Which extraembryonic membrane in humans prevents desiccation of the embryo inside the uterus?
Chorion
Allantois
Yolk sac
Yolk sac
D.
Yolk sac
Amnion is an extraembryonic membrane that surrounds embryo in reptiles, birds and mammals. It provides a kind of private aquarium to the embryo and protects it from mechanical shock and desiccation.
Chorion (serosa) is the outermost extraembryonic membrane in reptiles, birds and mammals. It surrounds the whole embryonic system of the embryo.
Yolk sac contains yolk in reptiles and birds. In mammals yolk, the sac is also known as a umnillical vesicle. It is connected to enter on of the embryo by a slender yolk stalk.
Allantois functions as an embryonic urinary bladder or as a respiratory extension of a handgun in reptiles and birds. In mammals, it is modified to carry blood vessel to and from the placenta.
Which one of the following correctly describes the location of some body parts in the earthworm Pheretima?
Two pairs of accessory glands in 16-18 segments
Four pairs of spermathecae in 4-7 segments
One pair of ovaries attached at intersegmental septum of 14th and 15th segments
One pair of ovaries attached at intersegmental septum of 14th and 15th segments
Which one of the following is the most likely reason of not occurring regular menstruation cycle in females?
Fertilisation of the ovum
maintenance of the hypertrophical endometrial lining
Maintenance of high concentration of sex hormones in the blood stream
Maintenance of high concentration of sex hormones in the blood stream
Seminal plasma in human is rich in
fructose, calcium and certain enzymes
fructose and calcium but has no enzymes
glucose and certain enzymes but has no calcium
glucose and certain enzymes but has no calcium
The correct sequence of spermatogenetic stages leading to the formation of sperms in mature human testis is
spermatocyte-spermatoogonia-spermatid-sperms
spermatogonia-spermatocyte-spermatid
spermatid-spermatocyte-spermatogonia-sperms,
spermatid-spermatocyte-spermatogonia-sperms,
In human adult females, oxytocin
is secreted by the anterior pituitary
stimulates the growth of mammary glands
stimulates pituitary to secrete vasopressin
stimulates pituitary to secrete vasopressin
In humans, at the end of the first meiotic division, the male germ cells differentiate into the
Primary spermatocytes
Secondary spermatocytes
spermatids
spermatids
Which one of the following pairs of organs includes only the endocrine glands?
Parathyroid and adrenal
Pancreas and parathyroid
Thymus and testes
Thymus and testes
Which part of ovary in mammals acts as an endocrine gland after ovulation?
Graaffian follicle
Stroma
Germinal epithelium
Germinal epithelium
In the human female, menstruation can be deferred by the administration of
LH only
Combination of FSH and LH
Combination of estrogen and progesterone
Combination of estrogen and progesterone
