Multicellular organisms use cell division, mitosis, for growth and the maintenance and repair of cells and tissues. There are few cells in the body that do not undergo mitosis: most somatic cells divide regularly, some more than others. Single-celled organisms may use cell division as their method of reproduction. Regardless of the reason for mitosis, the process ensures genetic continuity. Consider the model of the cell cycle. Explain the purpose of the areas labelled checkpoint in the cycle? All BUT ONE could apply.

Neelaredoxin is a 15-kda protein that is a gene product common in anaerobic prokaryotes. it has superoxide-scavenging activity, and it is constitutively expressed. in addition, its expression is not further induced during its exposure to o2 or h2o2 (silva, g., et al. 2001. j. bacteriol. 183: 4413–4420). which of the following statements best describes neelaredoxin synthesis? a-neelaredoxin is produced at all times; levels are constant even when exposed to o2 or h2o2.b-neelaredoxin is produced at all times; exposure to o2 or h2o2 increases expression.c-neelaredoxin is produced at all times; exposure to o2 or h2o2 decreases or prevents expression.d-neelaredoxin is only produced when there is exposure to o2 or h2o2.

Apaleontologist finds a plant fossil that shows that the plant had seeds. what can the paleontologist conclude?

Which of the following is not a possible effectof increasimg carbon dioxide levels in the atmosphere ?