Following statements are regarding to the Surveillance mechanisms in cell cycle regulation.

A. Surveillance mechanisms known as checkpoint pathways establish dependencies among cell cycle events and ensure that the next cell cycle event does not occur prior to the completion of a preceding event.

B. In response to DNA damage, two related protein kinases, ATM and ATR, are recruited to the site of the damage, where they activate signaling pathways that lead to cell cycle arrest, repair, and under some circumstances, apoptosis.

C. The spindle assembly checkpoint pathway, which causes initiation of anaphase, utilizes Mad2 and other proteins to regulate APC/CCdc20, which targets securing and mitotic cyclins for ubiquitinylation.

D. The spindle position checkpoint pathway prevents mitotic CDK inactivation when the spindle is mispositioned. In this pathway, localized activators and inhibitors and a sensor that shuttles between them allow cells to sense spindle position.

Which of the following statement is incorrect?

#Question id: 4965

#SCPH28 | Zoology

What is thought to be the correct sequence of these events, from earliest to most recent, in the evolution of life on Earth?

1.  origin of mitochondria

2.  origin of multicellular eukaryotes

3.  origin of chloroplasts

4.  origin of cyanobacteria

5.  origin of fungal-plant symbioses

#Question id: 4966

#SCPH06 I Botany

If it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.2-billion-year-old stromatolites, then within such microfossils, one should be surprised to observe evidence of:

I. double-stranded DNA

II. a nuclear envelope

III. a nucleoid

IV. a nucleolus

V. nucleic acids

#Question id: 4966

#SCPH28 | Zoology

If it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.2-billion-year-old stromatolites, then within such microfossils, one should be surprised to observe evidence of:

I. double-stranded DNA

II. a nuclear envelope

III. a nucleoid

IV. a nucleolus

V. nucleic acids

#Question id: 4967

#SCPH06 I Botany

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

#Question id: 4967

#SCPH28 | Zoology

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

#Question id: 4968

#SCPH06 I Botany

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