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?

TLS Online TPP Program

#Question id: 5678

#Unit 5. Developmental Biology

Following process and their mechanism during fertilization in mammals.

a. Rheotaxis	i.A sensing mechanism in which, the oocyte and its accompanying cumulus cells secrete molecules that attract capacitated sperm toward the egg during the last stages of sperm migration
b.  Chemotaxis	ii.It is a transient event, and sperm are given a relatively brief window of competence during which they can successfully fertilize the egg.
c.  Capacitation		iii.it is the ability to sense temperature difference and preferentially swim from cooler to warmer sites is found only in capacitated sperm.
d. Thermotaxis		iv.Sperm receive long-distance directional cues from the flow of liquid from the oviduct to the uterus and they will migrate against the direction of the flow—using CatSper calcium channels to sense calcium influx and monitor the direction of the current

Which of the following option is correct?

TLS Online TPP Program

#Question id: 5089

#Unit 5. Developmental Biology

The archenteron of the developing sea urchin eventually develops into the ________.

TLS Online TPP Program

#Question id: 1004

#Unit 1. Molecules and their Interaction Relevant to Biology

Which structure below is PRPP?

TLS Online TPP Program

#Question id: 325

#Unit 1. Molecules and their Interaction Relevant to Biology

A true statement about hydrophobic interactions is that they:

TLS Online TPP Program

#Question id: 7274

#Unit 5. Developmental Biology

The following experiment is designed to study the role of several hormones in the regulation of metamorphosis in frogs.

Group #	Treatment	Days to Metamorphosis
1	Saline	30
2	Prolactin	> 100
3	TSH	15
4	Thyroxine	10
5	Corticosterone	30
6	Thyroxine + Corticosterone	5
7	Prolactin + TSH	30
8	Thyroid gland removed	> 100

 If the thyroid gland were removed from the tadpoles in Group 3, metamorphosis would