which type of male gamete fuses with the female gamete, the sex of the newborn child is decided.
    14 (a)
    Why is a pair of sex chromosomes in human beings called a mismatched pair in terms of type and size ?
    14 (b)
    Out of male or female, which of them has a perfect pair of sex chromosomes ? In case of a perfect pair, will the gametes produced be of the same kind or of a different kind ?
    14 (c) (i)
    Name two animals whose sex is not genetically determined. Explain the process of their sex determination.
    14 (c) (ii)
    With the help of a flowchart only, show how sex is genetically determined in human beings.

  2. Question 2

    Light — Reflection and Refraction. Asked once: 2023 (same type asked 3 times)

    31 (b)
    Define power of a lens. The focal length of a lens is −10-10 cm. Write the nature of the lens and find its power. If an object is placed at a distance of 20 cm from the optical centre of this lens, according to the New Cartesian Sign Convention, what will be the sign of magnification in this case ?

  3. Question 3

    Light — Reflection and Refraction. Asked once: 2024 (same type asked 3 times)

    24
    An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position of the image formed by the mirror.

  4. Question 4

    Our Environment. Asked once: 2023 (same type asked 3 times)

    Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the options given below.
    18
    Assertion (A) : An ecosystem consists of biotic components and abiotic components. Reason (R) : Biotic and abiotic components play important roles for the sustenance of life and work independently in all ecosystems.

    Tap an option to check your answer.

  5. Question 5

    Our Environment. Asked once: 2023 (same type asked 3 times)

    26
    (a) What is meant by trophic level ? (b) On an average, what percentage of energy is transferred to the second trophic level from the first trophic level ? Which categories of consumers do the organisms of the second trophic level belong to ?