The first outward sign of puberty in a girl is <span>the onset of nipple growth.
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The first visible evidence of puberty in girls is a lump in the size of a nickel under the nipples. These are called <span>Breast buds and they occur around nine or ten </span>years of age and is the first sign of puberty. They will<span> undergo different developmental stages to form normal healthy breasts. </span>
Answer
Glucose is absent, cAMP levels are high, CAP is inactive and cannot bind to the activator
Explanation:
The lac operon can only be transcribed in the absence of glucose. cAMP can only bind to CAP in the absence of glucose making it possible for CAP to bind to DNA.
Y-linked genes are linked to the Y chromosome. They are not as usual as the X-linked genes and can only be expressed by men or males. Sons' phenotype: 100% hairy ears. Daughters' phenotype: 100% not hairy ears.
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What are sex-liked genes?</h3>
When talking about sex-linked genes, we refer to genes located in one of the sex chromosomes.
Being linked to one of the sex chromosomes means that these genes, and their corresponding alleles, will only be inherited together with the chromosome.
In general, genes are linked to the X chromosome. These are X-linked genes. In these cases, a male that inherits the X chromosome from a heterozygous female can express either the dominant or the recessive trait, depending on which allele it got from the mother.
However, some genes are linked to the Y chromosome and hence, inherited only by males or men. Traits coded by Y-linked genes will only be inherited by males.
In the exposed example, we are referring to an Y-linked gene, so it will only be inherited by sons and not daughters.
- Expected phenotypes of the man's sons ⇒ 100% haired ears
- Expected phenotypes of the man's daughter ⇒ 100% not haired ears
You will learn more about Y-linked genes at
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The lymphatic system returns fluid that was lost back into circulation
