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The following is the biochemical pathway for purple pigment production in flowers of sweet pea:

Colorless precursor 1 —- Allele A—->  Colorless precursor 2 —--- Allele B—---> Purple pigment

Recessive mutation of either gene A or B leads to the formation of white flowers. A cross is made between two parents with the genotype: AaBb × aabb. Considering that the two genes are not linked, the phenotypes of the expected progenies are:

 

Option: 1

9 purple : 7 white


Option: 2

3 white : 1 purple


Option: 3

1 purple : 1 white


Option: 4

9 purple : 6 light purple : 1 white


3(white):1(purple)

In case of 'duplicate recessive epistasis homozygous recessive gene masks the other gene i.e., aa is epistatic to A or a || bb is epistatic to B or b

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Posted by

Riya

In the question one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below : Assertion (A) : Wing of an insect and wing of a bird are analogous organs. Reason (R) : The organs which are quite different in fundamental structure and origin but perform same function in different species are called analogous organs.
Option: 1 Both (A) and (R) are true and (R) is the correct explanation of the
assertion (A).
Option: 2 Both (A) and (R) are true, but (R) is not the correct explanation of
the assertion (A).
Option: 3 (A) is true, but (R) is false.
Option: 4 (A) is false, but (R) is true.

Both (A) and (R) are true and (R) is the correct explanation of the
assertion (A).

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Posted by

Safeer PP

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In the question two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the
correct answer to these questions from the codes (a), (b), (c) and (d) as given below : Assertion (A) : The sex of a child in human beings will be determined by the type of chromosome he/she inherits from the father. Reason (R) : A child who inherits ‘X’ chromosome from his father would be a girl (XX), while a child who inherits a ‘Y’ chromosome from the father would be a boy (XY).
Option: 1 Both (A) and (R) are true and (R) is the correct explanation of the
assertion (A).
Option: 2 Both (A) and (R) are true, but (R) is not the correct explanation of
the assertion (A).
Option: 3 (A) is true, but (R) is false.
Option: 4 (A) is false, but (R) is true.

Both (A) and (R) are true and (R) is the correct explanation of the
assertion (A).

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Posted by

Safeer PP

(a)    What is genetics? (b)    What are genes? Where are the genes located? (c)    State and define three factors responsible for the rise of a new species.
Option: 1
Option: 2
Option: 3
Option: 4

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Posted by

Safeer PP

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(a) What is the law of dominance of traits ? Explain with an example. (b) Why are the traits acquired during the life time of an individual not inherited ? Explain.
 

(a) Law of dominance which is also called Mendel's law of dominance that states that in a heterozygotic cross, one trait will suppress the presence of another trait. Instead of both alleles the dominant allele will be expressed exclusively in the phenotypic ratio.

Example:

where as, T is dominant and t is recessive.

So, the phynotipic ratio is 3:1.

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Posted by

Safeer PP

Experimental verification of the chromosomal theroy of the inheritance was done by:
Option: 1 Mendel 
Option: 2 Sutton
Option: 3 Boveri
Option: 4 Morgan  

The experimental verification of the chromosomal theory of inheritance was done by Thomas Hunt Morgan and his colleagues which led to discovering the basis for the variation that sexual reproduction produced.

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Posted by

Ritika Jonwal

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If the distance between two consecutive base pairs is 0.34nm and the total number of base pairs of a DNA helix in a typical mammalian cell is 6. 6 \times 10^{5} bp, then the length of the DNA is approximate:
Option: 1 2.0 meters
Option: 2 2.5 meters
Option: 3 2.2 meters
Option: 4 2.7 meters

Length of the DNA = Distance between two base pairs x Total no. of base pairs. 

Length of the DNA = 0.34 x 6.6x105  = 2.244 

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Posted by

Ritika Jonwal

Name the enzymes that facilitate the opening of DNA helix during transcription.
Option: 1 DNA ligase
Option: 2 DNA helicase
Option: 3 DNA polymerase
Option: 4 RNA polymerase
   

During initiation in the process of transcription, the RNA polymerase holoenzyme binds to the promoter region of the transcription unit. The RNA polymerase-sigma complex binds to the promoter and initiates transcription of a specific strand of DNA. The DNA strand unwinds by the action of this complex. 

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Ritika Jonwal

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Which of the following statements is correct?
Option: 1 Adenine pairs with thymine through two H-bonds
Option: 2 Adenine pairs with thymine through one H-bond
Option: 3 Adenine pairs with thymine through three H-bonds.
Option: 4 Adenine does not pair with thymine  

In double-stranded DNA, Adenine pairs with Thymine with two Hydrogen bonds that is (A=T) and Guanine pairs with Cytosine with three hydrogen bonds. 

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Posted by

Ritika Jonwal

Identify the wrong statement with reference to the gene 'I' that controls ABO blood groups  
Option: 1 The gene (I) has three alleles.
 
Option: 2 A person will have only two of the three alleles.
 
Option: 3 When IA and IB are present together, they express same type of sugar.
 
Option: 4 Allele "i" does not produce any sugar.

Option 4

 

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Posted by

Simran

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