Which extraembryonic membrane in humans prevents desiccation of the embryo inside the uterus?

• Chorion

• Allantois

• Yolk sac

• Amnion

72.

Prothallus of the fern produces

• Spores

• Gametes

• Both (a) and (b)

• Cones

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

In case of pregnancy, the heartbeat of embryo starts at

• 4th week

• 7th week

•  6th week

•  5th week

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

The middle piece of the sperm contains

• Proteins

• Centriole

• Nucleus

• Mitochondria

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

LH and FSH are collectively called

• oxytocin

• samatotrophins

• luteotropic

• gonadotropins