The nervous and the endocrine system are tightly linked together.
The main reason for this linkage is due to the connection of the hypothalamus (nervous system) and the hypophysis (a gland in the endocrine system)
The hypophysis is the ''controller'' of all of the other endocrine glands.
The connection between the hypothalamus and the hypophysis enables the nervous system to control the hormone levels of all of the major endocrine glands in the body.
The hypothalamus releases hormones into the bloodstream that leads to the hypophysis. These hormones induce a release of hypophysis hormones that enter the bloodstream and when they reach the target gland (for example pancreas) these hormones induce the release of the hormones of that gland (in the case of the pancreas, insulin).
The hypothalamus monitors the concentration of hormones in the blood, and a high level of a certain hormone blocks the release of the hypothalamus' hormones. Therefore, a high level of insulin blocks a cascade of hormone release that starts in the hypothalamus that leads to its release in the pancreas.
Population of older female elephants different from the younger female elephants is described below.
Explanation:
- THE OLDEST ELEPHANTS wandering Mozambique’s Gorongosa National Park bear the indelible markings of the civil war that gripped the country for 15 years: Many are tuskless. They’re the lone survivors of a conflict that killed about 90 percent of these beleaguered animals, slaughtered for ivory to finance weapons and for meat to feed the fighters.
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Hunting gave elephants that didn’t grow tusks a biological advantage in Gorongosa. Recent figures suggest that about a third of younger females—the generation born after the war ended in 1992—never developed tusks. Normally, tusklessness would occur only in about 2 to 4 percent of female African elephants.
- New, as yet unpublished, research she’s compiled indicates that of the 200 known adult females, 51 percent of those that survived the war—animals 25 years or older—are tuskless. And 32 percent of the female elephants born since the war are tuskless.
- A male elephant’s tusks are bigger and heavier than those of a female of the same age, says Poole, who serves as scientific director of a nonprofit called ElephantVoices. “But once there’s been heavy poaching pressure on a population, then the poachers start to focus on the older females as well,” she explains. “Over time, with the older age population, you start to get this really higher proportion of tuskless females.”
- “The prevalence of tusklessness in Addo is truly remarkable and underscores the fact that high levels of poaching pressure can do more than just remove individuals from a population,” says Ryan Long, a behavioral ecologist at the University of Idaho and a National Geographic Explorer. The “consequences of such dramatic changes in elephant populations are only just beginning to be explored.”
The pay raise was a stimulus for production
A cross between individuals that are heter0zyg0us for two different traits is a dihybrid cross. <em>A cross between two individuals that are heterozygous for eye and skin color would be an example of a _</em>dihybrid<em>_ cross.</em>
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Dihybrid crosses involve individuals that expresses two different traits and are heter0zyg0us for each of them.
So let us imagine we are studing the characters eye color and skin color. Let us assume that both of them are coded by single diallelic genes.
For eye color there is
- Dominant allele B that codes for brown eyes
- Recessive allele b that codes for blue eyes
For skin color there is
- Dominant allele A that codes for black skin
- Recessive allele a that codes for white skin
So, an individual that is heter0zyg0us for both of them, is BbAa.
If this person crosses to another person with the same genotype, we are talking about a <u>dihybrid cross</u>, because two dibybrid individuals are involved.
Cross: BbAa x BbAa
According to this information, we can aswer the question:
<em>When crossing two individuals that are heterozygous for eye and skin color we are referring to a</em><em> dihybrid cross.</em>
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Learn more about dihybrid crosses at
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