When Is a Species Is Considered to Be Critically Endangered

question 19

Multiple Choice

When is a species is considered to be critically endangered?

• A) If there is a 50% probability of extinction in 5 years or 2 generations, whichever is longer
• B) If there is a 50% probability of extinction in 10 years or 3 generations, whichever is longer
• C) If there is a 20% probability of extinction in 20 years or 3 generations, whichever is longer
• D) If there is a 20% probability of extinction in 20 years or 5 generations, whichever is longer

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Definitions:

Blastula

An early stage of embryonic development in animals, characterized by a spherical layer of cells (the blastoderm) surrounding a fluid-filled cavity (the blastocoel).

Embryonic Development

The process by which an embryo forms and develops, involving cell division, migration, and differentiation to establish the basic plan of an organism.

Neural Crest

A population of cells in vertebrate embryos that arises from the embryonic ectoderm and migrates to form diverse cell types, including melanocytes, craniofacial cartilage, and neurons.

Organogenesis

The phase during embryonic development where organs form from the three germ layers, setting the foundation for functional body systems.