Name the hormone that is released
Question: Name the hormone that is released by testes at the onset of puberty. Solution: Testosterone is the male hormone, which is released from the testes at the onset of puberty in males. It produces the male secondary sexual characteristics and causes the growth and development of male sex organs....
Read More →Give a suitable word for each of the following statements.
Question: Give a suitable word for each of the following statements. (a) The site which responds to a hormone. (b) Name of a gland which transports secretions through ducts. (c) Chemicals which control changes at adolescence stage. (d) It marks the beginning of reproductive period. Solution: (a) Target site (b) Sweat gland/salivary gland (c) Hormones (d) Puberty...
Read More →Complete the following sentences.
Question: Complete the following sentences. (i) In females, the uterine wall thickens to receive the (ii) Endocrine glands release hormones directly into for transportation to the (iii) The sex hormones, and oestrogen are responsible for the development of characters. (iv) Release of sex hormones is under the control of a hormone secreted from the Solution: (i) fertilised egg (ii) blood stream; target site/organ (iii) testosterone (iv) pituitary gland...
Read More →Unscramble the underlined words in the following sentences
Question: Unscramble the underlined words in the following sentences. (a) Reproductive life of a woman lasts from hacreemn to spauoemen. (b) The development of a caterpillar to an adult butterfly is termed as poommertaissh. (c) The overgrowth of sumselc in xalnvr leads to the hoarse voice in adolescent boys. (d) Dannalier helps the body to adjust and fight the stress. Solution: (a) menarche, menopause (b) metamorphosis (c) muscles, larynx (d) adrenaline...
Read More →Structures present in a cell
Question: Structures present in a cell which is responsible for determination of the sex of a baby is (a) cytoplasm (b) cell membrane (c) nucleus (d) chromosome Solution: (d) The sex of a baby is determined by the type of sex chromosomes present in the fertilised egg from which the baby develops. There are two types of sex chromosomes-X and Y. A female has only two X-chromosomes, i.e. XX, whereas a male has one X and one Y-chromosome, i.e. XY combination....
Read More →A piece of ice is in the form of a cube melts
Question: A piece of ice is in the form of a cube melts so that the percentage error in the edge of cube isa, then find the percentage error in its volume. Solution: Letxbe the side andVbe the volume of the cube. $V=x^{3}$ We have $\frac{\Delta x}{x} \times 100=a$ $\therefore \frac{d V}{d x}=3 x^{2}$ $\Rightarrow \frac{\Delta V}{V}=\frac{3 x^{2}}{V} d x=\frac{3 x^{2}}{x^{3}} \times \frac{a x}{100}$ $\Rightarrow \frac{\Delta V}{V} \times 100=3 a$ Hence, the percentage error in the volume is $3 a$...
Read More →Find the sum
Question: Find the sum $11^{2}+12^{2}+13^{2}+\ldots 20^{2}$ Solution: It is required to find the sum $11^{2}+12^{2}+13^{2}+\ldots 20^{2}$ $11^{2}+12^{2}+13^{2}+\ldots 20^{2}=$ Sum of squares of natural numbers starting from 1 to $20-$ Sum of squares of natural numbers starting from 1 to 10 . Note: Sum of squares of first $n$ natural numbers, $1^{2}+2^{2}+3^{2}+\ldots n^{2}$ $\sum_{k=1}^{n} k^{2}=\frac{n(n+1)(2 n+1)}{6}$ From the above identities, Sum of squares of natural numbers starting from 1...
Read More →The most conspicuous visible change
Question: The most conspicuous visible change that occurs in boys during puberty is (a) development in voice box (b) increase in height (c) production of sperms (d) increased sweating Solution: (b) The most visible change during puberty in boys is sudden increase in height. At this time, the long bones elongate and make a person tall....
Read More →A piece of ice is in the form of a cube melts so that the percentage error in the edge of cube is a, then find the percentage error in its volume.
Question: A piece of ice is in the form of a cube melts so that the percentage error in the edge of cube isa, then find the percentage error in its volume. Solution: Letxbe the side andVbe the volume of the cube. $V=x^{3}$ We have $\frac{\Delta x}{x} \times 100=a$ $\therefore \frac{d V}{d x}=3 x^{2}$ $\Rightarrow \frac{\Delta V}{V}=\frac{3 x^{2}}{V} d x=\frac{3 x^{2}}{x^{3}} \times \frac{a x}{100}$ $\Rightarrow \frac{\Delta V}{V} \times 100=3 a$ Hence, the percentage error in the volume is $3 a$...
Read More →A piece of ice is in the form of a cube melts so that the percentage error in the edge of cube is a, then find the percentage error in its volume.
Question: A piece of ice is in the form of a cube melts so that the percentage error in the edge of cube isa, then find the percentage error in its volume. Solution: Letxbe the side andVbe the volume of the cube. $V=x^{3}$ We have $\frac{\Delta x}{x} \times 100=a$ $\therefore \frac{d V}{d x}=3 x^{2}$ $\Rightarrow \frac{\Delta V}{V}=\frac{3 x^{2}}{V} d x=\frac{3 x^{2}}{x^{3}} \times \frac{a x}{100}$ $\Rightarrow \frac{\Delta V}{V} \times 100=3 a$ Hence, the percentage error in the volume is $3 a$...
Read More →For the metamorphosis of tadpoles
Question: For the metamorphosis of tadpoles which of the following elements must be available in water? (a) Chlorine (b) Carbon (c) Sulphur (d) Iodine Solution: (d) For metamorphosis of tadpoles, iodine should be present in water. This is because metamorphosis is brought about by thyroxine hormone that requires the presence of iodine for its production by thyroid gland....
Read More →Given below are events that lead
Question: Given below are events that lead to pregnancy and development of embryo. (i) Fertilisation of egg (ii) Maturation of egg (iii) Release of egg (iv) Embedding of embryo in uterus Which of the following options gives the correct order of sequence in which they occur? (a) (i), (ii), (iii), (iv) (b) (ii), (i), (iii), (iv) (c) (i), (iv), (ii), (iii) (d) (ii), (iii), (i), (iv) Solution: (d) The events in sequence are: Maturation of egg after puberty in the ovaries of a woman. Release of egg c...
Read More →If the percentage error in the radius of a sphere is α, find the percentage error in its volume.
Question: If the percentage error in the radius of a sphere is , find the percentage error in its volume. Solution: LetVbe the volume of the sphere. $V=\frac{4}{3} \pi x^{3}$ We have $\frac{\Delta x}{x} \times 100=\alpha$ $\Rightarrow \frac{d V}{d x}=4 \pi x^{2}$ $\Rightarrow \frac{d V}{V}=\frac{4 \pi x^{2}}{V} d x$ $\Rightarrow \frac{\Delta V}{V}=\frac{4 \pi x^{2}}{\frac{4}{3} \pi x^{2}} \times \frac{x \alpha}{100}$ $\Rightarrow \frac{\Delta V}{V} \times 100=3 \alpha$ Hence, the the percentage ...
Read More →If the percentage error in the radius of a sphere is α, find the percentage error in its volume.
Question: If the percentage error in the radius of a sphere is , find the percentage error in its volume. Solution: LetVbe the volume of the sphere. $V=\frac{4}{3} \pi x^{3}$ We have $\frac{\Delta x}{x} \times 100=\alpha$ $\Rightarrow \frac{d V}{d x}=4 \pi x^{2}$ $\Rightarrow \frac{d V}{V}=\frac{4 \pi x^{2}}{V} d x$ $\Rightarrow \frac{\Delta V}{V}=\frac{4 \pi x^{2}}{\frac{4}{3} \pi x^{2}} \times \frac{x \alpha}{100}$ $\Rightarrow \frac{\Delta V}{V} \times 100=3 \alpha$ Hence, the the percentage ...
Read More →AIDS can spread from an infected
Question: AIDS can spread from an infected person to another person through (a) sharing food (b) blood transfusion (c) sharing comb (d) a mosquito bite Solution: (b) AIDS causing virus can be easily passed from an infected person to another person through: 1. Sharing of syringes for blood transfusion, taking drugs, etc. 2. Sexual contact 3. From infected mother to foetus It is not spread through an insect vector (such as insect bite) or through casual contact (such as sharing food, comb, etc)....
Read More →Find the sum (41 + 42 + 43 + …. + 100).
Question: Find the sum (41 + 42 + 43 + . + 100). Solution: It is required to find the sum (41 + 42 + 43 + . + 100). $(41+42+43+\ldots .+100)=$ Sum of integers starting from 1 to $100-$ Sum of integers starting from 1 to 40 . Note: Sum of first n natural numbers, 1 + 2 +3+n, $\sum_{k=1}^{n} k=\frac{n(n+1)}{2}$ From the above identities, So, Sum of integers starting from 1 to 100 $=\frac{n(n+1)}{2}$ $=\frac{100(101)}{2}$ $=5050$ So, Sum of integers starting from 1 to 40 $=\frac{n(n+1)}{2}$ $=\frac...
Read More →If the relative error in measuring the radius of a circular plane is α,
Question: If the relative error in measuring the radius of a circular plane is , find the relative error in measuring its area. Solution: Letxbe the radius andybe the area of the circular plane. We have $\frac{\Delta x}{x}=\alpha$ and $y=x^{2}$ $\Rightarrow \frac{d y}{d x}=2 x$ $\Rightarrow \frac{\triangle y}{y}=\frac{2 x}{y} d x=\frac{2 x}{x^{2}} \times \alpha x=2 \alpha$ Hence, the relative error in the area of the circular plane is $2 \alpha$....
Read More →The belief that the mother is completely
Question: The belief that the mother is completely responsible for the sex of the child is wrong because the child (a) gets sex chromosome only from the mother (b) develops in the body of the mother (c) gets one sex chromosome from the mother and the other from the father (d) gets sex chromosome only from the father Solution: (c) The child gets one sex chrbmosome from the mother and one from the father. The mother has XX combination and always contributes an X- chromosome. It is the sperm of fat...
Read More →If the relative error in measuring the radius of a circular plane is α, find the relative error in measuring its area.
Question: If the relative error in measuring the radius of a circular plane is , find the relative error in measuring its area. Solution: Letxbe the radius andybe the area of the circular plane. We have $\frac{\Delta x}{x}=\alpha$ and $y=x^{2}$ $\Rightarrow \frac{d y}{d x}=2 x$ $\Rightarrow \frac{\triangle y}{y}=\frac{2 x}{y} d x=\frac{2 x}{x^{2}} \times \alpha x=2 \alpha$ Hence, the relative error in the area of the circular plane is $2 \alpha$....
Read More →If the relative error in measuring the radius of a circular plane is α, find the relative error in measuring its area.
Question: If the relative error in measuring the radius of a circular plane is , find the relative error in measuring its area. Solution: Letxbe the radius andybe the area of the circular plane. We have $\frac{\Delta x}{x}=\alpha$ and $y=x^{2}$ $\Rightarrow \frac{d y}{d x}=2 x$ $\Rightarrow \frac{\triangle y}{y}=\frac{2 x}{y} d x=\frac{2 x}{x^{2}} \times \alpha x=2 \alpha$ Hence, the relative error in the area of the circular plane is $2 \alpha$....
Read More →If the solve the problem
Question: If $y=\log _{e} x$, then find $\Delta y$ when $x=3$ and $\Delta x=0.03$. Solution: We have $x=3$ $\Delta x=0.03$ $y=\log _{e} x$ For $x=3$, $y=\log _{e} 3$ Also, $\frac{d y}{d x}=\frac{1}{x}$ $\Rightarrow\left(\frac{d y}{d x}\right)_{x=3}=\frac{1}{3}$ $\Rightarrow \Delta y=d y=\frac{d y}{d x} d x=\frac{1}{3} \times 0.03=0.01$...
Read More →Hens and frogs are both
Question: Hens and frogs are both oviparous exhibiting different types of fertilisation, explain. Solution: Hens are oviparous in which internal fertilisation takes place. The fertilised egg divides repeatedly to form an embryo inside the body. The embryo however, travels down the oviduct with many protective layers forming around it. After the hard egg shell is formed around the developing embryo, the hen lays the eggs outside. After about 3 weeks, the development of chick from egg takes place....
Read More →Find the sum (2 + 4 + 6 + 8 +… + 100).
Question: Find the sum (2 + 4 + 6 + 8 + + 100). Solution: It is required to find the sum of (2 + 4 + 6 + 8 + 100). Now, consider the series $(2+4+6+8+\ldots 100)$. If we take a common factor of 2 from all the terms, then, the series becomes, 2 (1 + 2 + 3 + 4 + 50). So, we need to find the sum of first 50 natural numbers. Note: Sum of first n natural numbers, 1 + 2 +3+n, $\sum_{k=1}^{n} k=\frac{n(n+1)}{2}$ From the above identities, So, Sum of first 50 natural numbers $=\frac{n(n+1)}{2}$ $=\frac{...
Read More →How can we say that fish
Question: How can we say that fish exhibits external fertilisation? Solution: Female fish lay eggs in water while male fish releases its sperms in water. Sperms swim and reach the eggs of fish, randomly due to water currents.When a sperm comes in contact with the viable egg, nuclei of both the cell fuses to form a zygote. This process of fertilisation takes place in water outside the female body, hence fertilisation is external in fishes....
Read More →Why do only malejjametes
Question: Why do only malejjametes have a tail? Solution: Male gametes or sperms have tail to facilitate movement of sperms and help them to reach the egg (female gamete) for fertilisation....
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