Organisms and Populations — BIOLOGY STD 12 Science — Question

What is a tree line?

Who proposed lac operon?

Which of the following diseases can be avoided in the progeny by analysing the pedigree of the parents? Turner's syndrome, Colour blindness, Tuberculosis.

What are cry genes? In which organisms are they present?

Why does an AIDS patient suffer from many other infections?

Read the following and answer any four questions from (i) to (v) given below:
One approach of gene therapy to treat cystic fibrosis uses viruses to deliver normal alleles of the CFTR gene into epithelial cells of the airways. A team of researchers in the USA developed a new strain of non-pathogenic adeno-associated virus (AAV), AAV2.ST. Genes for the CFTR protein and the enzyme luciferase were inserted into the DNA of the viruses. Luciferase catalyses the production of a green fluorescent protein when luciferin is added. The normal AAV strain and the AAV2.5T strain were added to cultures of epithelial cells from the airways. After adding luciferin, the number of cells that had taken up the viral genes was estimated using the intensity of the green fluorescence which developed. The result are shown in the given graph.

1. What could be the probable reason for inserting a gene for luciferase by researchers into the viral DNA?

1. Infected cells are able to produce luciferase.
2. It is easy to identify the infected cells that have taken up viral DNA under fluorescent lamp.
3. THe non-infected cells were easily identified under fluorescent lamp as they will glow.
4. Both (a) and (b).

2. Select the incorrect statement with respect to the graph given.

1. Both AAV and AAV2.ST can infect epithelial cells.
2. Intensity of green fluorescence increases more in AAV 2.5 T as compared to normal AAV.
3. AA V infect cells more readily than AAV 2.5 T.
4. None of these.

3. The name of first transgenic cow is:

1. cDNA does not contain non-coding regions such as intrans.
2. cDNA can be transcribed and translated directly.
3. There is no need of post-trancriptional modification such as splicing, etc.
4. All of these.

4. There is a decrease in intensity of green fluorescence in cells infected with AAV 2.ST during the last 10 day. This is because:

1. Green fluorescent protein was broken down.
2. Luciferin was used up.
3. Infected cells die.
4. All of these.

5. Which of the following best describe gene therapy?

1. Mutating the sequence of a particular gene.
2. Replacing a healthy gene with a defective gene.
3. Replacing a defective gene with a functional gene.
4. Transferring a healthy gene from one species with heathy gene of other species.

Which one of the following is the baker's yeast used in fermentation? Saccharum barberi, Saccharomyces cereviseae, Sonalika.

Angiosperms bearing unisexual flowers are said to be either monoecious or dioecious. Explain with the help of one example each.

Name the unlabelled areas ‘a’ and ‘b’ of the pie chart representing the biodiversity of plants showing their proportionate. Number of species of major taxa.

Give one example for each of the following types.
Biological control agent.