What are transgenic plants? Explain with any two examples - Biology


What are transgenic plants? Explain with any two examples



The plants which are genetically engineered to carry desirable traits like disease resistance, insect resistance, herbicide resistance are called as transgenic plants. 
Examples: Bt cotton, Golden rice, Flavr Savr tomato

a. Bacillus thuringiensis (Bt) is a soil bacterium that produces a protein with insecticidal property. Bt toxin proteins occur as inactive protoxin.
The ‘cry’ gene codes for this inactive protoxin. Crops have now been genetically engineered using rDNA technology, by inserting the
‘cry’ gene in plants. After the insects ingest the transgenic crops, they are killed because the inactive protoxin is converted into the active form due to alkaline pH of the insect gut. Bt toxin gene has been cloned and  introduced in many plants to provide resistance to insects without the need of insecticides. Bt cotton is commercially available to control the disease affecting the cotton balls.
b. Golden rice is genetically engineered rice with greater pro-vitamin A [β – carotene] content.
c. In Flavr Savr variety of tomato, the expression of a native gene that codes for the enzyme polygalacturonase, has been blocked. The enzyme is responsible for degradation of pectin during fruit ripening. In the absence of this enzyme, the fruit ripening or softening is delayed and hence, the fruit remains fresh for longer periods and flavour is saved.

Concept: Plant Breeding
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2015-2016 (July)


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What is ‘biofortification’?

Which steps would you follow to develop a new variety of crop plant by selective breeding?

What is plant breeding?

How has the mutation breeding helped in improving crop varieties? Give one example where this technique has helped.

With the help of suitable diagram define 'bagging' and 'tagging' of  flower.

In an agricultural field there is a prevalence of the following organisms and crop diseases which are affecting the crop yield badly:
(a) White rust
(b) Leaf and stripe rust
(c) Black rot
(d) Jussids

Recommend the varieties of crops the farmers should grow to get rid of the existing problem and thus improve the crop yiel.

List the two steps the classical plant breeding involves.

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What are components of water potential? Explain

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Answer each question in ‘One’ sentence only:

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Give the scientific term used for the preservation of germplasm at a very low temperature.

Give a reason for the following: 

Bagging is essential in artificial hybridization.

Describe briefly various steps of plant breeding methods.

While studying the history of the domestication of various cultivated plants _______ were recognized earlier.

Plants having similar genotypes produced by plant breeding are called

Importing better varieties and plants from outside and acclimatizing them to the local environment is called

Crosses between the plants of the same variety are called

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Variety Resistance to disease
a) Pusa Komal Bacterial blight
b) Pusa Sadabahar White rust
c) Pusa Shubhra Chilli mosaic virus
d) Brassica Pusa swarnim

Explain the best-suited type followed by plant breeders at present?

Column - I contains names of host plant while Column - II contains names of viral dieases. Find the correct option.

  Column-I   Column-II
(I) Banana (p) little leaf
(II) Sugarcane (q) bunchy top
(III) Papaya (r) leaf roll
(IV) Brinjal (s) grassy shoot
    (t) leaf curl

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Breeding of crops with high levels of minerals:

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The plant which is used for Studying hybrid vigour or heterocyst:

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Sugarcane which grow in North India, and which do not grow in north India. 

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  Column A   Column B
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What are A, B in the following table:

Transgenic Crop Substance Transgene
(i) A Flavonoids Chalone isomerase
(ii) Rice B Ferritin


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