Bt Toxin

Q. Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because:

1. Toxin is inactive
2. Toxin is immature
3. Bacteria are resistant to the toxin
4. Bacteria enclose toxin in a special sac

Q. Bt toxin kills certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). But, actually, the Bt toxin protein exists as inactive protoxins. What makes the activation of protoxin to active toxin in bollworm?

1. Acidic pH of stomach
2. Body temperature
3. Alkaline pH of gut
4. Moist surface of midgut

Q. Which of the following is not a genetically modified plant?

1. Bt-cotton
2. Flavr Savr tomato
3. Golden Rice
4. Pusa Swarnim

Q. What is true about Bt toxin?

1. The inactive protoxin gets converted into active form in the insect gut
2. Bt protein exists as active toxin in the bacillus
3. The activated toxin enters the ovaries of the pest to sterilise it and thus prevent its multiplication
4. The concerned Bacillus has antitoxins

Q.

Crystals of Bt-toxin produced by some bacteria do not kill the bacteria themselves because:

(a) bacteria are resistant to the toxin

(b) toxin is immature

(c) toxin is inactive

(d) bacteria encloses toxin in a special sac

Q. Why does Bt toxin not kill the Bacillus?

Q.

The first bio-insecticide developed on commercial-scale was _____________.

1. Quinine

2. DDT

3. Organophosphate

4. Sporeine

Q.

Most spoilage bacteria grow at:

1. neutral pH

2. acidic pH

3. alkaline pH

4. any pH.

Q. Bt-cotton produces a toxic protein which is encoded by the Cry gene which was obtained from the bacterium __.

Q. The trigger for activation of toxin of Bacillus thuringiensis is

1. alkaline pH of gut
2. mechanical action in the insect gut
3. acidic pH of stomach
4. high temperature

Q. What is true of Bt toxin?

1. The concerned Bacillus has antitoxins
2. The inactive protoxin gets converted into active form in the insect gut
3. Bt toxin exists as active toxin in the Bacillus
4. The activated toxin enters the ovaries of the pest to sterilize it and thus prevents its multiplication

Q. Bt toxin kills the insect by

1. blocking mitochondrial respiration
2. blocking transfer of nerve impulse
3. creating pores in body surface
4. creating pores in mid-gut epithelial cell

Q. The prefix “Bt” in Bt cotton means

1. “Barium treated” cotton seeds
2. “Bigger thread” variety of cotton with better tensile strength
3. Carrying an endotoxin gene from Bacillus thuringiensis
4. Produced by “biotechnology” using restriction enzymes and ligases

Q. Toxin produced by Bt cotton plant gets activated in:

1. Midgut of insect by alkaline pH
2. Leaves of plant by acidic pH
3. Mouth of insect by acidic pH
4. Stem of plant by alkaline pH

Q. Bt toxin kills insects by

1. inhibiting protein synthesis
2. generating excessive heat
3. creating pores in the midgut epithelial cells, leading to cell swelling and lysis
4. obstructing a biosynthetic pathway

Q.

What is Microcystis sp.?

Q.

What are the Cry proteins? Name an organism that produce it. How has a man exploited this protein to his benefit?

Q. What triggers activation of protoxin to active toxin of Bacillus thuringiensis in bollworm?

1. Acidic pH of stomach
2. Body temperature
3. Moist surface of midgut
4. Alkaline pH of gut

Q.

Nitrogen is a constituent of proteins.

1. True
2. False

Q. Which of the following could be the pH, where pro-toxin produced by Bacillus thuringiensis can be converted into active toxin?

1. 2
2. 5
3. 7.4
4. 10

Q. Identify the incorrect statement about Bt-toxin.

1. It kills the insects belonging to the orders lepidoptera, coleoptera, and diptera
2. It is activated by alkaline environment of insect midgut and by activity of protease
3. It binds to receptors on the epithelial cells of the midgut
4. It can affect humans too because it can bind to the epithelial cells of their duodenum

Q.

Name the bacteria responsible for nitrification in nature.

Q. Bt toxin kills insects by

1. inhibiting protein synthesis
2. generating excessive heat
3. creating pores in the midgut epithelial cells, leading to cell swelling and lysis
4. obstructing a biosynthetic pathway

Q. In Bt cotton, the Bt toxin present in plant tissue as protoxin is converted into active toxin due to

1. acidic pH of the insect gut
2. alkaline pH of the insect gut
3. presence of conversion factors in insect gut
4. action of gut microorganisms

Q.

What is the Bacillus thuringiensis?

Q. The insecticidal protein in Bt cotton is bound to the:

1. Foregut epithelial cells
2. Midgut mesothelial cells
3. Midgut epithelial cells
4. Hindgut mesothelial cells

Q.

The Bt toxin is not toxic to human beings because

1. conversion of pro-Bt toxin to Bt toxin takes place only in highly alkaline conditions

2. the Bt toxin formation from pre-Bt toxin requires pH lower than that present in the human stomach

3. the Bt toxin recognizes only insect-specific targets

4. the pro-Bt toxin activation requires a temperature above human body temperature

Q.

What are three benefits of using pesticides?

Q. The trigger for activation of toxin of Bacillus thuringiensis is

1. acidic pH of stomach
2. high temperature
3. alkaline pH of gut
4. mechanical action in the insect gut

Q. Cry I Ab and cry II Ab produce toxins that control

1. Corn borer and tobacco budworms respectively
2. Cotton bollworms and corn borer respectively
3. Nematodes and tobacco budworms respectively
4. Tobacco budworms and nematodes respectively