Biology Sexual Reproduction Unit Test Flashcards
What is Embryonic Development?
Early development that occurs after fertilization!
What is Differentiation?
The process in which the 3 cell layers eventually form the organs and tissues of a baby!
What is a zygote?
A fertilized egg
What are the 3 layers of the Gastrula?
Outer layer - Ectoderm,
Middle Layer - Mesoderm
Inner layer- Endoderm
(Hollow Center inside)
What forms in the Ectoderm?
Skin and nervous system
What forms in the mesoderm?
Kidneys, Skeleton, Blood Vessels and reproductive organs
What forms in the Endoderm?
Lungs, liver, and lining of digestive system
What happens during the first Trimester?
Organs begin to develop,
At 4 weeks the brain and spinal cord start forming
At 8 weeks Embryo is called a fetus and Bone cells form, ears, kidneys, lungs, liver, and muscles begin developing
At 12 weeks Sexual differentiation is almost complete
What happens during the second trimester?
AT 16-18 weeks fetal movements are felt,
At 24 weeks eyelids open and the fetus can live outside of the mother
What happens during the third trimester?
Significant growth of the brain
At 26-38 Weeks rapid weight gain and accumulation of fat occurs
What happens during Embryonic development?
Week 1 Zygote undergoes mitosis and rapid cell divisions, forming a ball of cells
Week 2 Hollow ball of cells called Blastula
Week 3 Cells of blastula are organized into 3 layers (This stage is called Gastrula)
What is a Morula?
A morula is a ball of cells that forms in the first week
What is a Gastrula?
A gastrula is the stage of development where the blastula organizes into 3 layers
What is a Blastula?
A blastula is a hollow ball of cells that forms in the first 2 weeks.
What are 4 Advantages of Sexual Reproduction?
- Very little energy required to find a mate (External Fertilization
- Greater numbers of offspring can repopulate after a disaster
- More protection is given to the embryo and more parental care is given (Internal)
- Offspring are genetically different from the parent, so they may survive new diseases or other threats that appear in the population