Which of the following can be considered fossils?a. a 1 billion year-old rock.
b. a 1 billion year-old piece of amber.
c. a 1 billion year-old piece of amber with a primitive insect inside.
d. all of the above

Answer:

the lock and key model.

Explanation:

The reason why this model for enzymes is called as lock and key model is because like a specific key fits into a particular lock meant for only that key, in a similar way a substrate also fits in an enzyme active site which is specifically meant for that particular substrate only.

Enzymes are very specific for their substrates and only a substrate which has a particular shape corresponding to the active site of that enzyme can get inside the enzyme for catalysis.

This model is extremely useful for blocking enzymatic activities. In order to block the enzyme we can use a structural analogue of that enzyme which rather than getting converted into products inhibits the enzyme and restricts its activity.

For example: Cholesterol biosynthesis can be restricted easily by using statin drugs which are structural analogues of HMG CoA. Statins bind HMG CoA reductase and stop its structural analogue which is HMG CoA from binding this enzyme. By doing this HMG CoA is not converted into mevalonate and hence cholesterol biosynthesis is halted.

Answer:

the lock and key model is the answer

Explanation:

Enzyme has a pre-determined shape for the active site

Only substrate of specific shape can bind with active site

Substrate contact with enzyme will change the shape of the active site

Allows small change in space to accommodate substrate

Answer:

I'm not sure what the options are but rna or ribonucleic acid is made up of a nucleobase called uracil instead of thymine (which is what dna has). It kinda looks like half of dna.  

The answer to this problem is in a Nadpt+

The answer is competition.

Competition is an interaction between members of the same species or between different species. If resources, such as food, water, sunlight, territory, are limited and several species depend on these resources, then, they must compete with other species to gain the resources. In this example, bears and coyotes depend on deer and when deer population is reduced, bears and coyotes must compete in order to survive.

Answer:

Its competition

Explanation:

Bears and coyotes will fight over the deer if the deer are in short supply so they won't have much deer to consume

Hi,

Which consist of sperm cells and egg cells?

A.gametes