Growth hormone secretion is regulated by negative feedback, three feedback loops including both long and short loops are involved,

a.  GHRH inhibits its own secretion from the hypothalamus via an ultrashort-loop feedback.

b. Somatomedins, which are by-products of the growth hormone action on target tissues, inhibit secretion of growth hormone by the anterior pituitary.

c. Both growth hormone and somatomedins stimulate the secretion of somatostatin by the hypothalamus.

d. SRIF is also secreted by the hypothalmus and acts on the somatotrophs to stimulate growth hormone secretion.

Which one of the following represents all correct statements?

#Question id: 5423

#Unit 8. Inheritance Biology

Maximum height of plant is 200 cm and minimum average height is 80cm. if plant height is controle by 5 pairs of polygene, which of the following plant exhibit average phenotype?

#Question id: 5424

#Unit 8. Inheritance Biology

Imagine that height in corn plants is determined by three loci. The baseline height is 100 cm. Every + allele adds 10cm to the plant’s potential height, every – allele subtracts 10 cm from the plant’s potential height. The shortest possible plant and the tallest possible plant are mated to form an F1, what is the height of the F1?

#Question id: 5425

#Unit 8. Inheritance Biology

Two varieties of maize averaging 50 and 20 inches in height, respectively, are crossed. The F1 progeny is quite uniform averaging 35 inches in height. Out Of the 16 F2 plants, the 5 are 35 inches. What is the probable number of independent segregating polygenes involved in this trait?

#Question id: 5426

#Unit 8. Inheritance Biology

Which of the following is incorrect regard polygenic inheritance?

#Question id: 5427

#Unit 8. Inheritance Biology

In a plant, height is control by three quantitative trait loci.  Each dominant additive allele is contributing 3 cm height in plant. Maximum expected plant height is 20 cm. What is minimum expected height? 

#Question id: 5428

#Unit 8. Inheritance Biology

If trait are governed by polygenic. If plant genotype AABB  ( 8 cm height ) were cross with aabb ( 2 cm height ) produced F1 and allowed to selfing . which of the following phenotypic height are not observe in F2 plant if all gamete participate in fertilization ?