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Biotechnology: Principles and Processes — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYBiotechnology: Principles and Processes4 Marks
Question
Explain: separation and isolation of DNA fragments.###How will you make separation and isolation of DNA fragments by using gel electrophoresis?
✓

Answer

→ The techniques used for separation and isolation of DNA fragments is known as gel electrophoresis.
→ In this method Agarose gel is used as a medium.
→ The cutting of DNA by restriction endonucleases results in the fragments of DNA.
→ These fragments can be separated by a technique as shown in figure.
Image
→ Since, DNA fragments are negatively charged molecules they can be separated by forcing them to move towards the anode under an electric field througha medium/matrix.
→ The DNA fragments separate (resolve) according to their size through sieving effect provided by the agarose gel.
→ Hence, the smaller the fragment size, the farther it moves.
→ The separated DNA fragments can be visualised only after staining the DNA with a compound known as ethidium bromide followed by exposure to UV radiation.
→ DNA appears as bright orange coloured bands of DNA in an ethidium bromide stained gel exposed to UV light.
→ The separated bands of DNA are cut out from the agarose gel and extracted from the gel piece. This step is known as elution.
→ The DNA fragments purified in this way are used in constructing recombinant DNA by joining them with cloning vectors.

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Ananya is a biologist, her research guide assigned project, i.e., to determine the effect ofin tra-specific competition on the growth of sapling of Eucalyptus. For this, she designed an experiment in which two sets of pots were used. ln the first set (set A) only I sapling was planted per pot and in the other set (set B) 16 saplings were planted per pot. To check for the effect of intra-specific competition on allocation of resources, a decreasing amount of water was added to each set. The results have been graphically indicated. Which of the following conclusions can indicated as follows:

  1. Which of the following statements can be concluded from the given study?
  1. More resources are allocated to the root during low water conditions.
  2. Competition for water among individuals of a population causes more root growth as compared to individuals who are growing alone.
  3. Lesser leaves are formed under low water conditions.
  4. Root growth is higher in individual grown singly as compared to individuals in populations.
  1. Which of the following associations is an example of competitions?
  1. Cuscuta and hedge plant.
  2. Balanus and Cathamalus.
  3. Cactus and moth.
  4. Orchid and mango.
  1. If '+' sign is assigned to beneficial interaction, '-' sign to detrimental and O sign to neutral interaction, then the population interaction of competition refers to:
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  2. similar adaptations.
  3. common resources.
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Reason: Different individuals of a species have different resource requirements.

  1. Both assertion and reason are true and reason is the correct explanation of assertion.
  2. Both assertion and reason are true but reason is not the correct explanation of assertion.
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Wetlands are called Ramsar sites because the first international convention on their conservation was held in Ramsar in Iran in 1971. Wetlands or Ramsar sites are low lying marshy areas which get filled up during rains due to runoff and overflow from other water bodies. They are often considered to be waste lands which are used as dumping areas and filled up to recover land for various constructions activities. As a result, a large number of wetlands have disappeared.
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Reason: Some sperms may pass into vagina before ejaculation.

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  1. Why is lactational amenorrhea effective for about 4-5 months after parturition?
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Growth of a population with time shows specific and predictable patterns. Two types of growth pattern of population are exponential and logistic growth. When resources in the habitat are unlimited each species has the ability to realise fully its innate potential to grow in number. Then the population grows in exponential fashion. When the resources are limited growth curve shows an initial slow rate and then it accelerates and finally slows giving the growth curve which is sigmoid.

  1. Which of the following statement is incorrect?
  1. Exponential growth occurs in organism such as lemmings.
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  2. $\text{dN}/\text{dt}=\text{rN}\Big(\frac{\text{K-N}}{\text{K}}\Big)$

  3. $\text{N}_\text{t}=\text{N}_\text{o}\text{e}^\text{rt}$

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  2. $\text{dN}/\text{dt}=\frac{\text{rN}}{\text{K}}$

  3. $\text{dN}/\text{dt}=\frac{\text{N}(\text{K}-\text{N})}{\text{K}}$

  4. $\text{dN}/\text{dt}=\frac{\text{r}(\text{K}-\text{N})}{\text{K}}$

  1. The population growth is generally described by the following equation:

$\frac{\text{dN}}{\text{dt}}=\text{rN}\Big(\frac{\text{K}-\text{N}}{\text{K}}\Big)$

What does 'r' represent in the given equation?

  1. Population density at time 't'.
  2. Intrinsic rate of natural increase.
  3. Carrying capacity.
  4. The base of natural logarithm.
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  1. Curve 'A: shows exponential growth, represented by equation $\frac{\text{dN}}{\text{dt}}=\text{rN}$.

  2. Curve 'B' shows logistic growth, represented by equation $\frac{\text{dN}}{\text{dt}}=\text{rN}\Big(\frac{\text{K}-\text{N}}{\text{K}}\Big)$

  3. Exponential growth curve is considered as more realistic than the logistic growth curve.
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Restriction endonuclease was isolated for the first ti me by W. Arb er in 1962 in bacteria. Restriction endonucleases cut the DNA duplex at specific points therefore they are also called as molecular scissors or biological scissors. Three types of restriction endonucleases are Type I, Type II and Type III but only Type II restriction endonucleases are used in recombinant DNA technology. Restriction endonuclease EcoR I recognises the base sequence GAATTC in DNA duplex and cut strands between G and A.

  1. Only type II restriction enzymes are used in gene manipulation because
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  2. It consists of three different subunits.
  3. It makes cleavage or cut in both the strands of DNA molecule.
  4. Both (a) and (c).
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  1. Mg2+ ions
  2. Mn2+ ions
  3. Na2+ ions
  4. K2+ ions
  1.  Restriction endonuclease was isolated for the first time in a:
  1. Plant cell.
  2. Animal cell.
  3. Prokaryotic cell.
  4. Genninal cell.
  1. Restriction endonucleases are also called as molecular or biological scissors because,
  1. They cleave base pairs of DNA only at their terminal ends.
  2. They cleave one or both the strands of DNA.
  3. They act only on single stranded DNA.
  4. None of these.
  1. Select the option that correctly states the working action of restriction endonuclease EcoR I on DNA sequence GAATTC

  1. $\ \ \ \ \ \ \ \ \ \ \ \ \downarrow\\5'-\text{GAATTC}-3'\\3'-\text{CTTAAG}-5'\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \uparrow$

  2. $ \ \ \ \ \ \ \ \ \ \ \downarrow\\5'-\text{GAATTC}-3'\\3'-\text{CTTAAG}-5'\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \uparrow$

  3. $\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \downarrow\\5'-\text{GAATTC}-3'\\3'-\text{CTTAAG}-5'\\\ \ \ \ \ \ \ \ \ \uparrow$

  4. $\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \downarrow\\5'-\text{GAATTC}-3'\\3'-\text{CTTAAG}-5'\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \uparrow$

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