The lac operon, which stands for Lactose operon is known as an inducible system. It is the an operon required for the transport and metabolism of lactose some enteric bacteria (Echerichia coli for example). The Lac operon is only activated in the presence of a key molecule. The key molecule is lactose.
From the given options the following best describes the Lac operon:
D. The repressor is freed from the operator when lactose is present.
Answer: D) Tree roots improve soil water retention
There are many reasons which states that deforestation increases the risk of flood. First , some water stay on the leaves and evaporates in to the atmosphere. Second, tree leaves reduce the impact of raindrops on the soil which causes less soil erosion.
Third, tree roots absorb water from the soil, which make the soil dry and it absorb more water rainwater. The roots of tree hold the soil in place and reduce the movement of sediment which reduce the capacity of river to break its banking. Thus, reducing the chances of flood.
Answer:
DNA replication a process of copying of a cell's DNA. DNA replication is semiconservative process which means that each strand in the double helix helps in the synthesis of new, complementary strand and conserve the parent template.
The Molecular mechanism of DNA replication is as following:
- The double starnded DN in binded with hydrogen bond, the enzyme helicase opens up the DNA at the replication fork.
- A single stranded binding protein prevent the rewinding of DNA and so binds to the DNA around the replication fork
- Topoisomerase prevent supercoiling at replication fork.
- The ezymes primase come in action and produces RNA primers which are complementary to the DNA strand.
- DNA polymerase III help to extends the primers and allow them to add to the 3' end, to make new DNA.
- DNA Polymerase then remove RNA primers and replace with DNA.
- DNA ligase blocks the the gaps between DNA fragments.
So, this is the molecuar mechanism of DNA replication.
b:failure of pituitary gland to secrete ADH .caauses diabetes inspidus.
c:located at the kidney.cortex dark in colour and its the outermost.medulla red in colour and lies at the centre.
