1. ANSWER: [C] Explanation: When an acid reacts with a metal, hydrogen gas is liberated. In the given reaction, when dilute sulphuric acid reacts with zinc granules, hydrogen gas is liberated and zinc sulphate solution is formed: Zn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂ (g) The presence of hydrogen gas is teRead more

    ANSWER: [C]

    Explanation: When an acid reacts with a metal, hydrogen gas is liberated. In the given reaction, when dilute sulphuric acid reacts with zinc granules, hydrogen gas is liberated and zinc sulphate solution is formed:

    Zn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂ (g)

    The presence of hydrogen gas is tested by bringing a lighted candle near it. When a lighted candle is brought near the test tube containing hydrogen gas, it burns with a “pop sound” making a little explosion. Hence, acid “X” is sulphuric acid and gas “Y” is hydrogen gas.

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  2. (i) Fertilization in human females takes place in the fallopian tube (oviduct). (ii) The inner lining of the uterus, called the endometrium, becomes thick, soft, and richly supplied with blood vessels each month. This provides a warm, nutrient-rich environment to receive the fertilized egg and suppoRead more

    (i) Fertilization in human females takes place in the fallopian tube (oviduct).

    (ii) The inner lining of the uterus, called the endometrium, becomes thick, soft, and richly supplied with blood vessels each month. This provides a warm, nutrient-rich environment to receive the fertilized egg and support the growing embryo.

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  3. The developing embryo gets nutrition from the mother’s blood through a special tissue called the placenta. The placenta forms a connection between the embryo and the mother’s uterus. Tiny finger-like structures, called villi, grow into the uterine tissue, increasing the surface area for exchange. ThRead more

    The developing embryo gets nutrition from the mother’s blood through a special tissue called the placenta. The placenta forms a connection between the embryo and the mother’s uterus. Tiny finger-like structures, called villi, grow into the uterine tissue, increasing the surface area for exchange. The mother’s blood vessels surround these villi and supply oxygen, glucose, amino acids, and other nutrients, which diffuse into the embryo’s blood. At the same time, waste products from the embryo pass into the mother’s blood for removal.

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  4. When the egg is not fertilized, it cannot develop into an embryo. The unfertilized egg disintegrates within the fallopian tube, and the hormone levels of estrogen and progesterone start to decline. As a result, the thickened uterine lining, which had been prepared to receive a fertilized egg, is noRead more

    When the egg is not fertilized, it cannot develop into an embryo. The unfertilized egg disintegrates within the fallopian tube, and the hormone levels of estrogen and progesterone start to decline. As a result, the thickened uterine lining, which had been prepared to receive a fertilized egg, is no longer maintained. The lining breaks down and is shed from the body through the vagina in the form of menstrual bleeding. This marks the start of a new menstrual cycle.

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  5. (i) Differentiate between self-pollination and cross-pollination. Self-pollination: Transfer of pollen from the anther to the stigma of the same flower or another flower on the same plant. Cross-pollination: Transfer of pollen from the anther of one plant to the stigma of a flower on a different plaRead more

    (i) Differentiate between self-pollination and cross-pollination.

    • Self-pollination: Transfer of pollen from the anther to the stigma of the same flower or another flower on the same plant.
    • Cross-pollination: Transfer of pollen from the anther of one plant to the stigma of a flower on a different plant of the same species.

    (ii) A – Stigma: Receives pollen grains during pollination.

    B – Style: Provides a passage for pollen tube to reach the ovary.

    C – Ovary: Contains ovules; after fertilization, ovary develops into a fruit.

     

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