Bird migrations began with the recession of the glaciers during the ice age. You will notice a great increase in insects in the spring time and early summer.The birds moved North to take advantage of this increase in the food supply that followed the warming in the spring and early summer. Their reproductive organs temporarily developed so they could lay eggs and raise a family. Look at the early flush of Night crawlers in the moist times of the early rains. By mid summer most of the insects have matured, mated and died. Their eggs have hatched and turned to larva and moved underground until next spring. The shortening of the days causes the reproductive functions to decrease and signals the birds that the food will soon become scarce. They move back to the area that makes it the easiest to find food and avoid freezing. which of course is the warmer climates nearer the equator. Not all birds move past the Tropics at approximately 30 degrees. Some like Chickadees may move down from Mi or Mn or Canada only as far south as Indiana. Some migrations may be quite short. For example from the mountains down to the plains. They don't generally reproduce in the warmer winter climes they migrate to. In the spring time they migrate along paths of the retreating glaciers. As the climate warms away from the tropics the birds follow the emerging insects etc to the birds selected breeding grounds.with increased insects and longer days to feed the hatching's. It is necesary to understand why they move to cooler climates in the summer to under stand why they move to eh warmer ones in the fall. As the days shorten the food supply dwindles and the babies have fledged. They move to warmer climates in winter to rest and refuel for the next years migration.
As the sun heats the surface of the oceans, two layers of water result. These layers are separated by the Thermocline.
so your answer is thermocline.
Earthquakes occur all the time all over the world, both along plate edges and along faults. Most earthquakes occur along the edge of the oceanic and continental plates. The earth's crust (the outer layer of the planet) is made up of several pieces, called plates.
Answer:
This question lacks proper arrangements but one can understand and chip in the appropriate terms. The terms missing there in order, which answers the question are:
Nucleus
Transcription
RNA polymerase
mRNA
Ribosome
Explanation:
The cellular process being described in this question is GENE EXPRESSION, which is the expression of the information contained in the genetic material in order to produce useful gene products (proteins). The genetic material (DNA) is stored in the nucleus of eukaryotic cells. The first process of this gene expression called TRANSCRIPTION involves the copying of the information contained in the DNA into an RNA molecule.
Transcription is carried out by an enzyme called RNA polymerase, which synthesizes a complementary strand of mRNA from a DNA template. mRNA ia called messenger RNA and it acts as a conveyer/carrier of this information present on its nucleotides out of the nucleus into the cytoplasm, specifically the site of protein synthesis called RIBOSOME.
The RIBOSOME is a cellular organnelle where the other process of gene expression called TRANSLATION will occur.
Answer:
- All of the following are correct
- Muscle cells are surrounded by a branching network of transverse tubules.
Explanation:
Muscle cells are composed of myofibrils, which are the fundamental and functional parts of a muscle cell. Myofibrils are the ones that are surrounded by a branching network of transverse tubules. These transverse tubules are extensions of the sarcolemma or the muscle cell's membrane. Their distribution and connection to myofibrils allow for the passage of Calcium ions needed for contraction.
