General Science Questions

A sinkhole (in Karst topography) is a hole in the ground that forms when water dissolves surface rock. Often, this surface rock is limestone, which is easily eroded, or worn away, by the movement of water.

Formation of a Sinkhole: In a landscape where limestone sits underneath the soil, water from rainfall collects in cracks in the stone. These cracks are called joints. Slowly, as the limestone dissolves and is carried away, the joints widen until the ground above them becomes unstable and collapses. The collapse often happens very suddenly and without very much warning. Water collects in these collapsed sections, forming sinkholes.

Sinkholes also form when the roofs of caves collapse. Sinkholes are often funnel-shaped, with the wide end open at the surface and the narrow end at the bottom of the pool.Sinkholes vary from shallow holes about 1 meter (3 feet) deep, to pits more than 50 meters (165 feet) deep.

Genetic alteration probably refers to altering Genes found on chromosomes.

Genetic alteration refers to altering DNA sequence. Gene alteration forms genetically modified products that modifies the gene sequence.

Genetic engineering, also called genetic modification or genetic manipulation, is the direct manipulation of an organism's genes using biotechnology.

Rejuvenation occurs when the river’s base level falls (i.e. when sea level falls). This can be a consequence of either a fall in the amount of sea water or the land rising. Incised meanders are meanders which are particularly well developed and occur when a river’s base level has fallen giving the river a large amount of vertical erosion power, allowing it to down cut. Hence, 2nd statement is correct.

There are two types of incised meanders, entrenched meanders and ingrown meanders.As they are products of rejuvenation, they are not formed in mature stage of a river

All   are   correct   except   4   as   a cloudburst  can  occur  anytime  and at  any  place  which  is  affected  by convective weather system.

1. Lichens are plants that grow in exposed places such as rocks or tree bark.

2.  Lichens are widely used as environmental indicators or bio-indicators. They can be used as air pollution indicators, especially of the concentration of sulfur-di-oxide in the atmosphere.  

3. They need to be very good at absorbing water and nutrients to grow there.

Glaciers cut distinctive U-shaped valleys with a flat floor and steep sides. These are an example of a glacial erosion landform.

Example: As the main glacier erodes deeper into the valley, the tributary is left higher up the steep sides of the glacier.