AP Bio 2012 Q1
AP® BIOLOGY
2012 SCORING GUIDELINES
Question 1
Note: At least 1 point must be earned from each of parts (a), (b), (c), and (d) in order to earn a maximum score of 10.
The ability to reproduce is a characteristic of life.
(a) Describe the process of embryological development in a typical vertebrate embryo, beginning with a fertilized egg and ending with the development of three tissue layers.
(4 points maximum)
Embryological process
Fertilization
Cleavage
(can occur in other stages)
Blastulation
Gastrulation
Description of embryological process (1 point per box)
• Egg is fertilized by sperm.
• Zygote is formed.
• Polyspermy is blocked.
• Diploid number of chromosomes is restored.
• Nuclei of egg and sperm fuse.
• Sex of offspring is determined.
• Polarity is determined.
• Rapid cell divisions.
• Cell divisions without cell growth.
• Cleavage divisions form a small, solid ball of cells (morula).
• Rapid DNA replications and mitotic divisions occur.
• Cells get smaller in early cleavage with each division.
• Cleavage divisions form a hollow ball of cells surrounding a fluidfilled cavity.
• Room for germ layers is developed.
• Germ cell layers (ectoderm, endoderm, and mesoderm) are established. • Opening called a blastopore forms.
• Cells near the surface of the blastula reorganize and move to an interior location.
• Primitive digestive gut (archenteron) forms.
(b) Identify the developmental origin of TWO of the following tissues in vertebrates:
• central nervous system
• digestive system
• muscle
(2 points maximum)
Tissue
Central nervous system
Digestive system
Muscle
Identification of developmental origin (1 point per box)
• Ectoderm / outer germ layer
• Endoderm / inner germ layer (lining)
• Mesoderm / middle germ layer (other layers of digestive tract)
• Mesoderm / middle germ layer
© 2012 The College Board.
Visit the College Board on the Web: www.collegeboard.org
AP® BIOLOGY
2012 SCORING
2012 SCORING GUIDELINES
Question 1
Note: At least 1 point must be earned from each of parts (a), (b), (c), and (d) in order to earn a maximum score of 10.
The ability to reproduce is a characteristic of life.
(a) Describe the process of embryological development in a typical vertebrate embryo, beginning with a fertilized egg and ending with the development of three tissue layers.
(4 points maximum)
Embryological process
Fertilization
Cleavage
(can occur in other stages)
Blastulation
Gastrulation
Description of embryological process (1 point per box)
• Egg is fertilized by sperm.
• Zygote is formed.
• Polyspermy is blocked.
• Diploid number of chromosomes is restored.
• Nuclei of egg and sperm fuse.
• Sex of offspring is determined.
• Polarity is determined.
• Rapid cell divisions.
• Cell divisions without cell growth.
• Cleavage divisions form a small, solid ball of cells (morula).
• Rapid DNA replications and mitotic divisions occur.
• Cells get smaller in early cleavage with each division.
• Cleavage divisions form a hollow ball of cells surrounding a fluidfilled cavity.
• Room for germ layers is developed.
• Germ cell layers (ectoderm, endoderm, and mesoderm) are established. • Opening called a blastopore forms.
• Cells near the surface of the blastula reorganize and move to an interior location.
• Primitive digestive gut (archenteron) forms.
(b) Identify the developmental origin of TWO of the following tissues in vertebrates:
• central nervous system
• digestive system
• muscle
(2 points maximum)
Tissue
Central nervous system
Digestive system
Muscle
Identification of developmental origin (1 point per box)
• Ectoderm / outer germ layer
• Endoderm / inner germ layer (lining)
• Mesoderm / middle germ layer (other layers of digestive tract)
• Mesoderm / middle germ layer
© 2012 The College Board.
Visit the College Board on the Web: www.collegeboard.org
AP® BIOLOGY
2012 SCORING