Explain why meiosis and gametogenesis are always interlinked?
Question: Explain why meiosis and gametogenesis are always interlinked? Solution: Meiosis is a process of reductional division in which the amount of genetic material is reduced. Gametogenesis is the process of the formation of gametes. Gametes produced by organisms are haploids (containing only one set of chromosomes), while the body of an organism is diploid. Therefore, for producing haploid gametes (gametogenesis), the germ cells of an organism undergo meiosis. During the process, the meiocyt...
Read More →Higher organisms have resorted to sexual reproduction in spite of its complexity.
Question: Higher organisms have resorted to sexual reproduction in spite of its complexity. Why? Solution: Although sexual reproduction involves more time and energy, higher organisms have resorted to sexual reproduction in spite of its complexity. This is because this mode of reproduction helps introduce new variations in progenies through the combination of the DNA from two (usually) different individuals. These variations allow the individual to cope with various environmental conditions and ...
Read More →Under certain circumstances, a nucleus can decay by emitting a particle more massive than an α-particle.
Question: Under certain circumstances, a nucleus can decay by emitting a particle more massive than an -particle. Consider the following decay processes: ${ }_{88}^{223} \mathrm{Ra} \longrightarrow{ }_{82}^{209} \mathrm{~Pb}+{ }_{6}^{14} \mathrm{C}$ ${ }_{88}^{223} \mathrm{Ra} \longrightarrow{ }_{86}^{219} \mathrm{Rn}+{ }_{2}^{4} \mathrm{He}$ Calculate theQ-values for these decays and determine that both are energetically allowed. Solution: Take a ${ }_{6}^{14} \mathrm{C}$ emission nuclear react...
Read More →Define
Question: Define (a)Juvenile phase, (b)Reproductive phase, (c)Senescent phase. Solution: (a)Juvenile phase: It is the period of growth in an individual organism after its birth and before it reaches reproductive maturity. (b)Reproductive phase: It is the period when an individual organism reproduces sexually. (c)Senescent phase: It is the period when an organism grows old and loses the ability to reproduce....
Read More →What is vegetative propagation?
Question: What is vegetative propagation? Give two suitable examples. Solution: Vegetative propagation is a mode of asexual reproduction in which new plants are obtained from the vegetative parts of plants. It does not involve the production of seeds or spores for the propagation of new plants. Vegetative parts of plants such as runners, rhizomes, suckers, tubers, etc. can be used as propagules for raising new plants. Examples of vegetative reproduction are: 1. Eyes of potato: The surface of a p...
Read More →A source contains two phosphorous radio nuclides
Question: A source contains two phosphorous radio nuclides ${ }_{15}^{32} \mathrm{P}\left(T_{1 / 2}=14.3 \mathrm{~d}\right)$ and ${ }_{15}^{33} \mathrm{P}\left(T_{1 / 2}=25.3 \mathrm{~d}\right) .$ Initially, $10 \%$ of the decays come from $_{15}^{33} \mathrm{P}$. How long one must wait until $90 \%$ do so? Solution: Half life of ${ }_{15}^{32} \mathrm{P}, T_{1 / 2}=14.3$ days Half life of ${ }_{15}^{33} \mathrm{P}, T_{1 / 2}^{\prime}=25.3$ days ${ }_{15}^{33} \mathrm{P}$ nucleus decay is $10 \%...
Read More →Discuss the continuity of the function f, where f is defined by
Question: Discuss the continuity of the functionf, wherefis defined by $f(x)=\left\{\begin{array}{l}3, \text { if } 0 \leq x \leq 1 \\ 4, \text { if } 1x3 \\ 5, \text { if } 3 \leq x \leq 10\end{array}\right.$ Solution: The given function is $f(x)=\left\{\begin{array}{l}3, \text { if } 0 \leq x \leq 1 \\ 4, \text { if } 1x3 \\ 5, \text { if } 3 \leq x \leq 10\end{array}\right.$ The given functionis defined at all points of the interval [0, 10]. Letcbe a point in the interval [0, 10]. Case I: If ...
Read More →Distinguish between asexual and sexual reproduction.
Question: Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered as a type of asexual reproduction? Solution: Vegetative propagation is a process in which new plants are obtained without the production of seeds or spores. It involves the propagation of plants through certain vegetative parts such as the rhizome, sucker, tuber, bulb, etc. It does not involve the fusion of the male and the female gamete and requires only one parent. Hence, vegetative re...
Read More →How does the progeny formed from asexual reproduction differ from those formed by sexual reproduction?
Question: How does the progeny formed from asexual reproduction differ from those formed by sexual reproduction? Solution:...
Read More →The neutron separation energy is defined as the energy required to remove a neutron from the nucleus.
Question: The neutron separation energy is defined as the energy required to remove a neutron from the nucleus. Obtain the neutron separation energies of the nuclei ${ }_{20}^{41} \mathrm{Ca}$ and ${ }_{13}^{27} \mathrm{Al}$ from the following data: $m\left({ }_{20}^{40} \mathrm{Ca}\right)=39.962591 \mathrm{u}$ $\left.m\left({ }_{20}^{41} \mathrm{Ca}\right)\right)=40.962278 \mathrm{u}$ $m\left(\begin{array}{c}26 \\ { }_{13}^{26} \mathrm{Al}\end{array}\right)=25.986895 \mathrm{u}$ $\left.m\left({...
Read More →Offspring formed due to sexual reproduction have better chances of survival.
Question: Offspring formed due to sexual reproduction have better chances of survival. Why? Is this statement always true? Solution: Sexual reproduction involves the fusion of the male and the female gamete. This fusion allows the formation of new variants by the combination of the DNA from two (usually) different members of the species. The variations allow the individuals to adapt under varied environmental conditions for better chances of survival. However, it is not always necessary that the...
Read More →Why is the offspring formed by asexual reproduction referred to as clone?
Question: Why is the offspring formed by asexual reproduction referred to as clone? Solution: A clone is a group of morphologically and genetically identical individuals. In the process of asexual reproduction, only one parent is involved and there is no fusion of the male and the female gamete. As a result, the offsprings so produced are morphologically and genetically similar to their parents and are thus, called clones....
Read More →150 workers were engaged to finish a job in a certain number of days.
Question: 150 workers were engaged to finish a job in a certain number of days. 4 workers dropped out on second day, 4 more workers dropped out on third day and so on. It took 8 more days to finish the work. Find the number of days in which the work was completed. Solution: Letxbe the number of days in which 150 workers finish the work. According to the given information, $150 x=150+146+142+\ldots(x+8)$ terms The series $150+146+142+\ldots .(x+8)$ terms is an A.P. with first term 150, common dif...
Read More →Which is a better mode of reproduction sexual or asexual?
Question: Which is a better mode of reproduction sexual or asexual? Why? Solution: Sexual reproduction is a better mode of reproduction. It allows the formation of new variants by the combination of the DNA from two different individuals, typically one of each sex. It involves the fusion of the male and the female gamete to produce variants, which are not identical to their parents and to themselves. This variation allows the individual to adapt to constantly changing and challenging environment...
Read More →Is the function defined by
Question: Is the function defined by $f(x)=\left\{\begin{array}{l}x+5, \text { if } x \leq 1 \\ x-5, \text { if } x1\end{array}\right.$ a continuous function? Solution: The given function is $f(x)=\left\{\begin{array}{l}x+5, \text { if } x \leq 1 \\ x-5, \text { if } x1\end{array}\right.$ Thegiven functionfis defined at all the points of the real line. Letcbe a point on the real line. Case I: If $c1$, then $f(c)=c+5$ and $\lim _{x \rightarrow c} f(x)=\lim _{x \rightarrow c}(x+5)=c+5$ $\therefore...
Read More →Why is reproduction essential for organisms?
Question: Why is reproduction essential for organisms? Solution: Reproduction is a fundamental feature of all living organisms. It is a biological process through which living organisms produce offsprings similar to them. Reproduction ensures the continuance of various species on the Earth. In the absence of reproduction, the species will not be able to exist for a long time and may soon get extinct....
Read More →In a periodic table the average atomic mass of magnesium is given as 24.312 u.
Question: In a periodic table the average atomic mass of magnesium is given as $24.312 \mathrm{u}$. The average value is based on their relative natural abundance on earth. The three isotopes and their masses are ${ }_{12}^{24} \mathrm{Mg}(23.98504 \mathrm{u}),{ }_{12}^{25} \mathrm{Mg}(24.98584 \mathrm{u})$ and ${ }_{12}^{26} \mathrm{Mg}$ ( $25.98259 \mathrm{u}$ ). The natural abundance of ${ }_{12}^{24} \mathrm{Mg}$ is $78.99 \%$ by mass. Calculate the abundances of other two isotopes. Solution...
Read More →For the
Question: For the $\beta^{+}$(positron) emission from a nucleus, there is another competing process known as electron capture (electron from an inner orbit, say, the K-shell, is captured by the nucleus and a neutrino is emitted). $e^{+}+_{Z}^{A} X \rightarrow_{Z-1}^{A} Y+v$ Show that if $\beta^{+}$emission is energetically allowed, electron capture is necessarily allowed but not vice-versa. Solution: Let the amount of energy released during the electron capture process beQ1. The nuclear reaction...
Read More →A manufacturer reckons that the value of a machine,
Question: A manufacturer reckons that the value of a machine, which costs him Rs 15625, will depreciate each year by 20%. Find the estimated value at the end of 5 years. Solution: Cost of machine = Rs 15625 Machine depreciates by 20% every year. Therefore, its value after every year is $80 \%$ of the original cost i.e., $\frac{4}{5}$ of the original cost. $\therefore$ Value at the end of 5 years $=15625 \times \underbrace{\frac{4}{5} \times \frac{4}{5} \times \ldots \times \frac{4}{5}}_{5 \text ...
Read More →For the
Question: For the $\beta^{+}$(positron) emission from a nucleus, there is another competing process known as electron capture (electron from an inner orbit, say, the K-shell, is captured by the nucleus and a neutrino is emitted). $e^{+}+_{Z}^{A} X \rightarrow_{Z-1}^{A} Y+v$ Show that if $\beta^{+}$emission is energetically allowed, electron capture is necessarily allowed but not vice-versa. Solution: Let the amount of energy released during the electron capture process beQ1. The nuclear reaction...
Read More →Find all points of discontinuity of f, where f is defined by
Question: Find all points of discontinuity off, wherefis defined by $f(x)= \begin{cases}x^{10}-1, \text { if } x \leq 1 \\ x^{2}, \text { if } x1\end{cases}$ Solution: The given function $f$ is $f(x)= \begin{cases}x^{10}-1, \text { if } x \leq 1 \\ x^{2}, \text { if } x1\end{cases}$ Thegiven functionfis defined at all the points of the real line. Letcbe a point on the real line. Case I: If $c1$, then $f(c)=c^{10}-1$ and $\lim _{x \rightarrow c} f(x)=\lim _{x \rightarrow c}\left(x^{10}-1\right)=c...
Read More →A man deposited Rs 10000 in a bank at the rate of 5% simple interest annually.
Question: A man deposited Rs 10000 in a bank at the rate of $5 \%$ simple interest annually. Find the amount in $15^{\text {th }}$ year since he deposited the amount and also calculate the total amount after 20 years. Solution: It is given that the man deposited Rs 10000 in a bank at the rate of 5% simple interest annually. $\therefore$ Interest in first year $=\frac{5}{100} \times$ Rs $10000=$ Rs 500 $\therefore$ Amount in $15^{\text {th }}$ year $=\mathrm{Rs} 10000+\underbrace{500+500+\ldots ....
Read More →For your agricultural field or garden you have developed a compost producing pit.
Question: For your agricultural field or garden you have developed a compost producing pit. Discuss the process in the light of bad odour, flies and recycling of wastes for a good produce. Solution: It is essential to take proper care of the compost producing pit in order to protect ourselves from bad odour and flies. It should be kept covered to minimize bad odour and prevent flies from entering it. The recyclable waste should not be dumped in the compost producing pit. It should be sent to the...
Read More →How can domestic waste be used as manure?
Question: How can domestic waste be used as manure? Solution: Depending upon the nature of the waste, domestic waste can be segregated into two categories i.e., biodegradable and nonbiodegradable. Biodegradable waste such as leaves, rotten food, etc. should be deposited in land fills, where they get decomposed aerobically and anaerobically into manure. Non-biodegradable waste (which cannot be degraded) such as plastic, glass, metal scraps etc. should be sent for recycling....
Read More →A person writes a letter to four of his friends.
Question: A person writes a letter to four of his friends. He asks each one of them to copy the letter and mail to four different persons with instruction that they move the chain similarly. Assuming that the chain is not broken and that it costs 50 paise to mail one letter. Find the amount spent on the postage when 8thset of letter is mailed. Solution: The numbers of letters mailed forms a G.P.: $4,4^{2}, \ldots 4^{8}$ First term = 4 Common ratio = 4 Number of terms = 8 It is known that the sum...
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