A. IS WHAT I WOULD CHOOSE
Answer:
Hypothalamus and anterior pituitary gland.
Explanation:
Lower levels of T3 and T4 in the blood or lower metabolic rate serve as signal and stimulate the release of thyrotropin-releasing hormone (TRH) from the hypothalamus. The TRH stimulates the anterior pituitary gland to release thyroid-stimulating hormone (TSH) which in turn makes the thyroid gland to release the thyroid hormones.
The elevated levels of thyroid hormones inhibit the release of TRH from the hypothalamus and that of TSH from the anterior pituitary gland.
Hence, the cells of hypothalamus and anterior pituitary gland would be inhibited by the binding of thyroid hormone to regulate the release of these hormones by a negative feedback mechanism.
Question in English:
A female carries a recessive lethal gene (l) on one of her X chromosomes, and a normal dominant allele (L) on the other. What is the sex ratio to be expected in this woman's dependency if she marries a normal man?
Answer:
2/3 females
1/3 males
Explanation:
Females have two X chromosomes (XX) and males have an X and a Y chromosome (XY).
The genotype of the female is XLXl. The genotype of the male is XLY, since he is normal.
The possible genotypes are:
<u> XL Xl</u>
<u>XL</u> <em>XLXL XLXl</em>
<u>Y</u> <em>XLY </em><em>XlY</em>
<em />
All female offspring will be normal as they will always have one normal copy of the X chromosome from their father.
50% of the male offspring will be normal, but 50% will inherit the lethal gene from their mother.
Because the allele is lethal, that means XlY males will not be born.
That means 2/3 of the children will be females, and 1/3 will be males.
If it displays the dominant genotype, we can assume that this plant would have a heterozygous (hybrid) genotype, i.e.
With a purebred recessive plant, the geneotypes would be 50% Bb and 50% bb.
With a purebred dominant plant, the genetpyes would be 50% BB and 50% Bb.
With a <span>heterozygous (hybrid) plant, the genotypes would be 25% BB, 50% Bb and 25% bb.</span>
