Ultrastructural studies have led to the characterization of two distinctive cytological

pathways of PCD in plants;

I) Vacuolar-type PCD

II) Hypersensitive response-type (HR-type) PCD

a) cytosol and all its organelles, including the plasma membrane, are completely brokendown

b) The vacuole loses water, resulting in marked cell shrinkage, contraction from the cell wall,

and nuclear DNA degradation

c) PCD occurs in leaves in response to microbial attack

d) cell wall is either partially or completely digested as well, as in endosperm tissue

e) Continued water loss from the cytosol leads to the breakdown of the plasma membrane

and the release of residual cellular contents into the apoplast

Given characterization of PCD pathway match with its type PCD?

#Question id: 5649

#Unit 5. Developmental Biology

From earliest to latest, the overall sequence of early development proceeds in which of the following sequences?

#Question id: 5648

#Unit 5. Developmental Biology

Use the following information to answer the question. In order to test how sea urchin sperm bind to eggs, scientists isolated the egg receptor protein that binds to the sperm acrosomal protein called bindin. Plastic beads were coated with egg receptor for bindin (ERB1) from eggs of the sea urchin Strongylocentrotus purpuratus, and then the beads mixed with sperm from S. purpuratus or from the related species, S. franciscanus. The researchers counted how many sperm were bound to each bead. The results are shown in the graph below. Treatments:

A: S. purpuratus sperm mixed with S. purpuratus ERB1 beads

B: S. purpuratus sperm mixed with beads containing no ERB1 protein

C: S. franciscanus sperm mixed with S. purpuratus ERB1 beads

D: S. franciscanus sperm mixed with beads containing no ERB1 protein

 What is a broader implication from the observations of the experiment?

#Question id: 5035

#Unit 5. Developmental Biology

 A fertilized egg is called a:

#Question id: 5036

#Unit 5. Developmental Biology

 The experiments of Spemann and Mangold first defined what feature of amphibian embryos?

#Question id: 5037

#Unit 5. Developmental Biology

Genes control development by:

#Question id: 5038

#Unit 5. Developmental Biology

The folding of sheets of cells, the migration of cells, and cell death are all mechanisms of