Which extraembryonic membrane in humans prevents desiccation of the embryo inside the uterus?
Chorion
Allantois
Yolk sac
Amnion
In human, during fertilization, a sperm firstly comes in contact with which layer of the ovum
Zona pellucida
Vitelline membrane
Jelly coat
Zona radiata
Due to alcohol abuse, brain-related disease Korsakkoff’s syndrome occurs. Which nutrient is responsible for this syndrome?
Vitamin-B12
Fat
Protein
Vitamin-B1
The number of chromosomes in a primary spermatocyte is
Same as in spermatid
Same as in spermatogonium
Help of that in spermatogonium
Same as in secondary spermatocyte
How many sperm cells are present in an average (3 mL) ejaculation?
200 million
300 million
400 million
500 million
The extra structure that provides nutrition to the embryo is
umbilicus
amnion
chorian
placenta
D.
placenta
Placenta is a connection between foetus and mother formed from fusion of allantois, chorian and uterine endometrium.
Functions:
(a) Provides nourishment
(b) Helps in respiration
(c) Helps in excretion
Amnion and chorian are foetal membranes. Amnion helps in protection and chorian helps in nourishment.