Q – 1 Choose the correct option. 10 1 Which of the following is true? (A)The baby is male/female is determined by mother’s chromosome. (B) The baby is male/female is determined by father’s chromosome. (C) Pair of Mother’s chromosome is X-Y . (D) Pair of Father’s chromosome is X-X . 2 ‘In a tug-of-war , when the two teams are pulling the rope, a stage comes when the rope does not move to either side at all’. Which of the following is the correct reason for this? (A) Both teams have the same number of members. (B) There is a lot of competition going on between the two teams. (C) The net force of forces acting in opposite directions is equal to the difference between the two forces. (D) The net force of forces acting in opposite directions is equal to the sum of the two forces. ૩ Which of the following does not happen due to friction? (A) A nail is fixed in the wall (B) fire can be produced with a matchstick. (C) heat is produced. (D) durability of chappals increases. 4 Which of the following are the benefits of special shape of an aeroplane? (i) Fluid friction is reduced. (ii) Fluid friction is increased. (iii)Energy loss is as low as possible. (iv) An aeroplane can fly like a bird. (A) (i), (ii) (B) (i), (ii), (iii) (C) (i), (iii), (iv) (D) (i), (ii), (iii),(iv) 5 Which of the following musical instruments uses air column to produce sound? (A) Veena (B) manjira(cymbals) (C)Flute (D) tabla 6 Which of the following is false for loudness of sound and amplitude of vibration? (A) Loudness of sound depends on its amplitude of the vibration. (B) Loudness of a sound is proportional to the square of the amplitude of the vibration producing the sound. (C) When the amplitude of vibration is large, the sound produced is loud. (D) If the amplitude of vibration is increased to 4 times of its initial value, then the loudness of sound becomes 6 times of its initial value. 7 Due to which of the following reasons Chromium plating is done on some objects used in everyday life? (i) Chromium is cheaper. (ii) Chromium has a shiny appearance. (iii)Chromium does not corrode. (iv) Chromium resists scratches. (A) (i), (ii), (iii) (B) (ii), (iii), (iv) (C) (i), (iii), (iv) (D) (i), (ii), (iii),(iv)
Answers
The X chromosome is one of the two sex chromosomes in humans (the other is the Y chromosome). The sex chromosomes form one of the 23 pairs of human chromosomes in each cell. The X chromosome spans about 155 million DNA building blocks (base pairs) and represents approximately 5 percent of the total DNA in cells.
Each person normally has one pair of sex chromosomes in each cell. Females have two X chromosomes, while males have one X and one Y chromosome. Early in embryonic development in females, one of the two X chromosomes is randomly and permanently inactivated in cells other than egg cells. This phenomenon is called X-inactivation or lyonization. X-inactivation ensures that females, like males, have one functional copy of the X chromosome in each body cell. Because X-inactivation is random, in normal females the X chromosome inherited from the mother is active in some cells, and the X chromosome inherited from the father is active in other cells.
Some genes on the X chromosome escape X-inactivation. Many of these genes are located at the ends of each arm of the X chromosome in areas known as the pseudoautosomal regions. Although many genes are unique to the X chromosome, genes in the pseudoautosomal regions are present on both sex chromosomes. As a result, men and women each have two functional copies of these genes. Many genes in the pseudoautosomal regions are essential for normal development.
Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. The X chromosome likely contains 800 to 900 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Answer:
bhai iska answer b(ii,iii,iv