Human Health and Disease — BIOLOGY STD 12 Science — Question

A student on a field trip suddenly felt breath-lessness and started to sneeze very badly. Name this response and explain what it is due to?

A recombinant DNA is formed when sticky ends of vector DNA and foreign DNA join. Explain how the sticky ends are formed and get joined.

Explain mechanism of pollination by water in marine water plants.###Explain - mechanism of pollination by water in Zostera###Explain mechanism of pollination by water in Sea-grasses.

Collect 5 examples of palindromic DNA sequences by consulting your teacher. Better try to create a palindromic sequence by following base pairs rules.

In a cross between two tall pea plants, some of the offsprings produced were dwarf. Show with the help of Punnet square, how this is possible.

The following graph shows the species-area relationship. Answer the following questions as directed.

1. Name the naturalist who studied the kind of relationship shown in the graph. Write the observations made by him.
2. Write the situations as discovered by the ecologists when the value of Z (slope of the line) lies between (a) 0.1 and 0.2 (b) 0.6 and 1.2. What does Z stand for?
3. When would the slope of the line 'B' become steeper?

What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.

Make a chart (with diagrammatic representation) showing a restriction enzyme, the substrate DNA on which it acts, the site at which it cuts DNA and the product it produces.

Linkage and crossing over of genes are alternatives of each other. Justify with the help of an example.

Attempt giving a clear definition of the term species.