Question 1
The _____________ is formed when the ovum and sperm unite and fertilization takes place.
◦ blastula
◦ blastocyst
◦ zygote
◦ embryo
Question 2
The ______________ form from the outer layer of the embryonic disk.
◦ digestive and respiratory systems
◦ brain and spinal cord
◦ skin, hair, nails, sensory organs, and nervous system
◦ lungs and heart