What is the full form of SCID? Mention the cure of this disorder. Mention any one point how SCID is different from AIDS.

Answer:- SCID stands for severe combined immunodeficiency disease. The SCID patient has a defective gene for the enzyme adenosine deaminase. He/she lacks functional T-lymphocytes and therefore fails to fight with infecting pathogens. It can be cured by gene therapy. 

In SCID, the patient lacks functional T-lymphocytes and it is congenital while in AIDS only T-helper cells are destroyed by virus, but is not congenital.

Biopiracy should be prevented. State why and how?

Answer. Some multinational companies of industrialised nations have a good economic status but are poor in biodiversity and are exploiting biodiversity of developing and underdeveloped countries without authorisation and proper compensation.

There has been growing realisation of the injustice, inadequate compensation and benefit sharing between developed and developing countries. Therefore, some nations are developing laws to prevent such unauthorised exploitation of their bioresources and traditional knowledge.

What is a transgenic crop ? Which plant is used to produce blood anticoagulant protein ? 

Answer. Transgenic crops or genetically modified crop contain and express one or more useful foreign genes or transgenes. Brassica napus is used to produce blood anticoagulant protein. The protein is called hirudin. 

The protein hirudin is an anticoagulant which is present in leech. Its gene was chemically synthesized and introduced in Brassica napus. The seeds of the latter came to have hirudin which could be extracted and purified.

 What is gene therapy?

Answer. Gene therapy is the technique of genetic engineering which involves replacement of a faulty gene by a normal healthy functional gene.

Name the transgenic plant from which hirudin is extracted.

Answer Brassica napus

Name the cry genes that control cotton bollworm and corn borer respectively.

Answer:- The genes cryIAc and cryIIAb control the cotton bollworms, whereas cryIAb controls corn borer.

Give the full form of SCID.

Answer Severe combined immunodeficiency disease.

Name two transgenic microorganisms that have been used for large scale production of amino acids.

Answer Two transgenic microorganisms used for large scale amino acid production are:

(i) Bacillus amyloliquefaciens 

(ii) Lactobacillus casei

 What is a patent ?

Answer A patent is the right granted by a government to an inventor to prevent others from commercial use of his/her invention.

Biotechnologists refer to Agrobacterium tumefaciens as a natural genetic engineer of plants. Give reasons to support the statement.

Answer Agrobacterium tumefaciens is called natural genetic engineer of plants because genes carried by its plasmid produce effect in several parts of the plant.

State the role of C peptide in human insulin.

Answer:-  The C-peptide joins the A-peptide with B-peptide in the proinsulin. It is not present in mature insulin and is removed during processing of proinsulin to insulin.

What was the speciality of the milk produced by the transgenic cow Rosie ?

Answer: first transgenic cow, Rosie produced human protein enriched milk which contained the human alpha lactalbumin and was nutritionally more balanced product for human babies than natural cow milk.

Assertion : Molecular probes are available for diagnosing genetic disorders, e.g., Duchenne muscular dystrophy, cystic fibrosis, Tay-sach’s disease.

Reason : The molecular probes are usually double stranded pieces of DNAs, labelled with radioisotopes such as 32P.

Answer:- (c) Assertion is true but reason is false. 

(c) : DNA probes are stretches of single-stranded DNA used to detect presence of complementary nucleic acid sequence (target sequences) by hybridisation. They are usually labelled with radioisotopes, to enable their detection.

Assertion : Flavr-Savr tomato was the first transgenic commercial crop that entered the market.

Reason : Roundup variety of soybean was prepared through breeding.

Answer (c) Assertion is true but reason is false. 

(c) : The Flavr-Savr tomato, was the first genetically modified fruit/vegetable to reach the market in USA. Roundup ready soybean is a genetically modified herbicide tolerant cultivar.

Assertion : ADA deficiency cannot be cured permanently by gene therapy.

Reason : The lymphocytes from the blood of patient are grown in culture outside the body. 

Answer (d) Assertion is false but reason is true.

(d) : As a first step towards gene therapy, lymphocytes, a kind of white blood cells, are extracted from the bone marrow of the patient and are grown in a culture outside the body. A functional ADA cDNA (using a retroviral vector) is then introduced into these lymphocytes, which are reinjected to the patient’s bone marrow. But as these cells do not always remain alive, the patient requires periodic infusion of such genetically engineered lymphocytes. However, if the isolated gene from bone marrow cells producing ADA is introduced into cells at early embryonic stages, it can be permanent cure.

Assertion : Agrobacterium tumefaciens is called natural genetic engineer.

Reason : Agrobacterium tumefaciens infects all broad-leaved agricultural crops but does not infect cereal crops.

Answer (b) Both assertion and reason are true but reason is not the correct explanation of assertion.

(b) : Ti plasmid (tumor inducing) from Agrobacterium tumefaciens is effectively used as a vector for gene transfer to plant cells. In nature, it induces tumors in broad leaf crops, e.g., tomato, soybean, cotton, etc.

Assertion : Mouse is the most preferred mammal for studies on gene transfers.

Reason : Mouse possesses features like short oestrous cycle and gestation period, relatively short generation time, production of several offspring per pregnancy, etc.

Answer (a) Both assertion and reason are true and reason is the correct explanation of assertion.

(a) : Mouse is the most preferred mammal for studies on gene transfers due to its many favourable features like (i) short oestrous cycle and gestation period, (ii) relatively short generation time, (iii) production of several offspring per pregnancy, (iv) convenient in vitro fertilisation, successful culture of embryos in vitro.

Assertion : Agrobacterium tumefaciens is popular in genetic engineering because this bacterium  is associated with the roots of all cereal and pulse crops.

Reason : Agrobacterium tumefaciens, is pathogen of several dicot plants is able to cause crown gall tumors. These tumors are incited by the conjugative transfer of DNA segment (T DNA). 

Answer (d) Assertion is false but reason is true.

(d) : A. tumefaciens causes crown gall disease on a wide range of dicot (broad leaved) plants especially members of rose family by transferring its own DNA into plant cells. But in laboratory, the ability to move all sorts of genes into plants has made the microbe the standard tool for investigating plant genetics and modifying crops.

Assertion : Biopatents are awarded for biological entities and all products derived from them.

Reason : Patent on use of turmeric in wound healing was cancelled in 2008.

Answer (c) : Biopatents are awarded for biological entities and all products derived from them. 1995 patent on ‘use of turmeric in wound healing’ was cancelled in 1998.

Assertion : Genetically modified microbes help in crop protection.

Reason : Transgenic bacteria control insects by producing endotoxins.

Answer (b) Both assertion and reason are true but reason is not the correct explanation of assertion.

Assertion : Transgenic food may cause toxicity or produce allergy.

Reason : Transgenic plants have high nutrient content.

Answer Both assertion and reason are true but reason is not the correct explanation of assertion.

Reason (b) : Plant in which foreign genes have been introduced through genetic engineering are called transgenic plants. Transgenic food from such plants may cause toxicity and or produce allergies. The enzyme produced by the antibiotic resistance genes can cause allergies because it is a foreign protein. GM plants enhance nutritional value of food, e.g., Golden rice.