Answer: The Dust Bowl was caused by several economic and agricultural factors, including federal land policies, changes in regional weather, farm economics and other cultural factors. After the Civil War, a series of federal land acts coaxed pioneers westward by incentivizing farming in the Great Plains.
Explanation:
1) Manifest Destiny: The US Government wanted settlers to move onto the Plains as they needed the land to be settled and farmed and for communities and towns to grow up and expand. This was needed if the USA was to be a rich and successful country. The government therefore promoted the idea of Manifest Destiny.
Answer:
The correct answer is : A.
Explanation:
- This is because of the following reasons:
- Escherichia coli is a bacteria and hence is a prokaryote.
- The cloning of human (eukaryote) genes is done to obtain in-vitro protein expression which are to be used a pharmaceutical compounds.
- Although the phenomenon of Central Dogma takes place in both Prokaryotes and Eukaryotes, the mechanism is very different.
- Some of the differences includes:
- Eukaryotic genes contain certain non-protein encoding sequences called the Intron sequences which needs to be removed from the transcribed mature mRNA by Spliceosome. This phenomenon is absent in prokaryotes as they do not possess introns. Hence, proper processing of eukaryotic mRNA is not possible in prokaryotes.
- The mature eukaryotic mRNA has a 5' cap and 3' polyadenylated tail which is added by a capping enzyme and a poly-A polymerase enzyme to increase their stability. This will not be possible in a prokaryote as they lack these enzymes.
- The translation of membrane proteins and secretory proteins is carried on by the ribosomes bound to the endoplasmic reticulum. This structure is absent in prokaryotes, hence they will be unable to produce a proper polypeptide sequence.
- Finally, the eukaryotic proteins undergo various modifications after formation, like methylation, acetylation, etc. These reactions cannot be carried out in a prokaryote as they lack the respective enzymes.
- Hence, we see a properly folded functional eukaryotic protein cannot be produced in a prokaryote.
Answer:
1. Fossil evidence
2. Homologous similarities.
3. Molecular evidence
To a plant, leaves are food producing organs. Leaves "absorb" some of the energy in the sunlight that strikes their surfaces and also take in carbon dioxide from the surrounding air in order to run the metabolic process of photosynthesis. The green color of leaves, in fact, is caused by an abundance of the pigment "chlorophyl" which is the specific chemical agent that acts to capture the sunlight energy needed for photosynthesis. The products of photosynthesis are sugars and polysaccharides. An important "waste product" of photosynthesis is oxygen. To an animal, a leaf may be a food source or a place to live on or under.
