Species-specific sperm attraction has been documented in numerous species. In echinoderms, sperm are attracted toward eggs of their species by chemotaxis. Following statements are about chemoattraction-

A. In this process Sperm follows a gradient of a chemical secreted by the egg.

B. These oocytes control only the type of sperm they attract, but not the time at which they attract them.

C. Releasing the chemotactic factor only when the sea urchin egg has completed all of its meiotic divisions .

D. Releasing the chemotactic factor only when the sea urchin egg is in second metaphase of its meiotic division.

E. The mechanisms of chemotaxis differ among species and chemotactic molecules are different even in closely related species.

Which of the following statement are incorrect about this process?

#Question id: 4967

#Unit 9. Evolution & Diversity of Life Forms

Recent evidence indicates that the first major diversification of multicellular eukaryotes may have coincided in time with the

#Question id: 4968

#Unit 9. Evolution & Diversity of Life Forms

Which of these observations fails to support the endosymbiotic theory for the origin of eukaryotic cells?

#Question id: 4969

#Unit 9. Evolution & Diversity of Life Forms

The snowball Earth hypothesis provides a possible explanation for the

#Question id: 4970

#Unit 9. Evolution & Diversity of Life Forms

If two continental land masses converge and are united, then the collision should cause

#Question id: 4971

#Unit 9. Evolution & Diversity of Life Forms

On the basis of their morphologies, how might Linnaeus have classified the Hawaiian silverswords?

#Question id: 4972

#Unit 9. Evolution & Diversity of Life Forms

Fossils of Lystrosaurus, a dicynodont therapsid, are most common in parts of modern-day South America, South Africa, Madagascar, India, South Australia, and Antarctica. It apparently lived in arid regions, and was mostly herbivorous. It originated during the mid-Permian period, survived the Permian extinction, and dwindled by the late Triassic, though there is evidence of a relict population in Australia during the Cretaceous. The dicynodonts had two large tusks, extending down from their upper jaws; the tusks were not used for food gathering, and in some species were limited to males. Food was gathered using an otherwise toothless beak. Judging from the fossil record, these pig-sized organisms were the most common mammal-like reptiles of the Permian. Anatomically, what was true of Lystrosaurus?