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.
TSH - Thyroid Stimulating Hormone is the hormone that stimulates the Thyroid Gland.
Answer:
c. When a rose bush cell divides, it copies its parts then divides into two cells <em><u>and</u></em>
d. The bacterium was formed when another bacterium divided
Explanation:
C is correct because the cells inside are part of a larger being (the rose bush), when they divide they are simply creating more cells (hence making the rose bush grow).
D is correct because bacterium are <u>unicellular</u> organisms, meaning they are themselves single cells that are organisms, unlike the rose bush consisting of many cells.
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<span>The correct answer, according to Lamarck's theory of evolution, is that A) "Land mammals progressively modified their organs to survive in water. These features were passed on to the next generation, and the mammal gradually evolved into today's aquatic mammals."
Lamarck believed that animals could (a) acquire the traits that they needed and (b) pass those acquired traits on to their offspring. According to part (a) of Lamarck's idea, if I needed to be a faster swimmer (if I were an athlete), I could modify my body to have webbing between my toes, which would allow me to beat the competition! Also, according to part (b) of Lamarck's idea, if I were a body builder and developed (acquired) very large muscles through my training, then my children should be born with very large muscles. Based on the these examples, you can see why Lamarck's theory of evolution is not the one that is generally accepted by scientists. Rather, Darwin's theory of evolution, in which the traits that we are born with confer either an advantage or disadvantage to us in our particular environment, which determine whether or not we are successful (ie, survive and reproduce). New traits come about randomly by mutation, not by our need for them.</span>
